endocrine 1.4

Question 1

pituitary gland - components, connections

Answer 1

we have neural and vascular connections between the hypothalamus and pituitary gland

-via the infundibulum : connects hypothalamus to pituitary gland, contains axons from neurons of the hypothalamus as well as blood vessels

anterior : is a gland

posterior : extension of neural components

Question 2

posterior pituitary connections

Answer 2

have the supraoptic and paraventricular nuclei that pass down the infundibulum
-(no connection between hypothalamus and ant pituitary)

Question 3

median eminence

Answer 3

junction between hypothalamus and infundibulum

Question 4

hypothalamo-hypophyseal portal vessels (or portal vein)

Question 5

posterior pituitary hormones : synthesize where? what are hormones it releases

Answer 5

-synthesized in the hypothalamus, specifically the cell bodies of the supraoptic and paraventricular nuclei
-two hormones : oxytocin and vasopressin
neural extension of hypothalamus

Question 6

oxytocin functions

Answer 6

1) contraction of smooth muscle cells in the breast which results in milk ejection during lactation
- positive feedback to increase more from suckling
2) contraction of uterine smooth muscle cells until the baby is born

Question 7

vasopressin (or ADH)

Answer 7

released when high osmolality of water or low BP
-detected by hypothalamus and act on posterior pituitary to release vasopressin, goes towards nephron in kidneys and increases sodium retention and water retention
-water follows salt so if we retain salt we can retain water
-second mechanism is via carotid sinus receptors detecting low BP and release vasopressin
there is negative feedback to stop these from happening

Question 8

anterior pituitary gland hormones and the hypothalamus

Answer 8

• hypothalamic neurons secrete hormones that control the secretion of all the anterior pituitary gland hormones
• hypophysiotropic hormones : hypothalamic hormones that regulate anterior pituitary gland function (can be excitatory or inhibitory)

Question 9

hypophysiotropic hormone

Answer 9

hypothalamic hormones that regulate anterior pituitary gland function (can be excitatory or inhibitory)

• carried by the hypothalamo-hypophyseal portal vessels to the anterior pituitary gland capillaries, into the interstitial fluid surrounding the various anterior pituitary gland cells
• all hypophysiotropic hormones are the first in a 3 hormone sequence (except for DOPAMINE)
• good to have a sequence bc it permits a variety of important hormonal feedback and amplification of response

Question 10

anterior pituitary hormones

Answer 10

secretes 6 peptide hormones

1. FSH
2. LH
3. GH growth hormone
4. TSH thyroid stimulating hormone
5. prolactine
6. ACTH Adrenocorticotropic hormone

Question 11

FSH and LH

Answer 11

known as gonadotropins effect on the gonads

Question 12

FSH LH and GH

Answer 12

stimulate target cells to synthesize and secrete other hormones and additional functions

Question 13

prolactin

Answer 13

no control over secretion of other hormones

-breast development and milk production in women

Question 14

GH

Answer 14

liver and other cells secrete IGF-1

• many organ and tissues do protein synthesis, carbohydrate and lipid metabolism

Question 15

TSH and ACTH

Answer 15

stimulate target cells to synthesize and secrete other hormones

-ACTH stimulates adrenal cortex to secrete cortisol

TSH stimulates thyroid to release thyroxine and triodothyronine

Question 16

similarities of anterior and posterior pituitary

Answer 16

• secrete hormones in the same manner
• are synthesized in cell bodies of the hypothalamic neurons
• passed down axons to the neuron terminal
• released in response to an AP

Question 17

anterior pituitary hormone sequence

Answer 17

• hypophysiotropic hormones begin in the hypothalamus and end on the capillaries in the median eminence
• hypophysiotropic hormones enter the capillaries in the median eminence and empty into the hypothalami-hypophyseal portal vessels which carry them to the cells of the anterior pituitary gland

Question 18

posterior pituitary hormone sequence

Answer 18

• hypothalamic neurons that secrete hormones that leave the hypothalamus and end in the posterior pituitary
• most capillaries into which the hormones are secreted are immediately drained into general circulation

Question 19

effect of portal vessels on concentration

Answer 19

• portal vessels have a small amount of blood so we dont need to release a high amount of hormones to have a high concentration
• if we release hormones from the hypothalamus directly into the general circulation we have to have a higher concentration

Question 20

hypothalamus releases hormones which have excitatory or inhibitory effects on Ant pit hormones*

Answer 20

GnRH, GHRH, SST, TRH, DA, CRH

Question 21

GnRH

Answer 21

excitatory effect on release of gonadotropins (FSH and LH)

Question 22

GHRH growth hormone releasing hormone and SST somatostatin effect on…

Answer 22

GHRH stimulates secretion of GH

SST inhibits GH

Question 23

TRH thyrotropin releasing hormone

Answer 23

stimulates secretion of TSH

Question 24

which hypophysiotropic hormones are peptides which are catecholamines?

Answer 24

dopamine is a catecholamine

all of the others are peptides

Question 25

Dopamine

Answer 25

inhibits prolactin (-)

Question 26

corticotropin releasing hormone (CRH)

Answer 26

stimulates secretion of ACTH adrenocropticotropin hormone

Question 27

neural control of hypophysiotropic hormones

Answer 27

receives stimulatory and inhibitory input from all areas of the CNS → have specific neural pathways influence the secretion of individual hormones NT ( catecholamine and seretonin) are released at synapses on the hypothalamic neurons -Have **circadian influence** (24 hour cycle) → are linked to inputs from visual pathways that recognize the presence or absence of light eg. CRH

Question 28

GH release, effects, role of leptin

Answer 28

GHRH in hypothalamus which releases GH from ant pit GH acts on bones for growth and repair, and on the liver to increase IGF-1 which increases growth When we have too much GH, IGF-1 has a negative feedback on ant pit and hypothalamus to stop the circuit Leptin affects GH, when we have a lot of fat leptin increased and appetite lowers. if you have too much leptin it will impair your bone function

Question 29

episodic endocrine secretion - diurnal rhythm (cortisol)

Answer 29

durnal : day and night cortisol increases at 4am peaks at 6am. regulated with day and night patterns naps do not increase cortisol

Question 30

episodic endocrine secretion - ultradian (GnRH)

Answer 30

minutes or hours GnRH increases by the hour LH peaks every 1 or 2 hours as well

Question 31

hormonal feedback control of the hypothalamus and anterior pituitary gland

Answer 31

negative feedback loops _long loop negative feedback_ : exerted onto the hypothalamus and/or anterior pituitary gland by the 3rd hormone in sequence _short loop negative feedback_ : exerted by the anterior pituitary gland hormone on the hypothalamus

Question 32

nonsequence hormones on the hypothalamus and ant pit gland

Answer 32

have many stimulatory and inhibitory hormonal influences on the hypothalamus and/or anterior pituitary gland other than those from a feedback loop example : estradiol and prolactin