homeostasis - topic 5

Question 1

what is homeostasis

Answer 1

the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes

Question 2

three main conditions the body needs to regulate

Answer 2

1. water levels
2. blood glucose concentration
   3.temperature

Question 3

what does a receptor do

Answer 3

detect the stimuli

Question 4

what does the coordination centre do

Answer 4

receive and process information from the receptors

Question 5

what does an effector do

Answer 5

bring about a response to restore optimal conditions

Question 6

what are the two main effectors

Answer 6

nervous system - muscles - contract
endocrine system - glands - release hormones

Question 7

what are some features of the nervous system

Answer 7

sends electrical impulses
its very fast but its effects are short lived
specific/ precise

Question 8

what is a neurone

Answer 8

nerve cells that carry electrical impulses, chemicals transmit over the synapses between different neurones

Question 9

what is the central nervous system (CNS)

Answer 9

the brain and spinal cord

Question 10

what is the peripheral nervous system (PNS)

Answer 10

all sensory and motor neurones

Question 11

what is the sensory neurone

Answer 11

the neurone that carries a signal from the receptor to the coordination centre

Question 12

what is the relay neurone

Answer 12

the neurone that acts as the coordination centre in reflex action. found in the CNS

Question 13

what is the motor neurone

Answer 13

the neurone that carries a signal from the coordination centre to the effector

Question 14

what is a reflex action

Answer 14

an automatic and rapid responses of the nervous system. does not involve the conscious part of the brain. it prevents damage and harm.

Question 15

what is the cerebrum (cerebral cortex)

Answer 15

the part of the brain that controls consciousness, intelligence, memory, language, personality etc

Question 16

what is the hypothalamus

Answer 16

the part of the brain that controls body temperature by sending signals to the pituitary gland

Question 17

what is the medulla oblongata

Answer 17

part of the brain that controls unconscious activities (heart rate/breathing)

Question 18

what is the cerebellum

Answer 18

part of the brain that controls balance and muscle coordination

Question 19

what is an electroencephalogram (EEG)

Answer 19

a non invasive brain procedure. directs weak electrical current using electrodes and the patient describes what they experience

Question 20

what is an MRI scan

Answer 20

it uses magnetic waves to detect brain activity, checks which parts of the brain are active whilst people are doing different activities

Question 21

what are the pros of brain surgery

Answer 21

treatment for disorders, reduces muscle tremors etc

Question 22

what are the cons of brain surgery

Answer 22

carries risk such as damage or increased problems as the brain is complex and delicate

Question 23

what is the cornea

Answer 23

the transparent outer layer that refracts light

Question 24

what is the iris

Answer 24

contains muscles to control diameter of the pupil

Question 25

what is the pupil

Answer 25

the hole that lets light through

Question 26

what does the lens do

Answer 26

refracts light to focus on the back of the retina

Question 27

what are the suspensory ligaments

Answer 27

ligaments that connect to the lens to control its thickness

Question 28

what do the ciliary muscles do

Answer 28

contract to widen lens and refract more light

Question 29

what is the sclera

Answer 29

tough, supporting layer

Question 30

what does the retina do

Answer 30

contains receptors cells sensitive to light intensity and colour rods - detect black and white cones - detect colour

Question 31

what does the optic nerve do

Answer 31

carries impulses from receptors to brain

Question 32

what do the circular muscles do

Answer 32

contract to make the pupil smaller during bright light

Question 33

what do the radial muscles do

Answer 33

contract to make pupil dilate during dim light

Question 34

what is accommodation

Answer 34

when the eye focuses the light on the back of the retina by changing the shape of the lens

Question 35

what happens when the eye focuses on a near object

Answer 35

- the ciliary muscles contract - the suspensory ligaments relax - lens becomes fatter - more refraction

Question 36

what happens when the eye focuses on a far object

Answer 36

- ciliary muscles relax - suspensory muscles tighten - lens becomes thinner - less refraction

Question 37

what happens to the eye in dim light

Answer 37

- radial muscles contract and circular muscles relax - pupil dilates

Question 38

what happens to the eye in bright light

Answer 38

- circular muscles contract and radial muscles relax - pupil constricts

Question 39

hyperopia (long - sighted)

Answer 39

the lens focuses behind the retina. corrected with a convex lens by narrowing the light rays upon entry to the lens

Question 40

myopia (near - sighted)

Answer 40

the lens focuses in front of the retina. corrected with a concave lens by widening the light rays upon entry to the lens