Homeostasis of blood sugar and gas concentrations

Question 1

where is insulin released from?

Answer 1

beta cells in the pancreas (Islets of Langerhans)

Question 2

where is glucagon released from?

Answer 2

alpha cells in the pancreas (Islets of Langerhans)

Question 3

what is glycogen?

Answer 3

glucose that is stored in mainly muscle and liver cells

Question 4

what are the roles of insulin and glucagon?

Answer 4

insulin lowers BGL and glucagon raises BGL

Question 5

what is glycogenesis?

Answer 5

conversion of glucose to glycogen

Question 6

what is glycogenolysis?

Answer 6

conversion of glycogen back into glucose

Question 7

what is the general role of the liver in BGL?

Answer 7

the liver is able to convert glucose into glycogen for storage or glycogen into glcose for release into blood. it also has the ability to store some glucose as glycogen.

Question 8

what are the four main effects that insulin has on the body to reduce BGL?

Answer 8

• enables entry of glucose into cells
• promotes conversion of glucose into glycogen in the liver and muscles
• promotes fat storage
• promotes protein synthesis

Question 9

what are the two main effects that glucagon has on the body to increae BGL?

Answer 9

• convert liver glycogen into glucose

- promote gluconeogenesis

Question 10

which hormone is secreted from the adrenal cortex?

Answer 10

glucocorticoids (cortisol)

Question 11

which hormones are secreted from the adrenal medulla?

Answer 11

adrenaline and noradrenaline

Question 12

what are the two roles of cortisol in maintaining BGL?

Answer 12

• stimulate conversion of glycogen into glucose in the liver

- stimulate protein breakdown in muscles and conversion of amino acids into glucose in the liver

Question 13

what is the role of adrenaline and noradrenaline in maintaining BGL?

Answer 13

• stimulates the breakdown of glycogen in the liver and rlease of glucose into the blood

Question 14

what is the diaphragm stimulated by?

Answer 14

impulses from the phrenic nerve

Question 15

what are the intercostal muscles stimulated by?

Answer 15

intercostal nerves

Question 16

where do the impulses from the intercostal muscles and diaphragm come from?

Answer 16

respiratory centre in the medulla oblongata

Question 17

what effect does oxygen have on breathing rate?

Answer 17

oxygen concentration has a very small effect on breathing rate

Question 18

what are aortic and carotid bodies and where are they located?

Answer 18

chemoreceptors located in the heart that are sensitive to oxygen concentration in blood plasma

Question 19

what effect does carbon dioxide have on breathing rate>

Answer 19

a small increase in the concentration of carbon dioxide will result in a large increase in breathing eate

Question 20

where are the chemoreceptors that are sensitive to carbon dioxide concentration located?

Answer 20

in the medulla oblongata

Question 21

why is voluntary control of breathing important?

Answer 21

it is important in speech and for activities such as swimming

Question 22

why is it impossible to stop breathing forever?

Answer 22

the build-up of carbon dioxide sends impulses to the inspiratory muscles which force a person to take a breath

Question 23

what is hyperventilation?

Answer 23

rapid, deep breathing that can provide more oxygen than required and can remove more carbon dioxide than necessary. it is brought about by physical stress (severe pain) or emotional stress such as anxiety)

Question 24

how is cardiac output determined?

Answer 24

heart rate X stroke volume

Question 25

what are some factors that blood pressure depends on?

Answer 25

• cardiac output

- diameter of blood vessles

Question 26

what is the sinoatrial node and atrioventricular node (SA node and AV node)?

Answer 26

bundles of specialised cells that control the heart’s activity.

Question 27

what is the role of the SA node? where is it located?

Answer 27

the SA node is located in the wall of the right atrium below the opening of the superior vena cava. It is responsible for the rhythmical contractions of the heart (aka pacemaker)

Question 28

what is the role of the AV node? Where is it located?

Answer 28

the AV node is located at the bottom of the right atrium and has conducting fibres that extend throughout the septum of the heart.

Question 29

what happens when the heart beats?

Answer 29

1. SA node sends out a nerve impulse that spreads throughout the atria
2. stimulus reaches the AV node and the contraction of the atria begins
3. stimulation of the AV node causes it to send impuses down the septum (between the ventricles)
4. the impulses then spread through the muscles of the ventricles. Atrial contraction ends and ventricular contraction begins.