Labs

Question 1

Where are the primary sites for energy storage in humans

Answer 1

Liver and muscle cells

Question 2

How is excess energy from diet stored

Answer 2

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

Question 3

Oxidising a gram of fat vs carbohydrate

Answer 3

About 2x more energy liberated from fat

Question 4

What does adipose tissue provide

Answer 4

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

Question 5

Normal range of conc of glucose in blood

Answer 5

70-110mg / 100mL

Question 6

What does glucose homeostasis rely on

Answer 6

On the antagonistic effects of 2 hormones; insulin and glucagon

Question 7

Glucose homeostasis: Insulin

Answer 7

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

Question 8

Glucose homeostasis: Glucagon

Answer 8

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

Question 9

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

Answer 9

Liver

Question 10

What does insulin and glucagon act on

Answer 10

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)

Question 11

Production of glucagon

Answer 11

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

Question 12

Production of insulin

Answer 12

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

Question 13

What is diabetes mellitus caused by

Answer 13

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

Question 14

Diabetes mellitus - glucose

Answer 14

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

Question 15

Diabetes mellitus - urine

Answer 15

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

Question 16

Two main types of diabetes mellitus

Answer 16

Type 1
Type 2

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

Question 17

Type 1 diabetes AKA…

Answer 17

Insulin-dependent diabetes

Question 18

Type 1 diabetes

Answer 18

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

Question 19

When does type 1 diabetes usually appear

Answer 19

During childhood

Question 20

Type 1 diabetes - treatments

Answer 20

Insulin injections - typically given several times daily

Question 21

Type 2 diabetes AKA…

Answer 21

Non-insulin-dependent diabetes

Question 22

Type 2 diabetes

Answer 22

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

Question 23

Type 2 diabetes - risk factors

Answer 23

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

Question 24

When does type 2 diabetes usually appear

Answer 24

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

Question 25

Where do endocrine glands secrete hormones

Answer 25

Directly into surrounding fluid

Question 26

Where do exocrine glands secrete hormones

Answer 26

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

Question 27

Pancreas - endocrine and exocrine tissues

Answer 27

Found in same gland | Ductless tissues secrete hormones, whereas tissues with ducts secret enzymes and bicarbonate

Question 28

Feedback regulation: Negative feedback

Answer 28

Where response reduces the initial stimulus

Question 29

Feedback regulation: Positive feedback

Answer 29

Reinforces a stimulus, leading to a greater response

Question 30

___ feedback helps restore a pre-existing state

Answer 30

Negative

Question 31

The ____ pituitary is an extension of the hypothalamus

Answer 31

Posterior

Question 32

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

Answer 32

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

Question 33

Amount of insulin vs glucagon in a pancreatic islet

Answer 33

Much more insulin, little glucagon

Question 34

Insulin and glucagon - number of amino acids

Answer 34

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

Question 35

How does glucagon raise blood glucose levels

Answer 35

Stimulates glycogen breakdown (and stops glycogen synthesis) | Signals liver cells to hydrolyse glycogen --> releases glucose into blood

Question 36

How does insulin lower blood glucose level

Answer 36

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

Question 37

Constant glucose management

Answer 37

Constantly fluctuates between insulin and glucagon activity

Question 38

Insulin - hormone family

Answer 38

Generally anabolic | Acts as a powerful growth hormone - enhances tissue glucose uptake

Question 39

Insulin - chains

Answer 39

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

Question 40

GLUT1 and GLUT2

Answer 40

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

Question 41

Diabetics - hypertrophic cardiomyopathy

Answer 41

Heart failure due to enlargement of heart muscle | Responsible for ~80% of deaths in diabetics

Question 42

Diabetes: Nephropathy

Answer 42

Normal kidney: - healthy function - proper size - low urine protein Kidney disease: - granular surface - decreased function - smaller size - high urine protein

Question 43

Diabetes: Retinopathy

Answer 43

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

Question 44

Diabetes: Peripheral circulation

Answer 44

Can cause issues with peripheral circulation

Question 45

Diabetes - hyperglycaemic

Answer 45

Excess glucose in blood appears in urine

Question 46

Type 2 diabetes - exercise

Answer 46

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