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Physiology > W3 - Endocrine Axes (essential reading) > Flashcards

W3 - Endocrine Axes (essential reading) Flashcards

1
Q

To maintain the internal environment, what is needed?

A

-ve feedback loop

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2
Q

What does the -ve feedback loop aim to get a controlled variable to?

A

Physiological set point

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3
Q

Describe +ve feedback loop in terms of variable and the physiological set point

A

Accelerates variable’s level away from physiological set point

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4
Q

What differs between the different types of feedback loops?

A

The number of control points

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5
Q

Direct/first order feedback loops, second order and third order feedback loops have how many control points?

A

Direct/first - one, second - two, third - three

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6
Q

What type of feedback loops are typically in vertebrates?

A

2nd and 3rd

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7
Q

Direct FL - a physiological stimulus directly stimulates the endocrine gland to release hormones into circulatory system, what is the one control point in this pathway?

A

After the target organ is acted on, the target organ produces a physiological response which decreases the incoming stimulus (this is the CP)

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8
Q

ANP is the one example of a DFL in mammals, what does it do to decrease the plasma volume (to stop stretched atria)?

A

Released from atrial cardiomyocytes, it acts on kidney to increase Na+ and therefore water lost in urine, decreasing plasma volume and the stretch

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9
Q

What is the CP in the ANP DFL?

A

The decreased volume of plasma decreasing the stretch in the atria lessens the stimulus to release ANP

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10
Q

What are series of interacting endocrine glands referred to as?

A

Endocrine axis

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11
Q

Describe the pathway of SODL from change in variable detected to target organ

A

Change in variable detected by sensor which sends signal via sensory neuron to integrator, integrator sends signal via neuron to intermediary endocrine gland, endo gland secretes hormones into circ system to act on target organ

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12
Q

What are the two CPs that are used in SOFLs?

A

Lowers stimulus to sensor AND suppresses action of endocrine gland

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13
Q

Describe the pathway of TODL from change in variable detected to endocrine gland 1

A

Change in variable detected by sensor which sends signal via sensory neuron to integrator, integrator sends signal to intermediary endocrine gland, endo gland 1 secretes H1

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14
Q

Describe pathway of TODL from endo gland 1 to target organ

A

H1 moves via circ system to second intermediary endo gland which secretes H2, H2 acts on target organ

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15
Q

What are the 3 CPs for a TODL?

A

Lowers stimulus to sensor, suppression of endo gland 1 activity AND endo gland 2

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16
Q

Where does the hypothalamus sit in relation to the thalamus and what connects the HT to the pituitary gland?

A

HT sits below T and HT is connected to the PG via the infundibulum

17
Q

The posterior pituitary lobe (neurohypophysis) is formed by an outgrowth of neural tissue down from the…

A

Hypothalamus

18
Q

The anterior pituitary lobe (adenohypophysis) is formed by a growth of glandular epithelial tissue up from the…

A

Roof of the buccal cavity

19
Q

The hypothalamus contains different neurons in discrete hypothalamic nuclei, the endocrine cells of the anterior pituitary also have distinct populations for different hormones, how many different hormones are there?

A

5

20
Q

Neurohypophyseal hormones are transc/transl in the HT and then transported along axons from HT to be secreted by post PG, what neurons are used here, where are their cell bodies and where do their axons travel?

A

Magnocellular neurons, cell bodies are in the HT and the axons travel down thee hypothalamo-hypophyseal tract

21
Q

How is the HT connected to the anterior PG and where are the two major capillary beds found?

A

Via the hypothalamo-hypophyseal portal circulation, capillary beds in median eminence of HT and in anterior PG

22
Q

Which neurons are involved in the anterior PG transport of hormones?

A

Hypothalamic parvicellular neurons

23
Q

The hypothalamus responds to endocrine or neural stimuli by synthesis/secretion of 6 hypophysiotropic hormones. How many of these are peptide hormones and how many are NTMs?

A

5 peptide HM, 1 NTM (dopamine)

24
Q

List the 6 hypophysiotropic hormones

A

Dopamine, TGH, CRH, GHRH, GHIH, GnRH

25
Q

What is the meaning of a hypophysiotropic hormone?

A

Normally the first hormone in an endocrine axis of 2/3 hormones

26
Q

TRH, CRH, GHRH and GnRH are releasing hormones, what two things do they stimulate?

A

Synthesis AND secretion of peptide/protein/glycoprotein HM from target cells in anterior PG

27
Q

GHIH is the antagonistic partner to GHRH and GHIH has the same effect as dopamine, what is their role in the anterior PG?

A

Inhibit adenohypophyseal HM synthesis/secretion

28
Q

What are the target cells of dopamine, TRH, CRH, GHRH, GHIH and GnRH?

A

Dop - lactotropes, TRH - thyrotropes, CRH - corticotropes, GHRH + GHIH - somatotropes, GnRH - Gonadotropes

29
Q

Why is prolactin secreted from lactotropes unique?

A

There has been no releasing hormone identified for PRL

30
Q

Dopamine acts on D2 receptors to…

A

Suppress PRL secretion for lactation

31
Q

What are the hormones involved in response from lactotropes, thyrotropes, corticotropes, somatotropes and gonadotropes?

A

Lactotropes - prolactin, thyrotropes - thyroid stim HM, corticotropes - adrenocorticotropic HM, somatotropes - GH and gonadotropes - FSH and LH

32
Q

What are the target organs and functions for PLC, TSH and ACTH?

A

PLC - mammary glands (lactation), TSH - thyroid glands (increases BMR), ACTH - adrenal cortex (trigger cell differentiation + elevates plasma glucose)

33
Q

What are the target organs and functions for GH, LH and FSH?

A

GH - liver and cells in body (growth + development), LH - gonad glands (male fertility, female reproductive receptivity and progesterone), FSH - testes/ovaries (spermatogenesis, female sexual characteristics)

34
Q

Long loop vs short loop -ve feedback example

A

Long - target organ to hypothalamus, short - pit. gland to hypothalamus

35
Q

Apart from ?? neurons, all hypothalamic neurons are neuroendocrine cells and release peptide HMs into H-H portal circulation of anterior pit.

A

Dopaminergic

36
Q

AVP and OT are stabilised by ?? bonding at between residues @ positions 1 + 6

A

Disulphide

37
Q

What cells can be found in the cross section of the pancreas and what do they secrete?

A

Delta - somatostatin, beta - insulin, alpha - glucagon, PP cells - pancreatic polypeptides

Physiology (14 decks)

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