Lecture 38: Homeostasis in Action Flashcards Preview

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Flashcards in Lecture 38: Homeostasis in Action Deck (21)

Increasing glucose level, ______ responds to high glucose by secreting _____. This causes _____, skeletal muscle, and ___ ____ to ....

- Pancreas
- Insulin
- Liver
- Other tissues
- Take up more glucose


Control of blood glucose is mainly by _____ _____.

- Negative feedback


Insulin can be thought of as...

- Signalling that the body has been fed
- i.e promotes uptake and storage of nutrients


If there's no insulin around then the body is going to act as if...

- It's "starved"
- Breaking down stores of glycogen and releasing that glucose to other tissues in the body
- Gluconeogenesis = liver is taking non carbohydrate sources (break down of amino acids) to make new glucose
- Breaking down fat stores to increase lipid levels in blood
- Increase ketone production which can be 'glucose sparing'.


Diabetes derived from Greek....
Mellitus derived from Latin...

- "Passing through"
- "Honey" or "Sweet"


Diabetes is historically referred to a disease state characterized by...

- Polyuria (passing large volumes of urine)
- Polydipsia (excessive thirst)
- Polyphagia (excessive hunger)


Type 1 Diabetes Mellitus:

- Little or NO INSULIN
- Typically younger onset (children or teenagers)
- May be associated with prior viral illness and subsequent autoimmune response that destroys pancreatic Beta Cells
Environmental agent + genetic predisposition ^^^
- Treatment = Insulin
- HYPO only occurs if they've been overtreated with insulin


Type II Diabetes Mellitus:

- Insulin Resistance
- Cells aren't responding to the insulin
- May have higher than normal levels of insulin, because glucose ends up staying in blood, which means lots and lots of insulin
- Eventually insulin level may drop off because pancreas has had enough
- May be related to:
>> Reduced numbers or function of insulin receptors
>> Altered intracellular signalling in target cells
- Other conditions (eg Cushing's disease, PCOS)
- Hyperglycemia but diff to Type I, insulin levels may still be adequate to suppress lipolysis and ketogenesis but not sufficient to control BGL
- Treatment: Exercise, Weight Loss, Oral Drugs, Insulin if needed


Oral Hypoglycemic Drug Classes are used for ____ ____ Diabetes people. These include:

- Type II
- Sulphonylureas : increase insulin secretion by beta cells, can cause hypoglycemia if not eating or overdose
- Metformin : reduces glucose output from liver by inhibiting gluconeogenesis
- Thiazolidinediones : increase insulin sensitivity of cells


Diabetes Insipidus:

- Lots of dilute urine but no glucose in it!!!
- Due to altered secretion of ADH or decreased responsiveness to it
- Often associated with brain injury or tumour in region of pituitary gland


Gestational Diabetes (important):

- Can affect women during pregnancy
- May resolve after pregnancy or not
- Large baby increased risk of birth injuries, neonatal hypoglycemia, congenital malformations, child/adult obesity?


Hyperglycemia is due to:

- Inability of most cells (not brain) to absorb glucose
>> glucose stays in blood, can't enter cells, decreased production
- Increased output of glucose by liver
>> Glycogenolysis and gluconeogenesis


Glycosuria is when...

- Renal tubes can't reabsorb the excessive glucose being filtered



- Excessive thirst


Acute Consequences...

- Breakdown of protein and fat
- (Diabetic) Ketoacidosis (DKA) : ketones are acidic and cause acidosis when produced in excess
- Acetone-like smell on breath and can also be detected in urine
- Acidosis causes hyperventilation
- Acidosis can cause hyperkalemia


Need to be careful when administering insulin in DKA - why?

- Increases uptake of amino acid and potassium
- Potassium is back in cells, total K is depleted


Chronic hyperglycemia can predispose blood vessels and nerves to damage. This includes:

- Cardiovascular disease
- Renal failure
- Retinal damage
- Poor wound healing
- Peripheral nerve damage
- Susceptibility to infection


Treatment of Type I Diabetes Mellitus:

- Insulin : Banting + best at UOT developed methods for extracting and purifying insulin from cattle pancreases.
- Now a much greater range of insulin types available
- Human insulin modifies to slow absorption


Homeostatic mechanisms restoring blood pressure and volume after haemorrhage

- Activation of platelets and the coagulation cascade
- Drop in pressure detected by sensors
- Info sent by nerves to cardiovascular control centres in brainstem
- Nerve impulses sent from brain to heart to increase HR and force of contraction


Signs typically associated with physiological shock...But what about blood volume?

- Looks pale and skin cool 'clammy'
- Vasoconstriction to blood vessels in skin and other organs
- Decreased blood pressure detected by stretch receptors in walls of renal arterioles
- Specialised cells in the kidney (integrator) cause the formation of a hormone (control signal) in the blood (communication pathway)
- Hormone 1 can (1) stimulate adrenal glands --> Aldosterone --> Na+ reabsorption by kidney
(2) stimulate ADH glands


Blood pressure and blood volume are restored but what about the lost RBCs?

- A few weeks

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