Brainscape's Knowledge GenomeTM

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


See full index

ESA 2 SEMESTER 2 TK > MEH - Hypothalamic Pituitary Axis > Flashcards

MEH - Hypothalamic Pituitary Axis Flashcards

1
Q

What is the hypothalamic pituitary axis?

A

The hypothalamus and pituitary gland form a complex functional unit together which serves as the major link between the endocrine and nervous systems

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

Where is the pituitary gland found?

A

Beneath the hypothalamus in a socket of bone called the sella turcica

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

Give some examples of processes modulated by the hypothalamus and the pituitary gland

A
  • body growth
  • reproduction
  • adrenal gland function
  • water homeostasis
  • milk secretion
  • lactation
  • thyroid gland function
  • puberty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the two parts of the pituitary gland?

A
  • anterior pituitary gland (adenohypophysis)

- posterior pituitary gland (neurohypophysis)

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

What is the embryological origin of the anterior pituitary?

A

It arises from evagination of the oral ectoderm (Rathke’s pouch) - this is primitive gut tissue

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

What is the embryological origin of the posterior pituitary?

A

It originates from the neuroectoderm - primitive brain tissue

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

How is the posterior pituitary connected to the hypothalamus?

A

It is physically connected through the infundibulum (pituitary stalk), because the hypothalamus originally drops down to form the posterior pituitary gland

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

How are oxytocin and ADH produced and released?

A
  • produced by neurosecretory cells in supraoptic and paraventricular nuclei of hypothalamus
  • transported down nerve cell axons to the posterior pituitary
  • stored/released from posterior pituitary into the general circulation to act on distant targets

Note: produced in HYPOTHALAMUS, released from POSTERIOR PITUITARY

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

How does the anterior pituitary function?

A
  • hormones synthesised in hypothalamus are transported down axons and stored in median eminence before release into hypophyseal portal system
  • hormones stimulate/inhibit target endocrine cells in the anterior pituitary gland
  • endocrine cells secrete hormones into the bloodstream (endocrine) and also effect neighbouring cells (autocrine/paracrine function)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Summarise the difference in mechanism of the anterior and posterior pituitary

A
  • POSTERIOR: direct effects on distant target tissues via oxytocin and antidiuretic hormone
  • ANTERIOR: hormones only go into hypophyseal portal system, and affect endocrine cells within the anterior pituitary
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the difference between antidiuretic hormone and vasopressin?

A

They’re the same!

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

What does it mean if a hormone is tropic?

A

It affects the release of other hormones in the target tissue

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

What are the six tropic hormones produced by the hypothalamus?

A
  • thyrotropin releasing hormone (TRH)
  • prolactin release-inhibiting hormone (PIH/dopamine)
  • corticotropin releasing hormone (CRH)
  • gonadotropin releasing hormone (GnRH)
  • growth hormone releasing hormone (GHRH)
  • growth hormone inhibiting hormone (GHIH/somatostatin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the six hormones produced by the anterior pituitary?

A
  • thyroid stimulating hormone (TSH)
  • adrenocorticotropic hormone (ACTH)
  • luteinising hormone (LH)
  • follicle stimulating hormone (FSH)
  • prolactin (PRL)
  • growth hormone (GH)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give some factors which influence growth

A

Nutrition, genetics, environment, hormones (growth hormone is the most important)

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

What stimulates growth hormone?

A

GHRH from the hypothalamus

17
Q

What inhibits growth hormone?

A

Somatostatin from hypothalamus

18
Q

Why must growth hormone be injected rather than taken orally?

A

It is a protein and would be digested

19
Q

True or false - the signal peptide remains on the growth hormone protein?

A

False - it must be cleaved before proper folding

20
Q

What are IGFs?

A

Insulin-like growth factors (somatomedins) produced by the liver and skeletal muscle in response to GH

21
Q

What is the role of GH and IGFs in adults?

A

Help maintain muscle and bone mass, promote healing and tissue repair, modulate metabolism and body composition

22
Q

What is the role of GH and IGFs in children?

A
  • GH stimulates long bone growth (length and width before epiphyseal closure, just width after)
  • IGFs stimulate bone and cartilage growth
23
Q

What events can cause GH secretion to rise?

A
  • rise in secretion after onset of deep sleep
  • stress (eg. Trauma, surgery or fever)
  • exercise
  • decrease in glucose or fatty acids
  • fasting
24
Q

What events can cause GH secretion to fall?

A
  • rapid eye movement sleep
  • increase in glucose or fatty acid levels
  • obesity
25
Q

How does long loop negative feedback inhibit GH?

A
  • IGFs inhibit release of GHRH from the hypothalamus
  • IGFs stimulate release of somatostatin from the hypothalamus
  • IGFs inhibit release of GH from anterior pituitary
26
Q

How does short loop negative feedback regulate GH?

A

It is mediated by GH itself via stimulation of somatostatin release

27
Q

What is pituitary dwarfism?

A

A growth hormone deficiency in childhood leading to proportionate dwarfism. The height is below the 3rd percentile on standard growth charts and there is delayed/no sexual development during teenage years. Responds to GH therapy

28
Q

What disorder can growth hormone excess in childhood cause?

A

Gigantism - in adulthood it leads to acromegaly

29
Q

How does GH exert its effect on cells?

A

GH receptors activate ‘janus kinases’ which cross phosphorylate and activate signalling pathways. Transcription factor activation and IGF production then occurs.

30
Q

What are the two IGFs found in mammals and what are they responsible for?

A
  • IGF1 is a major growth factor in adults

- IGF2 is mainly involved in foetal growth

31
Q

What can IGFs modulate?

A
  • cell growth (hypertrophy)
  • cell number (hyperplasia)
  • increase in rate of protein synthesis
  • increase in rate of lipolysis in adipose tissue
32
Q

What is the growth related action of insulin?

A

Enhances somatic growth, interacts with IGF receptors

33
Q

What is the growth related action of thyroid hormones?

A

Promotes CNS development and enhances GH secretion

34
Q

What are the growth related actions of androgens?

A

Accelerate pubertal growth spurt, increase muscle mass, promote closure of epiphyseal plates, inhibit somatic growth

ESA 2 SEMESTER 2 TK (87 decks)

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