Endo

Question 1

What is the hypothalamus made up of

Answer 1

• Nuclei (concentrations of neuronal cell bodies)
• Nerve tracts (axons)

Question 2

What does the hypothalamus do

Answer 2

Regulates and coordinates responses to changes in the external and internal environment

Question 3

What behavior does the hypothalamus regulate

Answer 3

• Reproductive
• feeding
• rage

Question 4

What does the hypothalamus maintain

Answer 4

• body temperature
• metabolism (hunger, safety, body mass, metabolic rate)
• water balance (blood volume, thirst/intake, urine output)
• growth
• stress
• reproduction

Question 5

What are the 2 main neurohormones secreted by the posterior pituitary gland

Answer 5

• Vasopressin (Anti-diuretic Hormone - ADH)
• Oxytocin

Question 6

What are the actions caused by vasopressin

Answer 6

• Decrease water excretion in kidneys (anti-diuretic)
• Vasoconstriction

Question 7

What are the actions caused by oxytocin

Answer 7

• Parturition: stimulates contraction of uterine smooth muscle
• Lactation: milk ejection during breastfeeding due to contraction of smooth muscle

Question 8

What stimulates oxytocin to secrete

Answer 8

• Pressure of baby in birth canal
• Sucking baby
• fear and anxiety

Question 9

What are 5 different types endocrine cells, each producing their own hormones

Answer 9

1. TSH (Thyroid Stimulating Hormone) → Thyrotrophs (Thyroid gland)
2. ACTH (Adrenocorticotropic) → Corticotrophs (Adrenal cortex)
3. Prolactin → Lactotrophs (breast)
4. GH (Growth Hormone) → Somatotrophs (Liver and other tissues)
5. LH (Luteinising Hormone) and FSH (Follicle Stimulating Hormone) → Gonadotrophins (Gonads)

Question 10

What are the actions of Prolactin

Answer 10

• Stimulates alveolar epithelium of mammary gland to synthesise and secrete of milk
• many non reproductive roles such as immune system and behaviour

Question 11

What other hormones are required for milk synthesis (lactopoiesis)

Answer 11

• cortisol
• thyroid hormone
• insulin

Question 12

What are the Growth Hormone concentrations in blood during the day/night

Answer 12

Low levels during day time (when awake)

high levels from 10pm-4am (when sleeping)

Question 13

How does the growth hormone pulsatile between females and males

Answer 13

• Females = small amplitude, frequent (more continuous)
• Males = large amplitude, infrequent (more pulsatile)

Question 14

What are the actions of Growth Hormone

Answer 14

• Increases number and size of cells un soft tissues such as skeletal muscle
• increases thickness and length of long bones
• also has metabolic effects

Question 15

What is involved in the regulation of Growth Hormone

Answer 15

From the hypothalamus there is an increase in GHRH and a decreases in Somatostain this leads to the anterior pituitary gland to produce GH which then targets the Liver and other tissues

Question 16

What is activated in Growth Hormone signaling

Answer 16

Growth hormone activates theJanus kinase (JAK)–signal transducer and activator of transcription (STAT) signaling pathway

Question 17

Why are plasma IGF1 levels so stable from hour to hour when its secretion is stimulated by a pulsatile pattern of HG

Answer 17

Synthesis takes time following GH = lag but also OGF binding proteins maintain pool circulating IGF1

Question 18

In the growth of long bones, what causes the difference in between proliferation and hypertrophy

Answer 18

• Proliferation is due to GH
• Hypertrophy is due to IGF1

Question 19

What happens to GH/IGF1 after growth plate closure in long bones

Answer 19

They can no longer cause further growth however can increase the thickness of bones)

Question 20

GH by its self does not create optimal growth, what is needed to achieve optimal growth?

Answer 20

• Thyroid hormones
• Glucocorticoids
• Sex steroids (Testosterone & Oestrogen)
• Insulin

Question 21

What is excess GH called in children and what can it cause?

Answer 21

Gigantism, usally abnormally tall however they will have normal body proportions

Question 22

How do other growth drugs work such as Sermorelin, Mecasermin, Octreotide, and Lanreotride

Answer 22

• Sermorelin = GHRH agonist
• Mecasermin = rhIGF1
• Octreotide = Somatostain analogue (inhibit GH excess)
• Lanreotride = similar to Octreotide used for thyroid tumours