the Pituitary gland and Hypothalamus

Question 1

hypothalamus location

Answer 1

centre of the brain where the brain stem starts

Question 2

Pituitary gland location

Answer 2

dangling below the hypothalamus and has 2 distinct parts 
posterior lobe (neurohypophysis)
anterior lober (adenohypohysis)

Question 3

Pituitary gland function

Answer 3

the hypothalamus controls the secretion of pituitary hormones (when activated by neural input the hypothalamus stimulates the pituitary gland to secrete hormones)
some pituitary hormones stimulate target cells and some stimulate the secretion of hormones by other endocrine glands.
each lobe has a distinctive mechanism for hormone secretion. there can be a cascade of hormones being released meaning we can be very accurate with the hormone released.

Question 4

how does the hypothalamus communicate with the posterior pituitary lobe?

Answer 4

the hypothalamus is connected to the posterior lobe by neurons. the cell body is in the hypothalamus and the axons terminate in the posterior lobe.
posterior pituitary hormones are made in the hypothalamus (cell body of neuron) and travel down the axon and stored at the exon endings until required.

Question 5

mechanism for posterior pituitary hormone secretion

Answer 5

stimulus- neural input to the hypothalamus
hypothalamus signals the posterior pituitary to release stored hormones by neural stimulation (increase in action potential firing frequency.

Question 6

posterior pituitary gland hormones

Answer 6

Antidiuretic hormone (ADH)
Oxytocin
peptide hormones
these chemicals aren’t hormones when sitting in axon they become hormones when released into the blood stream.

Question 7

Antidiuretic hormone (ADH)

Answer 7

stimulates the kidneys to reabsorb water (the kidneys conserve water when the body dehydrates.

Question 8

Oxytocin

Answer 8

simulates the contraction of uterine muscles during childbirth (positive feedback)
stimulates milk release in breast feeding (milk ejection reflex)

Question 9

how does the hypothalamus communicate with the anterior pituitary gland?

Answer 9

the hypothalamus is connected to the anterior lobe by blood vessels
the hypothalamus communicated by hormones- either releasing hormones or inhibitory hormones.
the anterior pituitary hormones are made in the anterior pituitary by specific cells.

Question 10

mechanism for anterior pituitary hormone secretion

Answer 10

stimulus - neural input into the hypothalamus
the hypothalamus signals the anterior pituitary to release hormones by hormonal stimulation, releasing hormones or inhibiting hormones.
the hormone binds to receptors on membrane specific cell types within the anterior gland and a second hormone may or may not be produced. the second hormone is released into the blood stream of the body.

Question 11

mechanism for anterior lobe of the pituitary gland

Answer 11

first hormone released into a bed of capillaries between the pituitary gland and the hypothalamus.
hormones then move into a second large bed of capillaries where the hypothalamic hormones stimulate / inhibit the release of hormones from specific anterior pituitary cells where they then travel to the main bloodstream.
the first hormone finds a target cell in the pituitary gland.

Question 12

anterior pituitary gland and hypothalamus hormones

Answer 12

GHRH= growth hormone releasing hormone 
SS= inhibits the growth hormone 
GH = growth hormone - promotes growth of bones, muscle and other tissues.

Question 13

the sequence of events that leads to growth hormone secretion and the response of target cells

Answer 13

stimulus- stress, sleep, exercise or fasting
hypothalamus increase of GHRH and decrease of SS
the anterior pituitary releases GH into the blood stream
this hormone travels to the liver and some other cells where there is an increase in IGF-1 secretion which leads to an increase in cell division in many tissues.
all controlled by negative feedback

Question 14

IGF-1

Answer 14

is a growth factor (insulin like growth factor)

Question 15

Growth hormone

Answer 15

has a long term effect on growth and a short term effect on metabolism.
it has a huge peak from 10pm- 5am when GHRH is being released in a pulslie fashion. the hormone also gets released in small pulses throughout the day.
it promotes the growth of bones, muscle and other tissues by stimulating cell division.

Question 16

metabolic effect of he growth hormone

Answer 16

metabolic effects

• muscle= increase in protein synthesis and decrease in glucose uptake
• liver increase in glucose synthesis therefore increases blood glucose concentration.
• fat increase in fat breakdown (mobile fatty acids)

Question 17

GH age profile

Answer 17

GH concentrations are higher in children than adults with a peak during puberty
GH secretion declines with age

Question 18

Hypo-secretion

Answer 18

too little or none = very short/ dwarfism

Question 19

Hyper-secretion

Answer 19

too much = very tall/ giantism

Question 20

Hyposensitive receptor

Answer 20

little or no repsonse

Question 21

Hypersensitive recpetor

Answer 21

respond too much