Lecture #21: Hypthalamus and Pituitary Gland

Question 1

What are the difference between the hypthamlas and pituitary gland?

Answer 1

Hypothalamus recieves input from the cortex, thalamus, limibic system, and internal organs

It provides a link between the external and internal environment and the endocrine system

Pituitary gland can send signals throughout the body

Question 2

What is the similarity between the hypothamalas and pituitary gland?

Answer 2

Together control almost all aspects of growth, developement, metabolism, and homeostasis

Question 3

Draw out and describe the regions of the pituitary gland.

Answer 3

Spehnoid bone –> hypophyseal fossa–>Hypothalamus(oral cavity)->Anterior and posteriod pituitary (both serve different functions and tissues)–> infundibulum (forms a capillary of portal veins to a secondary capsule of caplliares)

Question 4

Draw out and label the hypothalamic and pituitary circulation.

Answer 4

Plexuses and capillaries

Question 5

What is the function of the hypothalamus to the anterior pituitary galnd and posterior putuitary galnd?

Answer 5

The hypothalamus controls the anterior pituitary gland with special hormones called releasing hormones and inbiting hormones.

Releases other hormones directly into circulation through the posterior pituitary. (Makes the hormones)

Question 6

What is the hypothalamus known for?

Answer 6

Known for recieving sensory input (to make decisions=control center) from cortex, chemicals in blood to various tissue effects (smooth muscle, glands etc.)

Question 7

How does the hypothalamus effect the endocrine system?

Answer 7

By secreting releasing and/or inhibiting hormones which act on the target cells in the anterior pituitary

Question 8

What are the 5 main cell types of the Anterior Pituitary?

Answer 8

Somatotrophs 
Thyrotrophs 
Lactotrophs 
Gonadotrophs 
Corticotrophs

Question 9

What hormone has somatotrophs?

Answer 9

Human Growth Hormone (hGH)

Question 10

What hormone does thyrotrophs secrete?

Answer 10

Thyroid Stimulating Hormone (TSH)

Question 11

What hormone does Lactotrophs secrete?

Answer 11

Prolactin (PRL)

Question 12

What hormone does Gonadotrophs secrete?

Answer 12

Follicle Stimulating hormone (FSH) and Lutenizing Hormone (LH)

Question 13

What hormone does Corticotrophs secrete?

Answer 13

Adrenocorticotropic Hormone (ACTH) and Melanocyte Stimulating Hormoen (MSH)

Question 14

What are human growth hormones (hGH)?

Answer 14

Produced by somatrophs in anterior pituitary

Target cells: liver, skeletal muscle, cartilage, bone

Question 15

What is the hGH purpose?

Answer 15

Increases synthesis of insulin-growth factors that act locally or enter bloodstream (IGFs)

Question 16

How do insulin growth factors help with hGH?

Answer 16

Increases cell growths and cell division by increasing the uptake of amino acids and synthesis of proteins

stimulate lipolysis in adipose tissue (released fatty acids are used
for ATP production in most body cells)

decrease glucose use by most body cells so blood glucose levels
remain high enough to supply the brain

Question 17

Are hGH released immediately or every few hours?

Answer 17

hGH is released in bursts every few hours

Question 18

How is release of hGH regulated?

Answer 18

Is regulated by Growth hormone releasing hormone (GHRH) and Growth hormone inbiting hormone (GHIH)

Question 19

What happens if you have a stimuli of GHRH?

Answer 19

Hypoglycemia, Deep sleep, Decreased fatty acids and increased amino acids
in the blood, Increased sympathetic stimulation

Other stimuli for GHRH include estrogens, insulin and glucagon, and
cortisol

Question 20

What happens if you have stimuli of GHIH?

Answer 20

Hyperglycemia, REM sleep, Increased fatty acids and decreased amino acids
in the blood, Obesity, Low levels of thyroid hormones, high levels of hGH

Question 21

What is the function of the follicle stimulating hormone? (FSH)

Answer 21

Gonadotropin releasing hormone (GnRH) from hypothalamus

stimulates gonadotrophs in anterior pituitary to produce FSH

Question 22

What is the reaction between male and female of FSH?

Answer 22

In females, FSH
– stimulates secretion of estrogen
– initiates the formation of follicles within the ovary

• In males, FSH
– stimulates sperm production in testes

Question 23

What is the function of the Luteinzing Hormone (LH)?

Answer 23

GnRH from hypothalamus stimulates gonadotrophs in

anterior pituitary to produce LH

Question 24

What is reaction between females and males of LH?

Answer 24

• In females, LH stimulates
– secretion of estrogen and progesterone
– ovulation
– formation of corpus luteum (prepare the uterus for implantation of a fertlized ovum)

• In males, LH stimulates
– secretion of testosterone

Question 25

There is no GnIH,what is the primary way of inhibiting GnRH release?

Answer 25

GnRH is inhibited by both increase of estrogen and testerone

Question 26

What is the function of prolactin?

Answer 26

``` Hypothalamus regulates lactotroph cells by secreting PRH and PIH (dopamine)--oxytocin is also needed for milk ejection ``` Lactotrophs in anterior pituitary produce prolactin

Question 27

In what conditions does prolactin need to be in...in order to produce milk?

Answer 27

The right conditions include “prepping” of mammary glands by other hormones during pregnancy. These hormones include estrogens, progesterone, glucocorticoids, hGH, thyroxine, and insulin. These hormones have a PERMISSIVE EFFECT for PRL.

Question 28

What reduces the levels of inhibition of prolactin?

Answer 28

• Suckling reduces levels of hypothalamic inhibition and | prolactin levels rise along with milk production

Question 29

What is the function of Melanocyte-stimulating hormone?

Answer 29

Secreted by corticotrophs in the anterior pituitary • Excessive levels of CRH from the hypothalamus increases MSH release from the anterior pituitary high levels increase skin pigmentation

Question 30

What inhibits the release of MSH?

Answer 30

PIH (dopamine) inhibits MSH release

Question 31

What is the function of the Adrenocorticotropic Hormone (ACTH)?

Answer 31

• Corticotropin releasing hormone (CRH) from the hypothalamus stimulates corticotrophs in the anterior pituitary to release ACTH • ACTH stimulates release of glucocorticoids (mainly cortisol) from adrenal cortex • ACTH release is also stimulated by hypoglycemia, physical trauma, and IL-1.

Question 32

What stimulates the regulation of ACTH?

Answer 32

• Hypothalamus releases CRH • CRH stimulates release of ACTH • ACTH stimulates release of cortisol • Cortisol inhibits release of CRH and ACT

Question 33

What is the function of the Thyroid Stimulating Hormone (TSH)?

Answer 33

Hypothalamus regulates thyrotrophs (via TRH) in anterior pituitary to produce TSH (thyrotropin) • TSH stimulates the synthesis & secretion of T3 and T4 (thyroid hormones) • Metabolic rate stimulated-- One way cells increase metabolic rate (ATP consumption) is to synthesize more Na+/K+ -ATPase pumps.

Question 34

What stimulates the regulation of Thyrotropin (TSH) to be released?

Answer 34

• Hypothalamus releases thyrotropin releasing hormone (TRH) • TRH causes release of thyroid stimulating hormone (TSH) from anterior pituitary cells • Thyroid gland cells activated to secrete more T3 & T4