Physiology Ch. 75: Pituitary Hormones

Front 1

adenohypophysis

Back 1

Anterior pituitary

Front 2

neurohypophysis

Back 2

Posterior pituitary

Front 3

Embryologic origin of Ant Pituitary? Post Pituitary?

Back 3

-A thickened area of ectodermal cells on the roof of the pharynx that invaginates RATHKE's POUCH
- Invagination of the floor of the developing ventricular system

Front 4

What type of general cells are contained within the anterior pitutiary

Back 4

granular cells

Front 5

Does the post pituitary contain grandular cells?

Back 5

No; instead it contains glial-type and axons and nerve terminals of neurons whose cell bodies lie in the hypothalamus.

Front 6

The hypothalamus forms the walls and floor of what structure?

Back 6

3rd ventricle

Front 7

The cell bodies of axons and terminals that are within the post pituitary arise where?

Back 7

The supraoptic and paraventricular nuclei of the anterior (supraoptic) region of the hypothalamus

Front 8

Separates the hypothalamus and thalamus

Back 8

Hypothalamic sulcus

Front 9

On the ventral surface of the brain, the hypothalamus lies just posterior to what structure?

Back 9

The tuber cinereum and mammilary bodies lie posterior to the optic chiasm

Front 10

A bulge located between the optic chiasm and the mammilary bodies. What arises from this posterior portion of this structure and continues inferiorly?

Back 10

Tuber cinereum
The pituitary stalk arises here

Front 11

Anterior portion of the infundibulum. Why is this important?

Back 11

Median eminence: Region where hypothalamic neurons release regulating factors that are carried by portal vessels to the anterior pituitary

Front 12

A bulge located between the optic chiasm and the mammilary bodies. What arises from this posterior portion of this structure and continues inferiorly?

Back 12

Tuber cinereum
The pituitary stalk arises here

Front 13

Where does the pituitary gland sit?

Back 13

Within the pituitary fossa in the sella turcica.

Front 14

What structure lies immediately beneath the floor of the sella turcica? lateral?

Back 14

Sphenoid sinus
The cavernous sinuses

Front 15

Dura covering the superior portion of the pituitary fossa

Back 15

Diaphragma sella

Front 16

the fibers of what structure pass through the hypothalamus dividing it into medial and lateral areas

Back 16

Fornix

Front 17

Controls circadian rhythms

Back 17

Suprachiasmatic nucleus

Front 18

Largest amount of anterior pituitary cells. How do they stain?

Back 18

Somatotropes stain acidophilic

Front 19

Actions of Somatotropes

Back 19

Stimulates body growth, lipolysis and secretion of IGF-1. Inhibits action of insulin on carbohydrate and lipid metabolism.

Front 20

How are hormones conducted from the hypothalamus to the ant pituitary? From the ant pituitary?

Back 20

Small arteries pass through the median eminence and form the primary capillary plexus. Here hormones diffuse into the blood and are carried via the hypophysial portal veins to the anterior pituitary. Then, hormones released in the anterior pituitary are picked up by the secondary capillary plexus and carried by draining veins to the cavernous sinus. the cavernous sinus drains via the superior and inferior pertrosal veins to the internal jugular vein.

Front 21

Where do the cell bodies of oxytocin and vasopressin hormones that are transmitted through neuronal terminals lie?

Back 21

Supraoptic and paraventricular regions

Front 22

Describe the blood supply of the ant pituitary

Back 22

Receives arterial blood from superior and inferior hypophysial arteries that originate from the internal carotid.

Front 23

Descending autonomic fibers mainly originate where?

Back 23

paraventricular nucleus of the hypothalamus

Front 24

How do the neurons of the hypothalamus differ from the rest of the CNS

Back 24

Their function is to secrete the hypothalamic releasing and inhibiting hormones into the ant pituitary. Their nerver fibers are sent to the median eminance and the tuber cinereum. This differs from the usual function of neuronal signal transmission

Front 25

Controls circadian rhythms

Back 25

Suprachiasmatic nucleus

Front 26

What is the function of dopamine within the hypothalamus

Back 26

Inhibits prolactin secretion. Also called Prolactin inhibiting Hormone

Front 27

Somatostatin

Back 27

Growth Hormone Inhibiting Hormone: Inhibits secretion of growth hormone

Front 28

Largest amount of anterior pituitary cells. How do they stain?

Back 28

Somatotropes stain acidophilic

Front 29

Actions of Somatotropes

Back 29

Stimulates body growth, lipolysis and secretion of IGF-1. Inhibits action of insulin on carbohydrate and lipid metabolism.

Front 30

How are hormones conducted from the hypothalamus to the ant pituitary? From the ant pituitary?

Back 30

Small arteries pass through the median eminence and form the primary capillary plexus. Here hormones diffuse into the blood and are carried via the hypophysial portal veins to the anterior pituitary. Then, hormones released in the anterior pituitary are picked up by the secondary capillary plexus and carried by draining veins to the cavernous sinus. the cavernous sinus drains via the superior and inferior pertrosal veins to the internal jugular vein.

Front 31

Where do the cell bodies of oxytocin and vasopressin hormones that are transmitted through neuronal terminals lie?

Back 31

Supraoptic and paraventricular regions

Front 32

What hypothalamic nucleus lies closest to the 3rd ventricle

Back 32

Periventricular nucleus

see p 741 in neuro

Front 33

The preoptic area of the hypothalamus is derived from what? How is this different?

Back 33

Telencephalon
This differs in that the rest of the hypothalamus is derived from the diencephalon

Front 34

Where are GABA neurons located in the hypothalamus? Histamine? Why is this important?

Back 34

Ventral lateral preoptic area
Tuberomammillary nucleus
The Gabaergic neurons contribute to non-REM sleep by inhibiting the histaminergic neurons

Front 35

What nucleus is important for appetite and a lesion here may cause a decrease in body weight? What nucleus inhibits appetite?

Back 35

Lateral hypothalamus
Ventromedial nucleus

Front 36

Leptin may bind to what receptors in the hypothalamus to control food intake and obesity?

Back 36

Ob receptors

Front 37

Lesions here may cause hyperthermia?

Back 37

Anterior hypothalamus detects increased body temperature and activates mechanisms of heat dissipation

Front 38

Bilateral lesions here cause poikilothermia

Back 38

Posterior hypothalamus that function to conserve heat. A lesion here causes the body temp to vary with the environement because they also destroy descending fibers for heat dissipation from the anterior hypothalamus

Front 39

thirst results from activation of what

Back 39

Osmoreceptors in the anterior hypothalamus

Front 40

Where is melonocyte producing hormone produced

Back 40

Pars intermedia of the pituitary

Front 41

What are the general affects of growth hormone?

Back 41

Causes growth of almost all tissues of the body, increases the size of cells, increases mitosis, and specific differentiation of certain types of cells such as bone growth and early muscle cells.

Front 42

How does growth hormone affect metabolism

Back 42

Increased rate of protein synthesis; increased mobilization of fatty acids, with increased FFA's in the plasma, and increased fatty acids used for energy; decreased rate of glucose utilization throughout the body.

Front 43

Growth hormones affects on protein synthesis

Back 43

Increases the transport of AA's through the cell membrane (similiar to insulin's actions), increases transcription and translation, and acts as a protein sparer by increased fatty acid utilization.

Front 44

Growth hormone enhances the conversion of fatty acids to what? In excess growth hormone states, what serious condition may occur as a result?

Back 44

acetyl-Coa
Excess acetyl-CoA may combine to form acetoacetic acid and thus cause ketoacidosis. A fatty liver may also result.

Front 45

How does growth hormone affect glucose uptake and insulin?

Back 45

Growth hormone decreases glucose uptake in the cells, increase glucose production in the liver, and increases insulin secretion. this occurs because of growth-hormone induced INSULIN RESISTANCE. This may be due to increased fatty acids that decrease the sensitivity of the muscle and liver to insulin

Front 46

What disease may growth hormone mimic the actions of?

Back 46

Type II Insulin resistant diabetes

Front 47

What organ is essential for growth hormone's effects to increase growth rates?

Back 47

Pancreas: Without the pancreas, there is not adequate insulin and carbohydrate availability, and energy is not provided for metabolism. Insulin may also increase the transport of some AA's into the cell.

Front 48

In adults, what tissue grows considerably under the influence of growth hormone?

Back 48

Soft tissues and organs

Front 49

How do the long bones grow in response to growth hormone? How does this affect bony fusion in the adolescent?

Back 49

The long bones elongate at the epiphyseal cartilages, where new cartilage is deposited and transformed into bone, thus elongating the shaft. At the same time the epiphyseal cartilage is used up so that by late adolescence not additional cartilage remains and bony fusion occurs at the shaft and epiphysis.

Front 50

What is the affect of growth hormone on osteoblasts?

Back 50

Growth hormone greatly stimulates osteoblasts, thereby increasing the rate of deposition and increasing the thickness of bones. This is especially true of the membranous bones.

Front 51

What affect does growth hormone have on chondrocytes?

Back 51

Increases their rate of transformation into osteogenic cells.

Front 52

Growth hormone exerts its effects through what intermediate substances? Where are these made?

Back 52

Somatomedins also called Insulin like growth factors are formed via the influence of growth hormone. They are made in the liver.

Front 53

What is the most important somatomedin? What would a deficiency cause?

Back 53

Somatomedin C
Dwarfism

Front 54

What is the length of action of growth hormone as compared to somatomedin C.

Back 54

Because growth hormone binds weakly to plasma proteins, its length of action is very short. Somatomedins bind strongly to plasma proteins, so their mechanism of action

Front 55

Growth hormone is released in what pattern

Back 55

Pulsatile

Front 56

What factors are known to increase growth hormone release?

Back 56

Starvation w/ protein deficiency, hypoglycemia, low fatty acid blood concentration, trauma, exercise, stress and excitement.

Front 57

In acute conditions what is the most potent stimulator of growth hormone? Chronic conditions?

Back 57

Hypoglycemia
Degree of cellular protein depletion

Front 58

What part of the hypothalamus controls GHRH secretion?

Back 58

Ventromedial nucleus, the same that controls appetite by monitoring blood glucose levels.

Front 59

What neurotransmitters have been shown to increase growth hormone secretion?

Back 59

Dopamine and serotonin

Front 60

Most of the control of growth hormone is mediated through what?

Back 60

GHRH

Front 61

How does GHRH cause release of growth hormones at the cellular level? What are the short term and long term effects?

Back 61

GHRH binds to receptors and activates adenylyl cyclase which activates cAMP.
The short term effects are an increase cell permeability to Ca2+, thereby increasing the intracellular calcium concentration, and allowing the secretory growth hormone vesicles to fuse with the membrane and be released into the blood.
The long term effect is to increase transcription in the nucleus.

Front 62

What are the effects of exogenous growth hormone on endogenous growth hormone

Back 62

Causes endogenous levels to decline either via GHRH or through enhancement of somatomedins which cause levels to decline

Front 63

Most common cause of panhypopituitarism?

Back 63

pituitary tumor

Front 64

Most instances of dwarfism result from what?

Back 64

Generalized deficiency of the anterior pituitary secretion during childhood. The physical parts grow in appropriate proportion, but the rate of growth is much slower.

Front 65

How is human growth hormone synthesized?

Back 65

From E Coli bacteria via recombinant DNA.

Front 66

A new mother develops circulatory shock after giving birth. How could this affect the pituitary gland?

Back 66

It could cause thrombosis of the gland with subsequent panhypothyroidism

Front 67

In the adult what are the effects of panhypothyroidism?

Back 67

hypothyroidism, decreased glucocorticoid secretion, and suppressed gonadotropic hormones

Front 68

What types of tumors may cause hypopituitarism?

Back 68

Craniopharyngiomas or chromophobe tumors may compress and destroy the gland

Front 69

Gigantism is associated with what physiologic condition? If not treated, what may this lead to? What condition occurs later in the course of the disease?

Back 69

Hyperglycemia- if not treated this will cause degeneration of pancreatic beta cells and diabetes mellitus
Panhypopituitarism occurs later in the course because the pituitary tumor eventually destroys the gland

Front 70

What type of cells compose the posterior pituitary gland? What is their function?

Back 70

Glial-like cells called pituicytes
They do not secrete hormones, but instead work as supporting cells for terminal nerve fibers and endings.

Front 71

Through what structure are hormones from the hypothalamus transferred to the post pituitary? How are the hormones carried How are they secreted into the capillaries

Back 71

Pituitary stalk
The hormones are carried in secretory proteins called neurophysins
Secreted via exocytosis

Front 72

In what nuclei is ADH formed? Oxytocin?

Back 72

Supraoptic
Paraventricular

Front 73

In the absence of ADH what occurs in the kidney?

Back 73

The tubules and collecting ducts become impermeable to water, which prevents reabsorption of water.

Front 74

How does ADH increase reabsorption of water?

Back 74

ADH binds to membrane receptors that activate adenylyl cyclase and cAMP. This phosphorylates and activates elements within special vesicles called aquaporins. The aquaporins bind to the membrane and increase permeability.

Front 75

How does a concentrated solution affect ADH secretion?

Back 75

Specialized osmoreceptors within the hypothalamus become dehydrated and shrink due to osmosis of fluid out of the cell. These receptors work to activate the supraoptic nuclei to release ADH.

Front 76

High concentrations of ADH are released when? What is the main effect? How does this occur?

Back 76

Decreased blood volume
Constriction of arterioles to increase blood pressure
Stretch receptors in the atria and aortic/carotid bodies are not excited and cannot send inhibitory signals to the nucleus solitarius.

Front 77

How may the absence of oxytocin affect birth?

Back 77

Oxytocin acts to increase uterine contractions during labor, so it would cause a prolonged labor. The cervix works to stimulate ADH secretion.

Front 78

Oxytocin has what effect on milk letdown

Back 78

Contraction of myoepithelial cells that form a lattice-work around the alveoli of the mammary gland.

Front 79

Somatostatin from the hypothalamus inhibits what hormones?

Back 79

TRH and GHRH

Front 80

Most common pituitary adenoma

Back 80

Prolactin, GH is second

Front 81

Are pituitary adenoma's histologically benign

Back 81

Yes, arising from glandular epithelial tissue

Front 82

Nonfunctioning pituitary adenomas may cause headache from what? What other symptom is very common?

Back 82

Irritation of pain fibers in the cavernous regions
Compression of the optic chiasm causes bitemporal hemianopia

Front 83

What are the clinical effects of prolactinomas?

Back 83

Amennhorrea, hypogonadism, galactorrhea, hair loss, decreased libido, and weight gain