Download Unit 8A

Unit 8 Lectures
Chapters 40-44
–
–
–
–
–
Animal Structure
Nutrition
Circulatory System
Immune System
Internal
Environment
Tissues: groups of cells with a common
structure and function (4 types)
Anatomy: structure
Physiology: function
1- Epithelial: outside of
body and lines organs
and cavities; held
together by tight
junctions
basement membrane:
dense mat of
extracellular matrix
Simple: single layer of
cells
Stratified: multiple tiers
of cells
Cuboidal (like dice)
Tissues, II
2- Connective: bind and support other tissues; scattered
cells through matrix; 3 kinds:
A-Collagenous fibers (collagen protein) B-Elastic fibers
(elastin protein) C-Reticular fibers (thin branched
collagen fibers)
Loose connective tissue: binds epithelia to underlying
tissue; holds organs
1-Fibroblasts- secretes extracellular proteins 2Macrophages- amoeboid WBC’s; phagocytosis 3-Adipose
tissue- fat storage; insulation
Fibrous connective tissue: parallel bundles of cells
1-Tendons- muscles to bones 2-Ligaments- bones to
bones; joints
Cartilage: collagen in a rubbery matrix (chondroitin);
flexible support
Bone: mineralized tissue by osteoblasts
Tissues
Tissues, III
3-Nervous: senses
stimuli and transmits
signals from 1 part of
the animal to another
Neuron: functional
unit that transmits
impulses
Dendrites: transmit
impulses from tips to
rest of neuron
Axons: transmit
impulses toward
another neuron or
effector
Tissues, IV
4- Muscle: capable of
contracting when
stimulated by nerve
impulses; myofibrils
composed of proteins
actin and myosin; 3
types:
A- Skeletal: voluntary
movement (striated)
B- Cardiac: contractile
wall of heart (branched
striated)
C- Smooth: involuntary
activities (no striations)
Organ systems
Organ: organization
of tissues
Mesentaries:
suspension of organs
(connective tissue)
Thoracic cavity
(lungs and heart)
Abdominal cavity
(intestines)
Diaphragm
(respiration)
Organ systems…...
Digestive-food processing
Circulatory-internal
distribution
Respiratory-gas exchange
Immune/Lymphatic-defense
Excretory-waste disposal;
osmoregulation
Endocrine-coordination of
body
activities
Reproductive-reproduction
Nervous-detection of stimuli
Integumentary-protection
Skeletal-support; protection
Muscular-movement;
locomotion
Internal regulation
Interstitial fluid: internal fluid
environment of vertebrates;
exchanges nutrients and
wastes
Homeostasis: “steady state”
or internal balance
Negative feedback: change in
a physiological variable that
is being monitored triggers a
response that counteracts the
initial fluctuation; i.e., body
temperature
Positive feedback:
physiological control
mechanism in which a
change in some variable
triggers mechanisms that
Metabolism: sum of all energyrequiring biochemical reactions
Catabolic processes of
cellular respiration
Calorie; kilocalorie/C
Endotherms: bodies
warmed by metabolic heat
Ectotherms: bodies
warmed by environment
Basal Metabolic Rate
(BMR): minimal rate
powering basic functions of
life (endotherms)
Standard Metabolic Rate
(SMR): minimal rate
powering basic functions of
life (ectotherms)
Nutritional requirements
Undernourishment:
caloric deficiency
Overnourishment
(obesity): excessive
food intake
Malnourishment:
essential nutrient
deficiency
Essential nutrients:
materials that must be
obtained in
preassembled form
Essential amino acids:
the 8 amino acids that
must be obtained in the
diet
Essential fatty acids:
Food types/feeding
mechanisms
Opportunistic
Herbivore: eat autotrophs
Carnivore: eat other animals
Omnivore: both
Feeding Adaptations
Suspension-feeders: sift food from water (baleen whale)
Substrate-feeders: live in or on their food (leaf miner)
(earthworm:
deposit-feeder)
Fluid-feeders: suck fluids from a host (mosquito)
Bulk-feeders: eat large pieces of food (most animals)
Overview of food processing
1-Ingestion: act of eating
2-Digestion: process of food break down
enzymatic hydrolysis
intracellular: breakdown within cells (sponges)
extracellular: breakdown outside cells (most animals)
alimentary canals (digestive tract)
3- Absorption: cells take up small molecules
4- Elimination: removal of undigested material
Mammalian digestion
Mammalian digestion
Peristalsis: rhythmic waves of contraction by smooth
muscle
Sphincters: ring-like valves that regulate passage of
material
Accessory glands: salivary glands; pancreas; liver; gall
bladder
Oral cavity •salivary amylase •bolus
Pharynx
•epiglottis
Esophagus
Stomach •gastric juice •pepsin/pepsinogen (HCl)
•acid chyme •pyloric sphincter
Mammalian Digestion
Small intestine •duodenum •bile
Intestinal digestion: a-carbohydrate b-protein cnucleic acid d-fat
Villi / microvilli
Lacteal (lymphatic)
Chylomicrons (fats mixed with cholesterol)
Hepatic portal vessel
Large intestine (colon)
Cecum
Appendix
Feces
Rectum/anus
Digestive Hormones
Hormonal Action:
Gastrin food---> stomach wall ---> gastric
juice
Enterogastrones (duodenum)
1-Secretin:
– acidic chyme---> pancreas to release
bicarbonate
2-Cholecystokinin (CCK)
– amino/fatty acids---> pancreas to
release enzymes and gall bladder to
Circulation system evolution, I
Gastrovascular cavity (cnidarians, flatworms)
Open circulatory •hemolymph (blood & interstitial
fluid) •sinuses (spaces surrounding organs)
Closed circulatory: blood confined to vessels
Cardiovascular system
•heart (atria/ventricles)
•blood vessels
arteries,
arterioles, capillary
beds, venules,
veins)
•blood (circulatory
fluid)
Circulation system evolution, II
Fish: 2-chambered heart; single circuit of blood
flow
Amphibians: 3-chambered heart; 2 circuits of
blood flow- pulmocutaneous (lungs and skin);
systemic (some mixing)
Mammals: 4-chambered heart; double
circulation; complete separation between
oxygen-rich and oxygen poor blood
Double circulation
From right ventricle to
lungs via pulmonary
arteries through
semilunar valve
(pulmonary
circulation)
Capillary beds in lungs
to left atrium via
pulmonary veins
Left atrium to left
ventricle (through
atrioventricular valve)
to aorta
Aorta to coronary
arteries; then systemic
circulation
The mammalian heart
Cardiac cycle:
sequence of filling and
pumping
Systole- contraction
Diastole- relaxation
Cardiac output: volume of
blood per minute
Heart rate- number of
beats per minute
Stroke volume- amount of
blood pumped with each
contraction
Pulse: rhythmic stretching
of arteries by heart
contraction
The heartbeat
Sinoatrial (SA) node (“pacemaker”): sets rate
and timing of cardiac contraction by generating
electrical signals
Atrioventricular (AV) node: relay point (0.1
second delay) spreading impulse to walls of
ventricles
Electrocardiogram (ECG or EKG)
Blood Pressure
Blood pressure: the hydrostatic force that
blood exerts against a vessel wall
– Main force propelling blood from the heart
through the vessels
Peripheral resistance: results from
impedance by arterioles; blood enters
faster than it leaves
– Creates pressure even in diastole,
continuously driving blood into capillaries
Blood vessel structural differences
Capillaries
•endothelium; basement
membrane
Arteries
•thick connective tissue;
thick smooth muscle;
endothelium; basement
membrane
Veins
•thin connective tissue; thin
smooth muscle; endothelium;
basement membrane
The lymphatic system
Lymphatic system: system
of vessels and lymph
nodes, separate from the
circulatory system, that
returns fluid and protein to
blood
Lymph: colorless fluid,
derived from interstitial
fluid
Lymph nodes: filter lymph
and help attack viruses and
bacteria
Body defense / immunity
Blood
Plasma: liquid matrix of blood in which cells
are suspended (90% water)
Erythrocytes (RBCs): transport O2 via
hemoglobin
Leukocytes (WBCs): defense and immunity
Platelets: clotting
Stem cells: pluripotent cells in the red
marrow of bones
Blood clotting: fibrinogen (inactive)/ fibrin
(active); hemophilia; thrombus (clot)
Blood
Cardiovascular disease
Cardiovascular disease
(>50% of all deaths)
Heart attack- death of
cardiac tissue due to
coronary blockage
Stroke- death of nervous
tissue in brain due to
arterial blockage
Atherosclerosis: arterial
plaques deposits
Arteriosclerosis: plaque
hardening by calcium
deposits
Hypertension: high blood
pressure
Gas exchange
CO2 <---> O2
Aquatic:
•gills •ventilation
•countercurrent
exchange
Terrestrial:
•tracheal systems •lungs
Mammalian respiratory systems
Larynx (upper part of
respiratory tract)
Vocal cords (sound
production)
Trachea (windpipe)
Bronchi (tube to lungs)
Bronchioles
Alveoli (air sacs)
Diaphragm (breathing
muscle)
Breathing
Breathing
Positive pressure breathing: pushes air into
lungs (frog)
Negative pressure breathing: pulls air into lungs
(mammals)
Inhalation: diaphragm contraction; Exhalation:
diaphragm relaxation
Tidal volume: amount of air inhaled and exhaled
with each breath (500ml)
Vital capacity: maximum tidal volume during
forced breathing (4L)
Regulation: CO2 concentration in blood (medulla
oblongata)
Respiratory pigments: gas
transport
Oxygen transportHemocyanin: found in
hemolymph of arthropods and
mollusks (Cu)
Hemoglobin: vertebrates (Fe)
Carbon dioxide transportBlood plasma (7%)
Hemoglobin (23%)
Bicarbonate ions (70%)
Deep-diving air-breathersMyoglobin: oxygen storing
protein
Gas Transport
Oxygen transport:
– Hemoglobin transports oxygen in the blood.
– Fe at the center of each heme group bonds
with O2
– Binding 1 O2 leads to a shape change that
increases affinity for 3 additional O2
molecules (4 total)
– A drop in pH lowers the affinity of
hemoglobin for O2 due to the entrance of
CO2 into blood.
– Unloading of one O2, leads to the release of
the other three
Gas Transport
Carbon dioxide transport
– Hemoglobin buffers blood from pH changes
– Three forms of CO2 transport
– Erythrocytes convert CO2 into bicarbonate, a
base, using carbonic anhydrase – reversible
reaction
Homeostasis: regulation of internal
environment
Thermoregulation
internal temperature
Osmoregulation
solute and water balance
Excretion
nitrogen containing waste
Regulation of body temperature
Thermoregulation
4 physical processes:
Conduction~transfer of heat
between molecules of body
and environment
Convection~transfer of heat as
water/air move across body
surface
Radiation~transfer of heat
produced by organisms
Evaporation~loss of heat from
liquid to gas
Sources of body heat:
Ectothermic: determined by
environment
Endothermic: high metabolic
Regulation during environmental
extremes
Torpor~ low activity;
decrease in metabolic rate
1- Hibernation
long term or winter
torpor (winter cold and
food scarcity); bears,
squirrels
2- Estivation
short term or summer
torpor (high temperatures
and water scarcity); fish,
amphibians, reptiles
Both often triggered by
length of daylight
Water balance and waste
disposal
Osmoregulation:
management of the
body’s water content and
solute composition
Nitrogenous wastes:
breakdown products of
proteins and nucleic acids;
ammonia-very toxic
Deamination~
Ammonia: most aquatic
animals,
many
fish
Urea: mammals, most
amphibians,
sharks,
bony fish (in liver;
combo of NH3 and CO2)
Uric acid: birds, insects, many
reptiles, land
Osmoregulators
Osmoconformer: no active adjustment of internal
osmolarity (marine animals); isoosmotic to environment
Osmoregulator: adjust internal osmolarity (freshwater,
marine, terrestrial)
Freshwater fishes (hyperosmotic)- gains water, loses;
excretes large amounts of urine salt vs. marine fishes
(hypoosmotic)- loses water, gains salt; drinks large
amount of saltwater
Excretory
Systems
Production of urine by 2 steps: • Filtration (nonselective) •
Reabsorption (secretion of solutes)
Protonephridia ~ flatworms (“flame-bulb” systems) (Left)
Metanephridia ~ annelids (ciliated funnel system) (Center)
Malpighian tubules ~ insects
(tubes in digestive tract) (Right)
Kidneys ~ vertebrates
Kidney Functional Units
Renal artery/vein: kidney
blood flow
Ureter: urine excretory
duct
Urinary bladder: urine
storage
Urethra: urine elimination
tube
Renal cortex (outer region)
Renal medulla (inner
region)
Nephron: functional unit of
kidney
Cortical nephrons (cortex;
Nephron Structure
Afferent arteriole: supplies blood to
nephron from renal artery
Glomerulus: ball of capillaries
Efferent arteriole: blood from
glomerulus
Bowman’s capsule:
surrounds glomerulus
Proximal tubule:
secretion & reabsorption
Peritubular capillaries:
from efferent arteriole;
surround proximal & distal tubules
Loop of Henle: water & salt balance
Distal tubule: secretion & reabsorption
Collecting duct:
carries filtrate to renal pelvis
Kidney regulation: hormones
Antidiuretic hormone
(ADH) ~ secretion
increases permeability
of distal tubules and
collecting ducts to water
(H2O back to body);
inhibited by alcohol and
coffee
– Negative feedback
Juxtaglomerular
apparatus (JGA) ~
reduced salt intake-->enzyme renin initiates
conversion of
angiotension (plasma
protein) to angiotension
II (peptide); increase
blood pressure and
blood volume by
Kidney Regulation
Angiotension II also
stimulates adrenal
glands to secrete
aldosterone; acts on
distal tubules to
reabsorb more
sodium, thereby
increasing blood
pressure (reninangiotensionaldosterone system;
RAAS)
– Negative feedback
Atrial natriuretic
factor (ANF) ~ walls
of atria; inhibits
Lines of Defense
Nonspecific Defense Mechanisms……
Phagocytic and Natural Killer Cells
Neutrophils
60-70% WBCs;
engulf and destroy microbes
at infected tissue
Monocytes
5% WBCs;
develop into….
Macrophages
enzymatically
destroy microbes
Eosinophils
1.5% WBCs;
destroy large parasitic
invaders (blood flukes)
Natural killer (NK) cells
The Inflammatory Response
1- Tissue injury; release of chemical signals~
• histamine (basophils/mast cells): causes Step
2...
• prostaglandins: increases blood flow &
vessel permeability
2/3- Dilation and increased permeability of capillary~
• chemokines: secreted by blood vessel
endothelial cells mediates
phagocytotic
migration of WBCs
4- Phagocytosis of pathogens~
directed by
chemokines
• fever & pyrogens:
leukocyte-released molecules increase body temperature
Inflammatory Response
Natural Killer (NK) cells target viral
infected cells and cancer cells
Surface receptors are used to make
contact with the infected cells and in
recognition of infected cells
Binding of receptors allows NK cells to
release chemicals that lead to apoptosis
of the infected cell
Its not 100% effective, but it does reduce
the incidence of viral infections and
cancer significantly
Specific (Acquired) Immunity
Lymphocyctes
•pluripotent stem
cells...
(bone marrow)
T Cells (thymus)
• B Cells
•
Antigen: a foreign
molecule that elicits a
response by lymphocytes
(virus, bacteria, fungus,
protozoa, parasitic worms)
Antibodies: antigen-
binding immunoglobulin,
produced by B cells
Antigen receptors:
plasma membrane
receptors on B and T cells
Lymphocyte Development
Lymphocytes begin development in bone
marrow
T Cells move to the thymus to develop
B Cells continue to develop in the bone
marrow
Lymph glands are storage areas for
lymphocytes
Binding of a specific antigen activates the
cell, causes proliferation and
differentiation for a specific response
Antibodies and Receptors
B Cell receptors (antibodies) are Y shaped
with heavy and light chains linked by
disulfide bridges
They are anchored to B cells by the
bottom of the Y shape in a transmembrane region.
The tips of the Y are varied between B
cells
Binding of the antigen to the receptor
allows B cells to recognize the antigen in
its natural state and begin to mount a
response with antibody production
Clonal selection – B Cells
Effector cells: short-lived
cells that combat the
antigen
Memory cells: long-lived
cells that bear receptors
for the antigen
Clonal selection: antigendriven cloning of
lymphocytes
“Each antigen, by binding
to specific receptors,
selectively activates a tiny
fraction of cells from the
body’s diverse pool of
lymphocytes; this
relatively small number of
selected cells gives rise to
Induction of Immune Responses
Primary immune response: lymphocyte proliferation and
differentiation the 1st time the body is exposed to an antigen
Plasma cells: antibody-producing effector B-cells
Secondary immune response: immune response if the
individual is exposed to the same antigen at some later time~
Immunological memory
Self/Non-self Recognition
Self-tolerance: capacity to distinguish self from nonself
Autoimmune diseases: failure of self-tolerance;
multiple sclerosis, lupus, rheumatoid arthritis,
insulin-dependent diabetes mellitus
Antigen presentation: process by which an MHC
molecule “presents’ an intracellular protein to an
antigen receptor on a nearby T cell
Cytotoxic T cells (TC): bind to protein fragments
displayed on class I MHC molecules
Helper T cells (TH): bind to proteins displayed by
Self/Non-self Recognition
Major Histocompatability Complex (MHC): body cell surface
antigens coded by a family of genes; they are known as anitgenpresenting cells, two types:
Class I MHC molecules: found on all nucleated cells
– Display foreign antigens (proteins) produced within the cell on the
exterior so they can be recognized by NK cells as infected.
Class II MHC molecules: found on macrophages, B cells, and
activated T cells
– Display antigens and fragments that have been internalized through
endocytosis.
Types of immune responses
Humoral immunity
B cell activation
Production of antibodies
Defend against bacteria,
toxins, and viruses free in
the lymph and blood
plasma
Cell-mediated immunity
T cell activation
Binds to and/or lyses cells
Defend against cells
infected with bacteria,
viruses, fungi, protozoa,
and parasites; nonself
interaction
Helper T lymphocytes
Function in both humoral & cell-mediated immunity
Stimulated by antigen presenting cells (APCs)
T cell surface protein CD4 enhances activation (positive feedback)
Cytokines secreted (stimulate other lymphocytes):
a) interleukin-2 (IL-2): activates B cells and cytotoxic
T cells
b) interleukin-1 (IL-1): activates helper T cell
to produce IL-2
Cell-mediated: cytotoxic T cells
Destroy cells infected by intracellular pathogens and cancer
cells
Class I MHC molecules (nucleated body cells) expose foreign
proteins
Activity enhanced by CD8 surface protein present on most
cytotoxic T cells (similar to CD4 and class II MHC)
TC cell releases perforin, a protein that forms pores in the
target cell membrane; cell lysis and pathogen exposure to
circulating antibodies
Humoral response: B cells
Stimulated by T-dependent
antigens (help from TH
cells)
Macrophage (APCs) with
class II MHC proteins
Helper T cell (CD4 protein)
Activated T cell secretes IL2 (cytokines) that activate
B cell
B cell differentiates into
memory and plasma cells
(antibodies)
Antibody Structure & Function
Epitope: region on antigen surface recognized
by antibodies
2 heavy chains and 2 light chains joined by
disulfide bridges
Antigen-binding site (variable region)
5 classes of Immunoglobins
IgM: 1st to circulate; indicates
infection; too large to cross
placenta
IgG: most abundant; crosses
walls of blood vessels and
placenta; protects against
bacteria, viruses, & toxins;
activates complement
IgA: produced by cells in mucous
membranes; prevent attachment
of viruses/bacteria to epithelial
surfaces; also found in saliva,
tears, and perspiration
IgD: do not activate complement
and cannot cross placenta; found
on surfaces of B cells; probably
help differentiation of B cells into
plasma and memory cells
IgE: very large; small quantity;
releases histamines-allergic
Antibody-mediated Antigen
Disposal
Neutralization (opsonization): antibody binds to and
blocks antigen
activity
Agglutination: antigen clumping
Precipitation: cross-linking of soluble antigens
Complement fixation: activation of 20 serum proteins,
through
cascading action, lyse viruses and
pathogenic cells
Immunity in Health & Disease
Active immunity/natural:
conferred
immunity
by recovering from disease
Active immunity/artificial:
immunization and
vaccination; produces a
primary response
Passive immunity: transfer
of immunity from one
individual to another
• natural: mother to fetus;
breast milk; Ig transfer
• artificial: rabies antibodies
Immunity in Health & Disease
ABO blood groups (antigen presence)
– Blood type is determined by antigens on the surface of
the RBC. This is why you can only have blood
transfused from the same type
– Both A and B antigens are present in AB blood, while O
has no antigens at all – the Universal donor because of
no rejection
Organ Transplant: organs contain antigens
similar to blood, but are different from blood
antigens. For transplants they need to look at
MHC and tissue type to limit rejection
Rh factor (blood cell antigen); Rh- mother vs.
an Rh+ fetus (inherited from father): if blood
crosses the placenta, the mother will develop
Abnormal immune function
Allergies (anaphylactic shock): hypersensitive responses to
environmental antigens (allergens);
– causes dilation and blood vessel permeability
(antihistamines);
– Epinephrine reverses the reaction
Autoimmune disease
– multiple sclerosis: T cells infiltrate the CNS and destroy
myelin sheath
– Lupus: the immune system generate antibodies to self
molecules
– rheumatoid arthritis: damage and inflamation of the
bones and joints
– insulin-dependent diabetes mellitus: Tc cells target the
insulin producing beta cells in the pancreas – no insulin
produced
Abnormal immune function
Immunodeficiency disease:
– SCIDS. Severe Combined Immunodeficiency: both branches of the
immune system fail to function; NO immunity at all
Treatment includes gene therapy and bone marrow transplants to provide
working lymphocytes
– A.I.D.S. Acquired Immunodeficiency Syndrome: deficiency in T Cells
leading to both branches of the immune system being impared.
No treatment for the virus, treatments target the opportunistic infections
instead
HIV / AIDS
The first HIV cases can be traced to Africa
in the early 1970’s, major spread began in
the late 1970’s
There are three major strands of HIV, one
in the US and Western Europe, one in
Africa, and one in Asia; each differs from
the other slightly in genetic structure
As of 2003, over 40 million people world
wide are infected, millions more have died
HIV / AIDS
HIV: Human immunodeficiency virus; retrovirus
that uses the CD4 receptors to gain access to the
cell.
– Enters the cell and uses reverse transcriptase to
engineer its RNA genome into DNA and integrate it into
host DNA
Integration into DNA prevents any treatment
TH cells die through apoptosis generated by the
virus or through damage caused by viral
replication
Medication can slow the progress of the viral
replication and death of T cells, but are VERY
expensive and not widely available
HIV / AIDS
Treatments mostly target the opportunistic
infections such as Pneumocytis carinii
(pneumonia)or Kaposi’s Sarcoma (skin
cancer); most infections in HIV/AIDS
cases are rare in healthy individuals
There is some research towards natural
immunity – it appears there are
individuals of caucasian descent that
contain a specific cell receptor, CD 5, that
helps slow the progression of HIV