5.4 Hormonal communication

Question 1

define target cells

Answer 1

For non-steriod hormones cells that possess a specific receptor on their plasma membrane. The shape of the receptor is complementory to the shape of the hormone molecule many similar cells together from a target a tissue.

Question 2

Define Endocrine system

Answer 2

a communication system using hormones as signalling molecules.

Question 3

Define hormones

Answer 3

Molecules that are released by endocrine glands directly into the blood. they act as messenger carrying a signal from the endocrine gland to a specific target organ or tissue.

Question 4

State how the endocrine system transports hormones.

Answer 4

Via the circulatory system.

Question 5

Styate the different type of hormones and there differences

Answer 5

Protein -
they are not soluble in phospholipids and so are unable to enter the cell, and so they bind to cell surface receptors to create a second messenger (cAMP)

Steriod hormones, pass through phospholipids bilayer and have a direct effect on DNA.

Question 6

State the role of an endocrine gland.

Answer 6

They release hormones directly into blood and known as ductless glands

Question 7

Define adrenal cortext

Answer 7

the outer layer of the adrenal gland

Question 8

define adrenal gland

Answer 8

one of a pair of glands lying above the kindeys, which release adrenaline and a number of other hormones known as corticoids such as aldosterone.

Question 9

define adrenaline

Answer 9

A hormone relased from the adrenal glands, which stimulates the body for a fight or flight response.

Question 10

Define adrenal medulla

Answer 10

inner layer of the adrenal glands

Question 11

State the layers of tissue inside the adrenal gland.

Answer 11

capsule
zona glomerulosa
zona fasciculata
zona reticularis
medulla

Question 12

Name three corticoid hormones released by the adrenal gland.

Answer 12

Mineralcorticoids (aldosterone)
Glucocorticoids
Cortisol

Question 13

State the function of aldosterone

Answer 13

released from zona glomerulosa,
helps to control conc of Na+ and K+ in blood aswell as in kindeys as it increases absorption of Na+ and decrease for K+ in the distal tubules and collecting duct.

Question 14

State the function of glucocorticoids

Answer 14

released from the Zona fasciculata,

controls the metabolism of carbohydrates, fats and proteins.

Question 15

State the function of Cortisol

Answer 15

released from the zona reticularis,

if correct enzymes are not present then the precursor androgen, corisol converts sex hormones.

Question 16

State the roles of adrenaline

Answer 16

• Relaxing smooth muscles in the bronchioles
• increasing stoke volume of the heart
• increase heart rate
• causing general vascostriction to raise blood pressure
• stimulating conversion of glycogen to glucose
• dialting pupils
• increase mental awaerness
• inhibiting the action of the gut.
• erect body hairs.

Question 17

Define Beta cells

Answer 17

cells found in the islets of langerhans that secrete the hormones insulin.

Question 18

Define glucagon

Answer 18

a hormone that causes an increase in blood glucose concentration

Question 19

define insulin

Answer 19

the hormone, released from the pancreas that causes blood glucose levels to go down.

Question 20

explain why the pancreas is a special organ

Answer 20

is has both a endocrine and exocrine function:

• pancreatic juices contains enzymes which is secrated into the small intensines through the duodenum.
• hormones which are secreted from the islets of langerhan into the blood.-

Question 21

explain the role of the pancreas exocrine function

Answer 21

secretes substances into duct most cells synthesis and release digestive enzymes.

acini are groups of exocrine cells surrounding tiny tubules acinus plural

acini join to form intralobular ducts.

pancreatic duct carries fluid into the duodenum.
Fluid contains pancreatic amylase, typsinogen (deactivated trysin), lipase.

Question 22

Explain the endocrine function of the pancrease

Answer 22

The islets of langerhan contains the Aplha cells and beta cells.
a - glucogon.
b - insulin.

Question 23

State the effects of glucogon.

Answer 23

Glycogen is converted to glucose (glucogenolysis) by phosphorylase A, which is one of the zymes activated in the cascade.
more fatty acids are used in repiration
Amino acids and fats are converted into additional glucose, by gluconeogensis.

Question 24

Describe how glucogon and insulin are an example of negative feedback

Answer 24

as insulin concentration increases, it decrease the concentration of glucose in blood, this will stimulate the production of glucogon by alpha cells in the pancreas.
the increase in glucogon will trigger cells to breakdown glycogen into glucose and releasing it into blood increase blood glucose conentration.
the increase in blood glucose conentration causes beta cells to synthesis insulin and is release increase its concentration. and so on.

Question 25

define glycogensis

Answer 25

glucose in the cell is converted to glycogen for storage

Question 26

Explain how insulin is relased from beta cells.

Answer 26

1. cell membrane has K+ and Ca2+ channels
2. The potassium ion channels are normally open - so K+ flow out.
3. When blood glucose concentration is high the gllucose moves into the cell.
4. glucose is metabolised to produce ATP.
5. The ATP closes the K+ channel
6. The accumulation of K+ alters the potential difference across the cell membrane- the inside becomes less negative .
7. This change in potential difference opens the Ca2+ channels
8. Ca2+ enter the cell and cause the secretion of insulin by making the vesicles containing insulin move to the cell surface membrane and fuse with it, releasing insulin by exocytosis.

Question 27

Define Diabetes mellitus

Answer 27

a condition in which blood glucose concentrations cannot be controlled effectively.

Question 28

Define Stem cells

Answer 28

unspecialised cells that have the potential to develop into any type of cell.

Question 29

Explain the differences between type 1 and 2 diabetes

Answer 29

type 1 is insulin-dependent and is known as a result fo an autoimmune response while type 2 is known as non-insulin-dependent diabete and is due to insulin receptor becoming less responsive.

Question 30

Treatment for type 1 diabetes.

Answer 30

treated with insulin injections.
alternatives are 
- insulin pump therapy
- inslet cell transplantation
- a complete pancreas transplant.

Question 31

Treatment for type 2 diabetes.

Answer 31

No real treatment but lifestyle changes.

exercise regulary and carefully monitor their diet.