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BIOSCI 101 > Labs > Flashcards

Labs Flashcards

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1
Q

Where are the primary sites for energy storage in humans

A

Liver and muscle cells

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2
Q

How is excess energy from diet stored

A

In glycogen - a polymer made up of many glucose units

Once glycogen depots are full, excess energy is usually stored in fat in adipose cells

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3
Q

Oxidising a gram of fat vs carbohydrate

A

About 2x more energy liberated from fat

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4
Q

What does adipose tissue provide

A

A space-efficient way for body to store large amounts of energy

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5
Q

Normal range of conc of glucose in blood

A

70-110mg / 100mL

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6
Q

What does glucose homeostasis rely on

A

On the antagonistic effects of 2 hormones; insulin and glucagon

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7
Q

Glucose homeostasis: Insulin

A

When blood glucose level rises above normal range, secretion of insulin triggers uptake of glucose from blood into body cells –> decreases blood glucose conc

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8
Q

Glucose homeostasis: Glucagon

A

When blood glucose level drops below normal range, secretion of glucagon promotes release of glucose into blood from energy stores –> increases blood glucose conc

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9
Q

The _____ is a key site of action for insulin and glucagon

A

Liver

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10
Q

What does insulin and glucagon act on

A

Insulin: Nearly all body cells - except brain cells, which can take up glucose whether or not insulin is present (always has access to circulating fuel, even if supplies are low)

Glucagon: Only liver (and little bit the kidney)

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11
Q

Production of glucagon

A

Produced from alpha cells in pancreatic islet, then secreted into interstitial fluid

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12
Q

Production of insulin

A

Produced from beta cells in pancreatic islet then secreted into interstitial fluid

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13
Q

What is diabetes mellitus caused by

A

A deficiency of insulin or a decreased response to insulin in target tissues
Blood glucose level rises, but cells are unable to take up enough glucose to meet metabolic needs
Instead, fat becomes the main substrate for cellular respiration

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14
Q

Diabetes mellitus - glucose

A

Level of glucose in blood may exceed capacity of kidneys to reabsorb this nutrient
Glucose that remains in kidney filtrate is excreted

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15
Q

Diabetes mellitus - urine

A

Presence of sugar in urine is a test for diabetes mellitus

As glucose is concentrated in urine, more water is excreted along with it –> excessive volume of urine

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16
Q

Two main types of diabetes mellitus

A

Type 1
Type 2

Each is marked by high blood glucose levels, but with diff causes

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17
Q

Type 1 diabetes AKA…

A

Insulin-dependent diabetes

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18
Q

Type 1 diabetes

A

An autoimmune disorder where immune system destroys beta cells of pancreas –> destroys ability to produce insulin

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19
Q

When does type 1 diabetes usually appear

A

During childhood

20
Q

Type 1 diabetes - treatments

A

Insulin injections - typically given several times daily

21
Q

Type 2 diabetes AKA…

A

Non-insulin-dependent diabetes

22
Q

Type 2 diabetes

A

Characterised by failure of target cells to respond normally to insulin
Insulin is produced, but target cells fail to take up glucose from blood, and blood glucose levels remain elevated

23
Q

Type 2 diabetes - risk factors

A

Heredity can play a role, but excess body weight and lack of exercise significantly increase risk

24
Q

When does type 2 diabetes usually appear

A

After age of 40, but children can develop the disease, particularly if overweight and inactive

25
Q

Where do endocrine glands secrete hormones

A

Directly into surrounding fluid

26
Q

Where do exocrine glands secrete hormones

A

Have ducts that carry secreted substances onto body surfaces or into body cavities

27
Q

Pancreas - endocrine and exocrine tissues

A

Found in same gland

Ductless tissues secrete hormones, whereas tissues with ducts secret enzymes and bicarbonate

28
Q

Feedback regulation: Negative feedback

A

Where response reduces the initial stimulus

29
Q

Feedback regulation: Positive feedback

A

Reinforces a stimulus, leading to a greater response

30
Q

___ feedback helps restore a pre-existing state

A

Negative

31
Q

The ____ pituitary is an extension of the hypothalamus

A

Posterior

32
Q

During an overnight fast, blood glucose levels are maintained by…

A

Both glycogenolysis and gluconeogenesis, which are both tightly regulated by hormones

33
Q

Amount of insulin vs glucagon in a pancreatic islet

A

Much more insulin, little glucagon

34
Q

Insulin and glucagon - number of amino acids

A

Insulin: 51 amino acid polypeptide
Glucagon: 29 amino acid polypeptide

35
Q

How does glucagon raise blood glucose levels

A

Stimulates glycogen breakdown (and stops glycogen synthesis)

Signals liver cells to hydrolyse glycogen –> releases glucose into blood

36
Q

How does insulin lower blood glucose level

A

Stimulate all body cells (except brain cells) to take up glucose

37
Q

Constant glucose management

A

Constantly fluctuates between insulin and glucagon activity

38
Q

Insulin - hormone family

A

Generally anabolic

Acts as a powerful growth hormone - enhances tissue glucose uptake

39
Q

Insulin - chains

A

A-chain linked to C-chain linked to B-chain

When cleaved, C-chain is removed, and disulphide bonds form between A-chain and B-chain

40
Q

GLUT1 and GLUT2

A

GLUT1 is ubiquitous, and highly conserved
GLUT2 is found in pancreas beta-cells, liver and gut
GLUT2 has higher Km (low affinity) - glucose enters when conc is high

41
Q

Diabetics - hypertrophic cardiomyopathy

A

Heart failure due to enlargement of heart muscle

Responsible for ~80% of deaths in diabetics

42
Q

Diabetes: Nephropathy

A

Normal kidney:

  • healthy function
  • proper size
  • low urine protein

Kidney disease:

  • granular surface
  • decreased function
  • smaller size
  • high urine protein
43
Q

Diabetes: Retinopathy

A

Elevated glucose levels result in uncontrolled uptake in epithelial cells of blood vessels –> deterioration of vasculature around body
Results in hemorrhages and ‘cotton-wool’ spots at back of eye

44
Q

Diabetes: Peripheral circulation

A

Can cause issues with peripheral circulation

45
Q

Diabetes - hyperglycaemic

A

Excess glucose in blood appears in urine

46
Q

Type 2 diabetes - exercise

A

In almost all cases, exercise improves (if not eradicates) type 2 diabetes

BIOSCI 101 (4 decks)

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