BCSE - Basic and Clinical Sciences Examination Veterinary Anatomy and Physiology Questions and Answers — Questions and Answers
Question 1: A 6-year-old Quarter Horse presents with epistaxis and dysphagia. Endoscopic examination reveals a fungal plaque on the caudodorsal aspect of the medial guttural pouch, overlying a large artery. Which artery is most likely affected?
- Maxillary artery
- External carotid artery
- Linguofacial trunk
- Internal carotid artery (Correct answer)
Correct answer: Internal carotid artery
The internal carotid artery courses over the caudodorsal aspect of the medial guttural pouch and is the most common site for mycotic plaque formation leading to life-threatening hemorrhage. The external carotid and maxillary arteries are also associated with the guttural pouch, but the internal carotid's path makes it particularly vulnerable in this specific location.
Question 2: Which of the following statements most accurately describes a key physiological difference between the avian and mammalian respiratory systems?
- Avian lungs are highly elastic and expand significantly during inspiration.
- Mammals utilize a crosscurrent exchange system for maximum oxygen uptake.
- Birds have a unidirectional flow of air through their lungs, facilitated by air sacs. (Correct answer)
- Gas exchange in mammals occurs primarily in structures called parabronchi.
Correct answer: Birds have a unidirectional flow of air through their lungs, facilitated by air sacs.
The avian respiratory system is unique in that it features a unidirectional flow of air through rigid lungs, a process made possible by a system of air sacs. This allows for continuous gas exchange during both inspiration and expiration. In contrast, mammals have tidal airflow (in and out) in elastic lungs where gas exchange occurs in alveoli, not parabronchi. The crosscurrent exchange system is characteristic of birds, not mammals.
Question 3: A 10-year-old female spayed domestic shorthair cat is being evaluated for chronic kidney disease. Which of the following is considered the most sensitive indicator of its glomerular filtration rate (GFR)?
- Blood urea nitrogen (BUN)
- Urine specific gravity
- Serum creatinine
- Plasma clearance of iohexol (Correct answer)
Correct answer: Plasma clearance of iohexol
Plasma clearance of an exogenous marker like iohexol is considered the gold standard and most sensitive method for measuring GFR in clinical practice. While serum creatinine and BUN are commonly used, they are less sensitive markers and can be influenced by non-renal factors like muscle mass (for creatinine) and diet (for BUN). Urine specific gravity assesses tubular concentrating ability, not directly the filtration rate.
Question 4: A beef steer on a high-concentrate feedlot diet presents with anorexia, depression, and a staggering gait. Rumenocentesis reveals a pH of 4.8. The primary pathophysiological event responsible for this condition is the rapid fermentation of carbohydrates leading to an excessive production of which substances?
- Ketone bodies and ammonia
- Volatile fatty acids and lactic acid (Correct answer)
- Bicarbonate and phosphate
- Methane and carbon dioxide
Correct answer: Volatile fatty acids and lactic acid
Acute ruminal acidosis (grain overload) is caused by the ingestion of large amounts of highly fermentable carbohydrates. This leads to a massive and rapid production of volatile fatty acids (VFAs) and, crucially, lactic acid by rumen microbes. The accumulation of these acids overwhelms the rumen's buffering capacity, causing a sharp drop in pH and leading to the clinical signs observed.
Question 5: A dog is diagnosed with a ruptured cranial cruciate ligament (CCL). The instability caused by this injury, known as a positive cranial drawer sign, is due to the loss of the ligament's primary function. What is the primary function of the CCL in the canine stifle?
- To prevent abduction or varus angulation of the stifle
- To prevent hyperextension and limit internal rotation of the tibia (Correct answer)
- To prevent the femur from slipping caudally on the tibial plateau
- To provide shock absorption and distribute load within the joint
Correct answer: To prevent hyperextension and limit internal rotation of the tibia
The cranial cruciate ligament's main role is to prevent cranial translocation (forward movement) of the tibia relative to the femur. It also plays a crucial role in preventing hyperextension of the stifle joint and limiting internal rotation of the tibia. Preventing varus/valgus angulation is the primary role of the collateral ligaments. Preventing caudal slippage is the function of the caudal cruciate ligament, and shock absorption is a primary function of the menisci.
Question 6: During a neurological examination of a dog, the veterinarian notes an absence of the palpebral reflex and a slight drooping of the ear and lip on the left side. These clinical signs are most indicative of dysfunction of which cranial nerve?
- Cranial Nerve V (Trigeminal)
- Cranial Nerve III (Oculomotor)
- Cranial Nerve VII (Facial) (Correct answer)
- Cranial Nerve XII (Hypoglossal)
Correct answer: Cranial Nerve VII (Facial)
Cranial Nerve VII, the facial nerve, is primarily responsible for motor innervation to the muscles of facial expression, including those that control the eyelids (orbicularis oculi), ear (pinna), and lips. A deficit in this nerve leads to facial paralysis, manifesting as a dropped ear, drooping lip, and inability to blink (absent palpebral reflex). The trigeminal nerve (CN V) is mainly for mastication and facial sensation, the oculomotor (CN III) for eye movement and pupillary constriction, and the hypoglossal (CN XII) for tongue movement.
BCSE - Basic and Clinical Sciences Examination Veterinary Anatomy and Physiology Questions and Answers
A 6-year-old Quarter Horse presents with epistaxis and dysphagia.
Endoscopic examination reveals a fungal plaque on the caudodorsal aspect of the medial guttural pouch, overlying a large artery.
Which artery is most likely affected?