Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Regulatory Physiology and Pharmacology > The Hypothalamus-Pituitary Complex > Flashcards

The Hypothalamus-Pituitary Complex Flashcards

1
Q

What does the HP axis regulate?

A

The function of the thryoid, adrenal and reproductive glands

Growth, lactation, milk secretion and water metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where is the pituitary?

A

In a pocket of bone at the base of the brain below the hypothalamus close to the medial eminence
Connected to hypothalamus and is connected by a stalk containing nerve fibres and blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the key features of the anterior and posterior pituitary?

A

Anterior - unique blood supply where releasing factors are secreted into from the hypothalamus
Posterior - blood portal system takes hormones away with direct hormonal secretion from the posterior - not synthesised there however

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the key role of the posterior pituitary?

A

body fluid homeostasis and reproductive function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where are hormones synthesised for secretion by the posterior pituitary?

A

Magnocellular neurons secrete directly into pituitary
Paraventricular nuclei - oxytocin
Supraoptic nuclei - ADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the pre-prohormones of the posterior pituitary?

A

preprovasophysin

preprooxyphysin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are Herring Bodies?

A

Axonal swellings due to the storage of secretory granules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the main functions of ADH?

A

Maintenance of normal osmolarity of body fluids

Normal blood volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the primary targets of ADH?

A

Cells lining the distal renal tubule

Principle cells of the collecting ducts in the kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does ADH act on the signalling pathways?

A

Binds to V2Rs on basal side of renal cells
V2R is linked to Gs-cAMP-PKA pathway
Stimulates insertion of Aquaporin 2 to apical membrane
Enhances trans-epithlial flow of water from lumen to renal interstitium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens in the presence of ADH?

A

Urine flow decreases

Urine Osmolality increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is ADH released in response to?

A

increased EC fluid osmolality

decreased blood volume and pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do osmoreceptive neurons respond to changes in osmolality?

A

Respond to changes by shrinking or swelling
Innervate magnocellular neurons of PVN and SON
Increased osmolality stimulates ADH releases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is blood volume regulated?

A

Cardiovascular volume receptors in the atria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of oxytocin?

A

stimulates the contraction of uterine smooth muscle during labour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the positive feedback mechanism related to oxytocin?

A

Stretching of the cervix stimulates oxytocin release which in turn facilitates labour further as a neuroendocrine reflex
After birth, stretching of cervix lessens, breaking the cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is the anterior pituitary connected to the hypothalamus?

A

hypophyseal portal circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What kind of hormones are produced in the anterior pituitary?

A

tropic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What hormones does the anterior pituitary produce?

A 
Prolactin
GH
ACTH
TSH
FSH
LH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How are hormones released from the pituitary?

A

paravicellular neurosecretory cells secrete releasing factors into the capillaries of the pituitary portal system at the median eminance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the releasing factors associated with the hormones released?

A 
CRH - ACTH
TRH - TSH
GHRH - GH
Somatostatin - inhibits GH
GnRH - FSH, LH
PRH - Prolactin
Dopamine - inhibits prolactin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What percentage of cells are corticotrophs and what are their target organs?

A

15-20% - adrenal glands, adipocytes and melanocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What percentage of cells are thryotrophs and what are their target organs?

A

3-5% - thyroid gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What percentage of cells are gonadotrophs and what are their target organs?

A

10-15% - Gonads

25
Q

What percentage of cells are somatotrophs and what are their target organs?

A

40-50% - All tissues, liver

26
Q

What percentage of cells are lactotrophs and what are their target organs?

A

10-15% - breasts, gonads

27
Q

What is the key feature of the feedback regulation in the HP-axis?

A

the ability of hypothalamic releasing hormones to provide negative feedback on the system

28
Q

What is TSH?

A

a glycoprotein heterodimer composed of an a and b subunit

29
Q

Where does TSH bind?

A

thyroid epithelial cells with TSH receptors

30
Q

How is TRH released?

A

according to diurnal rhythm and regulated by various stresses i.e. starvation

31
Q

What does T3 negatively feedback on?

A

the thyrotropes and TRH-producing neurons

32
Q

What is the role of thyroid hormone?

A

regulates the body energy metabolism
maturation
growth
development

33
Q

What are the main targets for thyroid hormone?

A

brain, muscle, cardiovascular system and reproductive tissue

34
Q

How does GH act on tissues?

A

directly on peripheral tissues and indirectly via IGF-1

35
Q

What are the main sites for GH degradation?

A

Kidney and Liver

36
Q

How is GH secretion regulated?

A

GHRH stimulates release

Somatostatin inhibits GH and TSH

37
Q

How might b-adrenergic receptors inhibit GH secretion?

A

stimulate somatostatin which inhibits GH

38
Q

What are the pathological conditions involving GH?

A

dwarfism, gigantism, acromegaly

39
Q

How is ACTH synthesised?

A

CRH promotes POMC gene expression which produces ACTH by proteolytic processing

40
Q

What is the role of ACTH?

A

to regulate the stress response by regulating the adrenal cortex and the synthesis of adrenocorticosteroids

41
Q

What is a-MSH?

A

the first 13 aa in ACTH which stimulate melanocytes and can darken skin when ACTH is over-produced

42
Q

How is ACTH regulated?

A

CRH, ADH, stress, hypoglycaemia

ADH via inferior hypophyseal artery from pituitary

43
Q

How is ACTH secreted?

A

according to circadian rhythm although can be altered by jetlag
Stress both neurogenic and systemic stimulate ACTH secretion

44
Q

How does cortisol act to negatively regulate ACTH?

A

negatively feedback on pituitary reducing POMC expression and hypothalamus reducing pro-CRH gene expression and CRH release

45
Q

What is Cushing’s disease?

A

a benign tumour of the pituitary gland that produces a large amount of ACTH causing adrenal glands to produce elevated levels of cortisol

46
Q

What does increased cortisol secretion do?

A

causes a tendency:
weight gain characteristically in centripetal fat distribution
wasting of extremities, bruising easily and healing poorly
buffalo humo
moon face
high BP, severe fatigue and muscle weakness

47
Q

What regulates LH?

48
Q

What regulates FSH?

A

GnRH and Inhibin cause distinct patterns of LH and FSH secretion

49
Q

When does GnRH preferentially increase LH?

A

at one pulse per hour

50
Q

When does GnRH preferentially increase FSH?

A

at 1 pulse per 3 hours

51
Q

What are the different feedback mechanisms for LH and FSH in men and women?

A

men - testosterone on pituitary and hypothalamus
women - progesterone on pituitary and hypothalamus
oestrogen on FSH and LH secretion
Inhibin negatively feedsback on FSH in men and women

52
Q

What is the action of LH in men?

A

stimulates leydig cells to synthesise testosterone

53
Q

What is the action of LH in women?

A

acts on theca cells to produce testosterone which is converted to oestrogen by granulosa cells

54
Q

What is the function of FSH in women?

A

stimulates maturation of ovarian follicles

55
Q

what is the function of FSH in men?

A

supports the function of the sertoli cells which support aspects of sperm cell maturation

56
Q

How are FSH and LH regulated?

A

dopamine, endorphins and prolactin all inhibit GnRH release

57
Q

What can overproduction of prolactin cause and how might this be treated?

A

amenorrhea

treat with bromocryptine or surgical removal of tumour

58
Q

What stimulates ovulation?

A

high plasma estadiol which stimulates GnRH and LH surge

59
Q

How is prolactin different from other endocrine cells in the anterior pituitary?

A

acts on non-endocrine cells to induce physiological changes

secretion is mainly under inhibitory control by the hypothalamus

Regulatory Physiology and Pharmacology (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions