Biology B10: The human nervous system

studied byStudied by 0 people
0.0(0)
get a hint
hint

What do enzymes and cells need in order to work properly?

1 / 75

encourage image

There's no tags or description

Looks like no one added any tags here yet for you.

76 Terms

1

What do enzymes and cells need in order to work properly?

V stable conditions

  • Can’t work well if conditions around them change too much

New cards
2

Homeostasis

The regulation of the internal conditions of a cell / organism to maintain optimum conditions for function in response to internal + external changes

New cards
3

What does homeostasis do?

Maintains optimal conditions for enzyme action + cell functions

New cards
4

What does homeostasis consist of?

Automatic control systems that ensure internal body conditions stay as constant as possible

New cards
5

Internal conditions

The conditions inside your body

New cards
6

In the human body, what internal conditions does homeostasis control?

  1. Body temperature

  2. The water content of the body

  3. Blood glucose concentration

New cards
7

What do automatic control systems in humans involve?

  • Nervous responses in nervous system

  • Chemical responses in hormone system

New cards
8

What do all automatic control systems need to function?

  1. Receptor cells

  2. Coordination centres

  3. Effectors

<ol><li><p>Receptor cells</p></li><li><p>Coordination centres</p></li><li><p>Effectors</p></li></ol>
New cards
9

Receptors cells

Detect changes in the environment (stimuli)

  • Pass info to coordination centre

New cards
10

Environment

Refers to the bodies

  • Internal conditions (eg blood glucose concentration)

  • External conditions (eg temp of skin)

New cards
11

Stimulus

A change to the environment

New cards
12

Coordination centres

Receives + processes info from receptor cells

  • Sends instructions to the effector

New cards
13

Examples of coordination centres

  • Brain

  • Spinal cord

  • Pancreas

New cards
14

Effectors

  • Muscles or glands

  • Bring about responses to stimulus that restore body conditions to optimum levels

New cards
15

What does the human nervous system consist of?

  • Central nervous system (CNS)

  • Peripheral nervous system (PNS)

New cards
16

What makes up the central nervous system (CNS)?

  • The brain

  • Spinal cord

<ul><li><p>The brain</p></li><li><p>Spinal cord</p></li></ul>
New cards
17

What makes up the peripheral nervous system (PNS)?

All of the nerves in the body

New cards
18

Role of nervous system

Enables humans to react to surroundings + coordinate behaviour

  • Done thru reflec arc

New cards
19

Neurones

Nerve cells

New cards
20

How is information sent through the nervous system as?

Electrical impulses

  • Electrical signals that pass along neurones

New cards
21

Nerves

A bundle of neurones

New cards
22

How does our nervous system work?

  1. Receptors detect stimulus

  2. Sends EI down neurones to the CNS

  3. CNS = coordination centre

  4. CNS sends EI down the motor neurones to effectors

  5. Effectors bring about a response

    • Eg muscles contract or glands secrete hormones

New cards
23

Sensory neurones

Nerve cells that carry impulses from sense organs to CNS

New cards
24

Motor neurones

Carry impulses from the CNS to the rest of the body

  • To make effectors respond

New cards
25

How do effectors like muscles and glands respond to the arrival of impulses?

  • Muscles: contracts

  • Glands: secretes hormones

New cards
26

What makes reflexes automatic and rapid?

No decision making by conscious part of the brain

New cards
27

Since reflexes are automatic and rapid how does it help us?

Protect us from danger

  • So minimise damage to the body

New cards
28

Why are reflexes important?

  • Protect us from danger

  • They take care of basic body functions

    • Eg breathing

New cards
29

What types of neurones do reflexes involve?

  • Sensory neurones

  • Motor neurones

  • Relay neurones

<ul><li><p>Sensory neurones</p></li><li><p>Motor neurones</p></li><li><p>Relay neurones</p></li></ul>
New cards
30

Nerve cell labelled

  • Axon = Long, EI travel along

  • Axon surrounded by myelin sheath (fatty cells)

    • Insulates EI

  • Dendrites = branched endings, connect neurons tog

<ul><li><p>Axon =  Long, EI travel along</p></li><li><p>Axon surrounded by myelin sheath (fatty cells)</p><ul><li><p>Insulates EI</p></li></ul></li><li><p>Dendrites = branched endings, connect  neurons tog</p></li></ul>
New cards
31

Relay neurones

Connect a sensory + motor neurone

  • In CNS

New cards
32

Reflex pathway

  1. Stimulus

  2. Receptor

  3. Sensory neurone

  4. Relay neurone

  5. Motor neurone

  6. Effector

  7. Response

New cards
33

Synapses

Junction, gap where the ends of two neurons meet

  • Ensures EI travel only in 1 direction

New cards
34

In the reflex arc, where are synapses found?

Between

  • Sensory + relay neurones

  • Relay + motor neurones

New cards
35

How do synapses work?

  1. EI arrives at the end of the axon on the neuron

  2. Chemicals released from vesicles

  3. Diffuse across synaptic gap

  4. Chemicals attatch to surface of next neurone + set up new EI

<ol><li><p>EI arrives at the end of the axon on the neuron</p></li><li><p>Chemicals released from vesicles</p></li><li><p>Diffuse across synaptic gap</p></li><li><p>Chemicals attatch to surface of next neurone + set up new EI</p></li></ol>
New cards
36
<p>Which is the only place in the nervous system where drugs can affect the nervous system and why?</p>

Which is the only place in the nervous system where drugs can affect the nervous system and why?

Synapses

  • Only part of the NS where messages are chemical, not electrical

New cards
37

How do neurotransmitter chemicals cross the synapse?

Diffusion

  • Down a CG

  • Passive process

New cards
38

How can drugs trigger impulses in different regions of the brain?

When they bind to neurotransmitter receptors

New cards
39

What can the frequent use of drugs lead to?

Overstimulation of neurons → loss of function

New cards
40

Brain

  • Controls complex behaviours eg language

  • Made up of interconnected neurons

  • Organ part of the CNS

<ul><li><p>Controls complex behaviours eg language</p></li><li><p>Made up of interconnected neurons</p></li><li><p>Organ part of the CNS</p></li></ul>
New cards
41

Cerebral cortex

  • Highly folded, outer layer of the brain

  • Controls consciousness, memory + language

New cards
42

Cerebellum

Controls balance + coordinates movements

New cards
43

Medulla

  • Controls unconscious activities

    • Heart + breathing rate

<ul><li><p>Controls unconscious activities</p><ul><li><p>Heart + breathing rate</p></li></ul></li></ul>
New cards
44

Hypothalamus

Controls body temperature

New cards
45

Pituitary gland

Produces different hormones

New cards
46

Why is the understanding of the brain limited?

  • V complex

  • Diff regions can’t be studied in isolation

New cards
47

Why is studying the brain difficult + difficult to treat brain damage/diseases?

  • Protected by skull → tricky to access

  • Structures in brain are v complex

    • So difficult to work out which parts of the brain carry out specific functions

  • Delicate + easy to damage

New cards
48

Why can brain surgery be performed on conscious patients?

No sensory nerve endings in the brain

New cards
49

Benefits of procedures carried out on the brain and nervous system

Improving quality of someone’s life

New cards
50

Risks of procedures carried out on the brain and nervous system

  • More permanent damage

    • As we don’t fully understand how brain + NS work

New cards
51

Eye

  • Sense organ

  • Contains receptors sensitive to light intensity + colour of light

New cards
52

Cornea

  • Transparent lens

  • It refracts light rays as it enters the eye and focuses it onto the retina

New cards
53

Iris

Colored part of the eye

  • Controls size of the pupil (+ so how much light reaches the retina)

  • Made of muscles that contract or relax to change the size

New cards
54

Lens

  • Transparent lens

  • Starts focusing of light rays onto the retina

New cards
55

What can the lens do?

Change shape, allowing us the focus on distant or near objects

New cards
56

Retina

  • Back of the eye

  • Contains receptor cells for light

New cards
57

What do the receptor cells in the retina allow us to detect?

  • Light intensity

  • Light colour

New cards
58

Purpose of the eye?

To receive light + focus it onto the retina at the back of the eye

New cards
59

How does the eye detect light?

  1. Light rays pass thru the cornea → pupil in the centre of the iris → lens

  2. Lens focuses LR onto the retina (back of eye)

  3. Receptor cells in retina send the EI down the optic nerve to the brain

  4. When brain receives these messages + interprets them as a visual image

<ol><li><p>Light rays pass thru the cornea → pupil in the centre of the iris → lens</p></li><li><p>Lens focuses LR onto the retina (back of eye)</p></li><li><p>Receptor cells in retina send the EI down the optic nerve to the brain</p></li><li><p>When brain receives these messages + interprets them as a visual image</p></li></ol>
New cards
60

Sclera

  • White part of the eye

  • Tough outer structure that protects the eye

New cards
61

Optic nerve

Sensory neurone that carries impulses betw the eye + the brain

New cards
62

How do the ciliary muscles and suspensory ligaments work with the lens?

Allow us to focus on distant or near objects

New cards
63

Pupil

The space in the centre of the iris which light passes through

New cards
64

What two groups of muscle is the pupil reflex controlled by?

  • Radial muscle

  • Circular muscles

<ul><li><p>Radial muscle</p></li><li><p>Circular muscles</p></li></ul>
New cards
65

Blind spot

Point at which the optic nerve leaves the eye that has no retina

  • But the brain fills in the gap

New cards
66

How does focusing light differ in the cornea and the lens?

  • Cornea: fixed focus

  • Lens: allows us to focus on near and distant objects (shape of lens can change)

<ul><li><p>Cornea: fixed focus</p></li><li><p>Lens: allows us to focus on near and distant objects (shape of lens can change)</p></li></ul>
New cards
67

Accomodation

The ability to change the shape of the lens to focus on near or distant objects

New cards
68

How does light from distant and near objects need to be focused and why?

  • Distant: small amount

    • Light from distant objects travels in almost parallel rays

  • Near: a large amount

    • Light from near objects spreads out v strongly

<ul><li><p>Distant: small amount</p><ul><li><p>Light from distant objects travels in almost parallel rays</p></li></ul></li><li><p>Near: a large amount</p><ul><li><p>Light from near objects spreads out v strongly</p></li></ul></li></ul>
New cards
69

How do we focus on distant objects?

  1. Ciliary muscle relaxes

  2. So suspensory ligaments pulled tight

  3. Lens pulled thin

  4. So LR only slightly refracted

    • LR will be focused on a point on the retina

<ol><li><p>Ciliary muscle relaxes</p></li><li><p>So suspensory ligaments pulled tight</p></li><li><p>Lens pulled thin</p></li><li><p>So LR only slightly refracted</p><ul><li><p>LR will be focused on a point on the retina</p></li></ul></li></ol>
New cards
70

How do we focus on near objects?

  1. Ciliary muscle contracts

  2. So the suspensory ligaments loosen

  3. Lens is thicker

  4. It refracts the LR more strongly

    • The LR will be focused on a point in the retina

<ol><li><p>Ciliary muscle contracts</p></li><li><p>So the suspensory ligaments loosen</p></li><li><p>Lens is thicker</p></li><li><p>It refracts the LR more strongly</p><ul><li><p>The LR will be focused on a point in the retina</p></li></ul></li></ol>
New cards
71

Hyperopia

Long-sightedness

  • Can focus on distant objects

  • Can’t focus on nearby objects

New cards
72

Myopia

Short-sightedness

  • Can focus on near objects

  • Can’t focus on distant objects

New cards
73

How is an image formed?

Upside down

  • But the brain interprets it the right way up

New cards
74

General causes of eye defects

Light rays don’t focus correctly on the retina

  • So they are short or long-sighted

  • Image on retina = out of focus

New cards
75

What is the brain made of?

Billions of interconnected neurones

New cards
76

What does the brain have?

Diff regions that carry out diff functions

New cards

Explore top notes

note Note
studied byStudied by 101 people
Updated ... ago
5.0 Stars(2)
note Note
studied byStudied by 13 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 9 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 3 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 47 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 5 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 33 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 61 people
Updated ... ago
5.0 Stars(2)

Explore top flashcards

flashcards Flashcard27 terms
studied byStudied by 35 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard35 terms
studied byStudied by 124 people
Updated ... ago
5.0 Stars(6)
flashcards Flashcard44 terms
studied byStudied by 33 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard61 terms
studied byStudied by 32 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard59 terms
studied byStudied by 117 people
Updated ... ago
5.0 Stars(4)
flashcards Flashcard39 terms
studied byStudied by 5 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard48 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard52 terms
studied byStudied by 413 people
Updated ... ago
5.0 Stars(2)