C14 Hormonal Communcation

Question 1

What does the endocrine system use to carry out its function?

Answer 1

The endocrine system uses hormones to send information about changes in environment around the body, bring about designated response.

Question 2

What does the close proximity of the pituitary gland to hypothalamus ensure?

Answer 2

The close proximity of pituitary gland to hypothalamus, ensures that nervous and hormonal responses are closely linked and coordinated.

Question 3

What are hormones?

Answer 3

Hormones (chemical messengers) are produced from Endocrine glands

Question 4

Endocrine glands with the following features:

Answer 4

-the secretion (hormone) are released straight into the blood
-carried in blood, to target organs.
-Hormones, usually proteins, exceptions are sex hormones (are steroids, i.e fat soluble).

Question 5

Where are enzymes and other (watery) secretions produced from?

Answer 5

Exocrine glands

Question 6

Exocrine glands with the following features:

Answer 6

-hormones pass down tube / duct into blood or onto surface, skin or in gut etc.
-examples are sweat glands, salivary glands.

Question 7

What does the nervous and endocrine systems work together?

Answer 7

Nervous and endocrine systems work together, detect and respond appropriately to stimuli.

Question 8

What is one of the main functions of adrenaline?

Answer 8

One adrenaline’s main functions, trigger liver cells undergo glycogenolysis (so glucose released bloodstream), respiration increase, more energy available muscle contraction.

Question 9

(Fight or Flight Response)
What happens once a threat has been detected?

Answer 9

Once threat detected, by autonomic nerve system, the hypothalamus communicates with sympathetic nervous system and the adrenal- cortical system.

-Sympathetic nervous system uses neural pathways, initiate body reaction reactions, whereas adrenal- cortical system uses hormones in bloodstream.

-Sympathetic nervous system sends out impulses to glands and smooth muscles and tells adrenal medulla, release adrenaline and noradrenaline into bloodstream, these stress hormones cause several changes in body.

Question 10

Describe features of the hormone, Adrenaline?

Answer 10

Adrenaline is a hormone (hydrophilic, can’t pass through cell membranes), so binds to receptors on surface liver cell membrane, triggers chain reaction inside the cell

Question 11

What is the effect called, where a first messenger, leads to multiple second messenger being activated, then even more different mols to be activated?

Answer 11

Cascade effect

Question 12

(Physical response)
Heart rate increases
Purpose?

Answer 12

To pump more oxygenated blood around the body

Question 13

(Physical response)
Pupils dilate
Purpose?

Answer 13

Take in as much light as possible for better vision

Question 14

(Physical response)
Arterioles in skin constrict
Purpose?

Answer 14

More blood to major muscle groups, brain, heart, and muscles of ventilation

Question 15

(Physical response)
Blood glucose level increases
Purpose?

Answer 15

Increase respiration to provide energy for muscle contraction

Question 16

(Physical response)
Smooth muscle of airways relaxes
Purpose?

Answer 16

To allow more oxygen into lungs

Question 17

(Physical response)
Non-essential systems (like digestion) shut down
Purpose?

Answer 17

Focus resources on emergency functions

Question 18

(Physical response)
Difficulty focusing on small tasks
Purpose?

Answer 18

Brain solely focused only on where threat is coming from

Question 19

(Fight or Flight Response)
Hypothalamus activates the sympathetic nervous system…

Answer 19

-The sympathetic nervous system actives the adrenal medulla, releases noradrenaline a d adrenaline into bloodstream

-The impulses from the activated sympathetic nervous system also activates glands and smooth muscles.

COMBINATION of neuronal and hormonal activity results in ‘flight or fight’ response

Question 20

(Fight or Flight Response)
Hypothalamus activates the adrenal-cortical system by…

Answer 20

Releasing CRF, activating pituitary gland to secrete hormone ACTH. It arrives at adrenal cortex and releases approximately 30 hormones, that go into the bloodstream.

COMBINATION of neuronal and hormonal activity results in ‘flight or fight’ response

Question 21

3 stages of the second messenger model of hormone action

Answer 21

-The hormone adrenaline approaches receptor site

-Adrenaline fuses to receptor site, and in doing so activates an enzyme inside the membrane

-The activated enzymes converts ATOto cyclic AMP, which acts as a second messenger that activates other enzymes that, in turn, convert glycogen into glucose

Question 22

Thyroid Gland:

Answer 22

Produces thyroxine, controls rate metabolism and rate that glucose used up in respiration, and promotes growth

Question 23

Adrenal Glands:

Answer 23

Produces adrenaline which increases heart and breathing rate and raises blood sugar levels

Question 24

Pancreas:

Answer 24

Produces insulin which converts excess glucose into glycogen in the liver; and glucagon, which converts glycogen back to glucose in the liver.

Question 25

Function of the pancreas (2)
Exocrine gland:
Endocrine gland:

Answer 25

-Exocrine gland: to produce enzymes and release then via a duct into the duodenum.

-Endocrine gland: to produce hormones and release them into blood.

Question 26

Role as an Exocrine Gland (within Pancreas)

Answer 26

-Most of the pancreas made of exocrine glandular tissue (responsible for producing digestive enzymes and an alkaline fluid known pancreatic juice).

-The enzymes and juice secreted into ducts which eventually lead to the pancreatic duct (from here they released into the duodenum, the top part of small intestine).

Question 27

The pancreas produces 3 important types of digestive enzymes:
(What’s their functions)

Answer 27

-Amylase: break down starch into simple sugars (e.g pancreatic amylase).

-Proteases: break down protein into AA (e.g trypsin).

-Lipases: breaks down lipids into fatty acids and glycerol (e.g pancreatic lipase).

Question 28

Role as an Endocrine Gland:

Answer 28

-Pancreas responsible for producing insulin and glucagon (both play important role, controlling blood glucose conc).

-Within exocrine tissue there are small regions of endocrine tissue called islets of Langerhans (its cells inside, responsible producing insulin and glucagon, and secreting directly bloodstream).

Question 29

Histology of the Pancreas:

Answer 29

-Major difference between endocrine and exocrine pancreatic tissue.

Islets of Langerhans, Appearance: lightly stained, Shape: large spherical clusters, Type of tissue: endocrine pancreas.

Pancreatic acini (singular- acinus), darker stained, small berry-like clusters, exocrine pancreas.

Question 30

Islets of Langerhans:

Within the islets of Langerhans are different types cell.

How are the classified, and what are they?

Answer 30

-Classified according to hormone they secrete:
Alpha cells, these produce and secrete glucagon
Beta cells, these produce and secrete insulin

-Alpha are larger and more numerous then beta within an islet.

-The beta cells of the islets are stained blue.

-The alpha cells are stained pink.

Question 31

Control of Insulin Secretion:

When blood glucose conc rises above set level, detected by beta cells in the islets of Langerhans, and insulin is released.

Explain (in detail) the process:

Answer 31

1) At normal blood glucose conc levels, potassium channels in plasma membrane of beta cells are open, potassium ions diffuse out of the cell. The inside of the cell is at potential -70mV (with respect to outside).

2) When blood glucose conc rises, glucose enters the cells by a glucose transporter.

3) The glucose is metabolised inside the mitochondria, resulting production of ATP.

4) ATP binds to potassium channels, causes them to close (known as ATP-sensitive potassium channels).

5) As potassium ions can no longer diffuse out cell, potential difference reduces to around -30mV and depolarisation occurs.

6) Depolarisation causes voltage-gated calcium channels to open.

7) Calcium ions enter, cause secretory vesicles to release insulin they contain by exocytosis.