Cellular Housekeeping
A cardiac biopsy shows that adjacent cardiomyocytes can still contract, but electrical signals are no longer passing rapidly from one cell directly
Correct response: What are gap junctions?
Gap junctions permit inorganic ions and other water-soluble molecules to pass directly between adjacent cells. They are found in cardiac muscle and allow rapid communication between cells.
A spinal cord lesion primarily damages an area containing neuronal cell bodies while sparing the surrounding myelinated axons. Which type of matter was primarily damaged?
Correct response: What is gray matter?
Gray matter contains abundant neuronal cell bodies, whereas white matter is composed primarily of myelinated axons.
A tendon biopsy shows tightly arranged connective tissue designed to resist force primarily along one direction. Which type of connective tissue should predominate?
Correct response: What is dense regular connective tissue?
The connective tissue lab identifies dense regular connective tissue as the tissue forming tendons, whereas dense irregular CT forms structures such as fibrous capsules
A dog receives a drug that binds to a receptor with high affinity but produces no activation of that receptor. Instead, it prevents the endogenous ligand from producing its normal response. How should this drug be classified?
Correct response: What is an antagonist?
Antagonists have affinity for receptors but lack intrinsic activity/efficacy and prevent agonists from producing their effects.
A pathogen normally persists in a particular animal species in nature, allowing the pathogen to remain present even when no outbreak is occurring. What type of host is this animal?
Correct response: What is a reservoir host?
A reservoir host naturally maintains a pathogen in nature. This differs from an amplification host, where extensive pathogen multiplication increases transmission
An intestinal epithelial cell develops defective junctions that normally form a belt-like seal between neighboring cells. Water-soluble molecules can now pass between the epithelial cells more readily. Which junction has been disrupted?
Correct response: What is a tight junction (zonula occludens)?
Tight junctions seal adjacent epithelial cells and prevent passage of water-soluble molecules between them; the slides specifically identify them at the apical portion of intestinal epithelial cells.
A dog steps on a painful object. The sensory information reaches the spinal cord normally, but damage to one spinal nerve root prevents the motor command from leaving the spinal cord. Which root is damaged?
Correct response: What is the ventral root?
The dorsal root = sensory/afferent/incoming, while the ventral root = motor/efferent/outgoing
Following a bone injury, cells along the bone surface begin depositing osteoid that will later mineralize. Which bone cell is performing this function?
Correct response: What is an osteoblast?
Osteoblasts are found on bone surfaces and deposit the organic components of bone matrix. Once surrounded by matrix, they mature into osteocytes.
Two drugs can produce the same desired effect, but Drug A requires a much lower dose than Drug B to achieve it. Which pharmacologic property is greater for Drug A?
Correct response: What is potency?
Potency refers to the concentration/dose needed to produce a particular effect. A more potent drug requires a lower dose and has a lower EC50.
A parasite undergoes its asexual developmental stages within one host but must enter a different host to undergo sexual reproduction. How is the first host classified?
Correct response: What is an intermediate host?
The slides distinguish these based on what the pathogen/parasite does in the host: intermediate = asexual/developmental stages, while definitive = sexual reproduction.
A pathologist identifies intracellular accumulations of glycogen, lipid, and pigment within hepatocytes. Unlike mitochondria or lysosomes, these structures are nonliving products of cellular metabolism. What general cellular structures are being described?
Correct response: What are cell inclusions?
The Cytology lecture defines cell inclusions as nonliving, nonmoving cellular components generally formed from metabolic products and lists glycogen, lipids, and pigments as examples.
A neuronal membrane is depolarized by a stimulus, but threshold is never reached. What happens to the action potential?
Correct response: No action potential occurs.
Action potentials follow the all-or-none principle. Once threshold is reached, the full sequence of depolarization and repolarization occurs; a stimulus that does not reach threshold does not produce an action potential.
A young animal is forming a long bone by first developing a cartilage model that is progressively replaced by bone. Which type of ossification is occurring?
Correct response: What is endochondral ossification?
This distinguishes endochondral ossification from intramembranous ossification. In endochondral ossification, bone development occurs using a preexisting cartilage model.
A dog develops significant hypotension while anesthetized. The clinician wants to increase blood pressure by causing peripheral vasoconstriction. Which adrenergic receptor should the selected drug primarily stimulate?
Correct response: What is the α1-adrenergic receptor?
The slides identify α1 agonists as treatments for hypotension. Phenylephrine is a selective α1 agonist that produces vasoconstriction and increases blood pressure
A cat experiences severe hemorrhage. As circulating blood volume falls, cardiac output decreases and arterial pressure drops. The body activates responses that oppose the decrease in arterial pressure. What type of homeostatic control mechanism is occurring?
Correct response: What is negative feedback?
The hemorrhage lecture specifically connects blood loss, decreased cardiac output, decreased arterial pressure, and activation of the baroreceptor reflex as a negative-feedback response
A genetic defect prevents an epithelial cell from attaching properly to its underlying basal lamina. Cell-to-cell communication and adhesion between neighboring epithelial cells remain intact. Which junction is most directly affected?
Correct response: What is a hemidesmosome?
This requires distinguishing cell-to-cell junctions from cell-to-matrix attachment. Hemidesmosomes connect cells to extracellular matrix proteins or the basal lamina and are described as “half desmosomes,” rather than true intercellular junctions.
An action potential successfully reaches a presynaptic terminal, but voltage-gated calcium channels fail to open. What is the most immediate consequence at this chemical synapse?
Correct response: Neurotransmitter release will fail.
This makes them follow the sequence rather than just define a synapse: action potential reaches the terminal → voltage-gated Ca²⁺ channels open → Ca²⁺ enters → neurotransmitter-containing vesicles undergo exocytosis. Without Ca²⁺ entry, neurotransmitter release is disrupted.
A cow develops an infected mammary lesion. The affected tissue is red-black and wet, and histologically there is a combination of coagulative and liquefactive necrosis. What type of necrosis is present?
Correct response: What is wet gangrene?
The pathology PowerPoint describes wet gangrene as a combination of coagulative and liquefactive necrosis associated with infection and specifically uses an infected mammary gland as an example.
A patient is receiving a full agonist. A partial agonist is then administered and occupies a large proportion of the same receptors. Despite both drugs activating the receptor, the patient's overall response decreases. Why?
Correct response: The partial agonist produces a submaximal response and antagonizes the full agonist when it occupies the receptors.
A partial agonist activates the receptor but cannot produce the same maximal response as a full agonist. When it occupies enough receptors, it therefore antagonizes the effect of the full agonist
A dog with chronic kidney disease develops a decreased red blood cell count. Based on the kidney's endocrine functions discussed in class, decreased production of which hormone could contribute to this finding?
Correct response: What is erythropoietin (EPO)?
The renal lecture identifies the kidney as having endocrine functions involving erythrocytes and specifically lists erythropoietin among those functions.
A pancreatic secretory cell is still able to produce ATP and package cellular products, but it has a severe defect in the synthesis of proteins destined for secretion. Which organelle is most likely dysfunctional?
Correct response: What is the rough endoplasmic reticulum (RER)?
The RER is associated with ribosomes and is involved in protein synthesis, particularly proteins destined for secretion. The fact that ATP production and packaging remain intact helps rule out the mitochondria and Golgi complex.
A spinal cord injury selectively destroys the dorsal horn and dorsal root while leaving the ventral horn and ventral root intact. Based on the pathways affected, which function should be most directly impaired: sensory input into the spinal cord or motor output from the spinal cord?
Correct response: Sensory input into the spinal cord.
The dorsal horn receives afferent input from the dorsal nerve roots, whereas the ventral horn sends efferent axons through the ventral roots.
A severe hepatic injury destroys not only hepatocytes but also the local progenitor cells and the underlying supportive tissue. The animal survives. Which healing mechanism should now predominate?
Correct response: What is healing by repair?
This one makes them apply the determining factor rather than simply define the terms. Regeneration requires progenitor cells and intact supportive tissue. When both are lost, healing occurs by repair, with dead cells generally replaced by another cell type such as fibrous scar tissue.
A horse receives the same receptor agonist repeatedly over a prolonged period. Over time, the same exposure produces a smaller response. Testing shows that the total number of receptors on the cells has decreased. What cellular adaptation best explains the reduced drug response?
Correct response: What is receptor downregulation?
Long-term agonist exposure can cause receptors to undergo internalization and degradation, decreasing the total receptor number and therefore decreasing cellular sensitivity to the agonist. This specifically distinguishes downregulation from desensitization, which can occur without a significant change in receptor number
During a zoonotic disease outbreak, veterinarians work alongside physicians and environmental health professionals to investigate transmission and develop a coordinated control strategy. What overarching approach to health does this collaboration represent?
Correct response: What is One Health?
animal, human, and environmental health are interconnected and that veterinarians work collaboratively with professionals across those areas.