Chedy - theme 13

Question 1

The fuel problem:

Answer 1

Brain needs a constant supply of glucose, but you can’t just be eating all the time. Blood glucose must be 70-110 mg / 100 mL

Question 2

Effects of -glycemias:

Answer 2

Hypoglycemia: mild dysphoria, seizures, unconsciousness, permanent brain damage, death
Hyperglycemia: cell dehydration, glycation (spontaneous reaction between glucose and proteins, messing up the proteins), conversion from glucose to sorbitol causing cataracts

Question 3

Energy storage: why is glycogen a good storage molecule?

Answer 3

Because it’s insoluble in water - doesn’t affect osmotic pressure

Question 4

Sites of energy storage:

Answer 4

Glial cells (minor site), liver, muscle, fat

Question 5

Energy storage in liver:

Answer 5

Hepatic glycogen is broken down early. The liver is the primary site of gluconeogenesis.

Question 6

Energy storage in muscle:

Answer 6

Muscle cells are greedy and keep glucose for internal use only. They lack glucose-6-(p), so they can’t get glucose into the blood for transport. Stores AAs for gluconeogenesis in extreme starvation. Epinephrine from the adrenal medulla can power movement but can’t supply any other tissues with energy.

Question 7

Energy storage in adipose:

Answer 7

Primary long-term energy source. Triglycerides can be broken down into fatty acids as an alternative energy source for non-glucose dependent tissues. Fatty acids CANNOT be used for gluconeogenesis - need that glycerol backbone.

Question 8

Endocrine regulation of fuel metabolism: players

Answer 8

Pancreas, adrenal medulla, adrenal cortex, pit gland, thyroid gland

Question 9

Pancreas and endocrine regulation:

Answer 9

Insulin and glucagon shift metabolic pathways between catabolic and anabolic. Islets of Langerhans have alpha (glucagon), beta (insulin), and gamma (somatostatin) subunits.

Question 10

Endocrine and exocrine functions of the pancreas:

Answer 10

Endocrine - insulin and glucagon

Exocrine - production of digestive juices

Question 11

Insulin:

Answer 11

Produced in high glucose. Controls blood glucose, fat, and AA concentration.

Question 12

Somatostatin:

Answer 12

Inhibits insulin, glucagon, and itself.

Somatotropin is the weird nerd friend of insulin and glucagon who messes everything up.

Question 13

Diabetes mellitus: general.

Answer 13

Prolonged high blood glucose. Acute complications: diabetic ketoacidosis, nonketotic hyperosmolar coma. Long term complications: cardiovascular disease, stroke, kidney failure, foot ulcers, eye damage. Sweet pee - excess glucose can’t be taken up by kidneys.

Question 14

Diabetes type 1:

Answer 14

Insulin-dependent - pancreas fails to make enough insulin. Can be treated with insulin.

Question 15

Diabetes type 2:

Answer 15

Non insulin-dependent - cells fail to respond to insulin; glucose can’t get into the cells. Caused by excessive body weight or lack of exercise.

Question 16

Gestational diabetes:

Answer 16

Women without previous diabetes history develop high blood sugar during pregnancy.

Question 17

Normal blood glucose curve:

Answer 17

Spikes after eating. Takes about two hours for concentration to return to normal. Glucose level is maintained for a day before it falls.

Question 18

Insulin mechanism of action:

Answer 18

Binds cell surface receptors in adipose or muscle, activating glucose transporters.

Question 19

Exercise and diabetes:

Answer 19

Muscle contraction stimulates localization of GLUT4 transporter to cell surface. Doctors recommend exercise for type 2 diabetes!

Question 20

Metabolic effects of insulin:

Answer 20

Increases: glycogen synthesis, lipid synthesis and fatty acid esterification, AA uptake
Decreases: gluconeogenesis, proteolysis, lipolysis

Question 21

Glucagon:

Answer 21

It’s like pancreas-specific epinephrine. A peptide hormone that increases blood glucose by breaking down glycogen or by gluconeogenesis.

Question 22

Steroid hormones:

Answer 22

Pregnenolone is an inactive derivative of cholesterol. It is a precursor of progesterone, aldosterone, cortisol, and testosterone (which can be modified to estradiol).

Question 23

Functions of aldosterone and cortisol:

Answer 23

Aldosterone is involved in the metabolism of minerals and ions. Cortisol is somehow involved in stress.

Question 24

Adrenal glands: structure

Answer 24

Cortex (mesoderm) and medulla (ectoderm).

Question 25

Adrenal cortex: structure

Answer 25

Composed of (from outside in): zona glomerulosa, zona fasciculata, zone reticularis.

Question 26

Zona glomerulosa:

Answer 26

Involved in kidney regulation of ions

Question 27

Zona fasciculata:

Answer 27

Produces glucocorticoids

Question 28

Zone reticularis:

Answer 28

Somehow regulates sex determining hormones

Question 29

Products of the adrenal medulla:

Answer 29

Catecholamines - epinephrine and norepinephrine

Question 30

Products of the adrenal cortex:

Answer 30

Corticosteroids:
From glomerulosa - aldosterone (mineralocorticoid)
From fasciculata - cortisol and corticosterone (glucocorticoids)
From reticularis - androgen (sex steroid)

Question 31

Glucocorticoids:

Answer 31

Catabolic hormones that promote gluconeogenesis in liver in times of stress. Act on bone, muscle, fat, and immune tissue to break them down. Present during fight/flight reactions when feeding/digestion are not available.
Cortisol stimulates the liver to synthesize glucose from AAs and glycerol.

Question 32

Dual role of adrenal glands:

Answer 32

Promote glycogenolysis. When glycogen is used up, get glucose from other sources.

Question 33

What is the most important organ for survival during starvation?

Answer 33

ADRENAL CORTEX!

Question 34

Random detail: ACTH facilitates __ and __

Answer 34

Learning and behaviour