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Human Physiology:
The Systems of the Body
By Mindy Chen
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The Human Body: Systems Menu
Nervous System
Immune System
Reproductive System
Circulatory System
Digestive System
Skeletal System
EXIT
Endocrine System
Muscular System
Excretory System
Integumentary System
Respiratory System
The Nervous System: Standards
Standards:
 b. Students know how the nervous system mediates
communication between different parts of the body and
the body’s interactions with the environment
 c. Students know how feedback loops in the nervous
and endocrine systems regulate conditions in the body
 d. Students know the functions of the nervous system
and the role of neurons in transmitting electrochemical
impulses
 e. Students know the roles of sensory neurons,
interneurons, and motor neurons in sensation, thought,
and response
MENU
The Nervous System: Introduction
This system is made up of:

nervous tissue
Brain
Spinal cord
Peripheral nerves
All other body systems may be present, but humans
would essentially be nothing except for a body if not
for the nervous system, which, by responding to
stimulus from both the outside and inside of the
body allows for proper, healthy function. The
nervous system processes this information to
help a person survive, either voluntarily (as in dayto-day actions) or involuntarily (as in constant
breathing, digestion, or heart function). It is also
essential for memory.
The Nervous System: Neurons
Neurons are…

Basic units of the nervous
system

Control functions and
movements of the body

Carry impulses (electrical signals
of the nervous system)
The 3 kinds of neurons
a neuron

Sensory neurons
Responsible for bringing impulses detected by sense organs to the
brain and spinal cord

Interneurons
Act as a “middle-man” by relaying impulses between sensory and
motor neurons

Motor neurons
Responsible for bringing impulses from the brain and spinal cord to
the various muscles and glands of the body
The Nervous System: Nerve Impulse
Once an (electrical) nerve
impulse is initiated, it travels all
the way in whatever direction it
is moving
How it basically works

Sodium ions (a positive
charge) change the
charges of neuron’s cell’s
membranes

The impulse is conveyed
along, the opposite charge
on the outside of the
membrane is turned
negative
Nerve impulses travel along neurons which are
connected in long pathways called nerves. If there
is damage, as shown in the neuron on the right
side, then an impulse cannot be delivered.
The Nervous System: Sectors of the System
This graphic demonstrates the parts of the
brain and the branches of the nervous system.
Central Nervous System

Made up of: brain, spinal cord

This is the main central system of the
nervous system and functions to deal
with and work with information
Peripheral Nervous System

Made up of: all nerves and related
cells (not including brain and spinal
cord)
Sensory division
 Conveys impulses to the
central nervous system from
the body’s sense organs
Motor division
 Conveys impulses to the
muscles or glands that are
sent from the central
nervous system
Autonomic Nervous system

Deals with the involuntary functions
and workings of the human body
The Circulatory System: Standards

MENU
Standards:
– a. Students know how the complementary activity of
major body systems provides cells with oxygen and
nutrients and removes toxic waste products such as
carbon dioxide
The Circulatory System:
Introduction

This system is made up of:
– Heart
– Blood Vessels
– Blood
Without the circulatory system
constantly working, one would soon
die. That is because all the cells in a
human body need the oxygen and
nutrients that the circulatory system
brings to them. Also, the cells
produce wastes including carbon
dioxide that can only be effectively
removed through the circulatory
system.
Blood is pumped through the blood
vessels by the heart to every reach of
the body’s cells.
The Circulatory System: The Heart

The Heart
– A hollow organ
– About the size of a person’s fist
– Contracts (or beats) to pump blood to all of
the various parts of the body via blood
vessels.
– Completely surrounded by pericardium which
is a sac of tissue that protects the heart
Diagram labeling the various areas of the
heart and the direction of blood flow.

How the Heart Beats (turn up the volume!)
– Also known as the pacemaker, the small group
of cardiac muscle cells (in the right atrium)
called the sinoatrial node set the entire heart’s
beating rhythm
– The heart pumps blood faster or more slowly
depending on the body’s needs for
oxygen/nutrients
An animation showing the direction
of blood flows through the heart
The Circulatory System: Blood Vessels



Arteries- thick walled, large, hollow blood vessels that carry oxygen-rich blood
(except for pulmonary arteries which carry oxygen-depleted blood from the heart to
the lungs)
Capillaries- tiny blood vessels in which the key workings of the circulatory system is
carried out; this is where cells exchange their waste products (including carbon
dioxide) for nutrients, and most importantly, oxygen
Veins- valves in these blood vessels help to prevent gravity from getting in the way
of conveying nutrient depleted blood back to the heart
The Circulatory System: Paths of Circulation
CLICK HERE to view animation on circulatory pathways as shown in image below

Pulmonary circulation (contact w/ respiration)
– Direction blood is pumped: from right side
of the heart to lungs
– At lungs, carbon dioxide is removed from
the blood and the oxygen is replenished

Systemic circulation
– Oxygenated blood (that is back from the
lungs) returns to the left side of the heart
and is pumped and released to the rest of
the body
– The bod’s cells take in the oxygenated and
nutrient filled blood while putting out their
carbon dioxide into the bloodstream
– This causes the blood to become oxygen
depleted eventually
– The oxygen depleted blood makes its
rounds back to the right side of the heart
for pulmonary circulation to begin again.
The Skeletal System:
Components

This system is made up of:
 Bones
 Other connective tissue such as:
 cartilage – strong and flexible
connective tissue
 ligament – very tough and strong
band of connective tissue that
attaches to bones to keep them
together
Femur, or thigh bone, as seen
in an ultrasound image
MENU
Click on the walking
skeleton above to view
another animation that
also realistically simulates
human movement
The Skeletal System: Function

Functions





Supports the body by
providing a sturdy
framework
Provides protection for vital
internal organs with, for
example, the rib bones
Allows for movement when
muscles attached to them as
a result of joints
Stores minerals
Produces red blood cells in
the marrow of the bones
Diagram of a human skeleton with
the names of the bones labeled
The Skeletal System: Bone Structure
Diagram of a bone.
Bones have a hard, yet semi-flexible surface and are a frame for the
human body. Inside the bone is a hollow region which contains bone
marrow, where red and most white blood cells and platelets are created.
The Skeletal System: Joints

Joints – site where bones
attach to each other

Types
 Immovable Joints –
(a.k.a. fixed
joints) – these don’t allow motion
 Example: joints of the skull
 Slightly Moveable Joints – allows for
some, but limited motion
 Example: joints of the spine
between the vertebrae
 Freely Moveable Joints – allows for
motion in one or even more ways
 Example: knee joint, shoulder/hip
joint
This is a labeled
diagram of a knee joint
(one example of a
freely movable joint
The Muscular System: Standards
Standards:
– h. Students know the cellular and molecular basis of
muscle contraction, including the roles of actin,
myosin, Ca+2, and ATP
MENU
The Muscular System: Introduction
This system consists of:
– Muscle tissue (of the three different kinds) all
throughout the body which total up to more than 40%
of the mass of an average human
Without the muscular
system, humans could
not move. The runner
in the slide background
could not run and much
less hold a starting
position. Though the
skeleton gives a
framework to human
bodies, muscles are
required to provide the
movement factor.
The Muscular System:
Muscle Tissue 1 – Skeletal Muscles
This image shows the front an back view
of a person in terms of skeletal muscles
Skeletal muscles, as
seen under microscope
These are usually found
attached to bones and carry
out the voluntary motions of a
human
Consists of long, striped,
striated (meaning the
alternating dark and light
bands one would see going
across the cell),
multinucleated cells – these
properties, especially the fact
that the cells are narrow and
lengthy have caused them to
also be called muscle fibers
The Muscular System:
Muscle Tissue 2 – Smooth Muscles
These usually carry out
actions that are involuntary
(uncontrollable by the
human’s will)
Examples of where these
are located: hollow
structures such as stomach,
intestines (both small and
large) and blood vessels
The cells that form smooth
muscles have: single
nucleus, no striations, and
can function without nerve
stimulation
These parts of the digestive system
shown are all examples of locations
where smooth muscles do their work
Smooth muscle, as
seen under microscope
The Muscular System:
Muscle Tissue 3 – Cardiac Muscles
Animation of a
pumping heartpowered by
cardiac
muscles
The only place you can find
these are in the heart
Cardiac muscle cells: have
striations, but only one
nucleus and only
occasionally two nuclei
Obviously the cells must be
run in an involuntary
manner so as to keep the
heart pumping and the
person alive
Cardiac muscles, as seen
under a microscope
The Muscular System: How Muscles Contract
Muscle Contraction
– How does a muscle fiber contract?
Simply put, the thin filaments called
actin slide across and over the
thicker filaments called myosin
ATP that can be made by either
cellular respiration or fermentation
on the part of cells, serves as the
fuel for powering muscle fiber
contraction
– From where does this contraction arise?
(What triggers it?)
Calcium ions (Ca+2) are stimulated
to be released in a muscle fiber by
the impulse resulting from a certain
neurotransmitter’s (called
acetylcholine) presence
These calcium ions affect certain
regulatory proteins that are
responsible for letting actin-myosin
interaction happen
– When does the muscle relax?
When acetylcholine is no longer
present, or an enzyme blocks the
passage of acetylcholine to the cell
The location of actin and myosin
is demonstrated above
Animation above shows how the actin
(the thinner lilac colored filaments) and
myosin (thicker pink colored filaments)
interact to contract and relax at the
minute level.
The Integumentary System:
Components
• This system is made up of:
–
–
–
–
Skin
Hair
Nails
Various glands
The surface of
the skin is
covered with
pores.
MENU
This is a crosssection of skin as
viewed under a
microscope.
Notice the hair and
the hair follicle.
The Integumentary System: The Skin
Skin (largest component of
integumentary system)
Layer of skin as viewed
under a microscope.
Evident are the layers of
skin: upper, lower, and the
layer of fat beneath them.
– Many Protective Functions
• Helps prevent infections, injuries
• Maintains body temperature- layer of fat
beneath the skin layers helps to insulate
the body
• Removes wastes from the body passed
out through the pores
• Protection against ultraviolet sun
radiation- significant amount of radiation
deflected
– Contains sensory receptors that can detect
sensations from the outside world (including
heat, cold, pain, pressure, etc.)
The Integumentary System: Layers of the Skin 1
Epidermis – the outermost, exposed layer of skin
– 2 layers of epidermis
– Inner layer- made up of living cells that
divide quickly and push the older cells
upwards
• The older cells’ organelles
disintegrate; they begin to produce
keratin, a tough fiber-like protein
– Outer layer- made up of the older cells
after they die (dead cells)
• Very flexible yet tough and waterresistant
• A new outer layer is exposed in the
time of once every four or five
weeks
– Does not contain blood vessels, so small scratch
or cut on the skin’s surface causes no bleeding
– Contains melanocytes, cells that produce dark
brown pigment called melanin responsible for
coloring people’s skin
The epidermis is the
uppermost layer of the skin
and is exposed to the
outside world.
The Integumentary System: Layers of the Skin - 2
Dermis- inner layer of skin underneath the
epidermis
– This layer contains…
- Collagen fibers
- Sense organs
- Blood vessels
- Smooth muscles
- Nerve endings
- Hair follicles
- Glands
– Different types glands in the dermis
– Sweat glands: perspiration to
cools body (sweat evaporation
removes heat)
– Sebaceous (oil) glands: makes
The dermis contains many
oily substance (sebum) that
glands, blood vessels, and
spreads out on the skin’s
other structures.
surface to help maintain the
epidermis’ (outer skin layer’s)
- Function of Blood Vessels - widen
pliable and water-resistant
to allow more conveyance of heat
qualities
from within the body in warm or hot
conditions and narrow to prevent
excessive heat loss on cold days
The Integumentary System:
Hair and Nails
• Hair and Nails (both formed by keratin)
– Hair
• Protects body in variety of ways including from sun’s UV (Ultraviolet)
rays, heat, cold, and dirt/dust
– Nails
• Protect the ends of people’s fingers and toes
On the left are
pictures of nails
which demonstrate
their distinct and
necessary location.
To the right is a
diagram of a hair
in its hair follicle
The Respiratory System: Standards

MENU
Standards:
 a. Students know how the complementary activity of major
body systems provides cells with oxygen and nutrients and
removes toxic waste products such as carbon dioxide
The Respiratory System:
Introduction

This system is made up of:






Nose
Pharynx
Larynx
Trachea
Bronchi
Lungs
What is the main purpose of human’s
having a respiratory system?
Basically, the respiratory system allows
humans to exchange carbon dioxide,
the waste product of many body
functions, for oxygen, which powers
many human processes.
The Respiratory System:
The Process of Breathing/Respiration - 1
CLICK HERE and
scroll down to view
an animation of how
the diaphragm works


The Upper Respiratory System
How a person breathes to take in air and exhales to get rid of
“used” air
 The chest cavity containing the lungs is completely sealed
up, so when the diaphragm, a long, flat muscle beneath the
cavity contracts (downward), like a vacuum, a person
immediately sucks in air into their lungs
 To exhale, the diaphragm relaxes (upward) and thereby
forces air out of the lungs
Let’s follow the journey of breathed air:

Upper Respiratory System
 1. enter through the nose
 2. passes through the pharynx (tube for both food and air)
 3. goes through pharynx where the vocal cords are located and
into the trachea toward the lungs

All along the way, measures are taken to ensure the cleanest
air reaches the lungs
 Air must be slightly heated, made moister, and screened
 Dust particles filtered out by small hairs
 Mucus produced to trap particles and make the air
moist
The Respiratory System:
The Process of Breathing/Respirations - 2

Let’s continue following the journey of
breathed air:
 4. the air flows down the trachea
 5. then it reaches the bronchi, two large
tube-like passageways, each of which
leads to one of the two lungs
 6. the air continues on into smaller and
smaller passageways called bronchioles
 7. the air reaches the alveoli, the millions
of minute and bunched together air sacs
(alveoli are air sacs which are seemingly
covered in nets of tiny capillaries
 8. at the alveoli, an exchange of gases
occurs, which will be explained in the
next slide.
Notice how the lungs contain
many tubes called bronchioles
that branch out from the bronchi
The Respiratory System:
How oxygen taken in; carbon dioxide removed
This exchange of gases is carried out
at the alveoli (small sacs of air)
 In a normal, properly
functioning healthy lung there
exists around 350 million of
these alveoli
 How is oxygen switched with
carbon dioxide?
 The carbon dioxide diffuses
across the alveoli’s
membrane and into the air
sac to be exhaled
 The inhaled oxygen in the
alveoli’s air sac diffuses
across the membranes the
Above is a an alveoli. The (blue) blood arriving is
other way- into the
oxygen-deprived. At the alveoli, oxygen diffuses into the
bloodstream to be circulated
blood and carbon dioxide diffuses out. This leaves the
throughout the body
blood replenished with oxygen as it leaves (red).

The Excretory System: Standards

MENU
Standards:
– a. Students know how the complementary activity
of major body systems provides cells with oxygen
and nutrients and removes toxic waste products
such as carbon dioxide
– g. Students know the homeostatic role of the
kidneys in the removal of nitrogenous wastes and
the role of the liver in blood detoxification and
glucose balance
The Excretory System: Introduction

This system is made up of the:
– Skin
– Lungs
– Kidneys (main organs of the
excretory system)
– And the organs that are
related/connected in function to
them

The image above shows oxygen and
nutrients absorbed by cells, while
wastes are passed out to be taken
care of by the excretory system. Next
to it is a chart which matches wastes
with its various associations.
Why do we need an excretory
system?
– Human body needs this system to
carry out homeostasis, (process
constantly being carried with goal
of an internal balance within the
body.
– excretory system promotes this
healthy balance by removing from
the body toxic and/or harmful
waste in various ways as
discussed in the following slides…
The Excretory System: Skin and Lungs

Skin
– Excretes sweat out of the body
through its numerous sweat pores
 Contained in the sweat is:
– extra or excess water and
salt
– a little urea (a toxic
compound that forms
resulting from amino acids
being used for energy)

Above is an image depicting
the lungs, where wastes as
carbon dioxide are removed
from the bloodstream.
The red arrow points to a sweat
gland which secretes waste, when
necessary, through the sweat pore
at the surface.
Lungs
– The lungs excrete carbon dioxide,
which is produced as a waste
product resulting from energy
capturing from compounds in foods
The Excretory System: Kidneys

The two kidneys are the main organs of the excretory
system. What do they do?
– Waste-filled blood flows into the kidney
through renal artery (arteries carry
blood away from heart)
– In kidney, the wastes including excess
water, salts, urea filtered out
– The cleansed blood then continues to
circulate onward, leaving the kidney
through the renal vein
Above at the left is a labeled diagram of
a kidney, where blood filtering takes
place.
– Wastes that include urea, salts, water,
and others flow down the ureters to
At the right is the actual urinary system
the bladder and then are released from
which shows the location of the two
the body in urine through the urethra
kidneys and other components.
The Excretory System:
Homeostatic Function of Kidneys

So, in exactly what ways do the kidneys maintain the stable
internal balance achieved by homeostasis? They…
– Maintain and control the amount of water in the blood which directly
correlates with blood volume
– Maintain a specific pH for blood
– Prevents waste from accumulating by taking them out of the bloodstream
and then out of the body


Those functions are extremely important because a
person can be in a fatal condition in the event of damage
or disease affecting the kidneys
In that case, one would need to either get a new
transplanted kidney from a donor (the ideal, but difficult
to get solution) or undergo dialysis. A kidney dialysis
machine, though time consuming for a patient, works
similar to a kidney and cleanses blood to keep the
person alive.
Man hooked up to kidney
dialysis machine
The Endocrine System: Standards
 Standards:
 c. Students know how feedback loops in the nervous
and endocrine systems regulate conditions in the
body
 g. Students know the homeostatic role of the kidneys
in the removal of nitrogenous wastes and the role of
the liver in blood detoxification and glucose balance
 i. Students know how hormones (including digestive,
reproductive, osmoregulatory) provides internal
feedback mechanisms for homeostasis at the cellular
level and in whole organisms
MENU
The Endocrine System: Introduction
 This system is made up of:
 Hormone producing,
ductless glands
The endocrine system’s
glands are illustrated at the
right. These glands are
necessary to control the
rate of metabolism of a
body, rate or growth, and
sexual development/
function. All are controlled
by a feedback mechanism
that maintains the balanced
condition of homeostasis in
response to both outside and
inside stimulus.
The Endocrine System:
Feedback Mechanisms Control Function
 Hypothalamus, a part of the brain, will
This flow chart demonstrates one of the
feedback systems that helps control the
amounts of hormone in response to cold.
sense if there is excessive or too little
amounts of hormones in the blood
and signal the pituitary glands to
produce more or less of trophic, or
gland-stimulating, hormone
 If a gland is making too much of a
hormone:
 Pituitary gland signaled by
hypothalamus to produce less
trophic hormone to normalize
situation
 If a gland is making too little of a
hormone:
 Pituitary gland signaled by
hypothalamus to produce
more trophic hormone to
normalize situation
The Endocrine System: Glands and Parts (1)
 Pituitary Gland
 Connected to
hypothalamus
 Nine different hormones
are secreted by this
gland- these function to
maintain bodily functions
and keep under control
some of the other glands
that are part of the
endocrine system
 Hypothalamus (NOT A
GLAND)
 Part of the brain that
controls the functions
and actions of the
pituitary gland
Location and parts of the pituitary
gland and hypothalamus
The Endocrine System: Glands and Parts (2)
 Thyroid Gland
The location of the thyroid and
parathyroid glands in the neck.
 Controls and maintains
body metabolism
 Produces thyroxine, a
hormone, in a carefully
controlled manner to
maintain level of
metabolism of (most of
the) cells all around the
body
 Parathyroid Glands
 There are four of these
glands
 Produce hormones, along
with the thyroid gland, that
regulate calcium levels in
the blood for homeostasis
The Endocrine System: Glands and Parts (3)
 Adrenal Glands
 Responsible for
regulating some kidney
function and secreting
hormones that prepare a
person for stressful
situations (which may
call for a, for instance,
“fight of flight” response
Adrenal gland as seen
under high magnification
The adrenal glands are located
right on top of the kidneys.
The Endocrine System: Glands and Parts (3)
 Pancreas (NOT A GLAND)
 Secretes insulin,
glucagon to maintain
healthy blood sugar (or
glucose) levels
The pancreas’ location is shown here. (It also
has functions in the digestive system as shown
by its proximities and connections.
 Reproductive Glands (Gonads)
 Male
 Testes- make sperm
 Female
 Ovaries- make eggs (also
known as ova)
The Endocrine System: Liver
Anatomy of the liver
 Liver – some of its functions allow it to be considered
a member of the endocrine system
 Blood detoxification
 Liver gets blood from the intestines that
contains many nutrients, but along with that
toxins and chemicals that are potentially
harmful
 Before this blood can re-enter the circulatory
system, the liver cleanses out those toxins
and therefore plays a key role in cleaning the
blood
 This is why liver failure or poor function is
devastating to healthy function; the liver
prevents waste accumulation
 Glucose balance
 When there is too much glucose in the blood then the body’s cells need, the liver
converts the glucose into glycogen, which it stores
 When glucose is needed, then, (under stimulation from hormones), the liver will
reconvert the glycogen back into glucose and release the glucose back into the
bloodstream for cell’s use
 Other balancing acts
 Controlling and maintaining other items, such as amino acids
 Works constantly to clear poisonous substances such as alcohol
 Makes proteins
The Digestive System: Standards
 Standards:
 a. Students know how the complementary activity of
major body systems provides cells with oxygen and
nutrients and removes toxic waste products such as
carbon dioxide
 f. Students know the individual functions and sites of
secretion of digestive enzymes (amylases,
proteases, nucleases, lipases), stomach acid, and
bile salts
MENU
The Digestive System: Components
 This system is made up of:







Mouth
Esophagus
Stomach
Liver
Pancreas
Gallbladder
Small and large intestines
The main function of the digestive
system is to change the foods humans
eat into much smaller molecules that
cells can actually absorb and use.
The following slides takes this process step by
step by location…
The Digestive System - The Process of Digesting:
#1
The Mouth

Mouth – the first step of the digestive system
 Teeth
 Carry out the “physical” work of initial
digestion
 They are bones that have their bases attached
to the jaw bone, but are much stronger than
regular bones so as to give them the ability to
grind up food as thoroughly as possible into
small pieces
 Salivary Glands
 Controlled by the nervous system to secrete saliva
that aids in moistening the food to help the person
chew easier
 Saliva contains amylase- enzyme that breaks down
starch
 Saliva also contains lysozyme- enzyme that counters
infection by destroying bacteria’s cell walls
The Digestive System - The Process of Digesting:
#2



The Esophagus
After being chewed up, a clump of
food is then called a bolus
This bolus is pushed down into the
throat and down into the
esophagus
In the esophagus, the bolus is not
gravitationally drawn toward the
stomach, but instead, the
esophagus carries out
contractions called peristalsis,
which gradually squeezes the
bolus down into the stomach
The multi-image graphic at the
right shows the relative location
of the esophagus and depicts
how peristalsis works
To see a short video following a
bolus down the esophagus into the
stomach, click here and click on
the large image on the page.
The Digestive System - The Process of Digesting:
#3
The Stomach

The food that has been consumed now enters the stomach which
continues digesting it
 Chemical Digestion
 The lining of the stomach contains
 Glands that make mucus that function to lubricate and thus
prevent damage to the stomach wall
 Glands that make hydrochloric acid (or stomach acid), a very
acidic acid which thereby makes the stomach a very acidic
place and the enzyme nuclease, which works on breaking
down nucleic acid into smaller nucleotides
 Presence of hydrochloric acid activates pepsin, an enzyme
that, with hydrochloric acid, begins the process of digesting
proteins
A labeled
 Mechanical Digestion
stomach. Notice
 Since the stomach is a hollow muscular organ, it is able to churn
the multiple strong
the fluids and food contents within it
muscle layers/
 This produces chyme, the mixture of such stomach fluids and food
 After about 1-2 hours, the pyloric valve, which, when closed
prevents stomach content from spilling into the small intestine
prematurely, opens and chyme can then enter the small intestines
The Digestive System - The Process of Digesting:
#4
The Pancreas
 From the stomach, chyme enters the
duodenum, the first section of small intestines
where a significant amount of chemical
digestion occurs:
 The Pancreas
 Is a gland that makes
 Enzymes that help disintegrate
carbohydrates, nucleic acids,
proteins, lipids – these include…
 Amylase, which works on
breaking down starch
 Protease, which works on
breaking down protein
 Trypsin (an example of a
protease), which works on
breaking down protein
 Lipase, which works on breaking
down fat
This diagram shows the
location of the pancreas.
Ducts in the pancreas
pass enzymes into the
duodenum
The Digestive System - The Process of Digesting:
# 4 (continued)

The liver and its generalized
processes are depicted above.
The Liver
From the stomach, chyme enters the
duodenum, the first section of small
intestines where a significant amount of
chemical digestion occurs:
 The Liver
 Makes bile salts (bile is a fluid that
contains a lot of lipids and salts,
which separates, and dissolves
droplets of fat so that enzymes
can get to them)
 Bile salts are then stored in the
gall bladder to be released into
the duodenum through the bile
duct
The Digestive System - The Process of Digesting:
#5

The Intestines
(Small and Large)
Small Intestines
 Approximately three meters long- a lot longer
compared to the initial duodenum
 When chyme enters this organ, chemical digestion
is pretty much complete
 Villi, tiny protruding structures, absorb the nutrient
molecules in the chyme as the muscles contract to
move the chyme along
 The capillaries in the villi absorb the materials that
resulted from carbohydrates and protein digestion
 Some fatty acids and undigested fat molecules are
also absorbed into lacteals, which are lymph
vessels

This is an electron
micrograph of villi in
the small intestines
Large Intestines
 What was once food is now nutrient-less matter
that passes into the large intestines
 Through the large intestines, solid waste
(unneeded by the body or excreted if recognized to
be harmful or toxic) is passed out of the body
Location of the small
and large intestines
The Reproductive System

The primary function of the reproductive system is to help ensure
the continual survival of a species, in this case, humans
What makes this system one of the most, if not
the most vital system for the human race? The
reproductive system is responsible for making,
holding, and releasing gametes, specialized
cells. The male gamete is called the sperm
and the female gamete is called the egg.
When fertilization occurs, that is, a sperm
successfully makes contact with an egg and
enters it to fertilize it, a zygote is produced.
From the zygote, the single fertilized egg, a
baby soon develops.
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The Reproductive System: Hormones

Primary reproductive organs are called gonads
• In the Male they are the testes
 Releases male sex hormone: testosterone
• Produces sperm
• Promotes male physical characteristics and
development
Sperm cells
• In the Female they are the ovaries
 Releases female sex hormones: estrogen, progesterone
• Estrogen
 Needed for eggs to develop
 Promotes female physical characteristics and
development
• Progesterone
Egg cells
 Readies the uterus for developing embryo
The Reproductive System: Fertilization


This is an electron micrograph
showing that several sperm
have succeeded in reaching the
egg. However, only one will be
successful in actually fertilizing
the egg.


If an egg is located in a female’s
Fallopian tube (there are two of
these connected to the upper
region of the uterus) chances are
good that it will be fertilized in the
presence of sperm
Only about 1% of sperm ever
reach the egg cell and only one
may fertilize the egg cell
As soon as the single sperm
attaches to the egg, it enters and
conjoins its nucleus with the egg’s
(after the breakdown of the nuclear
membranes of both gametes)
Now the egg has been fertilized.
The Reproductive System:
Embryonic Development



From the singled celled zygote, or fertilized egg,
the cell continues to divide. In the animation to
the right, the first six weeks from fertilization are
depicted. (If the animation is not working click on
it.) The wall-like place that the embryo is seen
implanting itself is the uterine wall of the pregnant
woman.
Eventually, after about 9 months following
fertilization, the fetus (what the embryo is called
after more than eight weeks) has been prepared
physically for birth.
Contractions of the uterus, in which the baby has
been in for almost all of the woman’s pregnancy,
forces the baby out into the world to begin its life
as a new human being.
Early development from zygote to
(early) embryo
A newborn baby
The Immune Response System: Standards

Standards:

Organisms have a variety of mechanisms to combat disease. As a basis
for understanding the human immune response:






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a. Students know the role of the skin in providing nonspecific defenses
against infection
b. Students know the role of antibodies in the body’s response to infection
c. Students know how vaccination protects an individual from infectious
diseases
d. Students know there are important differences between bacteria and
viruses with respect to their requirements for growth and replication, the
body’s primary defenses against bacterial and viral infection, and effective
treatments of these infections
e. Students know why an individual with a compromised immune system
(for example, a person with AIDS) may be unable to fight off and survive
infections by microorganisms that are usually benign
f. Students know the roles of phagocytes, B-lymphocytes, and Tlymphocytes in the immune system
The Immune Response System: Components

This system is made up of:
 The cells and proteins that work together to protect the body from
 Any suspected microorganisms (examples: viruses, fungi, bacteria)
that may be harmful and infectious

Main Body Structures (External)







Eyes
Nose
Mouth
Respiratory tract
Stomach and intestines
Genitourinary system
Skin
The Immune System:
Nonspecific (or Innate) Immunity
If the skin, a major defense, is
broken the inflammatory
response takes effect…
This is the nonspecific and quickly- responding immune
response that humans are born with and includes..
 Barriers (both chemical and physical)
 The skin is the first defense against pathogens
 Inflammatory response occurs if pathogen gets
past skin
 Blood vessels by open wound enlarge to
allow the white blood cells to leak into the
tissue that is infected
 Phagocytes
 White blood cells that engulf a recognized
foreign body and then digest the foreign body
with enzymes (within the cell’s lysosomes)
 Interferons
Notice how the inflammation
 Virus-resistant proteins (acts to slow virus to
functions to allow pathogen and
allow more time for the immune system to
foreign body fighting white blood
respond)
cells into the affected tissue.

The Immune System:
Humoral Immunity

Provides bacterial defense
 Recognition process: since
there are so many varieties of
B-lymphocytes, only some
will be stimulated by antigens.
 T-lymphocytes help to keep a
control on this process to
ensure workings
 These T-lymphocytes, or
helper T cells help Blymphocytes, or B cells
become antibody making
plasma cells which produce
many antibodies to counter
the bacteria
 Antibodies, in the future, will
respond to the same antigen
to disable them
A close-up view of
a T-lymphocyte
Phagocytes engulfing bacterium to
initiate the humoral immunity process.
The Nervous System:
Vaccination
This is one of the ways a person can strengthen
their immune systems to protect them better
 How it works
 Weakened or dead microorganisms
(responsible for causing a specific
disease such as measles or influenza,
etc.) are introduced to the body
 Those microorganisms are not strong
enough to cause disease, but do trigger
an immune response that makes
antibodies against the microorganism
 In a future exposure to the
microorganism, those antibodies will be
Vaccination is important because it helps
a human’s body be better prepared for
activated and counter the microorganism
countering harmful disease.
effectively

virus
bacteria
The Immune System:
Virus vs. Bacteria

Virus
 Are not alive, parasitic (depend
on host for survival, replication
 Can lay dormant and be
reactivated
 Replicates by using a cell it has
entered, cell bursts and many
more viruses emerge
 Body’s primary defense: white
cells (macrophages) engulf viral
particles, lymphocytes make
antibodies countering virus
 Effective treatment: more difficult
to fight a virus caused disease
than bacterial; help patient’s
symptoms and hope immune
system strong enough (in some
cases), immunization
(sometimes)

Bacteria
 Single-cell microorganisms (so are alive)
 Reduction (sometimes full) in strength
after time
 Some are beneficial to humans
 Multiply and live in warm, wet conditions
and cannot move on their own
 Reproduce much less rapidly then viruses
because, as cells, they can only double in
a given time period
 Body’s primary defense: enzymes and
acid which kill bacteria, white blood cells
engulf them, antibodies
 Effective treatment: improve hygiene,
immunization
For Venn Diagram (that is not made by this powerpoint author) view the next slide…
Venn Diagram:
Comparing Virus and Bacteria
The Immune System:
Disorders and Consequences



Allergies
 Allergy inducing antigen attach to
mast cells, (which are common in
the body’s nasal passage)
 The mast cells are then stimulated
to make histamines, a chemical
that causes the irritations that
result from allergies.
Autoimmune Disease
 Occurs when the immune system
mistakes the bodies cells for its
enemies
AIDS (Acquired Immune Deficiency
Syndrome) which makes person’s
immune system dysfunctional; they will
contract illnesses normally easily
fended off by healthy immune system
In this case, the women’s
allergies are perhaps caused
by allergens in her pet’s hair.
Structure of
an HIV virus
which is the
cause of
AIDS.
The Human Body: Systems Menu
Nervous System
Reproductive System
Circulatory System
Skeletal System
Immune System
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sure?
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Digestive System
Endocrine System
Muscular System
Excretory System
Integumentary System
Respiratory System
THE END