Download 6.3 Defense against infectious disease

6.1 Digestion & Nutrition
6.1.1. Explain: why digestion of large food molecules is essential.
 large food molecules are usually polymers, such as polysaccharides, proteins and lipids, which are too large to be absorbed
from the digestive tract into the circulatory system for transport because they are simply too large to move across the
membranes of small intestine epithelial cells
 after digestion, polysaccharides are broken down into monosaccharides, polypeptides are broken down into amino acids, and
lipids are broken down into glycerol and fatty acids
 monomers, such as monosaccharides, amino acids, glycerol, and fatty acids are small enough to be absorbed by small
intestine epithelial cells, moving these substances by either diffusion, facilitated diffusion, or active transport through
membrane proteins
6.1.2. Explain: need for enzymes in digestion.
 at body temperature (37°C in mammals), reaction rates are too slow to be efficient at hydrolysis reactions of large food
molecules
 hydrolytic reactions in the digestion of large food molecules, such as polysaccharides, proteins and lipids into their
monomers, are exothermic, but occur very slowly due to considerable activation energy
 enzymes lower activation energy, catalyzing hydrolysis reactions of large food molecules into their monomers
6.1.3. State: source, substrate, products, optimum pH for one amylase, one protease, and one lipase.
enzyme
salivary amylase
pepsin
phospholipase A2
source
salivary glands
stomach
pancreas
substrate
starch
proteins
phospholipids
produce
maltose
polypeptides
glycerol, phosphate, fatty acids
optimum pH
7-8
2-3
8
6.1.4. Draw and label: a diagram of the digestive system.
mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, gall bladder, anus
6.1.5. Outline: the function of the stomach, small intestine and large intestine.
A. stomach:
 a large, expandable, muscular and glandular organ
 stores and mixes food, aiding in both physical and chemical digestion
 gastric pits secrete:
a) HCl, producing a stomach pH of about 2, facilitating pepsin activity, and killing foreign pathogens, such as bacteria
b) pepsinogen, an inactive precursor which is converted to pepsin under acidic conditions
c) pepsin catalyzes the hydrolysis of large proteins and polypeptides into smaller polypeptides and oligopeptides
d) mucus, which protects stomach cells from acidic conditions
e) chyme = product of stomach digestion, an acid fluid released from stomach into small intestine via pyloric sphincter
B. small intestine:
 digestion:
a) pancreas releases bicarbonate = NaHCO3-,
b) which neutralizes acidic chyme, producing a pH = 8, optimizing activities of intestinal enzymes
c) enzymes from pancreas, and small intestine epithelial cells hydrolyze large molecules into smaller molecules
d) polypeptides & oligopeptides digested into amino acids
e) polysaccharides & disaccharides digested into monosaccharides
f) triglycerides digested into fatty acids and glycerol
g) bile produced in liver, stored in gall bladder, released through pancreatic duct
h) emulsifying fat droplets into smaller particles on which pancreatic lipase can act more efficiently
 motility by peristalsis: rhythmic contractions of circular and longitudinal smooth muscles lining small intestine slowly force
chyme down intestinal tract
 absorption: lining of small intestine is folded, increasing surface area for absorption, and each fold is folded again into villi,
with each villus acting an absorptive unit (see 5.1.7)
C. large intestine:
 absorption of vitamin K produced by mutualistic bacteria
 reabsorption of water, Na+, K+ from intestinal lumen to capillaries
 motility by peristalsis: rhythmic contractions of circular and longitudinal smooth muscles lining large intestine slowly force
fecal matter down intestinal tract
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6.1.6. Distinguish between absorption and assimilation.
 absorption: movement of chemical substances from the lumen of the digestive tract across the membranes of cells lining the
digestive tract by diffusion, facilitated diffusion, or active transport, and then either into the circulatory or lymphatic systems
for distribution to all somatic cells
 assimilation: following digestion and absorption, nutrients are taken into somatic cells and converted to the biomass of the
organism
6.1.7. Explain: how the structure of the villus is related to its role in absorption and transport of the products of digestion.
A. surface area:
 folding: intestinal folding increases surface area by 3X;
 villi: within each fold, a second set of folds creates a series of villi, with each villus being a finger-like projection, increasing
intestinal surface area by an additional 10X;
 microvilli: along the lumen side of each small intestine epithelial cell a brush border of microvilli additionally expands
surface area by another 20X;
 thus, the total surface area increase = 3 x 10 x 20 = 600x
B. membranes of epithelial cells:
 diffusion of fatty acids, monoglycerides, fat-soluble vitamins, some mineral ions through membrane phospholipid bilayer
 facilitated diffusion of some monosaccharides, some vitamins and mineral ions using membrane proteins
 active transport of amino acids, most monosaccharides, some mineral ions, using membrane proteins & ATP produced by
mitochondria in epithelial cells
C. blood capillaries:
 oxygenated blood enters villus supplying oxygen for cellular respiration:
 cell growth replacing lost/injured cells
 ATP for active transport
 deoxygenated blood leaves villus rich in absorbed nutrients: amino acids, monosaccharides, mineral ions, vitamins
D. lacteals = branches of lymphatic system:
 fatty acids and glycerol are reformed into triglycerides in epithelial cell smooth ER/Golgi apparatus
 triglycerides, with phospholipids and cholesterol, aggregate into chylomicrons which are coated with proteins and then leave
epithelial cells and enter lacteals
6.2 The Transport System
6.2.1. Draw and label a diagram of the heart showing the four chambers, associated blood vessels, valves and the route of
blood through the heart.
6.2.2. State that coronary arteries supply heart muscle with oxygen and nutrients.
6.2.3. Explain the action of the heart in terms of collecting blood, pumping blood, and opening and closing of valves.
A. the heart: composed mainly of contractile muscle tissue, supported by connective, nerve, and epithelial tissues
B. collecting of blood:
 deoxygenated blood enters the right atrium from the inferior and superior vena cava
 oxygenated blood enters the left atrium from the pulmonary vein
C. pumping of blood:
 contraction of the atria (right and left) pumps the blood into the ventricles (right and left)
 contraction of ventricles (right and left) pumps the blood into the pulmonary artery(right) and aorta (left)
D. opening and closing of valves:
 as a function of pressure differences, one-way valves prevent backflow of blood
 atrioventricular valves prevent backflow from ventricles into atria
 semilunar valves prevent backflow of blood from pulmonary artery into right ventricle and from aorta
into left ventricle
6.2.4. Outline the control of the heartbeat in terms of myogenic muscle contraction, the role of the pacemaker, nerves, the
medulla of the brain and epinephrine (adrenaline).
A. heartbeat: electrical impulses cause regular contractions of, first the two atria, and then the two ventricles
B. pacemaker and myogenic muscle contraction:
 the sino-atrial node (SAN), known as the pacemaker, is a specialized set of cells located on the right
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atrium
SAN, not the brain, generates regular electrical impulses autonomously
SAN impulses spread throughout both atria, causing simultaneous contraction
impulse spread to ventricles only at the atrio-ventricular node (AVN) with a delay of about 0.1 seconds
AVN transmits electrical signals to heart apex via bundles of His
signals trigger powerful contractions of both ventricles from the apex toward the atria
bundle of His transmits electrical signals throughout ventricles via Purkinje fibers, causing simultaneous
contraction of ventricles
C. nerve stimulation:
 sympathetic nerves
from brain release epinephrine, increasing heart rate
 parasympathetic nerves from brain via vagus nerve decrease heart
D. hormone stimulation:
 adrenaline (epinephrine) from adrenal medulla increase heart rate
rate
6.2.5. Explain the relationship between the structure and function of arteries, capillaries, and veins.
Vessel
structure
function
-inner endothelium
move blood away from heart
artery
-thick walls of smooth muscle
under very high pressure
with elastic fibers
(80-120 mm Hg) & high speed
-outer layer of connective tissue
(10-40 cm/sec)
with elastic fibers
vein
capillary
-inner endothelium
-thin walls of smooth muscle
with elastic fiber
-outer layer of connective tissue
with elastic fibers
-valves
move blood toward the heart
under very low pressure
(10 mm Hg) & moderate
speed (5-20 cm/sec)
-thin single layer of endothelium
-surrounded by basement membrane
-numerous
allow diffusion of dissolved
materials between blood & tissues
under low pressure (20-40 mm Hg)
prevent backflow of blood
6.2.6. State that blood is composed of plasma, erythrocytes, leucocytes (phagocytes and lymphocytes), and platelets
6.2.7. State that the following are transported by the blood: nutrients, oxygen, carbon dioxide, hormones, antibodies, urea and
heat.
6.3 Defense against infectious disease
6.3.1 Define pathogen: an organism or virus that causes disease
6.3.2 Explain why antibiotics are effective against bacteria but not viruses
 antibiotics block specific metabolic pathways found in bacteria, but not eukaryotic cells
 because viruses reproduce using the host cell (eukaryotic) metabolic pathways, they are unaffected
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antibiotics
antibiotics have produced great benefits world-wide in the control of bacterial diseases
o Staphylococcus infections controlled
o STD's, such as gonorrhea and syphilis controlled
antibiotic resistance has evolved in bacterial populations
by
6.3.3 Outline the role of skin and mucous membranes in defense against pathogens
 1st line of defense = nonspecific
 skin:
o tightly bound barrier of dead, keratin-rich epidermal cells
 tough, elastic, waterproof surface
o sebum: oily secretions from sebaceous gland in hair folicles,
o inhibits growth of pathogens
 mucous membranes:
o linings of intestinal tract, respiratory tract, eyes, genitals
o mucous traps microbes
o lysozymes: antibacterial enzymes
o cilia: clear respiratory tract
o acidity:
 stomach: pH = 2
 vagina pH = 5-6
preventing skin cracking
6.3.4 Outline how phagocytic leucocytes ingest pathogens in the blood and in body tissues:
 damage to tissues allows invasion across 1st line of defense
o microbes successfully invade body fluids or tissues
o damaged cells release histamine and other chemicals initiating inflammation
 phagocytes attracted to site by chemotaxis toward histamine
o phagocytes recognize microbes as foreign by antigen recognition
o variety of phagocytic cells: neutrophils (65% of WBCs, monocytes (4% of WBCs,
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macrophages
(derived from monocytes)
phagocytes endocytotically engulf microbes in phagosomes, which are digested by enzymes held in
lysosomes
o digested microbe fragments are displayed on cell membrane
o phagocytes with microbe fragments displayed = antigen-presenting cells: APCs
.3.5 Distinguish between antigens and antibodies
 antigen: a molecule recognized as foreign by the immune system; it elicits
 antibody: =immunoglobulin
o a globular protein
o recognizes an antigen by its complementary shape and charge
o thus allowing it to attach to the antigen specifically
o marking it for attack by the immune system
an immune response
6.3.6 Explain antibody production = Humoral response:
 macrophages:
o following phagocytotic digestion, display antigen on surface
o becoming antigen-presenting cells = APCs
 macrophage APCs activate helper T-lymphocytes
o only T-lymphocytes with receptor proteins specifically matching the antigen of the APCs
 B-lymphocytes activated by helper T-lymphocytes
o only those B-lymphocytes with antibodies specifically matching helper T-lymphocytes receptor
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proteins are activated
clonal selection of activated B-lymphocytes
o produces a large population of B-lymphocytes
 plasma cells
 memory cells
B-lymphocyte plasma cells produce massive quantities of antibodies (1000s/sec)
o by protein synthesis
o releasing antibodies by exocytosis
o into the surrounding humors
 blood
 tissue fluids
 lymph
antibodies adhere to antigens
o marking them for phagocytosis by macrophages
memory lymphocytes specific to the pathogen remain in elevated quantities
o B-lymphocytes & helper T-lymphocytes
o reside in the lymph nodes
o upon subsequent exposure to the antigen
 produce a rapid and intense response
 = secondary response
6.3.7 Outline the effects of HIV on the immune system
 reduction in the number of active lymphocytes
 loss of the ability to produce antibodies
6.3.8 Discuss the cause, transmission and social implications of AIDS
 disease: AIDS
 cause: HIV: human immunodeficiency virus
 transmission:
o sexually transmitted (vaginal, oral, anal)
o interstitial fluid
o blood-borne (transfusion, mother/child: placenta or breast milk, contaminated needles)
 social implications:
o the vast majority of cases are in Africa, with rapid increases in Asia
o changes in sexual behavior
o unease over blood transfusions
o ostracizing PWA
o breakdown of family structure
o huge drain on medical resources
o huge loss in work force
o drugs are available to control effects of HIV, but cost is high
o poor families have limited resources, and are impoverished by the cost of drugs;
o poor nations have little drug availability
 moral implications:
o do those with technology and wealth have an obligation to help others lacking such resources?
6.4 Gas Exchange
1. Distinguish between ventilation, gas exchange, & cell respiration.
ventilation = breathing, or the bulk movement of air into and out of the lungs, by:
 inhalation, which occurs when muscular contractions increase the volume
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of the lungs thus decreasing
the pressure so air enters the lungs,
exhalation, when muscular relaxation decreases the volume of the lungs thus increasing pressure so
gases exit the lungs
gas exchange = the process whereby O2 is acquired and CO2 is removed between respiring cells and the
environment; the gas exchange surface = alveoli
cell respiration = breakdown of glucose and other molecules in the mitochondria of cells creating a
constant demand for O2 and a need to eliminate CO2
Click to view an animation showing gas exchange: http://www.airinfonow.org/html/lungattack/lungplay.htm
2. Explain: the need for a ventilation system.
 adequate lung ventilation is essential
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to gas exchange which is turn essential to cell respiration and the
energy needs of cells, tissues, organs and organisms
ventilation provides a continual supply of fresh air to the lungs and helps to maintain a large diffusion
gradient for respiratory gases across the gas exchange surface of the alveoli
O2 must be delivered regularly to supply the needs of respiring cells
CO2 must be quickly eliminated from the body to reduce its toxic effects
3. Describe the features of alveoli that adapt them for gas exchange.
alveoli = the millions of thin-walled, dead-ends of the bronchioles forming clusters of air sacs acting as the respiratory surface with
features of:
 large surface area: surface area of the alveolar epithelium - 100 m2
 thin: single cell layer of epithelium across which diffusion occurs
 moist: gasses need to dissolve before passing membranes
 rich blood supply: extensive net of capillaries for transport of gasses to and from alveoli
Click to view an animation showing gas exchange:
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter44/animations.html#
4. Draw and label a diagram: trachea, bronchi, bronchioles, lungs
Click to view an animation showing lung anatomy: http://sprojects.mmi.mcgill.ca/resp/anatomy.swf
5. Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and
external intercostal muscles, the diaphragm and the abdominal muscles.
6.5 Nerves, Hormones and Homeostasis
6.5.1. State that the nervous system consists of the central nervous system (CNS) and peripheral nerves, and is composed of
cells called neurons that can carry rapid electrical impulses.
6.5.2. Draw and label the structure of a motor neuron.
6.5.3. State that nerve impulses are conducted from receptors to the CNS by sensory neurons, within the CNS by relay
neurons, and from the CNS to effectors by motor neurons.
6.5.4. Define resting potential and action potential (depolarization and repolarization).
resting potential = an electrical potential across a cell membrane when not propagating an impulse
action potential - the localized reversal (depolarization) and then restoration (repolarization) of electrical potential between the inside
and outside of a neuron as the impulse passes along it
6.5.5. Explain how a nerve impulse passes along a non-myelinated neuron.
role of Na+ ions:
 resting potential: Na+ ions concentrated outside membrane
 action potential: Na+ ions rush to inside of membrane
role of K+ ions:
 resting potential: K+ ions concentrated inside membrane
 action potential: K+ ions rush to outside of membrane
role of ion channels:
 resting potential: Na+ & K+ ion channels closed
 action potential: Na+ channels open 1st, then close, just as K+ ion channels open
role of active transport:
 Na+/K+ pump moves Na+ to outside & K+ to inside of membrane
 pumps ions against concentration gradients; ATP expended
 changes in membrane polarization:
1. resting potential: - 70 mV potential across membrane
2. action potential:
a. Na+ channels open, reversing membrane
potential to + 30 mV
b. K+ channels open, restoring membrane potential to - 70 mV
6.5.6. Explain the principles of synaptic transmission.
Ca+2 influx and release:
 action potential open Ca+ channels; Ca+ flows in
 Ca+ cause exocytosis of neurotransmitter at synaptic cleft
diffusion and binding of neurotransmitter:
 neurotransmitter diffuses across synaptic cleft
 neurotransmitter binds to post-synaptic receptor
polarization of the post-synaptic membrane:
 EPSP: Na+ channels open; post-synaptic membrane depolarization
 IPSP: K+ channels open; post-synaptic membrane hyperpolarization
subsequent removal of neurotransmitter:
 enzymes hydrolyze neurotransmitter; pre-synaptic recycling
communication between neurons & glands or muscles takes place in synapses
6.5.7. State that the endocrine system consists of glands that release hormones that are transported in the blood.
8. State that homeostasis involves maintaining the internal environment between limits, including blood pH, carbon dioxide
concentration, blood glucose concentration, body termperature and water balance.
6.5.9. Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback
mechanisms.
 set-point: a constant value to which a variable is constrained, such that any time the variable fluctuates
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outside a given set-point range, negative feedback takes actions to return the variable to its set-point
sensors: sensors respond to stimuli, gathering information about a variable in question, signaling when
its value fluctuates from the set-point
control center: receives information from sensors, comparing the value to a set-point, and if necessary,
directing actions to return the variable to its set-point
effectors: a mechanism for taking action to return a variable to its set-point, switching on or off under
the direction of the control center
responses: the resulting action produced by an effector, returning a variable to its set-point value
6.5.10. Describe the control of body temperature including the transfer of heat in blood, the roles of the hypothalamus, sweat
glands, skin arterioles and shivering.
body temperature:
 set-point: core body temperature = 37°C
 sensors: stimulus = body and blood temperatures above and below 37°C
a. hypothalamus thermostat sensitivity to blood temperature
b. skin warmth receptors
c. skin cold receptors
 control center:
a. hypothalamus thermostat
b. cerebral cortex
 effectors:
a. if T > 37°C
1) involuntary responses by sympathetic nervous system
a) vasodilation => increases heat loss
b) decreased basal metabolic rate => decreases heat production
c) sweating => increases heat loss
d) lethargy => decreases heat production
2) voluntary responses directed by cerebral cortex
a) rest => decreases heat production
b) behavioral responses (fanning, change to cooler clothing, cool drink)
b. if T < 37°C
1) involuntary responses by sympathetic nervous system
a) vasoconstriction => decreases heat loss
b) increased basal metabolic rate => increases heat production
c) shivering => increases heat production
d) piloerection (goose bumps) => decreases heat loss
2) voluntary responses directed by cerebral cortex
a) rest => decreases heat loss
b) behavioral responses (muscular activity, change to warmer clothing, warm drink, curling up,
eating)
 response:
a. if T < 37°C, effectors:
1) increase heat production,
2) decrease heat loss
3) until T = 37°C
b. if T > 37°C, effectors:
1) decrease heat production,
2) increase heat loss
3) until T = 37°C
11. Explain the control of blood glucose concentration, including the roles of glucagon, insulin and å and ß cells in the
pancreatic islets.
levels of blood glucose
 set-point: blood glucose = 90 mg/100 ml
 sensors: stimulus = blood glucose levels above and below 90 mg/100 ml
a. glucose detectors in pancreas islet beta cells detect high glucose levels
b. glucose detectors in pancreas islet alpha cells
detect low glucose levels
 control center:
a. pancreas islet beta cells
b. pancreas islet alpha cells
 effectors:
a. if blood glucose > 90 mg/100 ml, then pancreas beta cells produce and release insulin
b. if blood glucose < 90 mg/100
ml, then pancreas alpha cells produce and release glucagon
 response:
a. if blood glucose > 90 mg/100 ml
1) insulin binds to receptors in muscle and liver cell membranes
2)
moving glucose from the blood into liver and muscle cells
3) where glucose is either metabolized or stored as glycogen or
fatty acids
4) in fat cells, insulin promotes glucose entry where it is converted to triglycerides
5) until blood
glucose = 90 mg/100 ml
b. if blood glucose < 90 mg/100 ml
1) glucagon binds to receptors in liver cell membranes
2) which activates a cascade of enzymes which degrade glycogen into glucose
3) glucose moves from the liver into the
blood
4) until blood glucose = 90 mg/100 ml
12. Distinguish between type I and type II diabetes.
Click to view an interactive tutorial about diabetes:
http://www.diabetes.org/type-1-diabetes/well-being/LinkForLifeAd/link_for_life/main.html
6.6 Reproduction
6.6.1. Draw and label diagrams of the adult human male and female reproductive systems.
Figure 6.6.1 - The female reproductive system
Figure 6.6.2 - The male reproductive system
6.6.2 Outline the role of hormones in the menstrual cycle:
FSH:
 released by anterior pituitary
 promotes oogenesis in primary follicle in ovary
estrogen:
 produced by ovaries
o follicle cells
 during 1st half of menstrual cycle
o corpus luteum
 during 2nd half of menstrual cycle
 throughout pregnancy
 promotes secondary sexual characteristics:
o breast development
o pubic hair
o fatty deposits developing rounder hips
o female behavior pattern
 inhibits milk production by mammary glands
 increases thickness of endometrium of uterus
 inhibits FSH production in anterior pituitary
 at very high levels, stimulates LH & FSH production in anterior pituitary
LH:
 released by anterior pituitary in response to increasing estrogen levels
 stimulates ovulation:
o release of secondary oocyte into oviduct
o follicle remains in ovary and matures into corpus luteum
progesterone:
 produced by corpus luteum
o during 2nd half of menstrual cycle
o throughout pregnancy
 inhibits milk production by mammary glands
 increases/maintains thickness of endometrium of uterus
 inhibits FSH production in anterior pituitary
 inhibits LH production in anterior pituitary
3. Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormone
levels and ovulation, menstruation and thickening of the endometrium.
4. List three roles of testosterone in males.
 pre-natal development of male genitalia
 promotes development of sexual characteristics:
o primary:
 development of genitalia, ducts, glands
 spermatogenesis
o secondary:
 larynx growth
 facial, body, and pubic hair
 muscle and bone development
 male behavior pattern
 maintenance of sex drive
6.6.5. Outline: the process of in vitro fertilization (IVF)
 IVF is fertilization outside body / "in glass"
 drug stops normal menstrual cycle
 FSH injections into female stimulate more than one follicle to mature
 HCG matures the follicles
 secondary oocytes harvested from follicles at ovulation, via suction into
 sperm donated from male
 washing / capacitation of sperm
 sperm mixed with eggs in petri dish, or injected directly into egg
 development to blastocyst stage in petri dish
 up to 4 embryos placed in uterus
 if implantation is successful, one or more embryos will develop
 pregnancy test is done to see if implantation / pregnancy has occurred
 additional embryos frozen for future use
6.6.6. Discuss the ethical issues associated with IVF.
 sperm donated may or may not be from legal marriage partner
 property of frozen embryos after divorce or death of parents
 problems of long-term storage of embryos
 post-menopausal pregnancy
 ethics of competition for sperm from elite males (eugenics)
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