Bio E: Homeostasis (PAPER 2)

Question 1

Homeostasis

Answer 1

The maintenance of a constant internal environment.
Homeostasis controls:
-  blood glucose levels 
-  body temperature
-  H2O levels
-  CO2 levels

Question 2

Synapse

Answer 2

The gap where 2 neurones meet.
Informations diffuses from the first neurone to the other through chemical neurotransmitters that bind to receptor sites at the terminal of the next neurone stimulating an electrical impulse.

Question 3

Nervous pathway / reflexes

Answer 3

1. Receptor detects a stimulus
2. Sensory neurone sends electrical impulses to the relay neurone (connects sensory and motor together)
3. motor neurone sends electrical impulse to the effector
4. effector produces a response

Question 4

Maintenance of sugar levels

Answer 4

When sugar levels rise the pancreas produces insulin and glucose is stored as glycogen in the liver. Furthermore, muscle cells take in glucose for respiration leading to the decline of blood levels.

When sugar levels decline, the pancreas produced glucagon and glycogen from the liver is converted into glucose, allowing blood levels to rise.

Question 5

Diabetes type 1 - Causes, effects and treatment

Answer 5

Found in children and young adults due to genetics.
Pancreas no longer produces enough insulin leading to uncontrolled high sugar levels.
Treated by insulin injections.

Question 6

Diabetes type 2 - Causes, effects and treatment

Answer 6

Found in adults who are obese and overweight.
Body no longer responds to insulin from the pancreas.
Treated by exercise and a carbohydrate based diet.

Question 7

Vasoconstriction

Answer 7

When its too cold the body narrows its blood vessels to reduce heat loss through the skin.

Question 8

Vasolidation

Answer 8

When its too hot the body widens its blood vessels to increase heat loss through the skin

Question 9

Negative Feedback

Answer 9

The response of the body to bring a system back to its set point.

Question 10

Temperature regulation

Answer 10

When a temp increase is detected by receptors in the brain, the body begins sweating and evaporates off the skins surface to cool the body down.

When a temp decrease is detected by receptors in the brain, the body shivers to increase muscle contraction meaning more heat energy is released.

Question 11

Thyroxine (Negative Feedback)

Answer 11

1. Hypotholamus receptors detect a decrease in energy.
2. Pituitary gland releases TSH into the blood.
3. TSH binds to the thyroid gland secreting thyroxine.
4. Thyroxine increase metabolic rate allowing cells to transfer additional energy.
5. Hypotholamus detects when cells have enough energy, inhibiting TSH production.

Question 12

Adrenaline

Answer 12

Adrenaline is produced by the adrenal gland in times of fear or stress.
It increases heart rate and boosts the delivery of oxygen and glucose to the brain and the muscles, preparing the body for ‘flight or flight’.

Question 13

Menstrual Cycle

Answer 13

1. FSH released from the pituitary gland causing the maturation and growth of the egg
2. Oestrogen release from the ovaries thickening the uterus lining
3. Increased oestrogen inhbits FSH production and stimulates LH
4. LH released from pituitary gland causing ovulation
5. Corpus Luteum left behind secreting progesterone which maintains thickening of the uterus lining
6. if fertilisation occurs O & P remain high. If not the cycle restarts.