Hypothalamus and Pituitary Flashcards
What connects the hypothalamus to posterior pituitary and why is it important
the infundibular stalk, so hormones (ADH and oxytocin) produced in the hypothalamus can be stored in the posterior pituitary
What is the name for the partial sheath from the anterior pituitary that warps around the infundibular stalk
pars tuberalis
The combination of the infundibular stalk and pars tuberalis form what
The infundibulum
True or False anterior pituitary hormones are produced in large quantities
False, made in small quantities and only when needed
True or False the hypothalamus produces releasing and inhibiting hormones
True
Where is the pituitary gland located
Inferior to the hypothalamus within the sella tunica of the sphenoid bone
-almost directly behind the nose
What is the pituitary gland also known as
Hypophysis
What is the anterior pituitary gland known as
adenohypophysis or pars distalis
What is the posterior pituitary gland known as
neurohypophysis or pars nervosa
What gland of the pituitary is larger and why
They anterior pituitary because it is metabolically active
How many cell types are located in the anterior pituitary and what are there names.
5 types
- Somatotrophs
- Thyrotrophs
- Gonadotrophs
- Lactotrophs
- Corticotrophs
What does somatotrophs produce
Human growth hormone (HGH) aka somatotropin
What does thyrotrophs produce
Thyroid stimulating hormone (TSH) aka thyrotropin
What does gonadotrophs produce
Follicle stimulating hormone and luteinizing hormone
What does lactotrophs produce
Prolactin (PRL)
What does corticotrophs produce
Adrenocorticotropic hormone (ACTH) aka cortictropin
and
Melanocyte stimulating hormone
What is human growth hormone also known as
somatotropin
True or false HGH is released in a diurnal/pulsatile manner
True
At what time does HGH increase
first 2 hours of deep sleep
What is the main fxn of HGH
promote synthesis and secretion of Insulin-like growth factors (somatomedins)
What are IGF’s also known as
Somatomedins
Where are IGF’s made
liver, skeletal muscle, bones and cartilage
What is believed to cause the changes in the body HGH or IGF’s
IGF’s
-Someone could have normal HGH but if they are not producing IGFs they will have abnormalities
Describe IGF synthesis/release starting from hypothalamus hormones
Growth hormone releasing hormones causes HGH to produced and released which in turn causes IGF’s to be synthesized and released
Growth hormone inhibitory hormone inhibits the production and release of HGH and thus decreases IGF synthetization/release
How does IGF’s affect bone, adipose, skeletal muscle, liver, immune system and CNS
- bone=increase formation new bone in children and bone turn over in adults (renewal)
- adipose= lipolysis/increase FFA’s
- skeletal muscle=anabolism
- liver=Gluconeogenesis, reduced glucose uptake. increased IGF production
- immune system= stimulates Bcell response, NK cells, macrophages, and T cell function
- CNS= modulates mood and behavior, but not well known
True or False IGF’s metabolically act similar to insulin
False, IGF’s counteracts insulin on lipid and glucose metabolism
When blood sugar is low what is the action of IGF’s do
work to increase blood glucose
- gluconeogenesis in liver
- release of FFAs for other tissues to use as energy
What is the hypersecretion of HGH in childhood called and what happens to the body
Gigantism
-epiphyseal plates do not close so person becomes very tall
- bones also become very thick/heavy
- hyperglycemia
-panhypopituitarism=somatotrophs become so large they kill off other pituitary gland cells
What is the hypersecretion of HGH in adulthood called and what happens to the body
Acromegaly
-enlarged facial features, hands and feet
- bone thickening
- enlargement of organs especially liver and kidneys
- skin thickening
What is the hyposecretion of HGH in childhood called what happens to the body
Dwarfism
-epiphyseal plates close before normal ht is achieved
What happens to HGH production as we age
Production decreases w/ age
What is the function of adrenocorticotropic hormone (ACTH) and what hypothalamic hormone stimulates its production.
- ACTH controls the production of glucocorticoid steroids (ie cortisol), certain adrogens, and certain mineral corticoids produced in adrenal cortex
- Stimulated by corticotropin releasing hormone (CRH)
When is adrenocorticotropic hormone (ACTH) released
During physiologic and physical stressors.
What hypothalamic hormone stimulates the production of Prolactin and what causes it to be released.
Prolactin releasing hormone
-released by suckling of the breast and increased estrogen
What hypothalamic hormone inhibits the production of Prolactin and what is another name for this hormone
Prolactin inhibitory hormone aka dopamine
What are the effects of prolactin
- stimulates the growth/development of mammary glands during pregnancy
- stimulates synthesis of milk during pregnancy
- plays a part in the menstrual cycle
Prior to menstruation what causes prolactin to be increased
low estrogen/progesterone inhibits PIH(dopamine)
Besides right before menstruation are prolactin levels high or low
low because estrogen levels increase so PIH (dopamine) increases.
What would be a sign of prolactin hypersecretion
- milky breast charge in males or non-pregnant/non-breast feeding females
- ED w/ no obvious cause
What is the function of follicle stimulating hormone (FSH)
- Initiates follicle production in women and produce ovarian production of estrogen
- stimulates production of sperm cells
What inhibits and promotes follicle stimulating hormone (FSH)
- Gonadotropin -releasing hormone from hypothalamus increases production
- Inhibited by increased estrogen or testosterone
What is the function of luteinizing hormone (LH)
females= ovulation and formation of corpus luteum and w/ FSH release estrogen from ovarian follicular cells
males= stimulates testes to produce testosterone
What hormone in the hypothalamus promotes luteinizing hormone (LH)
Gonadotropin-releasing hormone from hypothalamus increases production
Describe melanocyte stimulating hormones
a group of peptide hormones produced in the skin, anterior pituitary and other parts of the body that are involved in pigmenting skin cells
-possible production in suppressing appetite
What inhibits production of melanocyte stimulating hormones in the pituitary gland only
Dopamine
What is the name of the neural tissue that makes up the bulbar portion of the posterior pituitary
pars nervosa
What is antidiuretic hormone (ADH) also known as
Vassopressin
What is the fxn of ADH aka vasopressin
decreases urine production/excretion and increases vasoconstriction thus increasing BP
How does alcohol affect ADH
EtOH reduces release of ADH from posterior pituitary
How are ADH and blood osmotic pressure related
Osmoreceptors in the hypothalamus monitor blood osmotic pressure and stimulate/inhibit ADH release in response
high blood osmotic or low blood volume pressure (dehydration) =increased ADH
What body tissues are ADH targets
- Collecting ducts of renal tubules=reabsorbs waters
- Sudoriferous glands=inhibits sweats
- Vascular smooth muscle= constriction
What are other ways does ADH secretion get altered
Pain, stress, trauma, morphine, tranqs, some anesthetics, nicotine
Describe diabetes insipidus
Disease that is caused by defects in ADH receptors (nephrogenic) or inability to produce/secrete ADH (neurogenic) which causes excessive urination/thirst and dehydration
What are the known fxn of oxytocin and what stimulates its release
- Released during the delivery of a child, stretching of the cervix stimulates release, in a positive feed back loop
- also causes milk let down
What are the possible fxn of oxytocin
- possibly involved with emotional bonding in males
- possibly plays a part in feeling sexual pleasure during and after intercourse
What are the known fxn of oxytocin and what stimulates its release
- Released during the delivery of a child, stretching of the cervix stimulates release, in a positive feed back loop
- also causes milk let down
What are the possible fxn of oxytocin
- possibly involved with emotional bonding in males
- possibly plays a part in feeling sexual pleasure during and after intercourse
