homeostasis

Question 1

what is homeostatis

Answer 1

the regulation of conditions inside your body (and cells ) to maintain a stable internal environment in response to changes in both internal and external conditions.

Question 2

why do conditions inside your body need to be kept steady?

Answer 2

your cells need the right conditions for enzyme action even when the external environment changes

Question 3

how do you regulate your internal environment

Answer 3

through automatic control systems that include nervous and hormonal communication e.g. control systems that maintain your body temperature, blood glucose level and water content

Question 4

what are your automatic control systems made up of

Answer 4

3 main components- receptors, coordination centres (brain. spinal chord and pancreas) and effectors

Question 5

what is negative feedback

Answer 5

your automatic control systems keep your internal environment stable using a mechanism called negative feedback . when the level of something (e.g. water or temperature ) gets too high or low , your body uses negative feedback to bring it back to normal

Question 6

what is a sitmulus

Answer 6

a change in the environment

Question 7

what happens in negative feedback when the receptor detects a stimulus where the level is too high/low

Answer 7

the coordination centre receives and processes the info ,organises response, effector produces a response, this counteracts change and restores optium level, the level then decreases/ increases-
effectors carry on producing responses as long as theyre stimulated by the coordination centre , receptor detects when level becomes to different and negative feedback starts again

Question 8

How do organisms respond to th environment

Answer 8

organisms need to respond to stimuli in order to survive. single celled organisms just need to respond to environment, (cells of multicellular organisms need to communicate with each other first- theyve developed nervous and hormonal communication systems)

Question 9

what does the nervous system allow humans to do

Answer 9

allows them to react to their surroundings and coordinate their behaviour by detecting and reacting to stimuli

Question 10

what are the parts of the nervous system

Answer 10

central nervous system, sensory neurones, motor neurones, effectors

Question 11

what is the central nervous system

Answer 11

cns- in vertebrates (animals with backbones) this consists of brain and spinal chord only . in mammals the cns is connected to the body by sensory neuronoes and motor neurones

Question 12

sensory neurones?

Answer 12

neurones that carry information as electrical impulses from the receptors to the cns - you can find it in your arm

Question 13

motor neurones?

Answer 13

the neurones that carry electricla impulses from the cns to effectors (e.g. thigh)

Question 14

effectors?

Answer 14

all your muscles and glands which respond to nervous impulses (knee) and bring about a change

Question 15

receptors

Answer 15

cells that detect stimuli

Question 16

examples of types of receptors

Answer 16

taste receptors on the tongue and sound receptors in the ears

Question 17

what can receptors form

Answer 17

large complex organs e.g the retina of eye is covered in light receptor cels

Question 18

why are muscles and glands known as effectors

Answer 18

they respond in different ways, muslces contract in response to a nervous impulse whereas glands secrete hormones

Question 19

why is cns known as a coordination centre

Answer 19

it receives info from receptors and then coordinates a response - this response is carried out by the effectors

Question 20

example of cns

Answer 20

1- bird eats seed, bird spots cat coming near it (this is stimulus)
2- receptors in birds eye are stimulated, sensory neurones carry info from receptors to cns, cns decides what to do, cns sends info to muscles on birds wings(effectors) along motor neurons - muscles contract and bird flies away to safety

Question 21

function of neurones

Answer 21

neurones transmit info very quickly to and from the brain , brain quickly decides how to respond to the stimulus

Question 22

what is a synapse

Answer 22

connection between 2 neurones , synapses connect neurones, nerve signal is transferred by chemicals whichdiffuse across the gap, these chemicals then set off a new electrical signal in the next neurone

Question 23

how do reflexes help to prevent injury

Answer 23

they are rapid , automatic repsponses to certain stiuml that dont invlove the conscious part of the brain, reduce the chances of being injured e.g. if someone shines a bright light in your eyes, pupils get smaller so less light enters eye to prevent damage

OR if you get a shock , body release the hormone adrenaline automatically

Question 24

reflex arc

Answer 24

the passage of information in a reflex - from receptor to effector- caled reflex arc

Question 25

how does the reflex arc go through the central nervous system

Answer 25

1- neurones in reflex arcs go through spinal cord or through unconscious part of brain
2-when a stimulus (painful bee sting) is detected by receptors - impulses are sent along a sensory neurone to relay neurone in the CNS
3-when impulses reach synapse between sensory neurone - trigger chemicals to be released , chemicals cause impulses to be sent along relay neurone
4- when impulses reach synpase between relay neurone and motor neurone , same happens -chemicals released and cause impukses o be sent along motor neurone
5- impulses travel along motor neurone to effector e.g. muscle
6- muscle then contracts snd moves hand away from bee

Question 26

reaction time

Answer 26

time it takes to respond to a stimulus, often less than a second- can be affected by age, gender or drugs

Question 27

reaction time practical - how would you measue affect of caffeine on reaction time

Answer 27

1- person should sit with arm resting on edge of table
2- hold ruler vertically between thumb and forefinger , zero end of ruler is level w thummb and finger then relase withhout warning
3-person tested should try catch ruler as fast as possible
4- reaction time is measured by number on ruler when caught , number should be read from top of thumb
5- fuurther down the ruler is caught the slower the time
6- repeat to calculate the mean distance the ruler fell
7- the person being tested should then have a caffeinated drink and wait 10 mins to repeat steps again

control- same hand, same person, ruler should be dropped from same height, make sure they havent had any caffeine at beginning of experiment

Question 28

how can reaction time be measured using computer

Answer 28

single computer tests, e.g. person being tested has to click mouse or key as soon as they see stimulus on screen
computer gives more precise reaction time bc they remove possibility of human error from measurement
computer can record time in milliseconds - more accurate
e.g. in ruler test catcher may learn to anticipate drop by reading tester’s body language

Question 29

explain the brain and its functions

Answer 29

its responsible for complex behaviours, brain is part of the central nervous system, made up of biliions of interconnected neurones, controls and coordinates everything you do

Question 30

parts of brain and its functions

Answer 30

cerebral cortex- outer part, responsible for consciousness, intelligence, memory,language

medulla- controls unconscious activity like breathing and heartbeat

cerebellum- responsible for muscle coordination