Brainscape's Knowledge GenomeTM

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


See full index

Lecture Notes - Endocrinology > Pituitary Anatomy and Physiology > Flashcards

Pituitary Anatomy and Physiology Flashcards

1
Q

Describe the anatomical position of the pituitary gland

A

In the pituitary fossa (sella turcica) in the sphenoid bone.

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

What connects the pituitary to the hypothalamus

A

The pituitary stalk

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

How does venous blood drain from the pituitary gland

A

By a number of veins into the cavernous sinus

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

What is the anterior pituitary gland derived from

A

An upward growth of the ectoderm of the roof of the oropharynx (Rathke’s pouch) which becomes pinched off

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

What is the posterior pituitary gland derived from

A

Down growth of neuroectoderm of the floor of the third ventricle

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

Name the hormones secreted by the anterior pituitary

A 
Growth hormone (GH) 
Prolactin 
Adrenocorticotrophin hormone (ACTH) 
Thyroid stimulating hormone (TSH) 
Luteinizing hormone (LH) and follicle stimulating hormone (FSH)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the most abundant hormone secreted by the anterior pituitary gland

A

Growth hormone

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

What does GH stimulate

A

hepatic synthesis and secretion of insulin-like growth factor 1
Epiphyseal prechondrocyte differentiation and linear bone growth in children
lipolysis
increases protein synthesis
antagonises insulin action
phosphate, water and sodium retention

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

How does GH work

A

It binds to its plasma membrane receptor (usually in the liver) which leads to receptor dimerisation

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

What happens after receptor dimerisation ?

A

It is followed by a phosphorylation cascade mediated by Janus kinds (JAK) and components of the signal transduction and activators of transcription (STAT) family, which translocate to the nucleus and regulate target gene expression

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

How is the secretion of GH stimulated

A

BY hypothalamic GH releasing hormone

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

How does hypothalamic GH releasing hormone work

A

It acts via a G-protein coupled receptor and increases cyclic AMP leaves

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

What factors may stimulate GH release

A

stress
exercise
sleep
prolonged fasting

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

What inhibits GH secretion

A

IGF-1 and hypothalamic somatostatin

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

Describe the release of GH

A

pulsatile

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

What does prolactin stimulate

A

the proliferation of the breast lobule-alveolar epithelium and lactation

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

What does prolactin suppress

A

Gonadotrophin-releasing hormone (GnRH)

Pituitary gonadotrophin secretion

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

How does prolactin work

A

In the same way as GH - It binds to its plasma membrane receptor which leads to receptor dimerisation which is followed by a phosphorylation cascade

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

What inhibits prolactin secretion

A

Hypothalamic dopamine binding to D2 receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What stimulates prolactin secretion

A

hypothalamic thyrotrophin releasing hormone (TRH) and others including oestrogen, opiates, serotonin and ACh

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

When might prolactin levels be high

A 
in stress
during sleep 
following a suckling stimulus 
exercise 
meals 
sex 
epileptic fit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When are the prolactin secretory peaks

A

during rapid eye movement sleep (between 4 and 6am)

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

What does ACTH do

A

It stimulates the conversion of cholesterol to pregnenolone in the zone fasciculate and reticular
therefore stimulates the production of cortisol and adrenal androgens

24
Q

How does ACTH work

A

It binds to its plasma membrane receptor in the zone fasciculata of the adrenal gland which results in the activation of adenylate cyclase

25
Q

What does the activation of adenylate cyclase result in

A

an increased cyclic AMP production which then results in stimulation of steroidogenic acute regulatory protein

26
Q

what does steroidogenic acute regulatory protein do

A

It mediates the transport of cholesterol through the cytosol to the inner mitochondrial membrane where it is converted to pregnenolone

27
Q

What is the rate limiting step in cortisol synthesis

A

the transport of cholesterol through the cytosol to the inner mitochondrial membrane, where it is converted to pregnenolone

28
Q

What else does the activation of adenylate cycles result in

A

the unregulated gene expression of other enzymes involved in steroid synthesis

29
Q

What stimulates ACTH

A

hypothalamic corticotrophin-releasing hormone (CRH) as well as other factors, including stress

30
Q

What inhibits ACTH

A

cortisol

31
Q

When is there a peak of cortisol

A

8am

32
Q

What does TSH stimulate

A

Every step in thyroid hormone synthesis

also stimulates the expression of many genes in thyroid tissue and causes thyroid hyperplasia and hypertrophy

33
Q

What inhibits TSH synthesis

A

T4 and T3

34
Q

What are some other factors that may reduce TSH secretion

A

dopamine
somatostatin
acute non-thyroidal illness
increased human chorionic gonadotrophin (early pregnancy

35
Q

What do LH and FSH do in males

A

LH stimulates the production of testosterone

FSH stimulates spermatogenesis (alongside testosterone)

36
Q

How do the gonadotrophin work in males

A

Binding of LH and FSH to their plasma membrane receptors results in a stimulation of adenylate cyclese and increased cAMP production
LH stimulates testosterone synthesis by acting on the StAR protein which delivers cholesterol to the inner mitochondrial membrane where it is converted to pregnenolone

37
Q

What stimulates the release of LH and FSH

A

pulsatile release of hypothalamic GnRH

38
Q

What does testosterone inhibit

A

hypothalamic GNRH and pituitary LH production

39
Q

How does LH and FSH work in females

A

LH stimulates the early steps in steroidogenesis and the production of androgens in ovarian theca cells

40
Q

What does the LH surge induce

A

ovulation and thereafter maintains the secretory function of the corpus luteum

41
Q

What does FSH stimulate

A

the recruitment and growth of ovarian follicles and their secretion of estradiol

42
Q

What does FSH stimulate

A

The aromatase enzyme that converts androgens to oestrogen

43
Q

What is the secretion of FSH and LH fundamentally under the control of

A

negative feedback control by ovarian steroids (oestradiol) and by inhibin

44
Q

What does the oestrogen peak cause

A

the LH surge

45
Q

What are the hormones secreted by the posterior pituitary

A

Oxytocin

vasopressin (ADH)

46
Q

How are vasopressin and oxytocin synthesised and packaged

A

In granules in the cell bodies of specific magnocellular neurones in the supraoptic and paraventricular nuclei of the hypothalamus

47
Q

What stimulates vasopressin secretion

A

an increase in serum osmolality
decreased extracullar volume
decreased BP
stress

48
Q

What inhibits vasopressin secretion

A

alcohol and cold

49
Q

How does Vasopressin cause generation of cyclic AMP and activation of intracellular protein kinases

A

It binds to the VR2 membrane receptors on the distal renal tubular cells (in the collecting duct) causing activation of adenylate cyclase

50
Q

How does vasopressin cause urine to become concentrated

A

Insertion of water channel proteins into the tubular membrane, allowing a flow of solute free water from the hypotonic luminal fluid into the hypertonic renal interstitium

51
Q

What happens at high concentrations

A

Vasopressin binds to VR1 receptors on vascular smooth muscle and causes vasoconstriction

52
Q

Where else is vasopressin secreted into

A

the portal circulation

53
Q

What does vasopressin stimulate

A

ACTH release from the pituitary

54
Q

What stimulates oxytocin release

A

vaginal stimulation caused by the fetus during parturition, sex or nipple stimulation during lactation

55
Q

What is oxytocin released inhibited

A

Stress

56
Q

What does oxytocin stimulate

A

contractions of the uterine muscle which helps deliver the foetus and the placenta

57
Q

What is another function of oxytocin

A

Stimulate the contraction of the myoepithelial cells that surround the alveoli in the breast to aid milk ejection

Lecture Notes - Endocrinology (40 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions