Physiology Flashcards
Which of the following is not an effect of somatostatin?
It stimulates pancreatic acinar cells to release lipase It decreases gastric acid secretion It decreases gastrin release It decreases pepsin secretion It decreases glucagon release
It stimulates pancreatic acinar cells to release lipase
It inhibits pancreatic enzyme secretion.
A 32 year old man has a glomerular filtration rate of 110ml / minute at a systolic blood pressure of 120/80. If his blood pressure were to fall to 100/70 what would glomerular filtration rate be?
110ml / minute 100ml/ minute 55ml/ minute 25ml/ minute 75ml/ minute
110ml / minute
The proposed drop in blood pressure falls within the range within which the kidney autoregulates its blood supply. GFR will therefore remain unchanged.
What is the most significant event to contribute to wound healing immediately following injury?
Neutrophil activation Platelet degranulation Endothelial cell proliferation Migration of tissue macrophages Proliferation of wound bed fibroblasts
Platelet degranulation
Many of these events contribute to healing. However, platelet degranulation is the earliest phase and results in haemostasis, the main event in then allowing the release of cytokines to attract other cells types to the wound and co-ordinate healing.
A 48 year old man undergoes a right hemicolectomy for a large caecal polyp. In the immediate post operative period which of the physiological processes described below is least likely to occur?
Glycogenolysis Increased production of acute phase proteins Increased cortisol production Bronchoconstriction Release of nitric oxide by vessels
Bronchoconstriction
Response to surgery
Sympathetic nervous system
Noradrenaline from sympathetic nerves and adrenaline from adrenal medulla
Blood diverted from skin and visceral organs; bronchodilatation, reduced intestinal motility, increased glucagon and glycogenolysis, insulin reduced
Heart rate and myocardial contractility are increased
Acute phase response
TNF-α, IL-1, IL-2, IL-6, interferon and prostaglandins are released
Excess cytokines may cause SIRS
Cytokines increase the release of acute phase proteins
Endocrine response
Hypothalamus, pituitary, adrenal axis
Increases ACTH and cortisol production:
increases protein breakdown
increases blood glucose levels
Aldosterone increases sodium re-absorption
Vasopressin increases water re-absorption and causes vasoconstriction
Vascular endothelium
Nitric oxide produces vasodilatation
Platelet activating factor enhances the cytokine response
Prostaglandins produce vasodilatation and induce platelet aggregation
Which of the following inhibits gastric acid secretion?
Histamine Nausea Calcium Parasympathetic vagal stimulation Gastrin
Nausea
Nausea inhibits gastric secretion via higher cerebral activity and sympathetic innervation.
A healthy man has a blood pressure of 120/80 mmHg and an intra cranial pressure of 17 mmHg. What is the approximate cerebral perfusion pressure?
103 mmHg 63 mmHg 83 mmHg 91 mmHg 76 mmHg
76 mmHg
Cerebral perfusion pressure= Mean arterial pressure - intra cranial pressure
The mean arterial pressure can be calculated as:
MAP= Diastolic pressure+ 0.333(Systolic pressure- Diastolic pressure)
In this situation the MAP = 93.
The ICP is subtracted from this value; 93 - 17 = 76
he cerebral perfusion pressure (CPP) is defined as being the net pressure gradient causing blood flow to the brain. The CPP is tightly autoregulated to maximise cerebral perfusion. A sharp rise in CPP may result in a rising ICP, a fall in CPP may result in cerebral ischaemia. It may be calculated by the following equation:
CPP= Mean arterial pressure - Intra cranial pressure
Following trauma, the CPP has to be carefully controlled and the may require invasive monitoring of the ICP and MAP.
