Paper 2: B5: Homeostasis

Question 1

Homeostasis

Answer 1

an organisms ability to regulate/ control it’s internal conditions so crucial reactions can happen at optimum rates

Question 2

Nervous system is made up of:

Answer 2

CNS: central nervous system
PNS: peripheral nervous system

Question 3

CNS

Answer 3

central nervous system
brain and spinal cord

Question 4

PNS

Answer 4

all other nerves

Question 5

receptor

Answer 5

detects a change due to a stimulus (change in environment)

Question 6

Nerve travels how?

Answer 6

receptor —> sensory neurone —-> relay neurone —-> motor neurone —-> CNS —-> effector —> muscle or gland

travels between neurones via the neurotransmitter chemicals in the synapse (gap of empty space between both ends of a neurone)

Question 7

reflex arc

Answer 7

signal bypasses the brain and goes straight through spine to the effector - much faster than a conscious decision

Question 8

Practical: reaction times

Answer 8

1. drop ruler between finger and thumb
2. measure distance fallen before caught, repeat, calculate mean
3. independent vatiable: Stimulant (eg energy drink or coffee) increases neurotransmission
4. depressant (alcohol) decreases neurotransmission

Question 9

Cerebral cortex (brain)

Answer 9

responsible for higher level functions:
- memory
- speech
- problem solving

Question 10

Cerebellum (brain)

Answer 10

Responsible for motor skills:
- movement
- balance
- coordination

Question 11

Medulla oblongata ( brain )

Answer 11

Controls unconscious actions:
- heart and breathing rate
- signals to adrenal glands to release adrenaline

Question 12

Pituitary gland ( brain )

Answer 12

allows doctors to see brain activity without surgery via MRI scans

master gland: sends signals to other glands

Question 13

Accommodation for far objects

Answer 13

Ciliary muscles relax, suspensory ligaments tighten, thin lens meaning light is only refracted a little bit, focusing the light on the retina

Question 14

accommodation for near objects:

Answer 14

ciliary muscles contract, suspensory ligaments slacken, thick lens meaning light is refracted more, meaning the light comming from the object converges to the retina so you can see a clear image

Question 15

pupil

Answer 15

hole in the iris
can change size depending on the light intensity hitting the eye

Question 16

cornea

Answer 16

transparent outer layer through which light enters the eye
has a slight lensing effect

Question 17

sclera

Answer 17

white surface covering the rest of the eyeball

Question 18

Retina cells

Answer 18

• rods: only detect light intensity
• cones, three types, which detect green blue or red wavelengths of light

Question 19

optic nerve

Answer 19

provides information from the retina to the brain

Question 20

Myopia

Answer 20

short sightedness

Question 21

hyperopia

Answer 21

long sightedness

Question 22

how can myopia and hyperopia be treated?

Answer 22

both treated with glasses, contact lenses or laser eye surgery

Question 23

thermoregulation

Answer 23

body controlling it’s internal temp by the brain sensing blood temp then sending nervous and hormonal signals to various effectors around your body in order for the body to lose heat to its surroundings

Question 24

Examples of thermoregulation (hot)

Answer 24

Vasodilation: blood vessels dilating (widening) to increase blood flow to the skin to increase rate of heat loss

Sweating: sweat glands produce water which evaporated taking away heat

Question 25

Examples of thermoregulation (cold)

Answer 25

• hairs stand on end to trap air - insulation
• shivering - muscles produce more heat
• vasoconstriction: blood vessels contract to minimise blood flow to skin, minimising heat loss

Question 26

endocrine system

Answer 26

system of glands that secrete hormones to send signals to effectors, transported via blood (slower than nervous system)

Question 27

pancreas

Answer 27

secretes insulin (and glucagon) to control blood sugar

Question 28

thyroid

Answer 28

controls growth, metabolism digestive function

Question 29

adrenal gland

Answer 29

releases adrenaline

Question 30

ovaries

Answer 30

release eggs and secrete hormones

Question 31

testes

Answer 31

produce sperm

Question 32

high blood glucose levels:

Answer 32

• pancreas’s secretes insulinę
• causes glucose to move from bloodstream into cells to be used for respiration
• excess glucose converted into glycogen as energy store

Question 33

Glycogen

Answer 33

• excess glucose is converted into glycogen as energy store

Question 34

low blood glucose levels

Answer 34

• pancreas secretes glucagon
• causes liver and muscles to convert glycogen back into glucose
  ( example of negative feedback)

Question 35

Type 1 diabetes

Answer 35

pancreas cannot produce enough insulin, injections needed

Question 36

type 2 diabetes

Answer 36

cells no longer absorb glucose as they should
obesity increases risk of developing this type of