Topic 14

Question 1

2 parts of nervous system

Answer 1

• central nervous system (brain and spianl cord)
• peripheral nervous system (neurones outside CNS)

Question 2

Synapses

Answer 2

• a junction between 2 neurones
• consists of 2 neurones separated by a synaptic gap
• the neurone BEFORE the gap hold vesicles filled with neurotransmitters
• the endnof the neurone AFTER the gap has neurotransmitter receptor proteins
• nervous impluse passed across synapse: the nerve impluse reachesnthe end of the neuron before the synaptic gap and triggers the release of neurotransmitter molecules from versicles across synaptic gap; they diffuse across the synaptic gap and then bind to the neurotransmitter receptor proteins in the membrane of the next neurone; stimulates and electricsl impulse in next neurone.

Question 3

Reflex actions

Answer 3

Rapid, automatic responses to stimuli that don’t involve the concious part of the brain - body reacts without thinking

Question 4

Central nervous system

Answer 4

Stimulus (detected by receptors) - impluses go through sensory neurone - impulse reaches synapse between sensory neurone and relay neurone - sent along relay neurone - motor neurone - sent to effector (muscle/gland)

Question 5

Sense organ

Answer 5

Group of receptor cells that respond to a specific type of stimulus

Question 6

Iris

Answer 6

Contains muscles that control the diameter of the pupil

Question 7

Cornea

Answer 7

Transparent outer layer, refracts light into eye

Question 8

Blind spot

Answer 8

No light receptors

Question 9

Lens

Answer 9

Focuses light on the retina

Question 10

Pupil

Answer 10

Hole in the middle of the eye

Question 11

Fovea

Answer 11

Specifc area containing cones

Question 12

Optic nerve

Answer 12

Carries impulses from receptors to brain

Question 13

Retina

Answer 13

Contains rods and cones

Question 14

Rods

Answer 14

Found in peripheral parts of retina, sensitive to light (work well in dim light), gives information in black and white

Question 15

Bright light reflex

Answer 15

Pupil shrinks, circular muscles contract, radial muscles relax

Question 16

Dim light reflex

Answer 16

Pupil widens, radial muscles contract, circular muscles relax

Question 17

Near objects

Answer 17

Cilary muscles contract, suspensory ligaments slacken. Lens becomes fat increasing how much refracts.

Question 18

Distant objects

Answer 18

Cilary muscles relax, suspensory ligaments tighten. Lens goes thin, refracts by a smaller amount

Question 19

Hormones

Answer 19

Chemicals produced by glands amd carried by the blood, which change the activity of a specific target organ or organs.

Question 20

Ovaries - hormone

Answer 20

Produces oestrogen (only females)

Question 21

Adrenal glands

Answer 21

Produce adrenaline

Question 22

Testes

Answer 22

Produce testosterone (males only)

Question 23

Pancreas

Answer 23

Produces insulin and glucagon

Question 24

Insulin

Answer 24

Decreases blood sugar level when it gets too high

Question 25

Oestrogen

Answer 25

Main female sex hormone. Involed in menstrual cycle and promotes development of secondary sexual characteristics

Question 26

Testosterone

Answer 26

Main male sex hormone.controls sperm production and development of secondary sexual characteristics

Question 27

Adrenaline

Answer 27

• prepares you for ‘fight or flight’
• when brain detects a dangerous or stressful situation it sends nerve impulses to adrenal gland to secrete adrenaline.
• causes increase in breathing rate and heart rate and causes pupils to widen.
• increase in heart and breathing rate imcrease metabolic activity - more blood flow to muscles so cells recieve more oxygem and glucose for respuration
• adrenalime also causes liver to break down its glycogen ans release glucose

Question 28

Nerve impulses

Answer 28

Fast message, act for a short time

Question 29

Hormone

Answer 29

Slower message, acts for longer

Question 30

Homeostasis

Answer 30

The maintenance of a constant internal environment e.g body temperature 37 degrees
- conditions are kept steady by negative feedback system

Question 31

Mechanisms to reduce body temperature

Answer 31

Hairs lie flat, sweating, vasodilation

Question 32

Vasodilation

Answer 32

Whem it is hot arterioles near the surface of the skin dialate. more blood flows through the surface of the skin more heat lost temp lowered

Question 33

Mechanisms to increase body temperature

Answer 33

Hairs stand up, much less sweat, shivering , vasoconstriction

Question 34

Vasoconstriction

Answer 34

When its cold arterioles near the surface constrict so less blood flows through thr capillaries in the suface layers of the skin. This reduces heat loss

Question 35

Controlling Blood Glucose Concentration

Answer 35

• excess glucose can be stored as glycogen in the liver and in muscles
• changes in glucose levels are controlled by the pancrea using insulin and glucagon
• when blood glucose concentration is too HIGH - INSULIN is secreted
  . when insulin makes liver turn glucose into glycogen
  . glucose moves from blood into liver and muscles cells
• when blood glucose concentration is too LOW - GLUCAGON is secreted by pancreas
  . glucose released into blood by liver
  . glucagon makes liver turn glycogen into glucose

Question 36

Type 1 diabetes

Answer 36

• caused by lack of insulin produced by pancreas
• treated with insulin therapy
• injections usually done at meal time
• not eatong too many simple carbs (sugars), taking regular exercise (removes excess glucose)