The nervous system

Question 1

Diagram to show structure of the nervous system

Answer 1

Question 2

function of the nervous system

Answer 2

detect and respond to changes inside and outside of the body

Question 3

two types of nervous tissue

Answer 3

neurones

neuroglia

Question 4

neurones function

Answer 4

to generate anf transmit nerve impulses

Question 5

what do neurones consist of?

Answer 5

Cell body and it’s processes: one axon and usually many dendrites

neurones are different structures depending on it’s function

Question 6

Structure of the different neurones

Answer 6

Question 7

what is an Action potential?

Answer 7

electrical impulse transmitted by neurons

Question 8

what stimilis can action potentials be initiated in response from?

Answer 8

outside the body - eg. touch, light waves

inside the body - eg. change in the concentration of CO2 in the blood alters respirationm, a thought may result in voluntary movement

Question 9

Relay neurones

Answer 9

a neurone which recieves an action potential, passes it on or sometimes redirect it. (short axon). only found in CNS.

Question 10

interneurons

Answer 10

Carry electrical impulse from sensory neuron to motor neuron. only found in CNS.

Question 11

why do neurons need a continuous supply of oxygen and glucose?

Answer 11

as they can’t divide. unlike many other cells, neurons can normally synethise chemical energy (ATP) only from glucose.

Question 12

Cell bodies

Answer 12

form the grey matter of the nervous system. found in the periphery of the brain and in the centre of the spinal cord. Group of cell bodies are called the nuclei in the CNS and ganglia in the PNS.

Question 13

Axon and dendrites

Answer 13

extensions of cell bodies and form the white matter of the nervous system. axons are found deep within the brain and in groups, called tracts, at the periphery of the spinal cord. They are referred to as nerves or nerve fibres outside the brain and spinal cord.

Question 14

Axon

Answer 14

carry impulses away from the cell body and are usually much longer than the dendrites.

Question 15

multipolar neuron

Answer 15

a type of neuron that possesses a single axon and many dendrites (and dendritic branches). the most common type of neuron. They are located in the central nervous system (brain and spinal cord) and in autonomic ganglia.

Question 16

bipolar neuron

Answer 16

a neuron with only two extensions—an axon and a dendrite—that run from opposite sides of the cell body. Cells of this type are found primarily in the retina

Question 17

unipolar neuron

Answer 17

the simplest class of neurons that exhibit a single extension that gives rise to branches, some of which are receptive (dendrites). they are located within the skin, joints, muscles, and internal organs.

Question 18

schwann cell

Answer 18

nucleus of schwann cell is found on the axon of myelinated neurones. it produced myelin sheath.

Question 19

Dendrites

Answer 19

many short processes that recieve and carry incoming action potentials towards cell bodies.

in Motor Neurons they form part of the synapses

in sensory neurons they form the sensory receptors that respond to specific stimuli

Question 20

how does an Action potential travel through a neuron

Answer 20

There’s already a resting membrane potential between the outside (positive) and the inside of the neuron (negative). When the action potential enters the cell, it causes the sodium channels to open, which cause Na+ to enter the cell, which depolarises the cell. This causes the action potential to conduct along the axon. After the action potential is conducted along the axon K+ leaves the neurone to repolarise the cell and to restore the resting membrane potential.

Question 21

Travel of Action potential diagram

Answer 21

Question 22

Refractorary period

Answer 22

The neuron hyperpolarises to allow the neuron to restore membrane potential before allowing any other action potentials to be generated.

Question 23

Saltatory conduction

Answer 23

in myelated neurones where the movement of ions across the membrane can only occur at the nodes of ranvier (where there is no myelin sheath), which causes the conduction of the action potential to ‘jump’ along the axon, which is a quicker conduction compared to no mylenated neurons.

Question 24

Synapse process

Answer 24

the electrical action potential reaches the pre-synaptic bulb which causes the voltage gated calcium channels to open and allow ca2+ ion to enter. This causes vesicles containg chemical neurotransmitters to fuse with the membrane and leave the neuron and enter the synaptic cleft. via diffusion the neurotransmitters bind to receptors on the post-synaptic bulb and causes ligand gated sodium channels to open. this allows Na+ ions to enter the cell, causing the neuron to depolarise and generate an action potential.

Question 25

synapse diagram

Answer 25

Question 26

what are the three proctetive connective tissues?

Answer 26

Endoneurium Perineurium Epineurium

Question 27

diagram of the protective connective tissues

Answer 27

Question 28

Endoneurium

Answer 28

delicate tissue surrounding each individual fibre (chain of neuron)

Question 29

Perineurium

Answer 29

smooth connective tissue surrounding each bundle of fibres

Question 30

Epineurium

Answer 30

fibrous tissue surrounding and enclosing a number of bundle of nerve fibres. Most large nerves are covered by epineurium.

Question 31

sensory (afferent nerves) function

Answer 31

carry information from the body to the spinal cord.

Question 32

sensory receptors

Answer 32

specialised endings of sensory neurones respond to different stimili inside and outside the body

Question 33

Somatic, cutaneous or common senses

Answer 33

originate from the skin. pain touch heat and cold

Question 34

proprioreceptor senses

Answer 34

originate in the muscle and joints. they send information to the brain about the position of the body and it's parts in space, enabling maintenance of posture and balance.

Question 35

special senses

Answer 35

hight, hearing, balance, smell and taste

Question 36

autonomic afferent nerves

Answer 36

originate in internal organs, glands and tissues e.g. the baroreceptoes involved in the control of BP. and the chemoreceptors involved in the control of respiration and are associated with reflex regulation of involuntary activity and visceral pain.

Question 37

Motor / efferent nerves

Answer 37

originate in the brain, spinal cord and autonomic ganglia. they transmit impulses to the effector organs: muscles and glands.

Question 38

what are the two types of motor nerves?

Answer 38

somatic nerves - involved in volunatary and reflex skeletal muscle contraction autonomic nerves (sympathetic and parasympathetic) - involved in cardiac and smooth muscle contraction and glandular secretion, all involuntary functions.

Question 39

mixed nerves

Answer 39

this is where outside the spinal cord called sensory and motor nerves are enclosed within the same sheath of connective tissue, compared to in the spinal cord where they're enclose in separate tracts.

Question 40

Autonomic motor cells

Answer 40

sympathetic (adrenergic and cholinergic) and parasympathetic

Question 41

Sympathetic nervous system

Answer 41

fight or flight

Question 42

parasympathetic nervous system

Answer 42

rest and digest (involuntary)

Question 43

neuroglia

Answer 43

general term to describe the four glia cells. all can replicate throughout life.

Question 44

what are the 4 neuroglia cells?

Answer 44

Astrocytes oligodendrocytes ependymal cells microglia

Question 45

Astrocytes

Answer 45

most abudant neuroglia. Blood is separated from the neurones by the capillary wall and a layer of astrocyte foot processes which form together the blood brain barrier.

Question 46

blood brain barrier

Answer 46

a selective barrier that protects the brain from potentially toxic substances and chemical variations in the blood. eg. after a meal O2, C02, glucose and other lipid-soluble substances, such as alcohol quickly pass the barrier into the brain. some large molecules, many drugs, inorganic ions and amino acids pass more slowly or don't pass at all, from the blood to the brain.

Question 47

Oligodendrocytes

Answer 47

smaller than astrocytes. found in clusters round nerve cell bodies in grey matter and are located adjacent to and along the length of myelinated nerve fibres. They form and maintain myelin in the CNS and myelanate many cells at once, whereas schwann cells in the PNS can only myleanate one cell at a time.

Question 48

Ependymal cells

Answer 48

forms the epithelial lining of the ventricles of the brain and central canal of the spinal cord. they're part of the choroid plexuses. some also have cilia that assist the floe with the CSF.

Question 49

Microglia

Answer 49

least abundant glia cells. they are dispersed throughout the brain and migrate to become phagocytocytic, removing microbes and damaged tissue, in areas of inflammation and cell destruction.

Question 50

What can cause damage to neurones? (7)

Answer 50

hypoxia (lack of oxygen to tissue) and anoxia (no oxygen at all) nutritional deficiencies poisons e.g. organic lead trauma infections ageing hypoglycaemia (low blood glucose)

Question 51

what to astrocytes do when their cells are damaged?

Answer 51

Their processes multiple forming a mesh ('scar') around the damaged CNS neurones, inhibiting the regrowth of them

Question 52

what do oligodendrocytes do when they are damaged?

Answer 52

they increase in number round the degenerating neurones and are destroyed in demylinating diseases such as multiple sclerosis

Question 53

What do microglia do when they are damaged?

Answer 53

when there's inflammation and cell destruction, they are activted and migrate to site of damage, and become phagocytic. this occurs in diseases such as MS, alzheimers and strokes

Question 54

What makes up the central nervous system?

Answer 54

the brain and spinal cord

Question 55

what protects the CNS?

Answer 55

Skull - brain Vertebrae - spinal cord meninges - provide further protection for both

Question 56

Meninges

Answer 56

membrane covering consisting of three layers of tissue, lying between the skull and brain and between the verterbral foramina and the spinal cord to provide protection.

Question 57

three layers of the mininges

Answer 57

dura mater arachnoid mater pia mater

Question 58

the two spaces associated with the miniges in the brain

Answer 58

the subdural space the subarachnoid space

Question 59

the three spaces associated with the meninges in the spinal cord

Answer 59

the subdural space the subarachnoid space the epidural space (additional space in the spinal cord compared to brain)

Question 60

Dura matter

Answer 60

consists of 2 layers of fibrous tissue. at certain points of the brain the two layers have space inbetween them that has dural venous sinus that venous blood from the brain drains into.

Question 61

what are the two layers of the dura matter?

Answer 61

periosteum dura meningeal dura

Question 62

periosteum dura matter

Answer 62

outer layer of dura matter on the inner surface of the skull bones

Question 63

meningeal dura matter

Answer 63

inner layer of dura mater provides a protective covering of the brain.

Question 64

where does the two layers of dura matter connect after separating in the brain?

Answer 64

falx cerebri tentorium cerebelli

Question 65

what does the dura mater do?

Answer 65

provides protection of the brain and ensures all structures structures stay in place

Question 66

arachnoid mater

Answer 66

layer of fibrous tissue that protects the brain and spinal cord from sudden impact. it's lies between the dura matter (separated by the subdural space) and the pia mater (separated by subdural space, ehich contains cebrospinal fluid CSF). it accomanies the layers of the dura mater to create the falx cerebri and tentorium cerebeli.

Question 67

pia mater

Answer 67

the innermost layer of the meninges. It is a delicate layer of connective tissue containing many minute blood vessels.closely covers the brain. It acts as a barrier and aids in the production of cerebrospinal fluid.

Question 68

what are the four ventricles of the brain

Answer 68

right and left lateral ventricles third ventricle fourth ventricle they are all irrelegular-shaped cavities

Question 69

function of the brian ventricles

Answer 69

to produce and secrete cerebrospinal fluid to protect and maintain your central nervous system

Question 70

lateral ventricles

Answer 70

these cavities lie within the cerebral hemispheres, 1 each side of the median plane just below the corpus callosum. they are separated by a thin membrane called the septum lucidum and are lined with ciliated epithelium.

Question 71

interventricular foramina

Answer 71

opening between the lateral ventricles and the third ventricle, which allows cerebrospinal fluid to pass between them and communication to occur.

Question 72

third ventricle

Answer 72

a cavity situated below the lateral ventricles between the two parts of the thalamus. it communicates with the fouth ventricle by a canal called the cerebral aqueduct.

Question 73

The cerebral aqueduct

Answer 73

a channel that connects the third ventricle with the fourth ventricle and allows cerebrospinal fluid to pass between them.

Question 74

fourth ventricle

Answer 74

diamond shaped cavity located below and behind the third ventricle between the cerebellum and pons. it's continuous below the central canal of the spinal cord and communicates with the subarachnoid space by foramina in it's roof. CSF enters the subarachnoid through these opening.

Question 75

Diagram of the brains ventricles

Answer 75

Question 76

Cerebrospinal fluid

Answer 76

circulates constantly from the ventricles through the subarachnoid space around the brain and spinal cord. It is a clear, slightly alkaline fluid with a specific gravity of 1.005. continually produced and flowing. it consists of: water mineral salts]glucose plasma proteins (small amount of albumin and globulin) a few leukocytes small amounts of creatinine small amounts of urea

Question 77

CSF Functions

Answer 77

supports and protects the brain and spinal cord by maintaining a uniform pressure around these vital structures and by maintaining uniform pressure around these vital structures. acts as a cushion or shock absorber between the brain and the skull. keeps brain and spinal cord moist and is involved in regulation of breathing as it bathes the surface of the medulla.

Question 78

choroid plexuses

Answer 78

secretes CSF into each of the 4 brain ventricles. theses are vascular areas that are rich in blood vessels and surrounded by ependymal cells in the lining of the ventricle walls.

Question 79

What does CSF pass back into the blood through?

Answer 79

tiny finger-like projections of arachnoid mater, called arachnoid villi, which project into the venous sinuses.

Question 80

how is the movement of CSF from the subarachnoid space to venous sinuses controlled?

Answer 80

by difference in pressure each side of the walls of the arachnoid villi, which act as one way valves. when pressure of CSF is higher than the venous pressure , CSF is pushed into the blood and vice versa. when venous pressure is higher the arachnoid villi collapse, preventing the passage of blood constituents into the CSF. there may also be some reabsorption of CSF by cells in the walls of the ventricles.

Question 81

How does CSF flow from the roof of the fourth ventricle into the subarachnoid space?

Answer 81

CSF flows through foramina into the subarachnoid space and completely surrounds the brain and spinal cord. its movement is aided by pulsating blood vessels, respiration and changes of posture.

Question 82

parts of the brain (7)

Answer 82

cerebrum thalamus hypothalumus midbrain pons medulla oblongata cerebellum

Question 83

Diagram to show structure of the brain

Answer 83

Question 84

cerebrum

Answer 84

the uppermost part of the brain. It contains two hemispheres split by a central fissure. The cerebrum itself contains the major lobes of the brain and is responsible for receiving and giving meaning to information from the sense organs, as well as controlling the body. initiates and coordinates movement and regulates temperature. Other areas of the cerebrum enable speech, judgment, thinking and reasoning, problem-solving, emotions and learning. Other functions relate to vision, hearing, touch and other senses.

Question 85

cerebral cortex

Answer 85

the outermost layer of the brain that is associated with our highest mental capabilities. The cerebral cortex is primarily constructed of grey matter. is associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory

Question 86

diencephalon

Answer 86

connects the cerebrum and the midbrain.thalamus and hypothalamus are sitiuated here.

Question 87

thalamus

Answer 87

mostly gray matter structure of the diencephalon. The thalamus is composed of different nuclei that each serve a unique role, ranging from relaying sensory and motor signals, as well as regulation of consciousness and alertness.

Question 88

hypothalamus

Answer 88

controls your hormone system. It releases hormones to another part of your brain called the pituitary gland, which sends hormones out to your different organs

Question 89

mid brain

Answer 89

also called mesencephalon, region of the developing vertebrate brain that is composed of the tectum and tegmentum. The midbrain serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing.

Question 90

pons

Answer 90

part of a highway-like structure between the brain and the body known as the brainstem. The brainstem is made up of three sections, and carries vital information to the body. The pons relays information about motor function, sensation, eye movement, hearing, taste, and more

Question 91

medulla oblongata

Answer 91

lays a critical role in transmitting signals between the spinal cord and the higher parts of the brain and in controlling autonomic activities, such as heartbeat and respiration

Question 92

cerebellum

Answer 92

s important for making postural adjustments in order to maintain balance. Through its input from vestibular receptors and proprioceptors, it modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles.

Question 93

grey matter

Answer 93

serves to process information in the brain. The structures within the grey matter process signals from the sensory organs or from other areas of the grey matter. This tissue directs sensory stimuli to the neurons in the central nervous system where synapses induce a response to the stimuli.

Question 94

white matter

Answer 94

the tissue through which messages pass between different areas of grey matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons). functions in affecting learning and brain functions, modulating the distribution of action potential, and coordinating communication between the different brain regions

Question 95

grey matter and white matter in the spinal cord diagram

Answer 95

Question 96

Reflex arc

Answer 96

a neural pathway that controls a reflex. In vertebrates, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This allows for faster reflex actions to occur by activating spinal motor neurons without the delay of routing signals through the brain.