B10 - The HUman Nervous System

Question 1

What is homeostasis ?

Answer 1

The regulation of the itnernal conditions of a cell of an organsism to maintain the optimum conditiosn for fuction in response to internal and external changes .

Question 2

An example of why we need homeostasis .

Answer 2

-Enxymes and cells require very stable condtions in order to work .
-What that mens is that enzymes and cells cannot work well if the conditions around them change too uch .
-Because of this , our bodies hae sysems in place to keep the itnernal conditions optimum , in order for the cells to function , this is HOEMOSTASIS .

Question 3

What does homeostasis consits of ?

Answer 3

-Automatic control sytems , making usre the internal conditions of the body ,s tay as constant as possible .

Question 4

e.g of the card above .

Answer 4

-An endurance athelete .
-Exercise places lots of demans ont he body .
*FOr exmapel respiration will use glucose to generate energy .
-Causin the blood flucose concentration to fall .
-Causing the atheltes body temperature to rise , they will also loose wter through sweitng .
-So int he human body , homeostasis is used to keep the blood glcose concentration , bodystemperture and water levels cosntant .

Question 5

IN THE EXAM , ou could be asked to descrie the gerneal features of an automatic contol sytem .

Answer 5

-The automatic control sytems in the body , can involve the nervous or hormones .
Features of an automatic control system invovle ;
RECEPTOR CELLS
CO-ORDINTION CENTER
EFFECTOR

Question 6

S1
-What are recepotr cells .

Answer 6

Recepotr cells detect changes in the environement .
-THe word ‘environment’ , cold be used to mean the body’s internal conditions , (concentration of glucose in the blood .)
-Or , could mean , the bodies externaal conditions - (temperature of the skin )

Question 7

What do scientists call a change to the environement ?

Answer 7

Stimulus

Question 8

S2
The Coordination center.

Answer 8

-The receptor cells , now pss information to the COORDINATION CENTER (THIS COULD EITHER BE THE BRAIN , SPINAL CORD , OR PANCREAS)
-The coordination center , receievs and processes the information fromt he recepotr cells .

Question 9

S3
EFFECTOR .

Answer 9

The coordination centernows sends instructions to the effector .
-An EFFECTOR , is a muscle or gland .
-THE JOB , of the effector , is to carry out a response (restore the optimum level).

Question 10

Although , there are lots of systems …

Answer 10

THEY ALL HAV A STIMULUS , RECEPOTR , COORDINATION CENTER , AN EFFECTOR , AND RESPONSE. THIS IS THE ORDER THE WORK IN .

Question 11

A key part of homeostasis involves …

Answer 11

the nervous sytem .

Question 12

The nervous sytem contains two parts , what are they ?

Answer 12

(1)The CENTRAL NERVOUS SYTEM (CNS)
This includes thebrian and spinalc ord

(2) Other nerves running to and from the nervous system.

Question 13

S1
How does the nervous sytem work ?

Answer 13

-Recepotrs detec a stimulus , and sed electrical impulses down nerurones to the central nervous sytem .
(neurones is anoher way of aying nerve cells

Question 14

S2
How does the nervous system work ?

Answer 14

-The central nervous system IS the cooridntion center .
-This now sends electrical impulses , down the other neurones to the effecotrs .
-And the effectors bring about the resposne .

Question 15

S3
How does the nervous sytem work?

Answer 15

-The effectors are usually a msucle which contracts , or a gland which secretes a hormone .

Question 16

A KEY , role of the nervous system is ?

Answer 16

That it enables humans to react to their surroundings and coordinate thier behabiour .
-One wya this is done is thorugh the REFLEX ARC .

Question 17

EXAM QUESTION

Answer 17

WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Question 18

S1-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 18

-First the stimuus is detected by the receptor .
-In this case , the stimulus is heat , and the receptors in the skin .

Question 19

S2-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 19

Eleectrical impulses now pass from the receptor , along a sensory neurone , to the central nervous system.

Question 20

Sensory Neurones

Answer 20

Sensory neurones are connected to receptors , and receptors allow us to sense our environment.

Question 21

S3-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 21

At the end of a sensory neurone , is a junction called a synapse . t the syynapse , a chemical is released .

Question 22

S4-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 22

The chemical now diffuses acorss a relayneurone , in the central nervous system , where it triggers an electrical impulse .

Question 23

S5-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 23

The electrical impulse , now passes across the replay neurone and reaches another synapse .

Question 24

S6-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 24

Once again , this chemical is released.

Question 25

S7-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 25

This chemical , triggers ,a ne electrical impulse in the motor neurones .

Question 26

S8-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 26

The electrical impulse now passes down the motor neurone to an effector . (in this case a muscle )

Question 27

S9-WHAT HAPPENS WHEN YOU TOUCH HOT OBJECTS .

Answer 27

-The msucle now contracts and (pulls the hand away from the hand - this is the response).

Question 28

KEY POINT ABOUT REFLEXES ,

Answer 28

-THE CNS acts as a cooridnator , and in most cases , the brian makes decisions about what ction to call . -However , int he case of reflexes , there is NO DECISION MAKING , by the conscious part of the brain , Maing reflexes AUTOATIC and RAPID . -As they are RAPID , reflexes help to protect us from danger .

Question 29

WHAT IS THE RQP ABOTU ?

Answer 29

-Describe , how to measure a persons reaction time . Practical requires 2 peopme (perosn1 +and person2) -Peron 2 will measure the reaction fime of person 1

Question 30

S1 of RQP

Answer 30

First , person 1 , sits on a stoll , with a good upright posture .

Question 31

S2 of RQP

Answer 31

Person 2 , then places their forearm of the dominant arm , across the able , with their hand overhanging the egde . 9if you are rightahdned , thats your dominant hand).

Question 32

S3 of RQP

Answer 32

pERSON 2 HOLDS , a ruler verticallly

Question 33

S4 OF RQP

Answer 33

the 0 cm mark , XHOULD BE ETWEEN PERSON1'S THUMB AND FIRST finger .

Question 34

Person 2 , then tells person 1 to prepeare to catch the ruler , then person 2 drops the ruler at a random time .

Answer 34

Person 2 , then tells person 1 to prepeare to catch the ruler , then person 2 drops the ruler at a random time .

Question 35

S5 RQP

Answer 35

Person 2 , then tells person 1 to prepeare to catch the ruler , then person 2 drops the ruler at a random time .

Question 36

S6 RQP

Answer 36

Person 1 , has to catch the ruler with their thumb and first finger as quickly as possible , when it drops .

Question 37

S7 RQP

Answer 37

Persn 2 ,, now records the measurmemen , ont he ruler ,t hat is level with the top of person1's thumb .

Question 38

S8 RQP

Answer 38

Person 1 , now has a hsort break . -The tests is then rpeeated several times , and then a mean is clacualted .

Question 39

S9 of RQP

Answer 39

From these experiments , we can covert our results to a reaction time . (We can use a onversion tbale online to do this .)

Question 40

S10 RQP

Answer 40

Now person 1+2 switch places , with person1 , teasting the reaction time of person 2 .

Question 41

S11 of RQP

Answer 41

This allws us to see whether the two people have different reactiont imes .

Question 42

What is the Independant variable ?

Answer 42

Person haveing thier reaction time tested .

Question 43

What is the dependant variable ?

Answer 43

Reaction time .

Question 44

What is the control varible ?

Answer 44

-Starting distance between the finger and thumb , easure ruler always at the top of the thumb . -Keep the conditions of the room safe , lighting nd background noise .

Question 45

What would happen if the control variables changed ?

Answer 45

Could effect the dependant variable , the reactiont ime .

Question 46

One other indepedant variable we could investiage ?

Answer 46

-Effect of practise , tos ee if reactoin time changes depending on the number of tries . -as they have more tires . (Might expect thier reaction time to be shorter , as the person has gotten more practise.)

Question 47

Another independant , variable we could investigate ?

Answer 47

-Whether reaction time depends on the hand , cthcing the ruler . (Carry out this test with dominant hand , and non dominant hand of the same person .) -As the dominant hand is used more often , might expect , reactoin time to be shorter , with the domiannt hand , rather than the non-dominant hand .

Question 48

Final independant varibale we could investigate ?

Answer 48

-Whether chemicals affect reactoin time e.,g caffeine . -Test subject drinks a measured amount of cola half an hr beofre the expermient . -Then compare this reaction time , with thier normal reaction time . Problem - there could be another chemical in the cola , which is affecring the reaction toieme , -So use a caffeine free cola , and compare this reaction time with thier normal reaction time .

Question 49

Safet of this RQP WITH CHEMCCAL independant variable .

Answer 49

*As we are giving test subjects something to drink , make sure there is no medical issue affected by caffeine , like heart conditions or allergy . -Also , carry out the tests , here hazardous chemicals are not usually used .

Question 50

What do brain do ?

Answer 50

-The Brain plays a critical role in the CENTRL NERVOUS SYSTEM . -As the brian controlls complex behaviour e.g language . -To do this , the brian contains billions of interconnected neurones .

Question 51

Different parts of the brain carry out different functions . -In the exam , you coul dbe asked to identify three different pats of the brain and describe their functions .

Answer 51

... yeah

Question 52

CEREBAL CORTEX

Answer 52

-The highly folded outer part of the brain is the cerebal cortex . -The functions of this cerebal cortex include , language , memory and consciousness .

Question 53

CEREBELLUM

Answer 53

-The second part of the brain is called the cerebellum . -This controls balance and co-odiantes our movements .

Question 54

MEDULLA

Answer 54

-FInal part of the brain is the medulla . -This controlls our heartrae and breathing rate .

Question 55

Studying the brain is extremely difficult . -It is also difficult to treat brain diseases , or brain damage .

Answer 55

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Question 56

One reason why the brain is difficult ot study .

Answer 56

-The brain is proteced by the skull . So it is very tricky acess

Question 57

Another reason why the brain is difficult to study .

Answer 57

-Strucutres of the brain are extremely complex . -It is difficult to work out exactly , which parts of the brain carry out specific functions .

Question 58

Final reason why the brain is difficult to study .

Answer 58

-The brain is extremely delicate and eay to damage .

Question 59

There are three ways scientists can use to investigate the brain .

Answer 59

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Question 60

One way scientists can use to investigate the brain .

Answer 60

-Many scientsits look t patients who have suffered brain damage . -By looking to see where the damage has taken palce , they cn try to link that part of the rain to its function .

Question 61

Another way scientists can use to investigate the brain .

Answer 61

-We can also electrically stimulate different parts of the brain and look at the effects oon the persons behaviour . -allowing us to narrow down specific regions to their funcitons .

Question 62

The final way scientists can use to investigate the brain .

Answer 62

-We can also use MRI scanning , to look at which parts of the brain are most active during activities . (e.g when a person is looking at images , we can see greater activity in the part of the brain responsible for image processing .)

Question 63

What type of organ is the eye ?

Answer 63

The eye is a SENSE ORGAN . -It contians receptors sensitive to both light intensity and also he colour of light .

Question 64

How the eye detects light S1

Answer 64

-Light rays pass through the transparent frnt of the eye , this is called the cornea . -The JOB of the cornea is to start the focussing of the light rays .

Question 65

How the eye detects light S2

Answer 65

-The light rays then pass through the pupil , in the center of the iris . -This IRIS , is the coloured part of the eye .

Question 66

How the eye detects light S3

Answer 66

-Light rays then [ass through the lens . -The JOB of the lens is to focus the light rays onto the back of the eye .

Question 67

What is one KEY feature of the lens ?

Answer 67

-It can chnage its shape , allowing us to foucs on distant or near objects . This is known as ACCOMODATION .

Question 68

How the eye detects light S4

Answer 68

-The light rays are then focused onto the back of these , this is called the RETINA . -The retina contains the receptor cells for lgiht . -These receptors allow us to detect light intensity and light colour .

Question 69

How the eye detects light S5

Answer 69

-The receptor cells in the retina , now send electrical impulses down the optic nerve , to the brain .

Question 70

OTHER PARTS OF THE EYE I NEED TO KNOW .(1)

Answer 70

-The white part of the eye is known as the sclera . -This tough outer structure protects the eye .

Question 71

OTHER PARTS OF THE EYE I NEED TO KNOW (2)

Answer 71

-the cillary muscles and suspensory ligaments work with the cells . -Together they allow u to focus in distant or near objects .

Question 72

THE PUPIL

Answer 72

-The pupil is the space in the center of the iris , where light passes through . -The pupil allows light rays to pass into the eye and the job of the iris is to control the size of the pupil .

Question 73

What happens if you enter a DARK ROOM ?

Answer 73

-The amount of light entering the eye is now LOW . -This drop in light intensity is now sensed by the light receptors in the retina , and these send electical impulses to the brain . -The brain then sends electrical impulses to specific muslces in the iris . -These muscles hen conract causing the pupil to become larger . -This now allows more light to enter they eye .

Question 74

What happens in a LIGHT ROOM ?

Answer 74

-We can see the opposite in a light room . -In this case , the reflex causes the pupil to become smaller , reducing the amount of light entering the eye , protecting it from dmage .

Question 75

A lot of the foucidng of objects is crried out by what ?

Answer 75

-By the cornea . -But the cornea is a fixed focus .

Question 76

The rest of the foucsing is carried out by the lens .

Answer 76

-The lens allows us to focus on near , or distant objects . -To do this , the shape of the lesn can change . -tHIS IS accomaadatoin

Question 77

How does accomodation take place s1

Answer 77

-The lens is surroudnd by a circular msucle , clled the CILLARY MUSLCE . -This is conected to the lens by fibres , which ar called supsensory ligaments .

Question 78

How does accomodation take place S2

Answer 78

-by contracting or relaxing the cillary muscle can change , the thickness of the lens .

Question 79

How does accomodation take place S3

Answer 79

-When the cillary msucle contracts , the suspensory ligaments loosen . -The lens is now thicker and refracts rays more strongly .

Question 80

How does accomodation take place S4

Answer 80

-However , when the cillary muslce relaxes , the suspensory ligaments are pulled tight . -THe lens is now pulled thin , and only slightly refrcts ligh rays .

Question 81

FOCUSING ON DISTANT OBJECTS ;

Answer 81

KEY - Light from didstant objects need to be focused only a relatively small amount . -So in this cas e, the cillry muscle relaxs , and the suspensory ligamnets re pulled tight . -The lens is now pulled thin ,. -As the lens is thinn , the light rays are only lsightly refracted . -The light rays are now focused to a pointon the retina .

Question 82

NEAR OBJECT

Answer 82

-Light from near objects need to be focused a large amount . -In this case , the cillary msucle contrac ts . -This causes the suspensorY ligamnets to loosen

Question 83

NEAR OBJECT (2)

Answer 83

-Now the lens is thicker and reracts the light rays more strongly . -Again , the light rays are now focused to a point on the retina .

Question 84

In some people , the light rays do not focus correctly on the retina.

Answer 84

-These people can be shortsighted or longsighted .

Question 85

LONGSIGHTEDNESS

Answer 85

AKA AS HYPEROPIA -people with longishtedness have no problem at all focusing on distant objects . -But they cannot focus on nearby objects . -In amny cases , the eyeball is too short .. -So the light is focused t a point behind the retina .

Question 86

Elderly people - longsightedness .

Answer 86

-In some cases , especially in the elderly , the lens becomes less elastic . -n this case , the lens cannot become thick enough to focus on near objecs.

Question 87

TREATMENT TO LONGSIGHTEDNESS.

Answer 87

-Glasses with convex lenses , these partially focus the light efore it enters the eye .

Question 88

SHORTSIGHTEDNESS

Answer 88

AKA MYOPIA -People with shoert sight can focus on nearby objects , but cannot focus on ones far away . -In people with short siht , the eyeball can be too long . -So the light is focused on a point in front of the retina .

Question 89

SHORTSIGHTEDNESS (2)

Answer 89

-Short sight can also be caused when the lens is too thick , therefore , light is focused infront of the retina . THE TREATMENT FOR SHORT SIGHTENDESS , s glasses with CONCAVE LENSES . -This is to partially unfocus the light before it enters the eyE .

Question 90

CONTACT LENSES

Answer 90

-Instead of glasses , people can use hard or soft contact lenses , -These lenses sit on the eyeball , and they refract the light the same way as glasses.

Question 91

Recently - new trements have been developed for short+long sightedness

Answer 91

-LASER SURGERY - can be used to change the shape of the cornea , so it refracts the light to a greater or lesser extent . -SOmetimes , the lens inside the eye can be replaced using an ARTIFICAL LENS .