BCSE Veterinary Anatomy and Physiology 3 — Questions and Answers
Question 1: In the avian respiratory system, which structures allow unidirectional airflow through the lungs?
- Alveoli and bronchioles
- Air sacs and parabronchi (Correct answer)
- Syrinx and tracheal rings
- Nares and infraorbital sinuses
Correct answer: Air sacs and parabronchi
Air sacs act as bellows to move air through rigid parabronchi in a unidirectional pattern, allowing continuous gas exchange during both inhalation and exhalation.
Question 2: Which muscle is responsible for the main propulsive force during inspiration in most mammals?
- External intercostal muscles
- Internal intercostal muscles
- Serratus ventralis
- Diaphragm (Correct answer)
Correct answer: Diaphragm
The diaphragm is the primary muscle of inspiration; its contraction flattens the thoracic cavity, increasing volume and drawing air into the lungs.
Question 3: What is the name of the specialized myocardial cells that form the ventricular conduction pathway from the bundle of His to the ventricular walls?
- Purkinje fibers (Correct answer)
- Gap junctions
- Intercalated discs
- Bachmann's bundle fibers
Correct answer: Purkinje fibers
Purkinje fibers are large, rapidly conducting cardiac muscle cells that transmit the electrical impulse from the bundle branches to the ventricular myocardium.
Question 4: Which feline-specific anatomical feature explains why cats are obligate carnivores unable to synthesize sufficient taurine endogenously?
- Absence of a functional gallbladder
- Very limited hepatic cysteine sulfinic acid decarboxylase activity (Correct answer)
- Lack of bile acid conjugation capacity
- Absence of hepatic glucokinase enzyme
Correct answer: Very limited hepatic cysteine sulfinic acid decarboxylase activity
Cats have very low activity of cysteine sulfinic acid decarboxylase, the rate-limiting enzyme for taurine synthesis, making dietary taurine essential.
Question 5: The tarsal glands (Meibomian glands) in the eyelid produce secretions that contribute to which layer of the tear film?
- Aqueous layer
- Mucin layer
- Lipid layer (Correct answer)
- Cellular debris layer
Correct answer: Lipid layer
Tarsal (Meibomian) glands produce a lipid-rich meibum that forms the outermost layer of the tear film, retarding evaporation.
Question 6: Which bone of the equine forelimb is commonly called the 'coffin bone' and is enclosed within the hoof capsule?
- Proximal phalanx (P1)
- Middle phalanx (P2)
- Distal phalanx (P3) (Correct answer)
- Navicular bone
Correct answer: Distal phalanx (P3)
The distal phalanx (P3, pedal bone) is the third phalanx, entirely enclosed within the hoof capsule and the primary bone affected in laminitis.
Question 7: In the cat, which anatomical structure is responsible for the tapetum lucidum that causes eyeshine in dim light?
- Choroid layer behind the retina (Correct answer)
- Corneal epithelium
- Lens capsule
- Optic disc
Correct answer: Choroid layer behind the retina
The tapetum lucidum is a reflective layer within the choroid of the eye that reflects light back through the photoreceptors, enhancing night vision.
BCSE Veterinary Anatomy and Physiology 3
In the avian respiratory system, which structures allow unidirectional airflow through the lungs?