B10 - The Human Nervous System

Question 1

Define homeostasis.

Answer 1

kpng condtns. inside cell or body @ optimum levels

Question 2

What is a stimulus?

Answer 2

△ in envrnmnt

Question 3

What do receptor cells do?

Answer 3

detects △ in envrnmnt (can be internal or external)

Question 4

Give 3 examples of a coordination centre.

Answer 4

brain, spinal cord & pancreas

Question 5

What does the coordination centre do?

Answer 5

processes info from receptor cells & sends instrctns -> effectors

Question 6

Define effector.

Answer 6

muscles eg.contracts or glands eg.secretes hormones that carries out response

Question 7

What is the typical order for automatic control system?

Answer 7

stimuli -> receptor -> coordination centre (CNS) -> effector -> response!

Question 8

What is the CNS? what does it consist of?

Answer 8

central nervous system - brain & spinal cord

Question 9

How do parts of the reflex arc send electrical impulses?

Answer 9

down neurones

Question 10

What would detect the heat if you touched a hot object?

Answer 10

temp. receptors in skin

Question 11

After receptors detecting that you have touched a hot object, what happens?

Answer 11

electrical impulses go from receptor, along sensory neurone -> CNS

Question 12

At the end of any neurone, what is there? What happens there?

Answer 12

synapse = which releases neurotransmitter that diffuses to next neurone in CNS & triggers electrical impulse

Question 13

Why does the temperature of your body need to be controlled?

Answer 13

too ↑ & enzymes dntr
too ↓ & enzymes work too slowly

Question 14

Where are temperature receptors found?

Answer 14

skin & brain

Question 15

Which coordination centre maintains temperature?

Answer 15

brain

Question 16

How do the effectors respond to a temperature change?

Answer 16

muscles - shiver
glands - sweat

Question 17

Why do the water and ion levels of plants need to be controlled?

Answer 17

too ↑ & H2O leaves cells by osmosis
too ↓ & H2O enters cells by osmosis & cells burst

Question 18

Where are water and ion level receptors found?

Answer 18

brain

Question 19

Which coordination centre maintains water and ion levels?

Answer 19

brain

Question 20

How do the effectors respond to a change in water & ion levels?

Answer 20

glands - release hormones change how dilute urine is

Question 21

Why does the blood sugar of the human body need to be controlled?

Answer 21

too ↑ & causes circulation probs.
too ↓ & can’t respire

Question 22

Where are the blood sugar receptors found?

Answer 22

pancreas

Question 23

What is the coordination centre that maintains blood sugar levels?

Answer 23

pancreas

Question 24

How do the effectors respond to low blood sugar levels?

Answer 24

glands - release hormones control blood sugar levels

Question 25

What is the order for the reflex arc?

Answer 25

sensory neurone -> relay neurone -> motor neurone

Question 26

Define synapse.

Answer 26

junction between neurones

Question 27

What happens at the synapse in the reflex arc?

Answer 27

- neurotransmitter released at end of snsry neurone - neurotransmitter diffuses across to rly neurone in CNS - this triggers electrical impulse - elctrcl impulse passes along rly neurone & reaches next synapse

Question 28

What does the cerebal cortex in the brain do?

Answer 28

controls consciousness, intelligence, memory & language

Question 29

What does the pituitary gland do?

Answer 29

produces many different hormones to coordinate & control body systems

Question 30

What does the cerebellum do?

Answer 30

controls coordinating muscular activity & balance

Question 31

What are 4 things that will affect reaction time?

Answer 31

alcohol, caffeine, biological sex, fatigue

Question 32

What 3 reasons explain why it is difficult to study the brain & treat brain disease/damage?

Answer 32

- brain = protected by skull so tricky to access - structures of brain = extremely complex - brain = extremely delicate & easy -> damage

Question 33

What are 3 ways that scientists investigate the brain?

Answer 33

- see where damage has tkn place & link to its function - elctrclly stimulate parts of brain & observe effects on person's behaviour - use MRI scanning -> see which parts of brain are most active during activities

Question 34

What is the cornea's function?

Answer 34

Refracts light - it bends as it enters the eye

Question 35

What is the lens' function?

Answer 35

Further refracts the light to focus it onto the retina

Question 36

What is the retina's function?

Answer 36

bck of eye - contains the light receptors which send elctrcl impulses -> optic nerve in brain

Question 37

What is the optic nerve's function?

Answer 37

Carries the electrical impulses between the brain & the eye

Question 38

What is the scelra's function?

Answer 38

tough white outer layer that protects eye

Question 39

What is the iris' function?

Answer 39

controls how much light enters eye - dark room= little light enters, muscle contracts & pupil size increases - bright room= lots of light enters, muscles relax & pupil size decreases

Question 40

What is the pupil's function?

Answer 40

Small hole at centre of iris through which light enters eye

Question 41

What is the suspensory ligaments function?

Answer 41

connects ciliary muscle -> lens & holds lens in place

Question 42

What is the ciliary muscle's function?

Answer 42

change thickness of lens by cntrctng or rlxng

Question 43

Define accomodation.

Answer 43

ability -> change shape of lens -> focus on nar or distant objects

Question 44

What are the cilary muscles?

Answer 44

muscles connctd -> lens by sspnsry lgmnts

Question 45

How does the eye focus on a near object?

Answer 45

- ciliary muscles contrct - sspnsry lgmnts loosen - lens is now thicker & rfrcts light rays more strongly

Question 46

How does the eye focus on a distant object?

Answer 46

- ciliary muscles contract - sspnsry lgmnts are pulled tight - lens is now pulled think & only slightly refracts light rays