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MCQs Flashcards

1
Q

Iron circulates in the blood bound to:

a) Transcobalamin II.

b) Ferritin.

c) Transferrin.

d) Ferroxidase.

e) None of the above.

A

Transferrin

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2
Q

The splanchnic circulation

a) Includes blood supply to the heart, stomach, liver, spleen and pancreas

b) Is about 750 mls at rest

c) Increases after a meal by the action of functional hyperaemia

d) Is greatly increased throughout the digestive tract by parasympathetic stimulation

e) Is the sole source of blood flow to the liver

A

Increases after a meal by the action of functional hyperaemia

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3
Q

Which of the following statements about the liver is INCORRECT

a) Secretes hepcidin

b) Acts as a blood reservoir

c) Stores glycogen

d) Breaks down some hormones

e) Stores of most water soluble vitamins

A

Stores of most water soluble vitamins (it only stores one water soluble vitamin, B12)

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4
Q

Which of the following would NOT be observed in a healthy subject following experimental stretch of the rectum, when the subject does not want to defaecate?

Reflex relaxation of the internal anal sphincter.
Reflex relaxation of the external anal sphincter.
The Valsalva manoeuvre.
Reflex relaxation of pelvic floor muscles.
Straightening of the ano-rectal angle.

A

The Valsalva manoeuvre

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5
Q

Lipids

a) Excess lipids in the stomach stimulate the secretion of CCK

b) Lipids are metabolised by the brain as an important energy source

c) Chylomicrons are secreted from the small intestine directly into the blood

d) Most dietary triglyceride is stored in the liver

e) Free fatty acids can be taken up by muscle and liver

A

Free fatty acids can be taken up by muscle and liver

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6
Q

Fibre in the diet has which of the following functions

a) acts as a substrate for gut flora

b) relieves constipation

c) promotes satiety

d) reduces risk of haemorrhoids

e) all of the above

A

All of the above

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7
Q

Which statement about smooth muscle in the GI tract is INCORRECT

a) The cells are connected to one another by gap junctions

b) Contraction is dependent on Ca2+ - calmodulin within the cell

c) Contraction is not dependant on action potentials

d) Binding of actin and myosin can be blocked by troponin

e) Contraction can be stimulated by a range of stimuli

A

Binding of actin and myosin can be blocked by troponin
(troponin and myosin)

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8
Q

Which of the following statements regarding the autonomic nerve supply to the gut is INCORRECT?

a) Many sympathetic fibres travel to the gut via the prevertebral ganglia.

b) Autonomic fibres to the lower parts of the gut travel in the pelvic nerves.

c) Parasympathetic fibres synapse once before reaching the gut

d) Postganglionic parasympathetic nerves in the gut release transmitters including Ach and VIP.

e) Sympathetic action on the gut is generally inhibitory

A

Parasympathetic fibres synapse once before reaching the gut

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9
Q

Stimulation by the parasympathetic nerves:

Is essential for the initiation of gut motility
Causes relaxation of sphincters through the inhibitory post ganglionic fibres
Decreases gastric juice secretion
Increases exocytosis of stored proteins from the acinus cells of the salivary glands
Regulates opening of the external anal sphincter

A

Causes relaxation of sphincters through the inhibitory post ganglionic fibres

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10
Q

The enteric nervous system:

Can co-ordinate entirely intrinsic reflex activity within the digestive tract
Acts independently of any sensory input from the gut walls
Forms a single plexus lying in the submucosa
Has pacemaker cells which are known to have periodic influx of Na+ to cause a pacemaker potential
Extends from the top of the oesophagus to the rectum

A

Can co-ordinate entirely intrinsic reflex activity within the digestive tract

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11
Q

The hypothalamus and the pituitary are interconnected

a) by portal vessels carrying GnRH to the anterior pituitary

b) by portal vessels carrying prolactin to the hypothalamus

c) by nerve fibres carrying dopamine to the anterior pituitary

d) all of the above (A-C)

e) two of the above (A and C)

A

Two of the above (A and C)

(Prolactin acts on breast tissue)

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12
Q

Which is the INCORRECT statement about hormones which bind to intracellular receptors:

a) bind to cytoplasmic receptors associated with heat shock proteins

b) the hormone, receptor and attached heat shock protein pass through the nuclear membrane

c) the hormone causes a change in gene transcription

d) includes thyroid hormones

e) tend to cause relatively long term changes to cell function

A

The hormone, receptor and attached heat shock protein pass through the nuclear membrane (the heat shock protein does not pass through the nuclear membrane)

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13
Q

Calcitonin

a) is secreted by the C cells of the thyroid gland

b) stimulates the osteoclast activity

c) is an amine hormone

d) secretion is inhibited by gastrin

e) is a hypercalcaemic hormone

A

is secreted by the C cells of the thyroid gland

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14
Q

Which of the following factors can influence growth?

a) environmental

b) genetic background

c) physiological

d) gender

e) all of the above

A

All of the above

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15
Q

Which is the INCORRECT statement concerning competitive ELISA assays:

a) An unknown amount of the test hormone is mixed with a known amount of the same hormone which is labelled

b) A single antibody is required for each assay

c) A standard curve is constructed using samples of pure hormone at a range of known concentrations

d) The results can be quantified by, for example, a colour change

e) The higher the hormone concentration in the test sample the greater the colour change

A

The higher the hormone concentration in the test sample the greater the colour change

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16
Q

Which of the following stimulates food intake?

a) insulin

b) CCK

c) ghrelin

d) GLP-1

e) pancreatic polypeptide

A

Grehlin

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17
Q

Somatomedins (eg IGF1)

a) are secreted by the anterior pituitary

b) have a half life of a few minutes

c) have a negative feedback effect on the pituitary gland through a long direct feedback loop

d) decrease protein synthesis in the liver

e) trigger fusion of the epiphyses at puberty

A

trigger fusion of the epiphyses at puberty

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18
Q

The reduced growth that occurs in Achondroplasia is:

a) Is often a result of growth hormone deficiency

b) results in normal body proportions but overall short stature

c) results from deficiency of IGF1

d) commonly occurs in older dogs

e) is caused by a mutation in fibroblast growth factor 3 (FGFR3)

A

is caused by a mutation in fibroblast growth factor 3 (FGFR3)

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19
Q

db/db mice:

a) have a mutation in the leptin gene

b) are anoretic

c) have low levels of leptin

d) will cause wild type mice to stop feeding if joined in parabiosis experiments

e) tend to be unusually thin

A

will cause wild type mice to stop feeding if joined in parabiosis experiments

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20
Q

Insulin:

a) is secreted in response to an increase in blood glucose concentrations

b) stimulates the uptake of glucose by GLUT 4 transporters

c) stimulates the conversion of glucose to glycogen in the liver

d) stimulates increased triglyceride synthesis in adipose tissue

e) all of the above

A

all of the above

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21
Q

The thyroid gland secretes:

a) one hormone

b) two hormones

c) three hormones

d) four hormones

e) five hormones

A

three hormones

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22
Q

Which of the following is NOT an action of cortisol:

a) increased lipolysis in fat cells

b) increased gluconeogenesis

c) increased triglyceride synthesis

d) increased vascular tone

e) immunosuppression

A

increased triglyceride synthesis

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23
Q

Which of the following feedback loops best describes the action of cortisol on the hypothalamus?

a) indirect, long

b) direct, long

c) indirect, short

d) direct, short

e) none of the above

A

indirect, long

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24
Q

The anterior pituitary secretes:

a) thyrotrophin releasing hormone

b) dopamine

c) somatostatin

d) growth hormone

e) antidiuretic hormone

A

growth hormone

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25
Q

Which of the following factors increase growth hormone secretion?

a) sleep

b) hypoglycaemia

c) exercise

d) ghrelin

e) all of the above

A

all of the above

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26
Q

Which is the INCORRECT statement concerning competitive ELISA assays:

a) An unknown amount of the test hormone is mixed with a known amount of the same hormone which is labelled

b) A single antibody is required for each assay

c) A standard curve is constructed using samples of pure hormone at a range of known concentrations

d) The results can be quantified by, for example, a colour change

e) The higher the hormone concentration in the test sample the greater the colour change

A

The higher the hormone concentration in the test sample the greater the colour change

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27
Q

Which of the following hormones is NOT derived from tyrosine?

a) tri-iodothyronine

b) dopamine

c) adrenaline

d) thyroxine

e) calcitonin

A

Calcitonin (from cholesterol)

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28
Q

Which change would you see in a patient with restrictive respiratory disease compared to a healthy individual:

A. An increase in total lung capacity

B. An increase in inspiratory capacity

C. An increase in the residual volume

D. An increase in the forced expiratory volume

E. None of the above

A

None of the above

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29
Q

Physiologic deadspace is:

⦁The volume of the airways

⦁ The volume of those alveoli with no or very little blood flow

⦁The sum of the volumes of the airways and alveoli with no or very little blood flow

⦁The volume of the airways and the residual volume

⦁The sum of the volumes of the airways and alveoli with no blood flow and the residual volume

A

The sum of the volumes of the airways and alveoli with no or very little blood flow

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30
Q

The fractional composition of air in the alveoli is:

⦁20% oxygen, 0.04% CO2, 79.9% N2

⦁15% oxygen, 40% CO2, 45% N2

⦁10% oxygen, 46% CO2 44% N2

⦁13.2% oxygen, 5.3% CO2, 75.4% N2

⦁12.5% oxygen, 30.6% CO2, 56.9% N2

A

13.2% oxygen, 5.3% CO2, 75.4% N2

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31
Q

During normal inspiration the inter-pleural pressure changes from
A. 0 → +5 cm H20
B. 0 → -5 cm H20
C. -5 → -8 cm H20
D. -8 → -12 cm H20
E. -12 → -15 cm H20

A

C. -5 → -8 cm H20

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32
Q

The velocity of shortening of a muscle is

A. Directly proportional to the load

B. Inversely proportional to the load

C. independent of the load

D. proportional to the square of the load

E. None of the above

A

Inversely proportional to the load

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33
Q

Power is maximal

A.During contraction at the maximal velocity

B. During isometric contraction

C. During relaxation of the muscle

D. When the load is about 0.3 x the isometric tension

E. When the load is 0.5 x the isometric tension

A

When the load is about 0.3 x the isometric tension

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34
Q

Power equals:

Force x Velocity
Force x Distance
Work / Load
Force per unit time
Force x Time

A

Force x Velocity

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35
Q

Those skeletal muscles involved in finely tuned movements

A. Have relatively long fibres and short tendons

B. Have motor units consisting of relatively few muscle fibres

C. Are innervated directly by motor neurones with their nerve cell bodies in the brain

D. Have multiply innervated muscle fibres

E. Have very long sarcomeres

A

Have motor units consisting of relatively few muscle fibres

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36
Q

The end plate potential can be blocked by:

A. D-tubocurarine

B. Eserine

C. Nicotine

D. Ouabain

E. Atropine

A

D-tubocurarine

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37
Q

Graded contraction of skeletal muscle

A. is achieved by altering the number of muscle fibres activated in each motor unit

B. is achieved by changing the amplitude of the action potential in the individual muscle fibres

C. involves the recruitment of smaller motor units before larger ones

D. is only possible by altering the number of active motor units

E. is dependant on central inhibition

A

involves the recruitment of smaller motor units before larger ones

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38
Q

Excitation-contraction coupling in skeletal muscle involves all the following EXCEPT:

A. Generation of an end plate potential

B. Binding of Ca2+ to myosin

C. Formation of cross bridges between actin and myosin

D. Depolarisation along the transverse tubules

E. hydrolysis of ATP to ADP

A

Generation of an end plate potential

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39
Q

Skeletal muscle fibres adapted to endurance running

A. are classified as aerobic rather than anaerobic
B. are classified as white rather than red
C. have relatively few mitochondria
D. have a relatively low myoglobin content
E. are relatively sensitive to fatigue

A

are classified as aerobic rather than anaerobic

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40
Q

The initiation of Ca2+ release from sarcoplasmic reticular Ca2+ stores in skeletal muscle:

A. Depends directly on the entry of Na+ that takes place during the action potential

B. Depends on a regenerative process involving Ca2+ -induced Ca2+ release via ryanodine receptors

C. Involves interactions between dihydropyridine receptors and ryanodine receptors

D. Involves entry of Ca2+ through a tubular membrane dihydropyridine receptor

E. Requires an elevation of intracellular inositol trisphosphate as a coupling molecule

A

Involves interactions between dihydropyridine receptors and ryanodine receptors

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41
Q

Relaxation in skeletal muscle is mediated by

A. ATP depletion

B. Spontaneous breakdown of actin-myosin cross-bridges

C. Inactivation of myosin light chain kinase

D. Ca2+ extrusion by the plasma membrane Ca2+ pump

E. Active Ca2+ uptake into the sarcoplasmic reticulum

A

Active Ca2+ uptake into the sarcoplasmic reticulum

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42
Q

During contraction of a skeletal muscle

A. The A bands stay the same length, and the H and I bands shorten

B. The A and I bands shorten, and the H bands stay the same length

C. The I bands stay the same length, and the A and H bands shorten

D. The H bands lengthen, and the A and I bands shorten

E. All the A, I and H bands shorten

A

The A bands stay the same length, and the H and I bands shorten

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43
Q

The initiation of cross-bridge action is controlled in skeletal muscle
A. By an action of Ca2+ on myosin phosphatase
B. By an action of Ca2+ on allosteric binding sites present on the actin subunit
C. By an interaction between Ca2+ and myosin
D. By a reaction between Ca2+ and tropomyosin
E. By a reaction between Ca2+ and troponin

A

By a reaction between Ca2+ and troponin

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44
Q

Which of the following can mediate fast inhibitory synaptic transmission?

A. Nicotinic cholinergic receptors

B. Glutamate AMPA receptors

C. GABA receptors

D. Metabotropic glutamate receptors

E. Muscarinic cholinergic receptors

A

GABA receptors

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45
Q

Which of the following are the same for the NMJ and a chemical synapse in the CNS?

A. The axon terminal always forms a synapse in a similar location on its target

B. A mechanism for removing transmitter from the synapse is required

C. There is always convergence of input

D. There is always divergence of input

E. The neurotransmitters released are always the same

A

A mechanism for removing transmitter from the synapse is required

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46
Q

EPSP at a central synapse does not always evoke an action potential because:

A. EPSP may be subthreshold

B. There may be inhibitory synapses present

C. Dendrites do not propagate electrical signals very well

D. All of the above

E. None of the above; EPSPs at central synapses always cause an action potential

A

There may be inhibitory synapses present

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47
Q

Which of the following statements is INCORRECT?

A. Post synaptic response amplitude depends on the number of quanta of neurotransmitter and the number of neurotransmitter receptors

B Chemical synapses in the CNS often have subthreshold potentials

C. The excitatory neurotransmitter at the NMJ is ACh

D. The inhibitory neurotransmitter at the NMJ is dopamine

E. There is only one type of neurotransmitter at the NMJ

A

The inhibitory neurotransmitter at the NMJ is dopamine

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48
Q

Which of the following statements about neurotransmitter receptors is INCORRECT?

A. Stimulation of receptor can cause either an excitatory or an inhibitory post synaptic potential

B. Receptors are either ionotropic or metabotropic

C. All cholinergic receptors are blocked by atropine

D. Inhibitory receptors in the CNS are stimulated primarily by GABA

E. The most prevalent receptors in the ANS are either cholinergic or androgenic

A

All cholinergic receptors are blocked by atropine

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49
Q

Synapses in the CNS:

A. Are large when compared to the neuromuscular junction

B. Contain more neurotransmitter than at the neuromuscular junction

C. A single EPSP may not be sufficient to evoke an action potential

D. All release Ach

E. IPSPs result from release of glutamate

A

A single EPSP may not be sufficient to evoke an action potential

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50
Q

Which of the following are NOT found at chemical junctions?

A. Neurotransmitter synthesising enzymes

B. Synaptic vesicles

C. Degradative enzymes

D. Voltage sensitive gates on the post-synaptic membrane

E. Voltage sensitive gates on the pre-synaptic membrane

A

Voltage sensitive gates on the post-synaptic membrane

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51
Q

The end-plate potential results from activity in post-synaptic

voltage-gated Ca2+ channels
ligand-gated cation channels
voltage-gated K+ channels.
voltage-gated Na+ channels
Na+/K+ pumps

A

ligand-gated cation channels

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52
Q

Which of the following statements about an ECG is INCORRECT?
⦁The P wave represents atrial depolarisatiom
⦁The QRS wave represents ventricular depolarisation
⦁The peak of the QRS wave will precede a peak in a finger pulse in the same subject
⦁Electrical systole will shorten during exercise
⦁A prolonged QRS might indicate that there is first-degree atrioventricular block

A

A prolonged QRS might indicate that there is first-degree atrioventricular block

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53
Q

Which of the following responses would occur within seconds of a major blood loss?
⦁Increased release of catecholamines, angiotensin 11 and ADH
⦁Increased vagal tone to the heart
⦁Increased inhibition of vasomotor centre
⦁Decreased venous tone
⦁Increased parasympathetic activity

A

Increased release of catecholamines, angiotensin 11 and ADH

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54
Q

During whole body dynamic exercise which of the following would NOT occur
⦁An increase in systolic pressure
⦁An increase in mean arterial pressure
⦁An increase in pulse pressure
⦁A small change or no change in diastolic pressure
⦁An increase in total peripheral resistance

A

An increase in total peripheral resistance

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55
Q

Congestive heart failure may result in
⦁Failure to adequately pump blood from the veins to the arteries
⦁A high right atrial pressure
⦁An inability to increase cardiac output
⦁Increased capillary pressure
⦁All of the above

A

All of the above

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56
Q

Which of the following would NOT affect mean systemic filling pressure?
⦁Arteriolar constriction
⦁Venoconstriction
⦁Splanchnic nerve stimulation
⦁Increasing blood volume by 20%
⦁Haemorrhage

A

Arteriolar constriction

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57
Q

Oedema can result from
⦁Decreased capillary blood pressure
⦁Persistent tonic contraction of precapillary sphincters
⦁Decreased plasma albumin
⦁Abnormal reabsorption of fluid into the capillaries
⦁None of the above

A

Decreased plasma albumin

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58
Q

During aerobic exercise which of the following does NOT occur?
⦁Venous return stays the same
⦁Total peripheral resistance decreases
⦁Cardiac output rises in proportion to O2 consumption
⦁Arterioles within active muscles vasodilate due to build-up of vasoactive metabolites
⦁Mean systemic filling pressure increases

A

Venous return stays the same

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59
Q

Which of the following statements concerning blood pressure is correct?
⦁Normal blood pressure should be in the range of 160/90mmHg
⦁Mean arterial blood pressure = systolic + 1/3 pulse pressure
⦁In the normal physiological range blood pressure is sensed by the carotid and aortic bodies
⦁High blood pressure can cause oedema
⦁Blood pressure tends to decrease in old age

A

High blood pressure can cause oedema

60
Q

Which of the following statements concerning fetal circulation is INCORRECT?
⦁Fetal blood carries relatively more oxygen than maternal blood
⦁Fetal haemoglobin releases its bound oxygen at a lower pO2 than maternal haemoglobin
⦁Oxygenated blood from the placenta bypasses most of the fetal liver
⦁Blood is shunted from the right atrium to the left
⦁There is high blood flow through the fetal pulmonary system

A

There is high blood flow through the fetal pulmonary system

61
Q

Poiseuille’s law states that the resistance of a blood vessel is:
⦁Inversely proportional to the square of its radius
⦁Directly proportional to the square of its radius
⦁Directly proportional to the fourth power of its radius
⦁Inversely proportional to the fourth power of its radius
⦁Inversely proportional to the square root of its radius

A

Inversely proportional to the fourth power of its radius

62
Q

During normal ventricular ejection:
⦁The right ventricle contracts before the left
⦁The pressure in both ventricles is similar
⦁The mitral value opens
⦁The pressure in the ventricles rises above the diastolic pressure
⦁90% of the blood in the ventricles is ejected

A

The pressure in the ventricles rises above the diastolic pressure

63
Q

Which of the following statements about the action potential in a ventricular myocyte is true?
⦁There is a plateau phase during which there is reduced permeability to K+ attributable to rectification properties of the K+ channel
⦁There is a pacemaker potential carried by the ‘If’ current which sets the overall heart rate
⦁During the upstroke the major current is carried by Ca2+
⦁During the plateau phase the major current is a result of prolonged activation of the Na+ channels
⦁Abnormally high frequency of action potentials could result in tetany

A

There is a plateau phase during which there is reduced permeability to K+ attributable to rectification properties of the K+ channel

64
Q

Ca2+ is involved in which phase of the action potential of the sino-atrial node of the heart?
⦁The funny current
⦁The upstroke
⦁The plateau
⦁The downstroke
⦁None of the above

A

The upstroke

65
Q

Which of the following is responsible for decreasing tension following contraction of striated muscle?
⦁Ca2+extrusion by the plasma membrane Ca2+ pump
⦁Active Ca2+ uptake into the sarcoplasmic reticulum
⦁ATP depletion
⦁Spontaneous breakdown of the actin-myosin cross bridges
⦁None of the above

A

Active Ca2+ uptake into the sarcoplasmic reticulum

66
Q

Which source of energy would be primarily utilised at the start of exercise?
⦁Stored ATP
⦁Creatine phosphate
⦁ATP from anaerobic metabolism
⦁ATP from aerobic metabolism
⦁Lipid metabolism

A

Stored ATP

67
Q

Which of the following statements about the contraction of smooth muscle is INCORRECT?
⦁Ca2+ enters the cell during the upstroke of any action potential
⦁Ca2+ binds to calmodulin to form a Ca2+-calmodulin complex
⦁The Ca2+- calmodulin complex activates the myosin light chain kinase
⦁The activated myosin light chain kinase phosphorylates the myosin regulatatory light chain enabling cross bridge formation
⦁Decreased Ca2+ levels will terminate contraction

A

Decreased Ca2+ levels will terminate contraction

68
Q

Which of the following statements with respect to contraction of skeletal muscle is CORRECT?
⦁Force = Power x Velocity
⦁Maximum power is developed when all the cross bridges are engaged on the thin filaments
⦁Total tension developed by each myofibril equals the sum of the tension developed by each individual sarcomere
⦁There are about 1500 cross bridges on each half of a thick filament
⦁During tetanus Ca2+ is bound to 50% of the troponin C binding sites

A

Maximum power is developed when all the cross bridges are engaged on the thin filaments

69
Q

Which of the following enables cross bridge formation in skeletal muscle?
⦁The binding of Ca2+ to myosin
⦁The binding of Ca2+ to tropomyosin
⦁The binding of Ca2+ to troponin
⦁The binding of Ca2+ to myosin phosphatase
⦁The binding of Ca2+ to calmodulin

A

The binding of Ca2+ to troponin

70
Q

Which of the following are NOT either molecular motors or a function of molecular motors?
⦁Myosins
⦁Kinesins
⦁Actins
⦁Dyneins
⦁Transducers converting chemical energy to mechanical energy

A

Actins

71
Q

Dihydropyridine receptors in skeletal muscles are:
⦁Ca2+ channels on the T-tubules
⦁Ca2+ channels on the sarcoplasmic reticulum
⦁Voltage sensors on the T-tubules
⦁Voltage sensors on the sarcoplasmic reticulum
⦁Ca2+ receptors on the end plate

A

Voltage sensors on the T-tubules

72
Q

Name the common feature between a nerve action potential and a motor end plate potential.
⦁Both obey the all-or-none law
⦁Both arise from the opening of voltage-gated ion channels
⦁Both depend on the strength of the stimulus
⦁Both are actively propagated
⦁Both are depolarising signals that require the influx of sodium ions

A

Both are depolarising signals that require the influx of sodium ions

73
Q

Which of the following statements about myelination is correct?
⦁Myelination is found only in vertebrates
⦁Increases conduction velocity of nerves by decreasing the length (or space) constant
⦁The conduction velocity for myelinated nerves is proportional to their diameter
⦁All post-ganglionic fibres in the autonomic nervous system are myelinated
⦁The myelin sheath is formed from collagen

A

The conduction velocity for myelinated nerves is proportional to their diameter

74
Q

Which of the following occurs at the peak of a nerve action potential?
⦁Voltage sensitive K+ gates begin to open
⦁The membrane potential reaches the equilibrium potential for Na+
⦁Voltage sensitive Na+ gates close in response to the voltage
⦁Voltage sensitive Na+ gates close in a time dependent manner
⦁Voltage sensitive Ca2+ gates open in response to the voltage

A

Voltage sensitive Na+ gates close in a time dependent manner

75
Q

In a squid axon bathed in a normal physiological saline, at what approximate potential would you have to clamp the membrane (zero outside) to prevent a net influx of sodium ions?
⦁- 100 mV
⦁+ 60 mV
⦁- 60 mV
⦁ 0 mV
⦁+ 150 mV

A

+ 60 mV

76
Q

If 10 picoamperes (10 x 10^-12 A) of current pass across a cell membrane resistance of 100 megaohms (100 x 10^6 Ω) what would the potential (voltage V) difference across the membrane be?
⦁1 Volt
⦁100 mV
⦁10 mV
⦁1 mV
⦁0.1 mV

A

1 mV

77
Q

Which of the following statements about the Na+/K+ pump is INCORRECT?
⦁The activity rate is dependant on the intracellular [Na+]
⦁The pump is blocked by glycosides such as digitalis
⦁It pumps 3K+ out of the cell in exchange for 2Na+ moved in
⦁It helps maintain the osmotic potential of the cell
⦁It is electrogenic

A

It pumps 3K+ out of the cell in exchange for 2Na+ moved in

78
Q

Movement of Ca2+ across a membrane can be the result of all of the following EXCEPT:
⦁Primary active transport
⦁Secondary active transport couple with K+
⦁Passive movement along a chemical gradient
⦁Opening of voltage sensitive gates
⦁Secondary active transport coupled with Na=

A

Secondary active transport couple with K+

79
Q

Which of the following statements about antiport exchangers is correct?
⦁They are fundamental to the short-term functioning of excitable tissues
⦁They always depend directly on the energy produced by primary active transport
⦁They are usually located on the basal membrane of a cell
⦁The movement of ions is dependant on the equilibrium potential of those ions
⦁They carry ions of the same charge in opposite directions

A

They carry ions of the same charge in opposite directions

80
Q

Which of the following would not be expected to affect the equilibrium potential of a specific ion?
⦁Extra-cellular concentration
⦁Intra-cellular concentration
⦁Ambient temperature
⦁Permeability of the membrane to other ions

A

Permeability of the membrane to other ions

81
Q

A patient suffering from Addison’s disease would show all of the following symptoms EXCEPT:
⦁Darkening of the skin
⦁Weakness and fatigue
⦁High levels of ACTH
⦁Low levels of cortisol
⦁Weight gain

A

Weight gain

82
Q

Which of the following statements about the posterior pituitary is correct?
⦁It is connected to the hypothalamus by a portal network
⦁It secretes 6 hormones
⦁Release of its hormones is stimulated by releasing or inhibiting hormones
⦁It synthesises the hormones it secretes
⦁It stores the hormones it secretes

A

It stores the hormones it secretes

83
Q

Which of the following variables is NOT controlled by negative feedback?
⦁Body temperature
⦁Salivation
⦁Plasma osmolarity
⦁Secretion of corticotrophin releasing hormone
⦁Blood pressure

A

Salivation

84
Q

Erythrocytes are about 6 µm in diameter what is this in cm?
⦁6 x 10^-2cm
⦁6 x 10^-3 cm
⦁6 x 10^-4 cm
⦁6 x 10^2 cm
⦁6 x 10^3 cm

A

6 x 10^-4 cm

85
Q

What is the equilibrium potential for 100nM CaCl2 +10mM mM KCl (test side) and 2mM CaCl2 +10mM KCl separated by a membrane permeable to Ca2+ at 37 o C ?
⦁-131 mV
⦁-91 mV
⦁-71 mV
⦁+71 mV
⦁+131 mV

A

+131 mV

86
Q

Which of the following compartments is closest to Claude Bernard’s “milieu intérieur”?
A. Cytoplasm
B. Extracellular fluid
C. Arterial blood
D. Lymph
E. Venous blood

A

Extracellular fluid

87
Q

Anticipatory changes in the control of action allow body temperature, blood glucose and PO2 to be more closely regulated than would otherwise be the case. Which of the following terms describes this form of control?
A. Positive feedback
B. Negative feedback
C. Feed-forward
D. Efferent
E. Constant

A

Feed-forward

88
Q

Instability in negative feedback loops can arise if:
A. The disturbance is very small.
B. The system response is very fast.
C. The system response is very slow.
D. The detectors are very sensitive.
E. The disturbance constantly changes.

A

The system response is very slow.

89
Q

Corticotrophin releasing hormone (CRH) directly results in the release of which of the following hormones?
A. Adrenocorticotrophic hormone (ACTH)
B. Cortisol
C. Aldosterone
D. Growth hormone
E. Vasopressin

A

Adrenocorticotrophic hormone (ACTH)

90
Q

What is the concentration of pure water, in moles per litre? The MW of H2O is 18 and the density of water can be taken to be 1 g.ml-1.
A. 1
B. 18
C. 56
D. 1000
E. Infinite

A

56

91
Q

Which of the following represents the approximate resting Ca2+ level in most animal cells?
A. 0.1 M
B. 1 mM
C. 10 μM
D. 100 nM
E. 10 pM

A

100 nM

92
Q

If a negatively chargedion is present at 120 mM outside a healthy nerve cell, and it is passively distributed across the cellmembrane, what would its intracellular concentration be?
A. ~1 mM
B. ~10 mM
C. ~100 mM
D. ~1 M
E. There is insufficient information available to answer this question.

A

There is insufficient information available to answer this question.

93
Q

The cardiac glycoside digitalis (from the foxglove) is a traditional treatment for the failing heart which works because:
A. It inhibits muscarinic acetylcholine receptors.
B It increases mitochondrial ATP production.
C. It stimulates the calcium ATPase in cardiac muscle.
D. It inhibits the sodium-potassium pump (Na+/K+-ATPase).
E. It increases the storage capacity of the sarcoplasmic reticulum.

A

It inhibits the sodium-potassium pump (Na+/K+-ATPase)

94
Q

Which of the following is a primary active transporter?
A. The sodium-potassium pump (Na+/K+-ATPase).
B. The sodium-glucose cotransporter SGLT1.
C. The glutamate uptake transporter.
D. The sodium-calcium exchanger (NCX).
E. The main acid-extruding intracellular pH regulator.

A

The sodium-potassium pump (Na+/K+-ATPase).

95
Q

Which of the following is the main excitatory transmitter in the central nervous system?
A. Glutamate
B. Glycine
C Acetylcholine
D. Noradrenaline
E. N-methyl D aspartate (NMDA)

A

Glutamate

96
Q

What is meant by an ionotropic receptor?
A. A receptor only activated by calcium ions.
B. A receptor which, when activated, directly causes the release of calcium ions from intracellular stores.
C. A receptor which is itself an ion channel.
D. A receptor which activates a G-protein.
E. A receptor which is activated by the ionized form of its transmitter.

A

A receptor which is itself an ion channel.

97
Q

Name the feature shared by a nerve action potential and a motor end-plate potential:
A. Both of the signals depend on the stimulus strength.
B. Both obey the all-or-none law.
C. Both arise from the opening of voltage-gated ion channels.
D. Both are actively propagated.
E. Both are depolarising signals that require an influx of sodium ions.

A

Both are depolarising signals that require an influx of sodium ions.

98
Q

In skeletal muscle:
A. The action potential is abolished by disruption of the transverse tubules by an osmotic shock.
B. The action potential has an enhanced after-hyperpolarization phase owing to prolonged transverse tubular inactivation.
C. There is an enhanced chloride conductance that enhances membrane excitability, thereby ensuring full activation of the transverse tubular system.
D. A reduction in chloride channel conductance is likely to permit inappropriate electrical activity following an action potential.
E. The after-depolarization phase that follows the action potential reflects a prolonged opening of surface sodium channels, which enhances conduction of the action potential along the surface membrane.

A

A reduction in chloride channel conductance is likely to permit inappropriate electrical activity following an action potential.

99
Q

The release of intracellularly-stored calcium in skeletal muscle following depolarisation:
A. Is dependent upon the transverse tubular membrane potential.
B. Is triggered by an influx of extracellular Na+ acting as a trigger for the sarcoplasmic reticulum.
C. Can potentially lead to re-entrant re-excitation, as illustrated by the clinical condition myotonia congenita.
D. Is dependent upon calcium-induced calcium release.
E. Follows an increased activity in the sodium-calcium exchanger.

A

Is dependent upon the transverse tubular membrane potential.

100
Q

In cardiac muscle:
A. A fast transient outward current (Ito) is carried by calcium ions and is responsible for the plateau phase of the action potential.
B. An increased inward Na+ current is responsible for enhanced excitability of the ventricular muscle, thereby predisposing to arrhythmogenesis.
C. Increased activity in the Na+/Ca2+ exchanger is responsible for the Stage III recovery in the action potential.
D. The upright form of the T wave in the electrocardiogram is a consequence of variations in action potential durations in different regions of the ventricle.
E. The transverse tubules are better developed than in skeletal muscle to permit extensive Ca2+ entry, thereby enhancing calcium-induced calcium release.

A

The upright form of the T wave in the electrocardiogram is a consequence of variations in action potential durations in different regions of the ventricle.

101
Q

Regarding the action potential in a ventricular myocyte:
A. There is a rapid upshoot phase during which the major current is carried by Ca2+.
B. There is a plateau phase during which the major current is attributable to activation of a persistent Na+ channel.
C. Answers (A) and (B) are both correct.
D. There is a plateau phase during which there is reduced permeability to K+, attributable to rectification properties of the K+ channel.
E. There is a pacemaker potential carried by the If current, which sets the overall heart rate.

A

There is a plateau phase during which there is reduced permeability to K+, attributable to rectification properties of the K+ channel.

102
Q

In smooth muscle:
A. The capacity to form “latch bridges” speeds up an otherwise slow activation process.
B. Activation of cross-bridge formation by enzymic activity on the myosin head, normally present in skeletal muscle, is absent.
C. Troponin is activated by increases in intracellular calcium levels considerably more slowly than is the case in skeletal muscle.
D. There is a stress-relaxation phenomenon found neither in skeletal nor in cardiac muscle.
E. There is a more gradual sodium channel activation in response to depolarisation than in either cardiac or skeletal muscle.

A

There is a stress-relaxation phenomenon found neither in skeletal nor in cardiac muscle.

103
Q

Which of the following represents a major physiological difference between parasympathetic and sympathetic responses?
A. Unlike sympathetic nerves, parasympathetic nerves are tonically active and responses occur by changing their tone.
B. The response time of the parasympathetic nerves is much faster than that of the sympathetic.
C. Parasympathetic reflex responses are often more localised than sympathetic.
D. Sympathetic nerves release VIP as well as acetylcholine.
E. All of the above are true.

A

Parasympathetic reflex responses are often more localised than sympathetic.

104
Q

When heart rate increases:
A. Ventricular systole is affected less than ventricular diastole.
B. Ventricular diastole is affected less than ventricular systole.
C. There is a proportional decrease in both ventricular systole and diastole.
D. The period of diastasis is longer.
E. The period of rapid filling is lengthened.

A

Ventricular systole is affected less than ventricular diastole.

105
Q

The region of the circulation showing the biggest change in pressure during the cardiac cycle is:
A. The aorta
B. The arterioles
C. The capillaries
D. The left ventricle
E. The pulmonary artery

A

The left ventricle

106
Q

Important features of Starling’s heart-lung preparation include all of the following EXCEPT:
A. Pre-load and after-load can be varied independently.
B. Cardiac volumes can be measured.
C. The heart is isolated from central neural inputs, so only mechanisms intrinsic to the heart are examined.
D. The chest is closed so that normal atrial pressures are maintained.
E. The heart is perfused with blood.

A

The chest is closed so that normal atrial pressures are maintained.

107
Q

Which of the following, relating to the differences between skeletal and cardiac muscle fibres, is TRUE?
A. Cardiac muscle sarcomeres are longer.
B. Within the body, skeletal muscle operates entirely within the rising phase of the length-tension curve.
C. Cardiac muscle has a long refractory period and so cannot be tetanised.
D. On average, skeletal muscle fibres have a smaller diameter than cardiac fibres.
E. All of the above are true.

A

Cardiac muscle has a long refractory period and so cannot be tetanised.

108
Q

Which of the following statements about the arterial chemoreceptors is true?
A. They are found in the carotid and aortic sinuses.
B. They respond to changes of PO2 only in the range 70 mmHg and above.
C. The carotid chemoreceptors are innervated by the sinus nerve, a branch of the IXth cranial nerve.
D. They send inhibitory signals to the cardio-acceleratory centres in the medulla oblongata.
E. All of the above are true.

A

The carotid chemoreceptors are innervated by the sinus nerve, a branch of the IXth cranial nerve.

109
Q

Abnormally high right atrial pressures may arise:
A. With a failing right ventricle.
B. Following arteriolar constriction.
C. During exercise.
D. Following dehydration.
E. All of the above.

A

With a failing right ventricle.

110
Q

Sympathetic vasoconstrictor fibres:
A. Are tonically active.
B. Are unmyelinated.
C. Release noradrenaline.
D. Innervate both arterioles and veins.
E. All of the above.

A

All of the above.

111
Q

Localised oedema may result from:
A. Reduced capillary colloid osmotic pressure.
B. Over 3 litres of fluid retention in the extra-cellular compartment.
C. Obstruction of lymph nodes.
D. Malnutrition.
E. All of the above.

A

Obstruction of lymph nodes.

112
Q

The major factor increasing blood flow to an exercising skeletal muscle is:
A. Decreased sympathetic tone.
B. Parasympathetic vasodilator fibres.
C. Metabolic hyperaemia.
D. Circulating adrenaline.
E. All of the above contribute significantly.

A

Metabolic hyperaemia.

113
Q

A patient is being ventilated during a surgical procedure and the anaesthetist is monitoring alveolar gas compositions. The alveolar PCO2 was found to be 40 mmHg. What course of action should be taken?
A. The surgery should be immediately terminated.
B. CO2 should be added to the patient’s inspired gas mixture.
C. The ventilation rate should be halved.
D. The ventilation rate should remain unchanged.
E. The patient should be ventilated with 100% O2.

A

The ventilation rate should remain unchanged

114
Q

The volume of air remaining in the lungs after maximum exhalation is referred to as:
The residual volume.
The inspiratory reserve volume.
The inspiratory capacity.
The expiratory reserve volume.
The functional residual capacity.

A

The residual volume.

115
Q

If you knew that a pregnant woman was going to give birth before the gestation period had reached 85% of the expected term, which of the following courses of action would be prudent?
A. Ensure that a ventilator capable of delivering continuous positive airway pressure was available.
B. Give the woman a course of adrenaline 24 hours before birth.
C. Ensure that a supply of foetal haemoglobin was available.
D. Ensure that a high-CO2 gas mixture was available.
E. All of the above.

A

Ensure that a ventilator capable of delivering continuous positive airway pressure was available.

116
Q

The lung can be functionally divided into three zones, distinguished by the interactions between arterial, venous and alveolar pressures within them. In “zone 2” (the middle zone) of the lung:
A. There is no blood flow.
B. Pulmonary venous pressure is greater than alveolar pressure.
C. Alveolar pressure is greater than pulmonary artery pressure.
D. The effective driving pressure determining blood flow through the lungs is pulmonary artery pressure minus alveolar pressure.
E. The effective driving pressure determining blood flow through the lungs does not change with vertical distance within the zone.

A

The effective driving pressure determining blood flow through the lungs is pulmonary artery pressure minus alveolar pressure

117
Q

In humans, the process of ventilating the alveoli unaided by external means requires:
A. An air-tight thoracic cage.
B. Adequate surfactant production to lower surface tension in the alveoli.
C. Expansion of the thoracic compartment.
D. A reduction in alveolar pressure below atmospheric pressure.
E. All of the above.

A

All of the above.

118
Q

A human subject travels from sea level to 3,000 metres in six hours. Within minutes of arrival at this altitude, adequate oxygenation of the tissues is achieved by:
A. The rapid production of red blood cells.
B. Alteration in the sensitivity of the peripheral chemoreceptor response to hypoxia.
C. An increase in alveolar ventilation.
D. Removal of the central chemoreceptor braking affect on ventilation.
E. All of the above, acting simultaneously.

A

An increase in alveolar ventilation.

119
Q

A female scuba diver submerges to 40 metres below the water surface while breathing normal air. Why must the diver be aware of how long she is submerged at that depth?
A. Because prolonged exposure to depth alters the transpulmonary pressure.
B. Because prolonged breathing of normal air under pressure results in hyperventilation.
C. Because prolonged exposure to depth increases the amount of CO2 dissolved in the cerebrospinal fluid.
D. Because prolonged breathing of normal air under pressure results in an accumulation of dissolved nitrogen in the body.
E. Because prolonged exposure to depth results in a fall in venous return.

A

Because prolonged breathing of normal air under pressure results in an accumulation of dissolved nitrogen in the body.

120
Q

Which of the following statements regarding the lungs is CORRECT?
A. Significant oxygen uptake occurs throughout the entire respiratory tree.
B. The cross-sectional area of the respiratory tree increases linearly from the mouth to the alveoli.
C. The rate of oxygen exchange between the alveoli and the pulmonary circulation is directly proportional to the length of the diffusion path and inversely proportional to the area of diffusion.
D. Regulation of alveolar ventilation rate to maintain an arterial PCO2 at normal levels will maintain arterial PO2 at a value close to 100 mmHg.
E. The equal pressure point during forced expiration from peak lung volume is independent of the elastic recoil forces of the lung.

A

Regulation of alveolar ventilation rate to maintain an arterial PCO2 at normal levels will maintain arterial PO2 at a value close to 100 mmHg.

121
Q

Which of the following would NOT result in a form of hypoxia?
A. Inadequate Hb saturation.
B. Hyperventilation.
C. Reduced oxygen-carrying capacity of the blood.
D. Reduced delivery of oxygen to the tissues.
E. Cyanide poisoning.

A

Hyperventilation.

122
Q

Which of the following would be expected to lead to a movement of fluid from the plasma into the interstitial space?
A. A decrease in the plasma Na+ concentration.
B. An increase in the plasma Na+ concentration.
C. A reduction in the interstitial fluid hydrostatic pressure.
D. An increase in plasma albumin concentration.
E. A decrease in the capillary hydrostatic pressure.

A

A reduction in the interstitial fluid hydrostatic pressure

123
Q

The clearance of inulin was measured as 80 ml/min in an experimental animal. The clearance of an experimental substance was measured as 170 ml/min in the same animal. What conclusion can be drawn about the renal handling of this substance?
A. It is partially reabsorbed.
B. It is not freely filtered.
C. It is completely cleared.
D. Its clearance ratio is less than 1.
E. It is secreted.

A

It is secreted.

124
Q

Constriction of the efferent renal arteriole would result in:
A. Reduced renal plasma flow and increased filtration fraction.
B. Reduced renal plasma flow and decreased filtration fraction.
C. Increased renal plasma flow and increased filtration fraction.
D. Increased renal plasma flow and decreased filtration fraction.
E. Increased pressure in the peritubular capillaries.

A

Reduced renal plasma flow and increased filtration fraction.

125
Q

Which of the following describes part of a feed-forward mechanism that is involved in the control of plasma K+?
A. Aldosterone is released in response to raised plasma K+ concentration.
B. Adrenaline is released as exercise begins.
C. Increased plasma K+ concentration causes hyperpolarization of cells.
D. ADH greatly increases K+ excretion by the kidneys.
E. The sodium pump maintains a low intracellular K+ concentration.

A

Adrenaline is released as exercise begins.

126
Q

Which of the following processes is required for HCO3- reabsorption in the proximal tubule of the kidney?
A. Carrier-mediated diffusion of HCO3- from the tubule into the cells.
B. Active transport of HCO3- from the tubule into the cells.
C. Primary active transport of H+ from the tubule into the cells.
D. Secondary active transport of H+ from the tubule into the cells.
E. Diffusion of CO2 from the tubule into the cells.

A

Diffusion of CO2 from the tubule into the cells.

127
Q

Concerning antidiuretic hormone (ADH), which of the following statements is FALSE?
A. ADH is also known as vasopressin.
B. ADH is secreted from the adenohypophysis.
C. ADH is a cyclic nonapeptide.
D. ADH is a vasoconstrictor.
E. ADH secretion is stimulated by significant hypovolaemia.

A

ADH is secreted from the adenohypophysis.

128
Q

Sodium excretion by the kidney nephron:
A. Is promoted by a decrease in glomerular filtration rate.
B. Is promoted by renal parasympathetic nerve activity.
C. Is promoted by a rise in angiotensin II.
D. Is promoted by hypervolaemia.
E. Is promoted by aldosterone.

A

Is promoted by hypervolaemia.

129
Q

Which protein converts angiotensinogen to angiotensin I?
A. Angiotensin converting enzyme
B. Renin
C. Aldosterone
D. Atrial natriuretic peptide
E. None of the above

A

Renin

130
Q

Which of the following is a dipsogenic stimulus?
A. Hypervolaemia
B. An increase in venous pressure
C. Angiotensin II
D. A fall in the extracellular fluid osmotic pressure
E. None of the above

A

Angiotensin II

131
Q

Which would produce the most rapid diuresis?
A. Drinking 1 litre of isotonic saline.
B. Drinking 1 litre of fresh water.
C. Drinking 1 litre of sea water.
D. A fall in arterial blood pressure by >10%.
E. A rise in the extracellular fluid osmotic pressure by >2%.

A

Drinking 1 litre of fresh water.

132
Q

Which of the following is correct?
A. Hypocalcaemia more than hypercalcaemia leads to kidney stone formation.
B. Hypercalcaemia can be diagnosed from positive Trousseau’s or Chvostek’s signs.
C. Primary hyper-parathyroidism is a problem originating within the parathyroid gland.
D. Secondary hyper-parathyroidism occurs because of increased reactivity of the kidney to PTH.
E. High extracellular [Ca2+] results in a reduced threshold for action potentials in excitable cells.

A

Primary hyper-parathyroidism is a problem originating within the parathyroid gland.

133
Q

Which of the following is not secreted in saliva?
Lysozyme
Amylose
Bicarbonate ions
IgA antibodies
Mucus

A

Amylose

134
Q

Which of the following is released by enterochromaffin cells in the gut to elicit a peristaltic contraction?
Somatostatin
Nitric oxide
Serotonin
Noradrenaline
Salbutamol

A

Serotonin

135
Q

Mepyramine is an antihistamine drug, which works by blocking H1 receptors. What would its likely effect be on stomach acid secretion?
It would markedly reduce secretion.
It would markedly stimulate secretion.
It would potentiate the effect of ACh on secretion.
It would antagonise the effect of ACh on secretion.
It is unlikely to have a marked effect on acid secretion because these secretory effects of histamine are mediated by a different receptor subtype.

A

It is unlikely to have a marked effect on acid secretion because these secretory effects of histamine are mediated by a different receptor subtype.

136
Q

A major role of four of the following five cell types is to move NaCl across an epithelium, an NKCC transporter (which co-transports Na+, K+ and Cl-) representing a key part of the mechanism. Which is the odd one out?
Salivary acinar cell
Pancreatic acinar cell
Pancreatic duct cell
Secretory cell of the crypts of Lieberkühn
Cell from the ascending thick limb of the loop of Henle

A

Pancreatic duct cell

137
Q

The failure of enteric neuron precursors to migrate to the distal colon is the basis of which of the following conditions?
Hirschsprung’s disease
Rectal prolapse
Achalasia
Megaoesophagus
Ulcerative colitis

A

Hirschsprung’s disease

138
Q

Gluconeogenesis occurs:
A. In the liver only
B. In the kidney only
C. In the brain only
D. In the spleen only
E. In both the liver and kidney

A

In both the liver and kidney

139
Q

Insulin release from the pancreas is increased by:
A. Increasing blood glucose levels
B. Parasympathetic stimulation
C. Amino acids
D. Incretins
E. All of the above

A

All of the above

140
Q

Which of the following reduces hormone secretion by certain cells in the anterior pituitary?
A. Adrenocorticotrophic hormone (ACTH)
B. Thyrotropin
C. Growth hormone-releasing hormone (GHRH)
D. Oxytocin
E. Somatostatin

A

Somatostatin

141
Q

A prolonged increase in the level of which of the following is correlated with acromegaly in humans?
A. Thryoid hormone
B. Gonadal steroids
C. Growth hormone
D. Corticotrophin
E. Aldosterone

A

Growth hormone

142
Q

Which of the following is a hormone secreted by adipose tissue cells?
A. Glucagon
B. Insulin
C. Leptin
D. Ghrelin
E. Cholecystokinin

A

Leptin

143
Q

Where in the mammalian brain is the “feeding centre”?
A. The lateral cerebral cortex
B The pineal gland
C. The dorsal medulla
D. The cerebellum
E. The hypothalamus

A

The hypothalamus

144
Q

With reference to their thermoregulatory strategy, mammals are regarded as which of the following?
A. Ectotherms
B. Endotherms
C. Poikilotherms
D. Homeotherms
E. Both B and D

A

Both B and D
(Endotherms and homeotherms)

145
Q

A major function of the blood vessels in the skin is to play a role in thermoregulation. Which of the following best describes how this is done?
A. Sympathetic nerves release noradrenaline to cause vasoconstriction when heat loss must be reduced.
B. The hormone secretin causes vasodilatation when it is hot.
C. The parasympathetic nervous system causes vasoconstriction in the cold.
D. The sympathetic nervous system releases acetylcholine to cause constriction in the cold.
E. The enteric nervous system releases “enterin”, which makes the blood vessels dilate.

A

Sympathetic nerves release noradrenaline to cause vasoconstriction when heat loss must be reduced.

HOM (3 decks)

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