Hypothalamus/ Ant and Post Pituitary Flashcards Preview

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Flashcards in Hypothalamus/ Ant and Post Pituitary Deck (42):
1

Types of Secretory Patterns

-Circadian (diurnal) Rhythm
- Ultradian Rhythm
- Stimulus Induced
- Longer time interval Rhythms

2

What is the most common example of a circadian rhythm hormone?

Cortisol
- ACTH stimulates cortisol release so it also has a circadian rhythm

3

What is an ultradian rhythm and what is an example?

An Ultradian rhythm is one that occurs multiple times each day.
LH (leutenizing Hormone) release is an example

4

Three methods of controlling plasma hormone concentrations?

1) Increases or decrease secretion rate
2) Increase or decrease the level of hormone biding protein for that particular hormone
3) Increase or decrease degradation rate

5

Positive feedback

The endocrine system's response to a stimulus reinforces that stimulus.
Ex: stretch of the cervix stimulates oxytocin release, this leads to more stretch of the cervix

6

Negative feedback

The endocrine system's response to a stimulus is to reduce that stimulus

7

Describe the negative feedback mechanism associated with a rise in plasma glucose

Plasma glucose ^^ --> Rise in Insulin secretion--> Inc concentration of insulin in the plasma --> Rise in glucose uptake and utilization by the muscle and adipose tissue --> plasma glucose slowly goes back down to normal

So...how does the plasma glucose level keep from dropping too far below normal?

As Plasma Glucose Goes down --> GLUCAGON is secreted --> Hepatic Glucose is released --> Plasma glucose concentration comes back to normal.

8

How do hormones move from the top region of the pituitary gland to the bottom?

Axoplasmic flow...takes about a week for them to move this short distance.

9

How does hormone get stimulated to start the movement down the center of the pituitary?

Action potential

10

Where is the Pituitary gland located

base of brain in a bony pocket called the Sella turcica

11

What connects the pituitary to the base of the brain?

Infundibulum...this contains the nerves and veins

12

What are the two posterior pituitary gland hormones?

ADH and OT (oxytocin)

13

The posterior pituitary is basically a neural extension of the hypothalamus...where do the nerve axons come from?

Mainly from two nuclei in the hypothalamus: the Supraoptic nucleus (SON) and the Paraventricular Nucleus (PVN). The axon terminals are located near capillaries in the posterior pituitary and release their hormones here.

14

The area where hormones are released in the posterior pituitary is called?

Pars Nervosa

15

What is the function of Oxytocin...KNOW

stimulates contraction of the uterus and myoepithelial cells in the mammary gland (pushes out breastmilk)

16

WHat is the function of ADH,,,KNOW

regulates retention of water by increasing water channels in the walls of the kidney.
Also increases the contractility of vascular smooth muscle...Pressor effectM

REMEMBER: Oxytocin and Vasopressin have slightly overlapping activity

17

What is the chemical structure of ADH and OT

Nonapeptides (nine amino acids), both have a disulfide bridge, very similar structure which explains their overlapping activity

18

When are ADH and OT secreted

When action potentials reach their nerve terminals. Analogous to neurotransmitter release
- They are secreted together with their respective neurophysins

19

Main stimuli of ADH

Low ECF (plasma) volume

20

Plasma volume has to drop by how much to lead to increase in ADH secretion

5-10 %

21

Osmolarity has to change by how much to increase ADH secretion

1-2%

22

KNOW THE EXPERIMENT ON STALK SECTION AND RECOVERY

ok

23

Where does most of the blood supply to the pituitary gland come from

looks like it comes from the Internal carotid artery for the most part

24

What are the six major hormones of the anterior pituitary glands

GH (Growth Hormone), PRL (Prolactin), ACTH (adrenocorticotrophic hormone), LH, FSH, TSH

Most are called Trophic hormones....means it makes target tissues grow

25

Chemical nature of the hormones secreted from ant pituitary)

ACTH....39 amino acids, straight chain

Glycoproteins: TSH, FSH, LH....all are dimers of alpha and beta subunits and all have alpha and beta subunits that are very similar, but different enough to lead to different bioloogical functions. (Beta subunit accounts for the difference), SO IF YOU DO AN ASSAY, YOU WANT TO MEASURE THE BETA SUBUNIT>>>>KNOW THIS

Proteins: GH and PRL. These are the acidophils (they occupy about 75% of the Pituitary)

26

The biological activity of ACTH is found at what end?

The end opposite of the COOH....you only need about 20 amino acids for biological activity

27

ACTH 1-24?

Its the first 24 AAs but it has full activity

28

MSH activity is what

Melanocyte stimulating hormone...the structure of this hormone lies within ACTH so excess ACTH causes hyperpigmentation

29

The six releasing hormones and their effects

CRH- Corticotrophin releasing hormone increases ACTH secretion

TRH- increases TSH secretion

GNRH- inc LH and FSH

GHRH- Gh release

Somatostatin- GH goes down

Dopamine- Prolactin decreases

30

Where are the osmoreceptors that sense changes in plasma osmolarity that would lead to an upregulation in vasopressin (ADH)?

Hypothalamus...KNOW

31

So changes in plasma osmolarity are realized by osmoreceptors where?

hypothalamus (Supraoptic and Paraventricular Nuclei)

32

Changes in plasma volume (ECF volume) are recognized by volume receptors where?

Central nervous System

33

Which hormones from teh anterior pituitary stain acidophilic

GH, Prolactin

34

Regarding the family groupings of anterior pituitary hormones, which fall into the glycoprotein family

TSH, LH, FSH

35

Regarding the family groupings of the anterior pituitary hormones, which fall into the protein family

GH and Prolactin

36

Oxytocin secretion is tied to sensory input and emotional input when it comes to the release of milk.

In a study, it was shown that oxytocin levels rose even before suckling began. This was in anticipation of suckling like upon seeing or hearing the baby.

37

GH and Prolactin (the proteins and acidophiles) consume how much of the anterior pituitary's volume?

75%

38

Somatotrophs are what

GH producing cells

39

How much of the anterior pit volume do they occupy

50%

40

What hormone increases GH excretion

T3

41

Lactotrophs do what

produce prolactin

42

Basophils occupy what percentage of pituitary volume>

15-20