Miscellaneous metabolic

Question 1

What are the 3 zones of the adrenal cortex, from most superficial to the deepest zone.

Answer 1

Zona glomerulosa
Zona fasciculata
Zona reticularis

Question 2

What do each of the following adrenal zones secrete:

1) Zona glomerulosa
2) Zona fasciculata
3) Zona reticularis
4) Medulla

Answer 2

1) Mineralocorticoids (SALT)
2) Glucocorticoids (SWEET)
3) Androgens (SEX)
4) Catecholamines (FIGHT/ FLIGHT)

Question 3

Name the 2 hormones secreted by the posterior pituitary gland and state what their actions are.

Answer 3

ADH: causes water retention in renal tubules.
Oxytocin: causes the lactation let down reflex in the breasts and uterine contraction in the uterus.

Question 4

Where are ADH and oxytocin stored?

Answer 4

After being produced in the hypothalamus, they are stored in axon terminals within the posterior pituitary gland.

Question 5

What 2 hormones can somatostatin inhibit?

Answer 5

TSH and GH.

Question 6

What are the main 2 actions of TSH?

Answer 6

Causes T3 and T4 release and the peripheral conversion of T4 to T3.

Question 7

Where do the following hormones act upon:

a) TSH
b) GH
c) Prolactin
d) ACTH
e) LH and FSH

Answer 7

a) Thyroid
b) Tissues (causing release of IGF-1)
c) Breasts (causing lactation)
d) Adrenal glands
e) Ovaries and testes (causing release of testosterone, oestrogen and progesterone).

Question 8

Which hormones released from the hypothalamus cause the release of the following hormones from the anterior pituitary:

a) TSH
b) GH
c) Prolactin
d) ACTH
e) LH and FSH

Answer 8

a) TRH
b) GnRH
c) DA
d) CRH
e) GnRH

Question 9

1) What is mineralocorticoid release controlled by?
2) What is catecholamine release controlled by?
3) What are the release of glucocorticoids and androgens controlled by?

Answer 9

1) Renin.
2) SNS and ACTH
3) ACTH.

Question 10

Describe the 2 main functions of the pancreas.

Answer 10

1) Release of digestive enzymes by exocrine cells into the duodenum through the ampulla of vater when food is detected.
2) Production of hormones such as insulin and glucagon by endocrine cells.

Question 11

1) What type of cells in the pancreas produce digestive enzymes?
2) How are endocrine cells found in the pancreas?

Answer 11

1) Acinar cells.

2) In clusters called islets of langerhans.

Question 12

Name the hormone secreted by each of the following cells:

1) Alpha cells
2) Beta cells
3) Gamma cells
4) Delta cells

Answer 12

1) Glucagon
2) Insulin
3) Polypeptides
4) Somatostatin

Question 13

Very briefly describe what normally happens when there is an increase in blood glucose levels.

Answer 13

Increased CBG levels > promotes insulin release > insulin stimulates glucose uptake and glycogen formation > lowers CBG levels.

Question 14

Very briefly describe what happens when there is a decrease in blood glucose levels.

Answer 14

Decreased CBG levels > promotes glucagon release > glucagon stimulates glycogen breakdown > increases CBG levelss.

Question 15

1) When do the major effects of insulin happen?
2) What is the effect of insulin on amino acids?
3) What is the effect of insulin on fats?

Answer 15

1) Just after eating.
2) Promotes uptake of amino acids from blood into liver where insulin promotes protein synthesis.
3) Fats are absorbed into lymphatic circulation and from here, insulin promotes the storage of fats in skeletal muscle as fatty acids. Insulin also promotes synthesis of triglycerides from fats in the liver.

Question 16

Name 3 pathways which insulin promotes.

Answer 16

1) Uptake of glucose from blood into liver
2) Conversion of glucose to glycogen (glycogenesis)
3) Conversion of glucose to pyruvate and then to acetyl CoA (glycolysis)

Question 17

What happens to the acetyl CoA after glucose has promoted glycolysis?

Answer 17

Acetyl CoA is converted to triacylglycerols which are packaged up into VLDLs which can then be stored in adipose tissue.

Question 18

When insulin binds to the insulin receptor on hepatocytes, what happens?

Answer 18

This causes IRS-1 to become phosphoryated and IRS-1 then has many actions within the hepatocyte.

• *IRS-1 = insulin receptor substrate 1.
• **Insulin receptor is a tyrosin kinase receptor.

Question 19

Describe the 4 actions of IRS-1.

Answer 19

1) Promotes glycogen synthesis (+glucose storage)
2) Promotes fat synthesis
3) Promotes protein synthesis
4) Promotes expression of glucose transporters (GLUT2 and GLUT4).

Question 20

1) Where are GLUT2 receptors found?

2) Where are GLUT4 receptors found?

Answer 20

1) In the liver.

2) In muscle and adipose tissue.

Question 21

1) During which bodily state is glucagon secreted?
2) Why does glucagon have no effect on skeletal muscle?
3) What is the effect of glucagon on adipose tissue?

Answer 21

1) The fasting state.
2) Because skeletal muscle does not have glucagon receptors.
3) Stimulates the breakdown of triacylglycerols into glycerol and fatty acids.

Question 22

How are fatty acids and glycerol used by the body during the fasting state?

Answer 22

Fatty acids and glycerol will travel to the liver.

Glucagon promotes conversion of FAs to ketone bodies which are used as a source of fuel during the fasting state.

Glycerol can be converted to glucose-6-phosphate via gluconeogenesis and then into glucose.

Question 23

Describe the effects of glucagon on the liver.

Answer 23

• Causes glycogenolysis.

- Proteins can be broken down to AAs which can undergo gluconeogenesis to create glucose-6-phosphate and then glucose.

Question 24

1) What is the effect of glucagon on the intestines?
2) What receptors does glucagon bind to on hepatocytes?
3) What happens when glucagon binds to the G-protein coupled receptor?

Answer 24

1) Causes GLP-1 and GLP-2 to be created from proglucagon.
2) A G-protein coupled receptor.
3) There is a cascade of events causing the activated of PKA which causes the intracellular effects of glucagon.

Question 25

State the 5 intracellular effects of glucagon.

Answer 25

1) Decreases glycogenesis
2) Increases gluconeogenesis
3) Increases glycogenolysis
4) Decreases glycolysis
5) Promotes lipolysis in adipose tissue.

Question 26

1) Why is glycolysis inhibited during the fasting state?

2) What are the 3 ways that insulin stores energy?

Answer 26

1) So that the glucose intermediates (acetyl CoA, oxaloacetate and pyruvate) can be used for gluconeogenesis.
2) Glycogen, triacylglycerols and proteins.