Brainscape's Knowledge GenomeTM

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


See full index

BRS Bioregulatory Systems > Pituitary Gland > Flashcards

Pituitary Gland Flashcards

1
Q

What is a hormone

A

A chemical messenger carried from the organ where they are produced to the organ they are affected
Peptide or steroid hormones

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

Peptide hormones

A

Made as prohormones which require further processing eg cleavage

Stored in vesicles and released by exocytosis

Bind receptors on cell membranes and transducer signals using 2nd messenger systems

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

Steroid hormones

A

Made in a series of reactions from cholesterol

Released immediately upon production

Bind to intracellular receptors to change gene expression

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

Where is the pituitary gland

A

Sits in sella turcica of sphenoid bone

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

What is the pituitary gland suspended from

A

Pituitary stalk (infundibulum)

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

Bitemporal hemianopia

A

Compression of the optic chasm by a pituitary tumour prevents transmission of sensory information from the visual fields to occipital lobe

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

What type of neurons regulate anterior pituitary function

A

Hypothalamic parvocellular neurones
These are short and terminate on median eminence
They release hypothalamic releasing and inhibitory factors into capillary plexus in the median eminence
The factors are carried by hypophyseal portal circulation made of leaky fenestrated blood vessels

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

Features of anterior pituitary

A

Anatomically distinct from hypothalamus
Derived from rathkes pouch
Derived from dorsal growth of buccal cavity
Made of endocrine cells

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

How does the hypothalamo-pituitary portal system work

A

Axon terminals of hypothalamic neurosecretory cells release Thyrotropin Releasing Hormone (TRH) into hypothalamo-hypophysial portal system.

TRH travels to anterior pituitary via portal system.

TRH stimulates release of TSH (thyrotropin) from anterior pituitary thryotrophs

TSH leaves gland via blood to travel to thyroid gland to stimulate thyroid hormone release (T4- thyroxine)

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

Endocrine cells making up anterior pituitary

A

Somatotrophs
Lactotrophs
Corticotrophs
Thyrotrops
Gonadotrophs

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

Somatotrophs

A

Growth hormone
Growth hormone releasing hormone is RH
Somatostatin is inhibiting
Receptors are found in general body tissues

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

Lactotrophs

A

Dopamine inhibits it
Releases prolactin
Receptors found in mammary gland

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

Corticotrophs

A

Released adrenocorticotrophic hormone
Corticotrophin releasing hormone regulates it
Receptors found in adrenal cortex

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

Thyrotrophs

A

Makes thyroid stimulating hormone
Thyrotropin releasing hormone is RH
Receptors found in thyroid

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

Gonadotrophs

A

Released LH and FSH
Gonadrotrophin releasing hormone is RH that regulates them
Receptors are found in testes and ovaries

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

Outline the neuroendocrine reflex arc for milk production?

A

Mechanical stimulation of the nipple stimulates the touch and sensory receptors, activating the afferent pathways. Action potentials traverse along the axons through the ascending sensory pathways

Afferent signals integrate in hypothalamus and inhibit dopamine release by dopaminergic parvocellular neurones

Less dopamine in the hypothalamic-pituitary portal system results in less inhibition of anterior pituitary lactotrophs

Increased plasma prolactin increases milk secretion in mammary glands

17
Q

What are the mechanisms of growth hormone action?

A

Secretion of growth hormone by endocrine somatotrophs from anterior pituitary directly binds to complementary target within general tissue (muscle and bone)

Growth hormone can bind to growth hormone receptors of liver → release of IGF-1 and IGF-2 (Insulin-like Growth Factor - Somatomedin)

  • Both produce same effects of growth and development
  • IGF-1 is the main one made in adults and children and IGF-2 is main in developing foetus
18
Q

Acromegaly

A

Excess growth hormone secreted by Somatotrophs due to pituitary adnoma
Causes - Coarsening of facial features
- Macroglossia- bigger tongue
- Prominent nose
- Obstructive sleep apnoea (soft-tissue changes surrounding upper airway leading to narrowing → Collapse during sleep → Causes disruption to sleep patterns)
- Sweatiness
- Increased hand and feet size
- Prognathism- large jaw
- Headaches
- Carpal tunnel due to growth of soft tissues around median nerve in wrist compressing it

Causes gigantism when growth plates haven’t fused

19
Q

Which hormones does the posterior pituitary release

A

Arginine vasopressin (AVP) also known as anti diuretic hormone

Oxytocin

20
Q

What type of neurones from the hypothalamus have axon fibres sending signals to the posterior pituitary gland?

A

Hypothalamic magnocellular neurones
These are long
Pass down from nuclei through pituitary stalk to posterior pituitary

21
Q

Which 2 hypothalamic nuclei do magnocellular axons extend from?

A

Supraoptic (AVP) and paraventricular (oxytocin)

22
Q

Features of posterior pituitary

A
  • It is anatomically continuous with hypothalamus
  • It’s made of only neuronal tissue, not endocrinal tissue like anterior pituitary
  • Stores hormones produced in the hypothalamus, does not make the hormones itself.
    Formed from down growth of diencephalon
23
Q

effects of release of AVP into body

A

AVP is anti diuretic hormone
AVP stimulates water reabsorption in renal collecting duct which concentrates urine through basolateral V2 receptor in kidney
Also vasoconstrictor via v1 receptor
Stimulates ACTH release
AVP binds to V2 receptor,cascade of events occur causing aquaporin 2 to be inserted allowing more water to be reabsorbed by aquaporin 3

24
Q

How does AVP concentrate urine and cellular level

A
  • AVP binds to V2 receptor on collecting duct cell which results in intracellular signalling cascade
  • This inserts aquaporin-2 molecules (water transport molecules) into apical membrane of duct cell
  • Water diffuses down its conc grad through aquaporin-2 from urine in nephron into collecting duct cell
  • It then moves through aquaporin-3 into plasma
25
Q

What are the 2 physiological actions that oxytocin release causes?

A
  • Contraction of myometrial cells in uterus at parturition (in labour) which leads to delivery of baby
  • Contraction of myoepithelial cells in breast during lactation which leads to milk ejection
26
Q

Outline the neuroendocrine reflex arc for milk ejection?

A

Mechanical stimulation of nipple and surrounding area activates afferent pathways

Afferent signals integrated in hypothalamus and stimulate oxytocin-releasing neuron activity

Action potentials travel down oxytocin neurons and oxytocin is secreted into the bloodstream

Increased plasma oxytocin increases milk ejection in mammary glands

27
Q

Regulation of posterior pituitary

A

Two sets of hypothalamic neurone rectory cells make AVP and oxytocin. This is transported to posterior pituitary
Excitation of hypothalamic magnocellular neurons stimulates release of avp or oxytocin into posterior pituitary

BRS Bioregulatory Systems (54 decks)

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