7.01 Amy, Chris, Cel, Gem: Endocrine Time

Front 1

The basal metabolic rate is defined as the _________________ expended by humans when completely ____________________ but not asleep, in the absence of ________________ _________________ and without any sympathetic nervous system arousal

Back 1

Energy; at rest; muscle movement

Front 2

BMR is hard to measure, so we generally measure Resting Metabolic Rate which is 10-15% higher/lower than BMR

Back 2

Lower

Front 3

Measuring RMR by measuring gaseous exchange of O2/CO2 is indirect/direct calorimetry

Back 3

Indirect

Front 4

Using a metabolic chamber is indirect/direct calorimetry

Back 4

Direct

Front 5

BMR is the major component of energy expenditure. The additional components are:
a. Cold induced thermogenesis or Thermoregulatory heat
b. Thermic effect of exercise which is the energy required for muscle activity and the energy lost as heat to maintain core temp by elimination
c. Thermic effect of food which is the energy required for absorption and processing of food
d. All of the above
e. None of the above

Back 5

D. all of the above

Front 6

True or false: a man of healthy weight will have a higher absolute BMR than an obese man because his lean body mass is larger (whereas the obese man has a larger fat mass instead)

Back 6

False. An obese subject has a greater lean body mass to support their fat mass and so will have a higher absolute BMR, however they will equal out when adjusted for lean body mass

Front 7

BMR is controlled by ________________________ pathways via the_____________________ nervous system and a range of_________________________. BMR is also influenced by ________________ factors.

Back 7

Hypothalamic; autonomic; neuropeptides; genetic

Front 8

To gain body heat, we use either shivering or non-shivering thermogenesis. What is the difference between the two?

Back 8

Shivering: muscle contraction and superficial circulatory vasoconstriction to reduce loss of normally produced heat energy to the atm

Non-shivering: production of additional heat via biochemical rxns

Front 9

True or false: the main site of energy production via non-shivering thermogenesis is in brown adipose tissue

Back 9

False. That’s in rodents. In humans, it’s in skeletal muscle

Front 10

Choose the correct response:
a. Adrenaline is secreted by the adrenal cortex
b. Noradrenaline is the transmitter of the sympathetic nervous system preganglionic fibres
c. After release from nerve endings, catecholamines are either recycled back into nerve endings or other tissues or catabolized into metabolites which are excreted in urine
d. Adrenoceptors are classes as either α or δ
e. Adrenaline and noradrenaline can be used to lower blood pressure in hypertensive patients

Back 10

i. C. is correct. A: adrenal medulla; b: postganglionic; d: alpha and beta; e. they increase blood pressure in hypotension secondary to shock

Front 11

Circle the correct response:
Beta adrenoceptors are activated by dobutamine/metoprolol and are selectively blocked by dobutamine/metoprolol

Back 11

Dobutamine; metoprolol (remember beta-blockers end in ‘-olol’)

Front 12

What is a phaeochromocytoma?

Back 12

Tumour of adrenal medulla that secretes adrenaline and/or noradrenaline. S&S: headache, anxiety, tremor, palpitations, sweating, dizziness, hypertension etc etc.

Front 13

True or false: Many symptoms of thyrotoxicosis are mediated via catecholamines and can be treated by blocking beta adrenoceptors.

Back 13

True

Front 14

Thermogenesis exists in two forms: obligatory (associated with RMR) and adaptive (when metabolic rate increases in response to, say, decreased temp or increased food). Adaptive thermogenesis is regulated. What is the sensor and what are the effectors?

Back 14

Hypothalamus senses temp and nutrients. Effectors = thyroid hormone and SNS

Front 15

Adaptive thermogenesis takes place in _____________________ adipose tissue in ___________________ (organelle)

Back 15

Brown, mitochondria

Front 16

In skeletal muscle, how does shivering produce heat?

Back 16

‘futile’ muscle contractions that breakdown ATP

Front 17

What is a ‘futile’ cycle?

Back 17

A futile cycle means that opposed pathways are coupled e.g coupled glycolysis and gluconeogenesis. The outcome is heat production

Front 18

How else is heat produced from metabolism? (there are 4 more)

Back 18

ATP breakdown without work, impaired efficiency of ATP-dependent ion transport (e.g. Ca2+ transport from Cytoplasm to SER store via SERCA), uncoupling nutrient metabolism from ATP synthesis (i.e metabolism without energy storage), Na+ leak across plasma membrane activates Na+/K+-ATPase to pump them out again (thyroid hormone may increase membrane Na+ permeability)

Front 19

Circle the correct response: the origin of the energy value of food is protons/neutrons/electrons

Back 19

Electrons (stripped from CHOs, fats and protein)

Front 20

How is heat generated from mitochondria?

Back 20

Essentially provides an alternative pathway. Shorts out the ATP synthase pathway. Electrons are stripped and protons pumped into intermembrane space, but not allowing for the normal coupling process that allows for ATP synthesis

Front 21

24. Which of the following is incorrect as to how heat production is regulated by thyroid hormone?
a. Increased expression of uncoupling proteins (e.g., UCP-2; UCP-3)
b. Reduced efficiency of mitochondrial proton pumping
c. Feeding electrons via complex II rather than complex I (less proton pumping)
d. Thyroid hormone promotes SERCA expression and impairs its efficiency
e. Parasympathetic nervous system effects (enhanced beta2-adrenergic receptor expression in muscle)

Back 21

i. E is incorrect. Sympathetic.

Front 22

true or false: Adrenalin and glucagon create heat by stimulating gluconeogenesis

Back 22

True

Front 23

true or false: Leptin promotes activation of the sympathetic NS and thus can produce heat

Back 23

True

Front 24

Exposure to heat causes insulin to stimulate metabolism and thus does not play a part in heat production

Back 24

False. Insulin: Cold exposure increases glucose uptake and metabolism (especially in fat cells) => producing heat

Front 25

Body heat increases arise from?

Back 25

- reduced efficiency
- enhanced ATP breakdown
- futile biochemical cycles
- uncoupling mitochondrial oxidative phosphorylation

Front 26

Where do the lesser and greater petrosal nerves enter the middle cranial fossa?

Back 26

Through the petrous portion of the temporal bone

Front 27

Choose the incorrect response regarding the greater petrosal nerve:
a. It is a branch of the glossopharyngeal nerve
b. It exits via the foramen lacerum
c. It travels below the trigeminal ganglion
d. It travels through the pterygoid canal into the pterygopalatine fossa
e. It is joined by the deep petrosal nerve (sympathetic)
f. Its fibres have synapses in the pterygopalatine ganglion

Back 27

A is incorrect (branch of facial)

Front 28

Choose the incorrect response regarding the lesser petrosal nerve:
a. It is a branch of the glossopharyngeal nerve
b. It travels medial to the greater petrosal nerve and exits via the foramen rotundum
c. It synapses in the otic ganglion
d. Its fibres exit the ganglion to supply the auriculotemporal and facial nerves and the parotid gland

Back 28

B. is incorrect (lateral to greater petrosal n; exits via foramen ovale)