ANSC Final Exam Study Guide
(5 pages, 17 questions)
ANSC 23000 Physiology of Domestic Animals
Exam 1-February 2, 2017
1. (5 points) Explain what the term “semi-permeability” means, as it applies to the cell membrane.
The cell membrane is said to have the property of being “semi-permeable” because the cell membrane selectively partitions proteins, ions, hormones and other factors between the cytoplasm within the cell and the extracellular space surrounding the cell. Only specific molecules are able to traverse the cell membrane.
2. (5 points) Describe the structure of the cell membrane. Be certain to discuss what molecules compose the membrane and how these molecules are
arranged in the membrane, and why these molecules are arranged in this manner.
The cell membrane is composed of a phospholipid bilayer. The membrane consists of two layers of phospholipids that are polarized (meaning each phospholipid as a hydrophilic domain and a hydrophobic domain). The hydrophobic domains of the tail region of the phospholipids cluster together in the center of the membrane, with the hydrophilic head domains facing the extracellular (and intracellular) surfaces of the cell. We also discuss several other topics like What is the link between leadership and influence?
Don't forget about the age old question of What is evapotranspiration and why is it important?
3. (4 points) Distinguish between an integral protein and a peripheral protein associated with a cell membrane.
An integral protein is embedded within the cell membrane and typically spans the membrane from the extracellular surface to the intracellular surface. Peripheral protein associate with only one side of the membrane and are not embedded with the membrane.
4. (4 points) Compare and contrast the roles of the somatic and autonomic branches of the central nervous system (CNS).
The somatic branch deals with events that are voluntary and consciously perceived, with the autonomic branch deals with events that are involuntary and not consciously perceived.
5. (12 points) Consider this scenario: A neuron has a resting membrane potential of - 70mV. At this point, the neuron is treated with a chemical that inhibits voltage-gated potassium channels such that these channels are unable to open. We also discuss several other topics like What anhedonia mean?
a. (6 points) Could this neuron experience a graded potential? Why or why not? Yes, a graded potential could occur, as graded potentials are small fluctuation in the membrane resting potential that do not involve the voltage gated K+ channels.If you want to learn more check out What does life consist of?
b. (6 points) Now imagine that the membrane potential of this neuron was brought to threshold, while the voltage-gated potassium channels were inhibited (do
not worry about the mechanism by which this neuron reached threshold,
just assume that membrane potential reached a threshold while the
potassium channels were inhibited). Would it be possible for this neuron to
experience an action potential? Would this action potential be any different from an action potential observed in a neuron that was not treated with this inhibitor? Why or why not?
Yes, an action potential could be initiated if the cell were brought to a threshold. The threshold membrane potential would enable the voltage gated Na+ channels to open, allowing the cell to depolarize. The cell would have much difficultly performing repolarization because the voltage gated K+ channels are responsible for repolarization. Therefore a neuron in which the voltage gated K+ channels were blocked would have a very different action potential as compared to a neuron not treated with this inhibitor. Don't forget about the age old question of What is bulletin board system (bbs)?
6. (8 points) Consider this scenario: A neuroscientist has identified a compound that disrupts signaling in the synaptic cleft between preganglionic and
postganglionic neurons that use acetylcholine as a neurotransmitter. At
this point it is unclear how this compound works, we only know that
treatment with this compound prevents the postganglionic neuron from
propagating an action potential. Consider what you have learned about
how acetylcholine acts as a neurotransmitter. Provide two possible
targets upon which this drug could act to cause this effect. In other words, If you want to learn more check out Is another world possible?
what are two possible mechanisms by which this compound could disrupt
acetylcholine signaling in the synaptic cleft? Be sure to state how a
disruption at each of these points you indicate would interfere with
Ca++ uptake by the presynaptic cell could be blocked, thereby preventing exocytosis of vesicles containing acetylcholine.
Vesicles that transport acetylcholine in the presynaptic cell could be blocked, thereby preventing acetylcholine release.
Acetylcholine receptors on the postsynaptic cell could be blocked from responding to acetylcholine in
the synaptic cleft.
7. (3 points) Where is the cerebrospinal fluid (CSF) produced; what produces the CSF; where is CSF located?
The cerebrospinal fluid is made by the ependymal cells in the choroid plexus found in the ventricles in the brain. CSF flows through the ventricles and fills the spaces within the meninges.
8. (10 points) A subdural hematoma refers to a collection of blood that collects within the meninges, typically following a traumatic head injury.
a. (6 points) Where exactly in the meninges would a subdural
hematoma be found (that is, where is the subdural space located)? The subdural space is located between the inner layer of the dura
mater and the arachnoid mater.
b. (4 points) If a person with a subdural hematoma exhibited
blurred or unfocused vision and dilated pupils, which cranial
nerve(s) do you think would most likely be impacted by the increase in intracranial pressure resulting from the accumulation of blood in the subdural space? Provide a brief justification (one short
sentence is sufficient) in your answer.
Possibilities include cranial nerves II, III, IV and VI (optic, oculomotor, trochlear, and abducens, respectively). All of with control some aspect of vision (from registering sight to controlling the various muscles of they eye).
9. (6 points) The inner ear plays a critical sensory function in the sense of balance and equilibrium. Explain how the receptors within the macula and crista of the inner ear are stimulated to ultimately provide sensory input to the cortex to determine balance (a sense of equilibrium). Be sure to identify the key structures involved in this process.
The macula and crista possess sensory hair cells that are covered by the otolithic membrane. The otolithic membrane contains a series of calcium carbonate crystals of differing sizes (collectively called otoliths). Due to changes in head position brought about by gravity and changes in body movement, the otolithics will make contact with the hair cells; this contact initiates an action potential. This information is processed by the brain to provide a sense of body position, orientation and equilibrium.
10. (6 points) The lens of the eye must change its shape to adjust the focal length necessary to image objects that are either very near to the eye, or very far from the eye. This process is referred to as accommodation. What are the structures that enable accommodation to occur and where are these structures located in relation to one another? What must happen in order for the lens to become more convex?
To make a lens more convex, the ciliary muscle must contract to enable the tension on the zonular fibers to relax. As tension on the zonular fibers relaxes, the tension on the lens is reduced, which enables the lens to take on a more convex shape.
11. (8 points) Outline the key components of the posterior column pathway. Are the neurons in this pathways efferent or afferent?
The posterior column pathway involves the following afferent neurons: First order neurons serve as sensory receptors and synapse with second order neurons. Second order neurons (interneurons) are typically located in the spinal cord and brainstem. If the sensation reaches our conscious awareness, second order neurons will activate third order neurons I the thalamus.
12. (12 points) Consider the structure of the middle ear as you answer the following questions:
a. (2 points) What is the key role of the auditory ossicles?
The auditory ossicles bring sound waves detected by the tympanic membrane to the cochlear portion of the inner ear.
b. (3 points) What are the names of the three ossicles?
The three auditory ossicles are the Malleus (hammer), Incus (anvil), and Stapes (stirrup).
c. (4 points) Name the structures that are attached to the auditory ossicles (you do not need to indicate where these attachments take place).
The auditory ossicles attach to the tensor tympani, stapedius, tympanic membrane, and the oval window.
d. (3 points) If the auditory ossicles were damaged, how would
equilibrium be impacted? Explain your answer.
The auditory ossicles do not play a role in balance and orientation, therefore damage to these bones would not impact equilibrium.
13. (4 points) There is a slight chance for certain inner ear infections to lead to meningitis (an inflammation of the meninges). Knowing what you do about the
structure of the ear, why does this possibility exist?
The cochlear aqueduct connects the perilymph in the inner ear with the cerebrospinal fluid surrounding the brain, spinal cord, and meninges. An infection in the perilymph has a route to spread to the cerebrospinal fluid.
14. (5 points) What larger structure contains the dorsal root? What does one find within the dorsal root ganglia?
The dorsal root is part of a spinal nerve. The dorsal root ganglia contain cell bodies of sensory neurons.
15. (5 points) List two types of glial cells found in the central nervous system (CNS), tell me the function of one of these glial cells.
Major glial cells in the CNS:
Astrocytes-form the blood-brain barrier
Microglial cells-phagocytic cells that are activated in response to neuron injury Ependymal cells-part of the choroid plexus, responsible for CSF production.
16. (4 points) What is the role of the sodium-potassium (Na+/K+) ATPase located within cell membrane of neurons? How does this function relate to membrane potential?
The Na+/K+ ATPase (also referred to as the Na+/K+ exchanger) uses the energy from ATP
hydrolysis to move Na+ and K+ ions across the cell membrane against their respective concentration gradients. It moves three Na+ ions to the extracellular space from the cytoplasm for every two K+ ions in bring into the cytoplasm from the extracellular space. This exchanger, along with K+ and Na+ leak channels work to maintain the charge differential across the cell membrane such that a resting potential in maintained.
17. (4 points) How might a defect in the Schwann cells lead to defective salutatory propagation?
Schwann cells produce myelin to insulate the axons of neurons. Between the insulated axon regions lie the nodes of Ravier, these nodes are critical for salutatory propagation. A defect in schwann cells could lead to a defect in the myelin sheath the covers the axons, thereby perturbing the placement of the nodes of Ravier and thereby altering salutatory propagation.
6 pages; 16 questions
ANSC 23000 Physiology of Domestic Animals
Exam 2-March 2, 2017
1. (6 points) MATCHING (1 point each, 6 points total)
J_____ tether the atrioventricular valves to papillary muscles in the ventricles C_____ sites of attachment between tendon and bone
A_____ another name for the right atrioventricular valve
H_____ region on an EKG that represents ventricular repolarization
M_____ enzyme that is activated by nitric oxide (NO) to induce vasodilation E_____ portion of the atria that expands as the atria fill with blood
Each of the blanks above are to be matched with ONE of the following terms. All of the following terms are used NO MORE THAN one time; not all terms will be used. A. tricuspid valve
B. mitral valve
C. perforating fibers
D. Purkinje fibers
F. intercalated disc
G. QRS wave
H. T wave
J. chordae tendineae
K. cGMP L. hypoxia
M. guanylate cyclase
N. AV node
O. P wave
P. SA node
Q. cAMP R. neuromuscular junction
T. bicuspid valve U. voltage gated channels
2. (4 points) Compare and contrast the functions of osteoblasts and osteoclasts. Osteoblasts are the cells that produce new bone matrix; osteoclasts are the cells that breakdown and demineralize existing bone.
3. (6 points) Describe how growth occurs at the end of long bones. Be sure to relate how the major structures and cell types work together to increase the length of these bones.
Chondrocytes at the epiphyseal plate (growth plate) produce cartilage. Once the chondrocytes die off, osteoblasts are recruited to the cartilage template and bone is then produced in its place.
4. (6 points) Precocious puberty is a condition in humans in which puberty begins before the age of 8 years in girls. Girls with precocious puberty experience the same biological changes that normally accompany puberty (i.e., increase in steroid hormones produced by the ovaries, menstruation, breast growth). In addition, some girls that experience precocious puberty end up having a shorter stature as adults, as compared to their peers (that is, women who experience precocious puberty tend to be shorter adults than their peers). Consider how the skeleton grows and provide a possible mechanism to explain why girls who experience precocious puberty end up being slightly shorter than their peers, once they reach adulthood.
Estrogen levels increase at puberty. Estrogen promotes the closure of the epiphyseal growth plates. If puberty was initiated at a very young age, the early increase in estrogen could lead to the epiphyseal growth plates closing early, thereby limiting the length of the bones.
5. (6 points) Describe blood flow in the long bones. Indicate the names of the major blood vessels that bring blood to and from the bone. Also, be sure to mention where these major vessels are found and how the blood vessels are arranged within the long bones. The nutrient artery and nutrient vein enter and leave the bone through the nutrient foramen in the middle portion of the diaphysis. The metaphyseal (or epiphyseal) arteries and veins enter and leave the epiphysis at the ends of the long bones. Arterioles and capillaries are found through the bones within the central canal of the osteons.
6. (6 points) Describe the structure of a skeletal muscle. Be certain to discuss what makes up the following structures and what key function(s) these structures perform in the skeletal muscle: epimysium, perimysium, & endomysium.
Epimysium - outer covering of a skeletal muscle
Perimysium - surrounds the fascicles within a skeletal muscle.
Endomysium - surrounds individual muscle fibers within a skeletal muscle.
7. (10 points) Below is a micrograph of a section of skeletal muscle. I have labeled the M lines in this image. Please identify the 5 indicated structures in the blanks provided. Also please indicate what will happen to the relative size of each of these structures when a muscle fiber contracts. Simply circle the word, “increase”, “decrease”, or “no change” to reflect your answer. Look at picture
8. (3 points) If a skeletal muscle were treated with a drug that blocked Ca2+ from binding to troponin, how would sarcomere shortening be impacted? Provide a clear and concise rationale for your answer.
Calcium binding to troponin is required to allow the troponin-tropomycin complex to shift position in the thin filament to expose the active sites of actin. These active sites are critical for cross bridge formation with the thick filaments; these cross bridges are required for sarcomere movement. Without calcium binding to troponin, no shortening of the sarcomere can occur.
9. (2 points) What structure does ATP bind to within the sarcomere (be specific)? ATP binds the myosin head region.
10. (8 points) Explain how stimulation at the motor end plate results in skeletal muscle contraction. Discuss the critical signaling molecules (including where they are made, where they act, how they are regulated) and the intracellular components that are involved in this pathway. Begin with an action potential that has reached the axon terminal of a motor neuron and end with the release of Ca2+ into the sarcoplasm. You do not need to discuss the changes that occur between the thin and thick filaments within the myofibrils. Motor neurons release acetylcholine (Ach) into the neuromuscular junction. Ach binds its receptors on the motor end plate of the muscle fiber to cause the generation of an action potential within the muscle fiber. The action potential is
transported through the muscle fiber with the T-tubules; the action potential is what triggers the sarcoplasmic reticulum to release calcium into the sarcoplasm.
11. (10 points) Some symptoms of particular neuromuscular diseases can be treated by giving patients inhibitors of acetylcholinesterase.
a. (5 points) Please provide a brief explanation as to why blocking acetylcholinesterase activity might be useful in treating some symptoms of certain neuromuscular diseases. Acetylcholinesterases breakdown acetylcholine in the synaptic cleft at the neuromuscular junction. Inhibiting the breakdown of acetylcholine increase the amount of acetylcholine in the synaptic cleft and increases the chances of acetylcholine binding its receptor to initiate an action potential in the muscle fiber.
b. (5 points) As stated above, not all neuromuscular diseases have symptoms that can be treated with acetylcholinesterase inhibitors. Knowing what you do about the neuromuscular junction, if the motor neurons that impinged on the muscle fibers of the leg muscles were destroyed, would administering an acetylcholinesterase inhibitor help the individual regain use of this muscle? Explain your answer.
Acetylcholine is only released from the motor neurons; without the motor neurons to provide acetylcholine at the neuromuscular junction, treating with an inhibitor of acetylcholinesterases would would have no effect.
12. (6 points) What are the two factors that determine cardiac output?
Heart rate and stroke volume
13. (10 points) Coordinated contraction of cardiac muscle is necessary to move blood through the heart and through the blood vessels effectively. Explain how contraction of the atria and ventricles are coordinated. Be certain to discuss the key structures that are involved in generating action potentials in the heart and how action potentials travel throughout the heart.
The SA node is composed of conducting cells that spontaneously depolarize and generate action potentials. These action potentials move through the cells of the atria rapidly due to the intercellular connections between the cardiac muscle cells (called the intercalated discs);
this allows the cells of the atria to depolarize synchronously to contract synchronously. The action potential is also routed to the AV node by conducting fibers between the SA node and AV node; the action potential is delayed by roughly 100 microseconds in this way. After simulating the AV node, the action potential travels through the bundle of his (or AV bundle) and ultimately the Purkinje fibers found throughout the ventricles. The Purkinje fibers and the
intercalated discs enable the cardiac muscle cells of the ventricles to depolarize synchronously, and thereby contract synchronously.
14. (3 points) What does it mean if a vascular network displays autoregulation? The vascular network can maintain blood flow despite changes in blood pressure.
15. (8 points) Norepinephrine stimulation of the heart can cause an increase in heart rate, but this increase is only transient because of something called the baroreflex. Outline the key steps involved in the baroreflex that ultimately lead to a decrease in heart rate.
Baroreceptors are mechanically gated stretch receptors in the major blood vessels. An increase in heart rate can increase the pressure by which blood moves through the blood vessels. This increased pressure causes increased stimulation of the baroreceptors. Action potential from the baroreceptors are transmitted to the medulla to the cardioinhibitory center. Parasympathetic neurons then release acetylcholine which acts on the SA node to slow heart rate.
16. (6 points) A given hormone can cause a variety of responses in different tissues throughout the body. For instance, norepinephrine release can result in vasoconstriction by stimulating vascular smooth muscle to contract, yet lead to smooth muscle relaxation in the bronchioles when it acts in the lungs. Norepinephrine can cause also cause a transient increase in heart rate when in acts in the heart (as discussed in question 15, above). Please provide a brief explanation as to why it is possible for one hormone (e.g., norepinephrine) to cause such different things to happen in these tissues.
A given hormone can bind various receptors. Each receptor can cause different intracellular reactions in a target tissue.
6 pages; 15 questions
ANSC 23000 Physiology of Domestic Animals
Exam 3-April 6, 2017
1. (11 points) MATCHING (1 point each, 11 points total)
__F___ the amount of air that is only removed from the lung during forced exhalation __B___ law pertaining to gases at constant temperature that states that the amount of a particular gas in a solution is directly proportional to its partial pressure __E___ rate of ventilation that is faster than normal
__L___ region of the respiratory tract that does not participate in gas exchange __S___ enzyme reversibly converts carbon dioxide and water into bicarbonate __U___ name of a compound that binds to receptors in the bronchioles that leads to smooth muscle relaxation in the bronchioles
__V___ Portion of the mammalian respiratory tract responsible for phonation
__W___ Portion of the avian respiratory where gas exchange occurs
__M___ capillary system found in the kidney that plays a major role in absorption in the kidney
__X___ structure that transports urine from the renal pelvis to urinary bladder __R__ enzyme produced by the kidney that converts angiotensinogen into angiotensin I Each of the blanks above are to be matched with ONE of the following terms. All of the following terms are used NO MORE THAN one time; not all terms will be used. A. beta2-antagonist
B. Henry’s Law
D. inspiratory reserve
F. expiratory reserve
G. pharynx H. syrinx
I. residual volume
L. dead space
M. peritubular capillaries
P. guanylate cyclase
Q. Dalton’s Law
S. carbonic anhydrase
T. ACE (angiotensin
2. (4 points) Glucose is freely filtered at the glomerulus, but is not found in the urine unless glucose has a concentration greater than 180 mg glucose/deciliter of blood.
a. (2 points) Outline the mechanism by which glucose is reabsorbed from the glomerular filtrate.
Carrier proteins bring glucose from the lumen of the tubule, into the cells of the collecting tubule, then out of those cells and into the interstitial space surrounding the peritubular capillaries.
b. (2 points) As noted above, glucose is not found in the urine unless glucose in present in the blood at a level greater than 180 mg/deciliter. What is the term used to describe this apparent limitation of glucose transport out of the collecting tubule? Transport threshold or Transport Maximum
3. (6 points) The majority (>98%) of O2 that is carried by the blood is bound to hemoglobin. Carbon dioxide is transported in three forms by the blood. For this question,
identify two ways in which CO2 is transported by the blood. Simply indicate in what form CO2 is transported and where this form of CO2 is located during transport. Please use a full sentence to answer this question.
~7% of CO2 is dissolved in the plasma
~23% of CO2 is bound to hemoglobin
~70% of CO2 is converted to HCO3- by carbanic anhydrase (within the red blood cells), this HCO3- is exported from the red blood cells and transported in the plasma.
4. (10 points) Avian and mammalian respiratory systems mediate gas exchange, allowing the blood to acquire oxygen and release carbon dioxide.
a. (6 points) Describe the process of ventilation for birds and mammals, indicate the key structures involved in moving air through the respiratory tract, highlighting the differences regarding air movement between birds and mammals.
In mammals, the diaphragm contracts, enlarging the thoracic cavity. Air then enters the nasal passage, proceeds to the trachea, bronchi, bronchioles and finally arrives in the alveoli. To exhale, the diaphragm relaxes and the air flows back the way it entered.
In birds, air is moved into and out of the animal by contraction and relaxation of the abdominal and costal muscles; there is no diaphragm in birds. Air is brought into the animal through the trachea to the bronchi, across the neopulmonic parabronchi to the caudal air sacs, air is then moved to the paleopulmonic parabronchi, then to the cranial air sacs. After reaching the cranial air sacs, air is then sent out of the animal via the trachea.
b. (4 points) Where in the respiratory tract, and what structures in the respiratory tract mediate gas exchange in avian and mammalian respiratory systems? You DO NOT need to discuss the mechanism of gas exchange in this part of the question. Birds: parabronchi
5. (5 points) Explain why O2 moves from the alveoli to the blood in the capillary beds surrounding the alveoli, what is the driving force (or reason) that allows this movement of gas molecules to occur.
Partials pressures of Oxygen govern its movement. The partial pressure of Oxygen in the alveoli is greater than the partial pressure of Oxygen in the blood. Therefore Oxygen flows from alveoli to the blood.
6. (8 points) The macula densa serves a key role in regulating the glomerular filtration rate. This process is critical to maintaining homeostasis. If the kidney experiences a decrease in the glomerular filtration rate, what is the mechanism by which the macula densa directs changes to restore glomerular filtration rate back to normal levels? Macula densa releases prostaglandins that cause the juxtoglomerular cells to release renin. Renin converts angiotensinogen into angiotensin I; the enzyme ACE converts angiotensin I into angiotensin II; angiotensis II causes vasoconstriction of the efferent arteriole, allowing pressure to build up in the glomerulus. This increase in glomerular pressure promotes filteration.
7. (10 points) The nephron is the functional unit of the kidney; the processes of filtration, reabsorption, and secretion take place in various parts of the nephron. For this question, outline how the following structures are linked together to form the nephron: Loop of Henle, distal collecting tubule, Bowman’s capsule, proximal collecting tubule, afferent arteriole, peritubular capillaries, efferent arteriole, glomerulus, and the afferent arteriole. You can make a diagram if that helps you answer this question, but a labeled diagram alone is not a sufficient answer to this question.
The afferent artiole brings blood to the glomerulus and the efferent artiole takes blood away from the glomerulus after filtration has occurred. The efferent arteriole then branches to form the peritubular capillaries; these vessels surround the distal and proximal collecting ducts to absorb fluid. Bowman’s capsule surrounds the glomerulus and recieves the filtrate from the glomerulus. The filtrate moves into the proximal collecting duct, then loop of Henle, then the distal collecting duct.
8. (6 points) Vasopressin (also known as antidiuretic hormone, or ADH) is a peptide hormone released by the posterior pituitary gland.
a. (3 points) What causes ADH release?
An increased level of solutes in the plasma (or blood).
b. (3 points) If an animal were treated with a drug that inhibited the release of ADH, how would the composition of the urine change, if at all? Explain your answer. would see an increased volume of very dilute urine.
9. (4 points) The kidney is an important regulator of Ca++ concentration. The kidney produces a substance called calcitrol, which functions in Ca++ homeostasis. What is calcitrol derived from, what does calcitrol do to impact Ca++ levels, where does calcitrol act? Calcitrol is derived from vitamin D; calcitrol acts on the cells in the gastrointestinal tract and promotes calcium absorbtion from the intestine.
10. (4 points) How does mammalian blood cell production differ between the mammalian fetus and an adult mammal (that is, what are the respective sites of blood cell formation at these different stages of development)?
In the fetus, blood cells are produced by the liver, spleen and bone marrow, while in adults blood cells are produced by the bone marrow.
11. (5 points) Inflammation is an immediate response to tissue damage that can involve localized redness, pain, and swelling; inflammation can also cause fever. What changes take place in blood vessels during inflammation?
vasodilation and increased permeability
12. (6 points) What is the role of erythropoietin (EPO)?
promotes blood cell formation
13. (8 points) What is lymph, where and how is it formed, where does it travel, what is the final destination of lymph (to where does it eventually flow)? Be sure to identify the major structures involved in the movement of lymph.
Lymph is the fluid the is carried by lymphatic vessels. Lymph capillaries absorb interstitial fluid (which
forms from fluid that leaves the capillary beds of the circulatory system) and moves the fluid to an afferent lymphatic vessel. The afferent lymphatic vessel carries the fluid to a lymph node, and from there into an efferent lymphatic vessel before joining with the circulatory system again when the efferent lymphatic vessels join with veins.
14. (7 points) Assume a young animal was exposed to (and infected) by a virus and then completely recovered. Assume that this same animal was exposed to this same exact virus 6 months later and did not become infected. There are several ways the immune system may defend the body from this second exposure to the virus. How might the following parts of the immune system have helped to avoid infection in response to the second exposure to the virus: B-cells, antibodies, macrophages, opsonization.
B-cells will produce antibodies that recognize and bind to the antigens specific to the virus. This antibody coated antigen is then targeted for engulfment by macrophages; a process referred to as opsonization. This happens rapidly because the B-cells that are activated are referred to as “memory B cells”; these cells are poised to rapidly produce antibodies to a specific antigen.
15. (7 points) Identify 4 ways that debris and pathogens can be cleared from the respiratory tract, which mechanism poses the greatest risk for permanent damage to the mammalian respiratory tract?
engulfed by macrophages,
expectoration and bound in mucus,
dissolved in interstital fluid
carried by the blood if enters the capillaries
trapped in the alveoli and covered in fibrous scar tissue…..this is the most risky mechanism for the lungs because it reduces the total area available to perform gas exchange.
5 pages; 13 questions
ANSC 23000 Physiology of Domestic Animals
Exam 4-April 20, 2016
1. (16 points) Indicate where the following structures are located and the major role they play in the processes of nutrient uptake and/or reproduction:
Kϋpffer cells: fixed macrophages in the liver that work to detoxify the blood.
Chief cells: Located in the stomach; produce pepsinogen. Enterokinase: Produced in the small intestine; activated proenzymes Parietal cells: Located in the stomach; produce HCl
Vas deferens (ductus deferens):
Located between the epididymis and pelvic urethra; part of the male tubular reproductive tract that transports sperm
Corpus luteum: Located on the ovary; produces progesterone
Broad ligament: Structure that holds the female reproductive tract in place; connected to the dorsal wall of the abdominal cavity.
Leydig cells (interstitial cells): Located in the testis; produces testosterone
2. (10 points) Provide an overview of how cellulose is digested in cattle. Be certain to explain where cellulose is digested, how it is broken down and what the end-products of cellulose breakdown are. How does the breakdown of cellulose differ when it is digested in the horse?
Cellulose is broken down in the forestomach by microbial fermentation. The end products of fermentation include the volitle fatty acids (VFAs). Cellulose is processed in the cecum in the horse.
3. (10 points) Explain how digested fats from the lumen of the intestine enter the circulatory system. Be certain to discuss the key substances produced by the body that allow fats and lipids. Also, be sure to describe how the structure of the mucosa in the intestine facilitates absorption of nutrients (that is, what are the key anatomical features that allow absorption to occur?). Fats are mixed with bile and emulsified. Small droplets of fats for micelles that are absorbed by the microvilli on the enterocytes (the epithelial cells that line the intestinal mucosa). The intestinal mucosa
also possess villi that increase the surface area in the intestine to facilitate absorbtion. The center of the villi contain blood vessels and lymphatics. Once inside the enterocytes, the micelles are processed to form chylomicrons that are then excreted into the intersitial space at the center of the villi. Here, lymphatics and blood vessels are able to absorb the chylomicrons where they enter the circulatory system and are transported by the hepatic portal system to the liver.
4. (6 points) Outline how swallowing is mediated. Be certain to explain what happens during the oral (voluntary) phase, the pharyngeal phase, and the esophageal phase.
The food bolus is moved to the back of the troat to the pharynx where touch receptors are stimulated. These touch receptors invoke a reflex arch that involves the release of NO that relaxes the upper esophageal sphincter, allowing food to enter the esophagus; the esophagus then
creates a series of peristaltic contractinos that move the food down the esophagus. NO then causes the lower esophageal sphincter to relax so that food bolus enters the stomach.
5. (4 points) Where are Meissner’s plexus and the Auerbach plexus located? What part of the nervous system do they belong?
Meissner’s plexus is located between the mucosa and muscularis layers in the intestine, while the Auerbach plexus is located between the inner circular and outer longitudinal layers of the muscularis of the intestine. Both are parts of the enteric nervous system.
6. (8 points) Differentiate between the endocrine and exocrine portions of the pancreas. What are the major cell types that compose these two portions, and what substances do these two portions produce?
The endocrine portion of the pancreas includes the alpha cells (which produce glucagon) and the beta cells (which produce insulin). These hormones are released into the blood to travel to their target tissues. The exocrine portion includes the acinar cells, which produce pancreatic enzymes that flow via a duct to the intestine to facilitate digestion.
7. (8 points) How does the liver recover bile salts after bile is released to the intestine to facilitate lipid and fat emulsification?
Blood is transported by the hepatic portal blood vessels to the liver. Blood then flows into the sinusoids that are lined by hepatocytes. The hepatocytes absorb the nutrients that were absorbed in the intestine and process them to recover the bile salts. The bile salts are then excreted into the bile canniculi in the liver, which allows bile to flow into the gall
8. (5 points) What blood vessel network brings nutrients absorbed by the intestine to the liver?
The Hepatic Portal System.
9. (8 points) Explain how sex is determined in mammals. Be brief but specific. Your answer should include the following points: 1) the general mechanism by which sex is determined, 2) what specifically determines the sex of mammals and 3) how this determining agent works to determine sex in mammals.
Sex is determined genetically in mammals. Presence of a Y chromosome (which contains the sex determining gene, SRY) causes an embryo to be male. SRY is a transcription factor, which activates the cascade of genes that cause the indifferent gonad to differentiate into a testis. In female embryos, there is no Y chromosome. Without SRY, the indifferent gonad will, by default, develop into an ovary.
10. (4 points) What would happen with regard to the development of the tubular reproductive tracts in each of the following scenarios? Tell me which duct system would continue to develop, and which duct system would regress.
a. in a genetically female embryo if the indifferent gonads were removed and the embryo treated with MIH and testosterone?
The paramesonephric ducts will regress and the mesonephric ducts will proliferate.
b. in a genetically male embryo if the indifferent gonads were removed and the embryo treated with testosterone and MIH?
The paramesonephric ducts will regress and the mesonephric ducts will proliferate.
11. (6 points) Differentiate between the terms “seminal plasma” and “semen”. Seminal plasma is the liquid fraction of the ejaculate that is produced by the accessory glands; semen in the combination of seminal plasma and sperm cells.
12. (8 points) Where is the hormone LH produced in males, in females? What are the major target tissues of LH in males and females, respectively? LH is made in the anterior pituitary in both males and females. In males, LH
acts on the Leydig cells in the testes; LH acts on the follicular and luteal cells of the ovary in females.
13. (9 points) The following diagram represents how estradiol, progesterone, PFG2α, and LH change in concentration over the bovine estrus cycle. Use this diagram to help you address the following questions:
1. What process is occurring at point A in the cycle?
2. What process is occurring at point B in the cycle?
3. Circle the region on the graph where you would expect to observe estrus.