STRUCTURE-->FUNCTION
A secretory cell must synthesize, modify, and package large quantities of protein. Which two organelles would be especially important for this function?
Rough endoplasmic reticulum and Golgi apparatus.
A hollow organ repeatedly expands and contracts. Its epithelial lining changes appearance depending on how distended the organ is. What type of epithelium would you expect?
Answer: Transitional epithelium/urothelium.
Location: Urinary tract.
A pathologist observes cells undergoing shrinkage and fragmentation rather than swelling and rupture. Which type of cell death is occurring?
Answer: Apoptosis
A mild tissue injury occurs, but the progenitor cells and underlying supportive tissue remain intact. Which healing mechanism would you expect to predominate?
Answer: Regeneration.
regeneration requires progenitor cells and underlying supportive tissue to remain in place
A tissue's primary function is to receive, transmit, and integrate information from inside and outside the body to control bodily activity.
Which of the basic tissue types is being described?
Answer: Nervous tissue
Histology of an epithelial surface reveals numerous apical projections that beat in a coordinated fashion. What function would you expect these structures to perform?
Move material over the epithelial surface.
Structures: Cilia. The slides specifically describe cilia as beating in a coordinated fashion to move material parallel to the epithelial surface.
A tissue is composed primarily of parallel bundles of collagen fibers and is specialized to withstand force predominantly along one direction. Which type of connective tissue is most likely present?
Answer: Dense regular connective tissue.
Example: Tendon. The connective tissue lab specifically identifies dense regular connective tissue as forming tendons.
Histologic examination of injured tissue reveals dead cells with nuclear changes including pyknosis, karyorrhexis, and karyolysis. Which major form of cell death is occurring?
Answer: Necrosis
A dog sustains a mild skeletal muscle injury. Which cell population must remain viable to allow regeneration of new skeletal muscle fibers?
Answer: Satellite cells.
Satellite cells become activated after injury, proliferate, and fuse to form new skeletal muscle fibers
A spinal cord injury selectively damages the ventral root of a spinal nerve.
Would you expect the resulting deficit to primarily affect sensory input or motor output?
Answer: Motor output.
Why: Motor neuron cell bodies are located in the ventral horns, and their axons form the ventral roots.
Cardiac muscle cells must repeatedly contract without pulling apart from one another. Which component of the intercalated disc is most directly responsible for maintaining this mechanical attachment?
Answer: Desmosomes.
Bonus: Which component allows rapid transmission of action potentials between cells?
Answer: Gap junctions
Histology reveals striated, branched muscle cells connected end-to-end by specialized junctions. Which type of muscle tissue is present?
Answer: Cardiac muscle.
Key clue: Branching and intercalated discs distinguish it from skeletal muscle.
A dog develops an infarct in the kidney. Histology reveals dead cells, but the general outline and architecture of the affected tissue remain recognizable.
What type of necrosis is most likely?
Answer: Coagulative necrosis.
Reasoning: Tissue architecture initially remains recognizable despite cell death.
Two patients sustain similar injuries: one to smooth muscle and one to cardiac muscle.
Which tissue would you expect to have the greater regenerative response?
Answer: Smooth muscle.
Why: Viable smooth muscle cells can undergo mitosis, whereas cardiac muscle lacks satellite cells and has very little regenerative capacity.
A young dog with canine parvovirus develops severe damage to rapidly dividing cells of the gastrointestinal tract.
Why can the affected cell population potentially be replaced relatively rapidly once the injury stops?
Answer: These are labile cells, which continuously divide and have a high regenerative capacity.
Key connection: Canine parvovirus targets rapidly dividing/labile cells.
A cell suffers damage that severely impairs the function of its lysosomes. Which normal cellular process would be most directly affected?
Answer: Intracellular degradation/digestion of macromolecules.
Why: Lysosomes contain hydrolytic enzymes and are responsible for degrading macromolecules
A biopsy is taken from an area that must withstand substantial mechanical abrasion. Histology reveals multiple layers of epithelial cells, with flattened cells at the free surface. How should this epithelium be classified?
Answer: Stratified squamous epithelium.
Reasoning: In stratified epithelia, classification is based on the shape of the superficial cells.
A lactating dog develops a bacterial infection of the mammary gland. The affected tissue is red-black, wet, and necrotic.
What type of necrosis is occurring?
Answer: Wet gangrene.
Why: Wet gangrene combines coagulative and liquefactive necrosis and occurs with infection; the PowerPoint specifically uses bacterial infection of the mammary gland as an example.
Two animals sustain similar tissue injuries.
In Animal A, progenitor cells and the underlying supportive tissue remain intact.
In Animal B, both the progenitor cells and supportive tissue are destroyed.
Predict the predominant healing mechanism in each animal.
Answer:
A peripheral nerve is damaged and conduction of action potentials along affected axons becomes slower because the insulating sheath around the axons has been disrupted.
Which cell type normally produces this sheath in the PNS?
Answer: Schwann cells.
Why: Schwann cells form myelin around PNS axons, and myelin increases conduction velocity.
A genetic defect prevents hemidesmosomes from functioning normally, but the epithelial cells can still form normal junctions with neighboring epithelial cells. Which structural relationship would be specifically weakened?
Answer: Attachment of epithelial cells to the basement membrane/basal lamina and underlying extracellular matrix.
Why: Hemidesmosomes connect epithelial cells to the basal lamina/ECM rather than connecting one epithelial cell to another.
A histologic sample contains elongated, fusiform cells with tapered ends and centrally located nuclei. No striations are visible. The cells are connected by gap junctions and function involuntarily.
What tissue is this?
Answer: Smooth muscle.
A young animal develops severe skeletal and cardiac muscle injury associated with inadequate antioxidant protection from vitamin E and/or selenium.
What major mechanism of cellular injury is responsible?
Answer: Oxidative/free-radical injury.
Associated disease: White muscle disease.
Vitamin E helps neutralize free radicals, while selenium is required for glutathione peroxidase, and the lecture specifically identifies white muscle disease as an important veterinary example of free-radical injury.
A severe CNS injury results in permanent loss of neural tissue. Rather than being replaced by identical neurons or typical fibrous scar tissue, other CNS cells proliferate at the damaged site.
Which cells participate in this response, and what structure is produced?
Answer: Astrocytes and microglial cells → glial scar.
Clinical consequence: Glial scar formation can inhibit neurologic function.
A dog sustains an injury that damages the myelin-producing cells of the CNS, but the neurons themselves initially remain intact. The dog develops impaired conduction of nerve impulses.
Which cell type was damaged, and what is the functional consequence of losing its myelin?
Answer: Oligodendrocytes. Loss of CNS myelin would decrease the speed/efficiency of impulse conduction along the affected axons.
oligodendrocytes form myelin in the CNS, Schwann cells form it in the PNS, and myelin increases conduction velocity.