Topic 9.3 and 9.4 Hormones and Homeostasis

Question 1

Define hormones (2)

Answer 1

chemical substance produced by the endocrine glands, which is carried by the blood

alters the activity of one or more specific target organs

Question 2

Define adrenaline (2)

Answer 2

horomone produced in the adrenal glands

released in “fight or flight” situations (in conditons of stress)

Question 3

Effects of adrenaline (3)

Answer 3

Increased pulse rate - blood, containing glucose is circulated more allowing more muscle contraction (cellular respiration)

Increased breathing - to take in more oxygen and take out more carbon from body

widened pupils - better vision

Question 4

How does adrenaline cause increase blood glucose levels? (2)

Answer 4

Glucose stored in livers as glycogen

Adrenaline triggeres the release of glucagon from pancreas , which breaks down glycogen to release glucose into blood

Question 5

Compare speed of transmission in nervous systems and hormonal systems

Answer 5

Nervous system - Fast (eg: reflex response)

Hormonal control system - Slow

Question 6

Compare longevity of nervous systems and hormonal control systems

Answer 6

Nervous system - Short

Hormonal control system - Long (present until hormone is broken down)

Question 7

Define homeostasis

Answer 7

maintenance of a constant internal environment within set limits

Question 8

Define negative feedback

Answer 8

Where a change in a stimulus causes a response that produces the opposite change

Question 9

Describe the control of the glucose content wehen its levels are low (3)

Answer 9

Pancreas releases glucagon

Glucagon converts some of the stored glycogen back into glucose

blood glucose concetration rises

Question 10

Describe the control of the glucose content when its levels are high (4)

Answer 10

Pancreas release insulin into blood

Insulin travels to liver and causes excess glucose to be converted into glycogen
+
Help glucose enter into cells to be used up for celullar respiration

blood glucose level decrease

Question 11

Describe the maintenance of a constant internal
body temperature in humans when core temperature rises too far (2 statements, doesn’t correlate to amount of marks )

Answer 11

Sweat released onto skin from gland, Sweat evaporates and evaporates require energy, so energy is removed as sweat evaporates, cooling the skin

Vasodilation occurs - arterioles carrying blood near surface get wider,making it easier for heat energy to be transferred to te skin surface and then to the environment via conduction

Question 12

Describe the maintenance of a constant internal
body temperature in humans when core temperature lowers too much (3 statements)

Answer 12

Body hair may rise , fur trap air next to the skin and air acts as insulation

muscles start to shiver, cellular respiration used to produce these contractions, releasing energy wiich warms the blood flowing through the muscles

Vasoconstriction occurs - arterioles near skin get narrower, reducing the blood flowing through the surface capillaries. Because blood kept deeper in skin, heat transfer rate is reduced