Lecture #21: Hypthalamus and Pituitary Gland Flashcards
What are the difference between the hypthamlas and pituitary gland?
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
What is the similarity between the hypothamalas and pituitary gland?
Together control almost all aspects of growth, developement, metabolism, and homeostasis
Draw out and describe the regions of the pituitary gland.
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)
Draw out and label the hypothalamic and pituitary circulation.
Plexuses and capillaries
What is the function of the hypothalamus to the anterior pituitary galnd and posterior putuitary galnd?
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)
What is the hypothalamus known for?
Known for recieving sensory input (to make decisions=control center) from cortex, chemicals in blood to various tissue effects (smooth muscle, glands etc.)
How does the hypothalamus effect the endocrine system?
By secreting releasing and/or inhibiting hormones which act on the target cells in the anterior pituitary
What are the 5 main cell types of the Anterior Pituitary?
Somatotrophs Thyrotrophs Lactotrophs Gonadotrophs Corticotrophs
What hormone has somatotrophs?
Human Growth Hormone (hGH)
What hormone does thyrotrophs secrete?
Thyroid Stimulating Hormone (TSH)
What hormone does Lactotrophs secrete?
Prolactin (PRL)
What hormone does Gonadotrophs secrete?
Follicle Stimulating hormone (FSH) and Lutenizing Hormone (LH)
What hormone does Corticotrophs secrete?
Adrenocorticotropic Hormone (ACTH) and Melanocyte Stimulating Hormoen (MSH)
What are human growth hormones (hGH)?
Produced by somatrophs in anterior pituitary
Target cells: liver, skeletal muscle, cartilage, bone
What is the hGH purpose?
Increases synthesis of insulin-growth factors that act locally or enter bloodstream (IGFs)
How do insulin growth factors help with hGH?
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
Are hGH released immediately or every few hours?
hGH is released in bursts every few hours
How is release of hGH regulated?
Is regulated by Growth hormone releasing hormone (GHRH) and Growth hormone inbiting hormone (GHIH)
What happens if you have a stimuli of GHRH?
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
What happens if you have stimuli of GHIH?
Hyperglycemia, REM sleep, Increased fatty acids and decreased amino acids
in the blood, Obesity, Low levels of thyroid hormones, high levels of hGH
What is the function of the follicle stimulating hormone? (FSH)
Gonadotropin releasing hormone (GnRH) from hypothalamus
stimulates gonadotrophs in anterior pituitary to produce FSH
What is the reaction between male and female of FSH?
In females, FSH
– stimulates secretion of estrogen
– initiates the formation of follicles within the ovary
• In males, FSH
– stimulates sperm production in testes
What is the function of the Luteinzing Hormone (LH)?
GnRH from hypothalamus stimulates gonadotrophs in
anterior pituitary to produce LH
What is reaction between females and males of LH?
• 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
There is no GnIH,what is the primary way of inhibiting GnRH release?
GnRH is inhibited by both increase of estrogen and testerone
What is the function of prolactin?
Hypothalamus regulates lactotroph cells by secreting PRH and PIH (dopamine)--oxytocin is also needed for milk ejection
Lactotrophs in anterior pituitary produce prolactin
In what conditions does prolactin need to be in…in order to produce milk?
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.
What reduces the levels of inhibition of prolactin?
• Suckling reduces levels of hypothalamic inhibition and
prolactin levels rise along with milk production
What is the function of Melanocyte-stimulating hormone?
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
What inhibits the release of MSH?
PIH (dopamine) inhibits MSH release
What is the function of the Adrenocorticotropic Hormone (ACTH)?
• 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.
What stimulates the regulation of ACTH?
• Hypothalamus
releases CRH
• CRH stimulates
release of ACTH
• ACTH stimulates
release of cortisol
• Cortisol inhibits
release of CRH and
ACT
What is the function of the Thyroid Stimulating Hormone (TSH)?
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.
What stimulates the regulation of Thyrotropin (TSH) to be released?
• 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
