L25

Question 1

explain the posterior pituitary

Answer 1

• 2 hormone produced by the neurosecretory cells fo the hypothalamus
  ○ Oxytocin (releases during birth in a pos. Feedback loop), linked to bonding with baby + marriage
  ○ Antidiuretic hormone (ADH= vasopressin), linked to memory + fidelity
  
  • Posterior pituitary just stores it, not makes it
  • Both hormones important neuropeptides
  • Axons from the neurosecretory cells from the hypothalamo-hypophyseal tract
    The posterior pituitary gland does not synthesise any hormones, but stores + releases from axon terminals

Question 2

explain ADH

Answer 2

• Diuresis= icnreased urine output
  
  • ADH= antidiuretic hormone
  • The amount fo ADH secreted varies with blood osmotic pressure (OP_
  • Function is to decrease urine output
    Osmoreceptors (neurons) in the hypothalamus monitors OP

Question 3

what occurs when blood volume increases

Answer 3

○ Decrease in OP
○ Decrease in ADH secretion
So more water is lost to maintain osmolarity

Question 4

what occurs when blood volume decreases

Answer 4

○ Increase in OP
○ Increase in ADH secretion
○ More water is reabsorbed

Question 5

explain the maintenance of homeostasis of ADH

Answer 5

REFER TO ONENOTE

Question 6

explain diabetes insipidus

Answer 6

○ Increase in urine output (3-15L/day)
○ But by providing electrolytes + sufficient water, can be stable
○ ADH decreases causes urine output increases
○ Result of kidneys retaining more water, which decreases ruin output
○ Sweat glands decrease water loss by perspiration from the skin

Question 7

causes of diabetes insipidus

Answer 7

§ Neurogenic
□ Insufficient production/release of ADH from pituitary
□ Often due to hypothalamic tumours, or after brain trauma or high ICP
§ Nephrogenic
□ Usually in end stage kidney diseases
□ Cell no longer receptive to ADH
§ Psychogenic
□ Increases H2O intake in mentally disabled or health freaks
Drink themselves to death

Question 8

explain oxytocin and the milk effect

Answer 8

• Circle
  
  • Baby suckles at breast, triggers posterior pitutiary, releases oxytocin, released into blood, break milk released
    Eventually baby stops suckling, so milk stops coming

Question 9

explain the inhibitors of ADH

Answer 9

• Low blood osmotic pressur
  
  • High blood volume
    Alcohol

Question 10

explain how the pancreas effects glucose

Answer 10

• Pancreate cells regulate blood gluocse using
  ○ Alpha cells
  § Secret glucagon
  § In response to low glucose
  ○ Beta cells
  § Secrete insulin
  § Inresposne to high glucose
  § Insluin is required to help transport glucose into some body cells
  § Beta cells contain glucose sensors (also found in neurons in nervous system)
  w Brain- hypothalamus, brainstem
  w Periphery- oral cavity, GIT, carotid body

Question 11

explain type 1 diabetes mellitus

Answer 11

• Type 1
  ○ Pacnreatic beta cells destroyed by immune system
  ○ Insulin dependent, required to aid transport glucose into some body cells
  ○ Not producing insulin
  ○ If no insulin, blodo glucose high
  § Polyuria- frequent urination
  § Polydipsia- excessive thirst
  § Polyphagia- excessive eating
  ® Polyuria + polydipsia
  ◊ Glucose transporters resposnible for reabsorbing glucose
  ◊ Saturated in kdiney
  ◊ Therefore glucose spills over into uring
  Water follows, which is why urine tastes sweet

Question 12

explain type 2 diabetes mellitus

Answer 12

• Type 2
  ○ Not insulin dependent
  ○ Producing insulin but is downregulated
  ○ Insulin resistant
  § Down regulation of insulin receptors
  § Cells become less sensitive to insulin
  Blood glucose goes up