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Chapter 43
THE BODY’S DEFENSE
I. Innate Immunity-Nonspecific mechanisms provide general barriers to infection
A. The skin and mucous membranes (Barrier defenses)
pH 3-5
Lysozymes
B. Phagocytic white cells and natural killer cells (Internal defenses)
Neutrophils - become phagocytic
Monocytes - become macrophages
Macrophages - large amoeboid cells use pseudopodia
Eosinophils - use cytoplasmic granules to attack outer covering of large invaders
Natural killer cells - destroys body’s own infected cells
C. Antimicrobial proteins two nonspecific protein groups (Internal defenses)
Complement system - 30 proteins interact which results in lysis of invading
microbes (Internal defenses)
Interferons - secreted by infected cells to produce proteins that inhibit viral
replication
D. The inflammatory response (Internal defenses)
1. Localized inflammatory response
Dilated vessels become more permeable
Chemical signals
2. Chemical signals
Histamine released from Basophils and Mast cells
Prostaglandins released from white blood cells
Neutrophils arrive first kill microbe and then die
Macrophages destroy pathogens and clean up
II. The immune system defends the body against specific invaders
A. Key features of the immune system (Adaptive Immunity)
Specificity - recognize and eliminate specific microorganisms
Antigen
Antibody
Diversity responds to numerous kinds of invaders which are recognized by their
antigenic markers
Memory - recognize previous antigens
Self/nonself recognition
B. Active versus passive acquired immunity
C. Humoral immunity and cell-mediated immunity
Humoral produces antibodies to free bacteria, viruses and toxins
Cell-mediated response of lymphocytes to intracellular parasites
D. Cells of the Immune System (lymphocytes)
Early B and T cells develop from multipotent stem cells
B cells mature in bone marrow and are responsible for humoral immunity
T cells migrate to thymus gland and are responsible for cell-mediated response
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Concentrated in lymph glands, spleen and other lymphatic glands
Effector cells
Activated B cells produce plasma cells to produce antibodies
Activated T cells produce two types
Helper T cells
Cytotoxic T cells
III. Clonal selection of lymphocytes is the cellular basis for immunological specificity and
diversity
IV. Memory cells in secondary immune response
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V. Molecular markers on cell surface function in self/nonself recognition
MHC = Major Histocompatibility Complex - contains glycoproteins
VI. In the humoral response, B cells defend against pathogens in body fluids by generating
specific antibodies
A. Activation of B cells (two steps)
1. Antigen attaches to specific receptor on B cells
2. B cell activation involves macrophages and helper T cells to produce plasma
cells
B. T-dependent and T-independent antigens
C. Molecular basis of antigen-antibody specificity
Epitope = antigen’s surface recognized by antibody
Comprised a specific class of proteins called immunoglobulins
Y shaped molecule comprised of four polypeptide chains
D. How antibodies work
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E. Monoclonal antibodies are defense proteins that descend from a single cell
VII. Cell mediated response; T cells defend against intracellular pathogens
A. Activation of T cells
T cells respond only to antigenic epitopes displayed on the surfaces of the
body’s own cells
The presence of a T cell surface molecule called CD4 enhances the
interactions between the cells and antigen presenting cells (APC)
The MHC-antigen complex displayed on the infected body cell stimulates T cells
with the proper receptor to multiply and form clones of activated TH and TC cells
which recognized the pathogen
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The cells stimulate B cells to make antibodies
The cells activate other T cell for cell-mediated response
B. How cytotoxic cells work
Cytotoxic cells TC actually destroy infected host cells
Releases perforin which is a protein that form lesions in the infected cells
membrane
Cytotoxic cells also function to destroy cancer cells which develop periodically in
the body
VIII. Complement proteins participate in both nonspecific and specific defenses
30 or so complement proteins circulate in the blood and these proteins become activated
in a series fashion
IX. The immune system can distinguish between self and nonself
A. Blood groups
B. Tissue grafts and other organ transplants
X. Abnormal immune function leads to disease
A. Autoimmune diseases react against itself
Lupus Erythematosus
Rheumatoid Arthritis
Diabetes
Heart valve damage from strep infections
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Grave’s Disease
B. Allergy
C. Immunodeficiency deficient in either humoral or cell mediated immune defense
D. Acquired immunodeficiency syndrome (AIDS)
E. Cancer and Immunity
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Controlling The Internal Environment
Chapter 44
I. Homeostatic mechanisms protect an animal’s internal environment
II. Cells require a balance between water uptake and loss
A. Osmoconformers and osmoregulators
Osmoconformers = animals that do not actively adjust their osmolarity
Osmoregulators = animals that regulate internal osmolarity by discharging excess
water or taking in additional water
B. Maintaining water balance different environments
Most marine invertebrates are osmoconformers
Marine bony fish are hypotonic to seawater
Freshwater animals are hypertonic to their environment and
constantly take in water by osmosis
Terrestrial animals live in a dehydrating environment that cannot survive
desiccation
III. Osmoregulation depends on transport epithelia
IV. Tubular systems function in osmoregulation and excretion in many invertebrates
A. Protonephridia: the flame-bulb system of flatworms
B. Metanephridia of earthworms
C. Malpighian tubules of insects
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V. The kidneys of most vertebrates are compact organs with many excretory tubules
A. The mammalian excretory system
Blood enters each kidney via the renal artery and exits the renal vein
Urine exits each kidney through a ureter and both ureters drain into a common
urinary bladder
Urine leaves the body from the urinary bladder though the urethra
B. The nephron and associated structures (functional unit of kidney)
Water, salts, urea and other small molecules are separated from the blood passing
through the glomerulus by blood pressure
The filtrate enters the Bowman’s Capsule
Filtrate then passes through the proximal tubule, the Loop of Henle, and the distal
tubule, which empties into a collecting tubule
VI. The kidneys transport epithelia regulate the composition of blood
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A. Production of urine from blood filtrate
1. Filtration of blood
2. Secretion adds plasma at proximal and distal tubules
3. Reabsorption of sugar, vitamins, organic materials
B. Transport properties of the nephron and collecting duct
1. Proximal tubules alters volume and composition of
filtrate
2. Descending Loop of Henle is freely permeable to
water but not salts
3. Ascending Loop of Henle is very permeable to salts but not to water
4. Distal tubule regulates K+, NaCl and pH
5. The collecting duct carries filtrate back through the medulla into the renal
pelvis
VII. The water-conserving ability of the kidney is a key terrestrial adaptation
A. Conservation of water by two solute concentrations
B. Regulation of kidney function by feedback circuits
Antidiuretic hormone
Juxtaglomerular apparatus
Atrial Natriuretic Factor
VIII. Diverse adaptations of the vertebrate kidney have evolved in different environments
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IX. An animal’s nitrogenous wastes are correlated with its phylogeny and habitat
X. Thermoregulation maintains body temperature within a range conducive to metabolism
Conduction
Convection
Radiation
Evaporation
XI. Ectotherms derive body heat mainly from their surroundings and endotherms derive it mainly
from metabolism
XII. Thermoregulation involves physiological and behavioral adjustments
1. Adjusting the rate of heat exchange between the animal and its surrounding
Vasodilation
Countercurrent Heat Exchanger
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2. Cooling by evaporative heat loss
3. Behavioral responses
4. Changing the rate of metabolic heat production
XIII. Comparative physiology reveals diverse mechanisms of thermoregulation
A. Invertebrates
B. Amphibians and reptiles
C. Fishes
D. Mammals and birds
Rate of heat may be increased
Contraction of muscles
Hormones increase the production of heat instead of ATP
Cooling the body by vasodilation, panting, and sweat glands
E. Thermoregulation in humans
Hypothalamus controls thermoregulation
F. Torpor = metabolism decreases and the heart and respiratory system slow down
G. Acclimatization = temperature range adjustment
XIV. Roles of liver in homeostasis
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