Download Integumentary system

ORGAN systemS
INTEGUMENTARY SYSTEM
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Skin
• largest organ in the body: 12-15% of body weight,
with a surface area of 1-2 meters
• continuous with, but structurally distinct from
mucous membranes that line the mouth, anus,
urethra, and vagina
• distinct layers occur in the skin: the dermis and
epidermis
• basic cell type of the epidermis is the keratinocyte,
which contain keratin, a fibrous protein
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Skin
• basal cells are the innermost layer of the
epidermis
• melanocytes produce the pigment melanin,
and are also in the inner layer of the
epidermis
• dermis is a connective tissue layer and
contains nerve endings, sensory receptors,
capillaries and elastic fibers
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Multiple Roles
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protection
temperature regulation
sensory reception
biochemical synthesis
absorption
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Follicles and Glands
• Hair follicles are lined with cells that synthesize the
proteins that form hair
• A sebaceous gland (that secretes the oily coating of
the hair shaft), capillary bed, nerve ending, and
small muscle are associated with each hair follicle
• If the sebaceous glands becomes plugged and
infected, it becomes a skin blemish (or pimple)
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Follicles and Glands
• sweat glands open to the surface through the skin pores
• Eccrine glands
• a type of sweat gland linked to the sympathetic nervous
system
• occur all over the body
• Apocrine glands
• larger and occur in the armpits and groin areas
• produce a solution that bacteria act upon to produce
"body odor"
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Hair and Nails
• hair, scales, feathers, claws, horns, and nails are animal
structures derived from skin
• hair shaft extends above the skin surface, the hair root extends
from the surface to the base or hair bulb
• Genetics controls several features of hair:
• baldness, color, texture
• Nails consist of highly keratinized, modified epidermal cells
• arises from the nail bed, which is thickened to form a lunula (or
little moon)
• Cells forming the nail bed are linked together to form the nail
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Skin and Homeostasis
• Skin functions in homeostasis include protection, regulation of
body temperature, sensory reception, water balance, synthesis
of vitamins and hormones, and absorption of materials
• The skin's primary functions are to serve as a barrier to the
entry of microbes and viruses, and to prevent water and
extracellular fluid loss
• Acidic secretions from skin glands also retard the growth of
fungi
• Melanocytes form a second barrier: protection from the
damaging effects of ultraviolet radiation
• When a microbe penetrates the skin (or when the skin is
breached by a cut) the inflammatory response occurs
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Skin and Homeostasis
• Heat and cold receptors are located in the skin
• When the body temperature rises, the hypothalamus sends a
nerve signal to the sweat-producing skin glands, causing them
to release about 1-2 liters of water per hour, cooling the body
• The hypothalamus also causes dilation of the blood vessels of
the skin, allowing more blood to flow into those areas, causing
heat to be convected away from the skin surface
• When body temperature falls, the sweat glands constrict and
sweat production decreases
• If the body temperature continues to fall, the body will engage
in thermiogenesis, or heat generation, by raising the body's
metabolic rate and by shivering
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Skin and Homeostasis
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Water loss occurs in the skin by two routes:
evaporation
sweating
In hot weather up to 4 liters per hour can be lost by
these mechanisms
• Skin damaged by burns is less effective at preventing
fluid loss, often resulting in a possibly life threatening
problem if not treated
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• Homeostasis
• (from Greek: ὅμος, homos, "equal"; and ιστημι,
histemi, "to stand" lit. "to stand equally"; coined by
Walter Bradford Cannon)
• the property of either an open system or a closed
system, especially a living organism, that regulates
its internal environment so as to maintain a stable,
constant condition
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Skin and Sensory Reception
• Sensory receptors in the skin include those for pain,
pressure (touch), and temperature
• Deeper within the skin are Meissner's corpuscles,
which are especially common in the tips of the
fingers and lips, and are very sensitive to touch
• Pacinian corpuscles respond to pressure
• Temperature receptors: more cold ones than hot
ones
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Skin and Synthesis
• Skin cells synthesize melanin and carotenes, which
give the skin its color
• The skin also assists in the synthesis of vitamin D
• Children lacking sufficient vitamin D develop bone
abnormalities known as rickets
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Skin Is Selectively Permeable
• The skin is selectively soluble to fat-soluble substances
such as vitamins A, D, E, and K, as well as steroid
hormones such as estrogen
• substances enter the bloodstream through the capillary
networks in the skin
• Patches have been used to deliver a number of
therapeutic drugs
• include estrogen, scopolamine (motion sickness),
nitroglycerin (heart problems), and nicotine (for those
trying to quit smoking)
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MUSCULAR SYSTEM
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Muscles
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the "machines" of the body
help move food from one organ to another
carry out our physical movement
three different kinds of muscles in our body:
cardiac
smooth
skeletal
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Cardiac
• involuntary and found only in the heart
• controlled by the medulla oblongata, which controls
involuntary action throughout the body
• single-nucleated long strip heart cells, one of the key
factors in determining which of the three classes any
particular muscle is
• located at the walls of the heart
• main function: to propel blood into circulation
• Contraction: impulse sent from the medulla oblongata
to the SA nerve located at the right atrium (linkcirculatory)
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Smooth
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involuntary
make up the internal organs
generally spherical
each contains one nucleus
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Skeletal
• the only voluntary muscles of your body, and make
up the muscular system
• the muscles that move the bones and show external
movement
• contain multiple nuclei because of its large size,
being in strips up to a couple of feet long
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Flexors
• Flexors bend at the joint, decreasing the interior
angle of the joint
• humorous, or bicep, is a flexor of the elbow joint,
bringing the fist towards the shoulder
• If a flexor appears in either the wrist or ankle joints,
it becomes a plantar flexor
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Extensors
• unbend at the joint, increasing the interior angle
• humorous, or tricep, is an extensor of the elbow
joint, taking the fist farther away from the shoulder
• if an extensor is found in the wrist or ankle joints, it
becomes a dorsiflexor
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Abductors
take away from the body, like lifting the arm to the side
Abd- means to take away, like abduct and abdicate
Spreading out of fingers uses abductors
Adductors
move toward the body
Add- means to increase or include
By lowing an arm raised to the side, or moving your
fingers together while keeping them straight, your
muscles are adducting
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Tendons and Ligaments
• muscles alone can't do the job
• at every joint, tendons and ligaments also help
out
• muscles are connected to tendons, when
themselves are connected to the bones
• when the muscles contract, they pull on the
tendons, which in turn pull on the muscles,
and that causes movement
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What if there are no ligaments…
• movement wouldn't be too useful because it would
not be directed movement
• bones would slide by each other
• Ligaments are what hold the bones together
• Ligaments connect at the ends of muscles and keep
them from slipping and sliding, and force them to
bend
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Major Skeletal Muscles
• Facial
• Orbicularis oculi-are the two muscles that move
the eye are
• Frontalis- and Temporalis- are the two muscles
which move the forehead and sides of your head
• Zygomaticus- and Masseter- are the two muscle
that work in conjunction to move the jaw and
upper lip area
• Orbicularis oris- is the muscle which moves your
lips
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Neck
• almost entirely moved by the sternohyoid and
sternocleidomastoid
• allow the neck to move your head left and right
• control how far you can move your head left and
right
• what allows your head to move up and down is the
trapezius
• it extend down to the shoulder and thorax area
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Major Skeletal Muscles
• Shoulder
• trapezius, deltoid, infraspinatus, teres major, and the rhomboid
major
• ball and socket joint shoulder muscles allow your arm to throw a
softball, pick things over your head, and give your arms a good stretch
earlyinthe morning
• Arm
• bicep brachii is the muscle that allows you to bring your forearm close
to your body and form a huge ball of muscle which catches a lot of
attentionamongstweightlifters
• tricep brachii and brachialis are the two other muscles located in the
arm region
– allowapersontodopush-ups
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Forearm
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help control a part of the arm
Berachiodialis major
palmaris longus
Flexor carpi radialis
– a good example of how muscles are named by their function
and location
– named carpi because of the bones that it helps move, the
carples
– name of radialis is made by the bone that its attached to, the
radius
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• Thorax
• set of muscles which carrying your head, arms, stomach, and
any other upper body areas
• trapezius and latissimus dorsi
• muscles can be damaged easily if one dose not stretch before
exercise, or lifts a heave load
• Abdomen
• allows you to bend down and move your waist from side to side
• internal oblique and external oblique are the muscles that
move your body from left to right
• transversus abdominus and rectus abdominus along with the
trapezius and latissimus dorsi allow you to bend down and
grab objects
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Hip
gluteusmedius-and gluteusmaximus
the gluteusset ofmusclesare used onlytosit downon
Pelvis/Thigh
pelvisareais usually referredtoas the upper partof the leg
pectineus and illiopsoas which help support the upper leg area are
knownas pelvicmuscles.
thighmuscles are veryrich incapillariesand supportthe wholebody
upper thigh muscles are abductor longus, gracilis, sartorius, and
tensorfasciaelatea
lowerthighmuscles are rectusfemoral, vastuslateralisandmedialis
the hamstrings-soundmuscles help you run, jump, and walk
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Leg
• gastrocnemius, soleus, porenius longus, and tibialis
anterior absorb the impact when one walks and
runs
• give better coordination for moving
• trust the body forward while the leg region
coordinates where it should be thrusted and where
it should stand
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SKELETAL SYSTEM
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What is the Skeletal System?
• all of the bones in the body and the tissues
such as tendons, ligaments and cartilage that
connect them
• teeth are also considered part of the skeletal
system but they are not counted as bones
• teeth are made of enamel and dentin
• enamel is the strongest substance in your
body
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How does the Skeletal System help us?
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Support
provide support for the body
Protection
helps protect your internal organs and fragile body tissues
cranium (skull) protects brain and eyes
ribs protect heart and lungs
vertebrae (spine, backbones) protect spinal cord
Movement
provide the structure for muscles to attach so that our
bodies are able to move
• tendons are tough inelastic bands that hold attach muscle
to bone
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Who has more bones a baby or an
adult?
• babies have more than adults
• at birth, babies have about 300 bones
• as babies grow older, small bones join together to
make big ones
• adults end up with about 206 bones
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Are bones alive?
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absolutely
old bones are dead, dry and brittle
in the body, bones are very much alive
have their own nerves and blood vessels
do various jobs, such as storing body minerals like
calcium
• bones are made of a mix of hard stuff that gives them
strength and tons of living cells which help them grow
and repair themselves
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What is a bone made of?
• an outer layer of hard or compact bone, which is
very strong, dense and tough
• an inner layer of spongy bone, which is like
honeycomb, lighter and slightly flexible
• in the middle of some bones is jelly-like bone
marrow, where new cells are constantly being
produced for the blood
• calcium is an important mineral that bone cells
need to stay strong so keep drinking that low-fat
milk
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• How do bones break and heal?
• bones are tough and usually don't break even
when we have some pretty bad falls
• bones will bend a little, but if you fall the wrong
way from some playground equipment or maybe
your bike or skateboard you can break a bone
• doctors call a broken bone a fracture
• when a bone is broken your bone will produce
lots of new cells to rebuild the bone
• these cells cover both ends of the broken part of
the bone and close up the break
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• How do I keep my bones healthy?
• walking, jogging, running and other physical activities
are important in keeping your bones strong and healthy
• riding your bike, basketball, soccer, gymnastics, baseball,
dancing, skateboarding and other activities are all good
for your bones
• strengthen your skeleton by drinking milk and eating
other dairy products (low-fat cheese, frozen yogurt, ice
cream)
• all contain calcium, which helps bones harden and
become strong
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Joints
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three structural classifications of joints:
fibrous joint –
- joined by fibrous connective tissue
cartilaginous joint –
- joined by cartilage
synovial joint –
- not directly joined
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• Functional classification
• can also be classified functionally, by the degree
of mobility they allow:
• synarthrosis - permits little or no mobility
• fibrous joints (skull)
• amphiarthrosis - permits slight mobility
• cartilaginous joints (e.g. Vertebrae)
• diarthrosis - permits a variety of movements
• synovial joints (e.g. shoulder, hip, elbow, knee
etc.)
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• Biomechanical classification
• subdivided into simple and compound, depending
on the number of bones involved, and into
complex and combination joints:
• Simple Joint: 2 articulation surfaces (eg. shoulder
joint, hip joint)
• Compound Joint: 3 or more articulation surfaces
(e.g.. radiocarpal joint)
• Complex Joint: 2 or more articulation surfaces
and an articular disc or meniscus (eg. knee joint)
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Anatomical Classification
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articulations of hand
elbow joints
wrist joints
axillary articulations
sternoclavicular joints
vertebral articulations
• temporomandibular
joints
• sacroiliac joints
• hip joints
• knee joints
• articulations of foot
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Gait
• manner of walking
• any part of the foot or hand comes in
contact with the ground when the
animal walks
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Plantigrade
• entire sole of the foot touches the
ground as in man, ape, bears, racoons
• the most primitive type
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Digitigrade
• digits which are provided with pads
touch the ground and the rest of the
foot is elevated
• members of the cat family
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Unguligrade
• tips of the digits touch the ground and
are specialized hoofs
• cows, carabaos, pigs, goats, etc.
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Gait
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Synarthroses or Immovable Joints
• Bones are connected by fibrous tissue or
cartilage like sutures which are the lines of
junction of the skull bones
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Amphiarthroses or Slightly Movable
Joints
• Symphysis – a joint where two long bony
surfaces are connected by a broad, flat disc of
fibrocartilage
• Synchondrosis – a temporary form of joint
made of cartilage which in the adult is
changed to bone as found between the
epiphysis and bodies of long bones
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Diarthroses or Freely Movable Joints
• Gliding – permit gliding movement only
– Joints between carpal bones of the wrist
– Between the tarsal bones of the ankle
– Between the articular processes of the vertebrae
• Hinge – allow angular movement in one
direction
– Between humerus and ulna
– In the knee and ankle joints, phalanges
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• Condyloid – angular movement in two directions
– Wrist joint
• Saddle – has articular surfaces which is concave in
one direction and convex in another
– Trapezium bone of the carpus
• Pivot – rotary movement in one axis
– Atlas and axis
– Radius and ulna
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Ball and Socket
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Angular movement in all directions
Head of the femur in the acetabulum
Head of the humerus in the glenoid cavity
Shoulder joint
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Reproductive
System
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Introduction
• reproductive system is a system of organs within an
organism which work together for the purpose of
reproduction
• fluids, hormones, and pheromones are important
accessories
• sexes of differentiated species
• differences allow for a combination of genetic
material between two individuals
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Parts
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the external genitalia (penis and vulva)
the gamete producing gonads (testicles and ovaries)
communicable sexually transmitted diseases
vertebrate animals have generally similar
reproductive systems consisting of gonads, ducts,
and openings
• diversity of physical adaptations and reproductive
strategies in every group of vertebrates
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Female Reproductive System
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Male Reproductive System
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Human Male
Genitalia
1. Testicles
2. Epididymis
3. Corpus cavernosa
4. Foreskin
5. Frenulum
6. Urethral opening
7. Glans penis
8. Corpus
spongiosum
9. Penis
10. Scrotum
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Female
Genitalia
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Pubic hair (shaved)
Clitoral hood
Clitoris
Labia majora
Labia minora
(enclosing the
Vaginal Opening)
6. Perineum
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Diseases
• 1) genetic or congenital abnormalities
• 2) cancers
• 3) infections which are often sexually transmitted
diseases
• 4) functional problems cause by environmental
factors, physical damage, psychological issues,
autoimmune disorders, or other causes
– sexual dysfunction
– infertility
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Examples of congenial abnormalities
• Kallmann syndrome - Genetic disorder causing
decreased functioning of the sex hormone-producing
glands caused by a deficiency of a hormone.
• Cryptorchidism - Absence of one or both testes from
the scrotum.
• Androgen insensitivity syndrome - A genetic disorder
causing people who are genetically male (i.e. XY
chromosome pair) to develop sexually as a female due
to an inability to utilize androgen.
• Intersexuality - A person who has genitalia or/and other
sexual traits which are not clearly male or female.
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Cancer
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Prostate cancer - Cancer of the prostate gland
Breast cancer - Cancer of the mammary gland
Ovarian cancer - Cancer of the ovary
Penile cancer - Cancer of penis
Uterine cancer - Cancer of the uterus
Testicular cancer - Cancer of the testicals
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Infections
• HIV - Infection by the retrovirus known as human
immunodeficiency virus.
• Genital warts - Sexually transmitted infection caused by
some sub-types of human papillomavirus (HPV).
• Herpes simplex - Sexually transmitted infection caused
by a virus called herpes simplex virus (HSV) type 2
• Gonorrhea - Common sexually transmitted disease
caused by the Gram-negative bacterium Neisseria
gonorrheae
• Yeast infection - Infection of the vagina by any species
of the fungus genus Candida.
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Infections
• Pelvic inflammatory disease - Painful infection of
the female uterus, fallopian tubes, and/or ovaries
with associated scar formation and adhesions to
nearby tissues and organs.
• Syphilis - Sexually transmitted infection caused by
the bacterium Treponema pallidum.
• Pubic lice - Infection of the pubic hair by crab lice,
Phthirius pubis.
• Trichomoniasis - Sexually transmitted infection by
the single-celled protozoan parasite Trichomonas
vaginalis.
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Functional Problems
• Impotence - The inability of a male to produce or maintain
an erection.
• Hypogonadism - A lack of function of the gonads, in regards
to either hormones or gamete production.
• Ectopic pregnancy - When a fertilized ovum is implanted in
any tissue other than the uterine wall.
• Inhibited sexual desire - A low level of sexual desire and
interest.
• Female sexual arousal disorder - A condition of decreased,
insufficient, or absent lubrication in females during sexual
activity
• Premature ejaculation - A lack of voluntary control over
ejaculation.
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Mammals
• most mammalian males have a penis which is
stored internally until erect, and most have a penis
bone or baculum
• have descended and undescended (elephant)
testicles found within a scrotum and ventral body
wall respectively
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Mammals
• marsupials have two vaginae and two prolonged penis
• - develop their offspring in an external pouch
containing teats to which their newborn young attach
themselves for post uterine development
• - have a unique prepenial scrotum
• uterus and vagina are unique to mammals with no
homologue in birds, reptiles, amphibians, or fish
• - cloaca is a shared exit-hole for gametes, urine, and
feces
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Mammals
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monotremes (i.e. platypus and echidnas)
- a group of egg-laying mammals
- lack a uterus and vagina
- have a reproductive system resembling
that of a reptile
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Reptiles
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almost all sexually dimorphic
exhibit internal fertilization through the cloaca
(some) lay eggs
(others) are viviparous (animals that deliver live young)
reproductive organs are found within the cloaca
(most male) have retracted or inverted copulatory
organs and stored inside the body
• in turtles and crocodilians, the male has a single
median penis-like organ, while male snakes and
lizards each possess a pair of penis-like organs
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Amphibians
• (most) exhibit external fertilization of eggs,
within the water
• (some) caecilians have internal fertilization
• all have paired, internal gonads, connected by
ducts to the cloaca
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Fish
• (most) oviparous and exhibit external fertilization
• females use their cloaca to release a large quantities
their gametes, called spawn, into the water and one
or more males release "milt", a white fluid
containing many sperm over the unfertilized eggs
• other species of fish are oviparous and have internal
fertilization aided by pelvic or anal fins that are
modified into an intromittent organ analogous to
the human penis
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Fish
• a small portion of fish species are either
viviparous or ovoviviparous, and are
collectively known as livebearers
• fish gonads are typically pairs of either ovaries
or testes
• most fish are sexually dimorphic but some
species are hermaphroditic or unisexual
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Invertebrates
• invertebrates have an extremely diverse array
of reproductive systems, the only
commonality may be that they all lay eggs
• aside from cephalopods, and arthropods,
nearly all other invertebrates are
hermaphroditic and exhibit external
fertilization
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http://www.infovisual.info/03/038_en.html
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Parts and Functions
• Nervous system: set of nerves, ganglions and nervous centers that
receivesensorysignal.
• Commandsand coordinatesvitalfunctions.
• Brachialplexus:networkofnervesof the arm.
• Intercostalnerve: cordconductingnerveimpulsesbetweenthe ribs.
• Radial nerve: cord conducting nerve impulses in the area of the
radius.
• Median nerve: main cord conducting nerve impulses in the upper
limb.
• Ulnar nerve: cord conducting nerve impulses in the area of the
elbow.
• Lumbarplexus:networkofnervesof the lowerback.
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Parts and Functions
• Sciatic nerve: cord conducting nerve impulses in the area
of the thigh and lower leg.
• Common peroneal nerve: cord conducting nerve impulses
along the inside of the lower leg.
• Superficial peroneal nerve: cord conducting nerve
impulses of the muscles and skin of the leg.
• Digital nerve: cord conducting nerve impulses of the
fingers.
• Sacral plexus: network of nerves of the sacrum.
• Spinal cord: substance belonging to the nervous system,
found
in
the
holes
of
the
vertebrae.
Cerebellum: nervous centre situated under the brain.
• Cerebrum: seat of the mental capacities.
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Vertebrates: Worms
• Planaria, a type of flatworm, have dual nerve cords
running along the length of the body and merging at the
tail and the mouth
• nerve cords are connected by transverse nerves like the
rungs of a ladder
• transverse nerves help coordinate the two sides of the
animal
• Two large ganglia at the head end function similar to a
simple brain
• Photoreceptors provide sensory information on light
and dark
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Caenorhabditis elegans
• The nervous system has been mapped out to the
cellular level
• Every neuron and its cellular lineage and most, if not all,
of the neural connections are known
• the nervous system is sexually dimorphic
• the nervous systems of the two sexes, males and
hermaphrodites, have different numbers of neurons and
groups of neurons that perform sex-specific functions
• males have exactly 383 neurons, while hermaphrodites
have exactly 302 neurons
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Arthropoda
• have a nervous system made up of a series of
ganglia
• connected by a ventral nerve cord made up of two
parallel connectives running along the length of the
belly
• each body segment has one ganglion on each side
• though some ganglia are fused to form the brain
and other large ganglia
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Arthropoda
• head segment contains the brain, also known as the
supraesophageal ganglion
• In the insect nervous system, the brain is anatomically divided
into the protocerebrum, deutocerebrum, and tritocerebrum
• behind the brain is the subesophageal ganglion, which is
composed of three pairs of fused ganglia
• controls the mouthparts, the salivary glands and certain
muscles
• have well-developed sensory organs, including compound eyes
for vision and antennae for olfaction and pheromone sensation
• sensory information from these organs is processed by the
brain
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Circulatory System
• an organ system that moves nutrients, gases, and wastes to and
from cells, helps fight diseases, and helps stabilize body
temperature and pH to maintain homeostasis
• as a blood distribution network
• composed of the cardiovascular system, which distributes
blood, and the lymphatic system, which distributes lymph
• humans and other vertebrates, have a closed cardiovascular
system (meaning that the blood never leaves the network of
arteries, veins and capillaries), some invertebrate groups have
an open cardiovascular system
• most primitive animal lack circulatory systems
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Circulatory System
• main components of the human circulatory system are the heart, the
blood,andthe bloodvessels
• includes:the pulmonarycirculation
• a "loop"throughthe lungs wherebloodisoxygenated
• systemiccirculation
• a "loop"throughthe restof the bodyto provideoxygenatedblood
• average adult contains roughly 4.7 to 5.7 liters of blood, which consists
ofplasma,red bloodcells, whitebloodcells,and platelets
• 2 types of fluids move through the circulatory system: blood and
lymph
• blood,heart,and bloodvesselsform the cardiovascularsystem
• lymph, lymph nodes,and lymph vesselsformthe lymphaticsystem
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CS of other Vertebrates
• closed, just as in humans
• In fish, the system has only one circuit, with the
blood being pumped through the capillaries of the
gills and on to the capillaries of the body tissues
• known as single cycle circulation
• heart of fish is only a single pump (consisting of two
chambers)
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Amphibians and Reptiles
• a double circulatory system
• amphibians have a three-chambered heart
• In reptiles, the ventricular septum of the heart is
incomplete and the pulmonary artery is equipped with a
sphincter muscle
• allows a second possible route of blood flow
• divert blood flow through the incomplete ventricular
septum into the left ventricle and out through the aorta
• the blood flows from the capillaries to the heart and
back to the capillaries instead of to the lungs
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Other Vertebrates
• birds and mammals show complete
separation of the heart into two pumps, for a
total of four heart chambers
• the four-chambered heart of birds evolved
independently from that of mamma
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Digestive System
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Digestive System
• Almost all animals have a tube-type digestive system
in which food enters the mouth, passes through a
long tube, and exits as feces (poop) through the
anus
• The smooth muscle in the walls of the tube-shaped
digestive organs rhythmically and efficiently moves
the food through the system, where it is broken
down into tiny absorbable atoms and molecules
100
Digestive System
• during the process of absorption, nutrients
from the food (including carbohydrates,
proteins, fats, vitamins, and minerals) pass
through channels in the intestinal wall and
into the bloodstream
• blood works to distribute these nutrients to
the rest of the body
• waste parts of food that the body can't use
are passed out of the body as feces
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How Digestion Works
• digestive system is made up of the alimentary canal
(also called the digestive tract) and the other
abdominal organs that play a part in digestion, such
as the liver and pancreas
• the long tube of organs — including the esophagus,
stomach, and intestines — that runs from the
mouth to the anus
• adult's digestive tract is about 30 feet (about 9
meters) long
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Digestion begins in the…
• mouth beforefoodreaches the stomach
• salivary glands, which are located under the tongue and near the
lowerjaw,beginproducingsaliva
• flow of saliva is set in motion by a brain reflex that's triggered when
we sense foodor thinkabouteating
• in response to sensory stimulation, the brain sends impulses through
the nerves that control the salivary glands, telling them to prepare for
a meal
• as the teeth tear and chop the food, saliva moistens it for easy
swallowing
• a digestive enzyme called amylase, which is found in saliva, starts to
break down some of the carbohydrates (starches and sugars) in the
foodevenbeforeit leavesthe mouth
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• swallowing, which is accomplished by muscle movements in
the tongue and mouth, moves the food into the throat, or
pharynx
• the pharynx, a passageway for food and air, is about 5 inches
(12.7 centimeters) long
• a flexible flap of tissue called the epiglottis reflexively closes over
the windpipe when we swallow to prevent choking
• from the throat, food travels down a muscular tube in the chest
called the esophagus
• waves of muscle contractions called peristalsis force food down
through the esophagus to the stomach
• a person normally isn't aware of the movements of the
esophagus, stomach, and intestine that take place as food
passes through the digestive tract
104
• At the end of the esophagus, a muscular ring or valve called a
sphincter allows food to enter the stomach and then squeezes shut
tokeep foodor fluid from flowingback up intothe esophagus
• The stomach muscles churn and mix the food with acids and
enzymes, breakingit intomuch smaller,digestiblepieces
• An acidic environment is needed for the digestion that takes place in
the stomach
• Glands in the stomach lining produce about 3 quarts (2.8 liters) of
these digestivejuiceseach day.
• Most substances in the food we eat need further digestion and must
travelintothe intestinebeforebeing absorbed
• When it's empty, an adult's stomach has a volume of one fifth of a
cup (1.6 fluid ounces), but it can expand to hold more than 8 cups (64
fluid ounces)of foodaftera largemeal.
105
• By the time food is ready to leave the stomach, it
has been processed into a thick liquid called
chyme
• A walnut-sized muscular valve at the outlet of the
stomach called the pylorus keeps chyme in the
stomach until it reaches the right consistency to
pass into the small intestine
• Chyme is then squirted down into the small
intestine, where digestion of food continues so
the body can absorb the nutrients into the
bloodstream
106
Parts and Functions
Lymphatic System
What is a lymphatic system?
• a network of conduits that carry a clear fluid called lymph
• includes the lymphoid tissue and lymphatic vessels through
which the lymph travels in a one-way system in which
lymph flows only toward the heart
• lymphoid tissue is found in the lymph nodes, and in the
lymphoid follicles associated with the digestive system such
as the tonsils
• includes all the structures dedicated to the circulation and
production of lymphocytes, which includes the spleen,
thymus, bone marrow and the lymphoid tissue associated
with the digestive system
• described independently by Olaus Rudbeck and Thomas
Bartholin
Five Interrelated Functions
• it is responsible for the removal of interstitial fluid from
tissues
• it absorbs and transports fatty acids and fats as chyle to the
circulatory system and to Nicklas cells
• it transports immune cells to and from the lymph nodes in to
the sheppardian part of the bone
• transports antigen-presenting cells (APCs), such as dendritic
cells, to the lymph nodes where an immune response is
stimulated
• carries lymphocytes from the efferent lymphatics exiting the
lymph nodes
Organization
• divided into the conducting system
• the lymphoid tissue
• conducting system carries the lymph and consists of tubular
vessels that include the lymph capillaries, the lymph vessels,
and the right and left thoracic ducts
• lymphoid tissue is involved in immune responses and
consists of lymphocytes and other white blood cells
• - regions of the lymphoid tissue that are densely packed with
lymphocytes are known as lymphoid follicles
Organization
• lymphoid tissue can either be
• structurally well organized as lymph nodes or
• may consist of loosely organized lymphoid
follicles known as the mucosa-associated
lymphoid tissue (MALT)
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Lymphoid Tissue
• concerned with immune functions in defending the
body against the infections and spread of tumors
• consists of connective tissue with various types of
white blood cells enmeshed in it, most numerous
being the lymphocytes
Lymphoid Tissue
• Primary (central) lymphoid tissues serve to
generate mature virgin lymphocytes from
immature progenitor cells
• thymus and the bone marrow constitute the
primary lymphoid tissues involved in the
production and early selection of lymphocytes
Secondary (peripheral) lymphoid
tissues
• provide a place where lymphocytes can talk to each
other
• - an environment for antigen focusing, where
lymphocytes can 'study' an antigen and sharpen up the
immune response by clonal expansion and affinity
maturation
• provide a home for lymphocytes, where they can be
available when they are needed
• provides the environment for the foreign or altered
native molecules (antigens) to interact with the
lymphocytes
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Tertiary lymphoid tissue
• contains few lymphocytes
• assumes an immune role only when
challenged with antigens that result in
inflammation
• achieves by importing the lymphocytes from
blood and lymph
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Lymph Node
• an organized collection of lymphoid tissue,
• located at intervals along the lymphatic system
• substance of a lymph node consists of lymphoid
follicles in the outer portion called the "cortex", which
contains the lymphoid follicles, and an inner portion
called "medulla", which is surrounded by the cortex on
all sides except for a portion known as the "hilum“
• arteries and veins supplying the lymph node with
blood enter and exit through the hilum.
• lymph follicles are a dense collection of lymphocytes,
the number, size and configuration of which change in
accordance with the functional state of the lymph node
Lymph nodes
• particularly numerous in the mediastinum in
the chest, neck, pelvis, axilla (armpit), inguinal
(groin) region and in association with the
blood vessels of the intestines
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Lymphatics
• based on that of blood vessels
• an inner lining of single flattened cells composed of a type
of epithelium is called endothelium, and the cells are called
endothelial cells
• mechanically transport fluid and since the basement
membrane on which it rests is discontinuous; it leaks easily
• next layer is that of smooth muscles that are arranged in a
circular fashion around the endothelium, which by
shortening (contracting) or relaxing alter the diameter
(caliber) of the lumen
• outermost layer is the adventitia that consists of fibrous
tissue
Lymphatics
• whole system consists of two types of
channels—the
initial
lymphatics,
the
prelymphatics or lymph capillaries that
specialize in collection of the lymph from the
ISF, and the larger lymph vessels that propel
the lymph forward
• not closed and has no central pump
• movement occurs despite low pressure due to
peristalsis, valves, and compression
Rhythmic Contraction
• may also help draw fluid into the smallest lymphatic
vessels, capillaries
• if tissue fluid builds up the tissue will swell; this is
called edema
• fluid is then transported to progressively larger
lymphatic vessels culminating in the right lymphatic
duct (for lymph from the right upper body) and the
thoracic duct (for the rest of the body)
Rhythmic Contraction
• both ducts drain into the circulatory system at
the right and left subclavian veins
• system collaborates with white blood cells in
lymph nodes to protect the body from being
infected by cancer cells, fungi, viruses or
bacteria
• known as a secondary circulatory system
Lymph Vessels
• lymph capillaries drain the lymph to larger contractile
lymphatics, which have valves as well as smooth muscle
walls
• as the collecting lymph vessel accumulates lymph from
more and more lymph capillaries in its course, it
becomes larger and is called the afferent lymph vessel as
it enters a lymph node.
• the functional unit of a lymph vessel is known as a
lymphangion, which is the segment between two valves
Disease of the Lymphatic System
• Lymphedema is the
swelling caused by the
accumulation of lymph
fluid
Stages of lymphedema
• Stage 1: Pressing the swollen limb leaves a pit
that takes a while to fill back in. Because there is
little fibrosis (hardening) it is often reversible.
Elevation reduces swelling.
• Stage 2: Pressure does not leave a pit. Elevation
does not help. If left untreated, the limb becomes
fibrotic.
• Stage 3: This stage of lymphedema is often called
elephantiasis. It is generally only in the legs after
lymphedema that has gone long untreated. While
treatment can help a little, it is not reversible.
Common causes of swollen lymph
nodes
• infections,
infectious
mononucleosis, and cancer
• In elephantiasis, infection of
the lymphatic vessels cause a
thickening of the skin and
enlargement of underlying
tissues, especially in the legs
and genitals
• commonly caused by a
parasitic disease known as
lymphatic filariasis
• Lymphangiosarcoma
is a malignant soft
tissue tumor (soft
tissue sarcoma)
• lymphangioma is a
benign
tumor
occurring frequently
in association with
Turner syndrome
• Lymphangioleiomyomatosis is a
benign tumor of the smooth
muscles of the lymphatics that
occurs in the lungs