Neuroendocrinology

Question 1

What is the definition of a hormone?

Answer 1

→ a cell secretes a hormone
→ not targeted
→ has an effect on target cells depending on whether they have the receptor or not

Question 2

How do neurotransmitters work?

Answer 2

→ nerve cell secretes NTs
→ across a spatially restricted area
→ acts on an effector cell

Question 3

What is paracrine secretions?

Answer 3

→ secreted from cells

→ exerts effects at local interstitial fluid

Question 4

What is autocrine signalling?

Answer 4

→ The cell has receptors for a hormone that it secretes

Question 5

What are neuroendocrine cells?

Answer 5

→ neurosecretory cells that release signal molecules from their synaptic terminals into the blood

Question 6

What are neuroendocrine cells controlled by?

Answer 6

→ synaptic transmission from presynaptic neurons

Question 7

What are 3 examples of neuroendocrine cells?

Answer 7

→ chromaffin cells of adrenal medulla
→ hypothalamic magnocellular neurons
→ hypothalamic parvocellular neurons

Question 8

How does neuroendocrine transmission work?

Answer 8

→ Nerve cell releases NT
→ NT acts on a neuroendocrine cell
→ Releases a signalling molecule from axonal end
→ it doesn’t synapse
→ terminals target capillaries
→ substance diffuses and acts as a hormone

Question 9

What is the pituitary made from?

Answer 9

→ 2 independent structures

Question 10

How does the pituitary form in the embryo?

Answer 10

→ Evagination of the floor of 3rd ventricle
→ Evagination of oral ectoderm
→ Rathkes pouch pinched off

Question 11

What is the posterior lobe of the pituitary an extension of?

Answer 11

→ The hypothalamus

Question 12

What are the two nuclei of the hypothalamus?

Answer 12

→ Parvocellular nuclei

→ Magnocellular nuclei

Question 13

Where do the parvocellular nuclei project to?

Answer 13

→ small neurons with small axons 
→ project to the median emininence
→ release hormones to the capillary network
→ carried by hypophyseal portal veins 
→ to anterior pituitary

Question 14

What is the posterior pituitary supplied and drained by?

Answer 14

→ Inferior hypophyseal artery

→ Inferior hypophyseal vein

Question 15

What is the anterior pituitary supplied and drained by?

Answer 15

→ Superior hypophyseal artery
→ forms a network at the base of the hypothalamus
→ Portal veins - a second capillary network

Question 16

Where do the magnocellular nuclei project ?

Answer 16

→ Project to the posterior pituitary

→ release capillaries supplied by inferior hypophyseal artery

Question 17

What is the pathway of ADH?

Answer 17

→ Synthesized in the magnocellular nuclei
→ packaged into vesicles and transported along the axons
→ stored in axon terminals
→ released into the hypophyseal capillaries

Question 18

What kind of hormones do the parvocellular nuclei release?

Answer 18

→ Trophic hormones

→ Hormone releasing hormones

Question 19

What hormones does the posterior pituitary release?

Answer 19

→ Oxytocin

→ ADH

Question 20

What hormones does the anterior pituitary release?

Answer 20

→ TSH 
→ ACTH
→ FSH + LH 
→ Growth hormone
→ Prolactin
→ Endorphins

Question 21

How does ADH get regulated?

Answer 21

→ Sensory neurons in the hypothalamus detect changes in ECF osmolality
→ passed on to magnocellular neurons (supraoptic)
→ increase or decrease in firing of magnocellular neurons
→ + or - in the release of ADH into the posterior pituitary

Question 22

Describe the cascade of TRH

Answer 22

→ Hypothalamic hormone TRH
→ changed into TSH in the anterior pituitary
→ stimulates thyroid
→ thyroid produces thyroid hormones

Question 23

Where are the parvocellular and magnocellular nuclei found?

Answer 23

→ in the hypothalamus

Question 24

What is the brain dependent on?

Answer 24

→ obligatory dependent on glucose

Question 25

In the absence of circulating glucose where does glucose come from?

Answer 25

→ glycogen stores

Question 26

When glycogen runs out where does glucose come from?

Answer 26

→ Gluconeogenesis

Question 27

What does growth hormone stimulate?

Answer 27

→ Lipolysis
→ Promotes release of fatty acids
→ so tissues use fat
→ glucose can be used in the brain

Question 28

What are the 7 factors that stimulate growth hormone?

Answer 28

→ GHRH
→ Ghrelin
→ Hypoglycaemia
→ Decreased fatty acids
→ Fasting
→ Excercise, sleep
→ stress

Question 29

What is ghrelin and where is it released from ?

Answer 29

→ Hunger hormone

→ Released by endocrine cells of the stomach

Question 30

What are the 5 factors that inhibit growth hormone?

Answer 30

→ Somatostatin
→ GH 
→ Hyperglycemia 
→ Increased fatty acids
→ IGF-1

Question 31

What are somatotropes?

Answer 31

→ endocrine cells in the anterior pituitary that secrete GH

Question 32

How does IGF get produced?

Answer 32

→ GH released from somatotropes
→ GH acts on liver and increases gluconeogenesis
→ Increases IGF

Question 33

What does IGF from the liver promote?

Answer 33

→ Increase somatic cell growth
→ Increase chondrocyte function (cartilage in bones)
→ Increase bone modelling

Question 34

What does GH do in the muscle?

Answer 34

→ Increases protein synthesis

Question 35

What does GH do in adipose tissue?

Answer 35

→ Promotes lipolysis

Question 36

What are GH concentrations like during life?

Answer 36

→ birth is low
→ increases and stays constant at childhood
→ Increases dramatically during puberty
→ decline during adult life and old age

Question 37

What does GH deficiency during childhood result in?

Answer 37

→ dwarfism

Question 38

What is the condition with excess hormone called?

Answer 38

→ Acromegaly

Question 39

What is acromegaly caused by?

Answer 39

→ pituitary adenoma

Question 40

What are metabolic effects of acromegaly?

Answer 40

→ Insulin resistance

→ Impaired glucose tolerance and hyperinsulinemia