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Physiology > The nervous system > Flashcards

The nervous system Flashcards

1
Q

what does the NS do?

A

detects and responds to changes inside and out of the body.

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2
Q

NS and endocrine system

A

these both work together but in different ways;

  • NS provides an immediate response
  • endocrine system provides a slower more prolonged response
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3
Q

NS components

A

CNS;
-consists of the brain & spinal cord
detecting changes

Peripheral (PNS);
-consists of all nerves outside the brain and spinal cord

Nerves;
-lots of ‘strands’ will run down and throughout the rest of the body

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4
Q

function of NS & examples

A

communication & control, e.g.

  • controlling the size of your pupils depending on exposure to light
  • coordination and balance
  • applying pressure in different ways, e.g. holding a syringe, applying pressure and using your eyes to decide where to insert it
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5
Q

two main types of cells in the NS;

A 
nerve cells (neurones);
-carry out the function of communication and control
glial cells (supporting cells);
-despite various types, glial cells support neurones to function and therefore support the NS
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6
Q

nerve cell structure;

A

Cell body;
-a ball-shaped structure where the organelles are found

Dendrites;
-shot, very thin and highly branched extensions sticking out from the cell body .receptors are found here

Axon;
-singularly sticks out from the cell body and is a long, thin extension. they are very long, measurable from the the top of the spine to the bottom the leg

Initial segment;
-part of the axon where it leaves the cell body

Terminal Buttons;
-similar to how the initial segment is at one end of the axon, this structure is found at the other end of the axon and splits the axon into branches. at the end of each of these new branches are tiny, swollen structures called terminal buttons.

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7
Q

how to nerve cells communicate/do their job?

A

1- the tigger point for nerve cell action is in the initial segment. when a neurone is activated, an electrical impulse is triggered at this stricture and when this happens, that electrical impulse is transmitted down the length of the axon.

2- each section of the axon electrically triggers the next, until it reaches the full length of the axon and into the axon branches at the very end. the electrical impulse (message) stays the same throughout its journey.

3- when the electrical impulse reaches the end of the axon branches, it causes the chemicals within the terminal buttons to release them.

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8
Q

what is an action potential?

A

the electrical impulse

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9
Q

what is a myelinated axon/ what is myelin made of?

A

some nerve cells have myelinated axons. this is where these structures have areas covered in broney-yellow stuff, a lipid material (fatty substance) and this insulates the axon.

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10
Q

what is myeline made from and how do they work?

A
  • myeline is made from a type of glial cell called a Shwann cell.
  • these cells grab hold of sections of the axon and wrap themselves around it many times.
  • these cells are only found in the PNS, as a different type of glial cell does a similar job.
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11
Q

name for gaps in myelinated axons?

A

nodes of Ranvier, which are important for the process of electrical transmission.

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12
Q

what affect do myelinated sheaths have on electrical transmissions?

A

the electrical signals that travel down the axon skip over the section of myelin due to their coverage and therefore from node to node (gap to gap). - this causes the electrical transmission to occur faster and onto the next nerve cell, meaning the outcome intended is faster also.

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13
Q

difference of outcomes between myelinated and non-myelinated axons

A

Myelinated;
- an immediate sensation, e.g. after putting your foot in a bath and suddenly pulling it back due to sudden pain (first pain message)

Non-myelinated;
-sensations that take a few seconds to feel, e.g. dull pain that follows immediate pain as the message/electrical pulse arrives slower

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14
Q

terminal buttons

A

when the electrical impulse reaches the end of the axon branches, it causes the chemicals within the terminal buttons to release them.

inside terminal buttons are lots of ‘peas’ called synaptic vesicles which contain neurotransmitter chemicals.

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15
Q

what are synaptic vesicles?

A

also known as ‘peas’ within terminal buttons which act as tiny storage packets that contain lots of neurotransmitter molecules.

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16
Q

what is the synaptic gap?

A

a tiny gap between the nerve cell releasing the chemical message and the next cell picking up/receiving the chemical message. - this gap is filled with fluid (ECF).

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17
Q

what is a synapse?

A

this term defines the point of chemical communication between two nerve cells.

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18
Q

what is synaptic transmission?

A

1- once the electrical impulse reaches the terminal buttons, it causes the synaptic vesicles to ‘spill out’ their contents (neurotransmitters) into the synaptic gap

2- the neurotransmitters then spread through the fluid in the gap and attach to the receptors on the surface of the dendrite (passing on the message)

3- this message then activates the next nerve cell, causing an electrical impulse to be triggered in this nerve cells initial segment, causing an action potential to then travel down its axon and the same process occurs

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19
Q

what is the PNS?

A

all the nervous tissue that lies outside the CNS.

all the nerves that carry messages out to the body

control our movement

carry messages from the body, e.g. about touch.

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20
Q

nerve notes;

A
  • a nerve is a bundle of axons running together outside the CNS
  • the axon is the thin, long extension of the nerve cell that carries the electrical signal
  • when axons travel out to the body or in from the body, are grouped together into nerves
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21
Q

what are bundles of axons called in the PNS and the CNS?

A

CNS; tracts

PNS; nerves

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22
Q

what is the somatic NS?

A

this system consists of nerves that control conscious, voluntary processes we have direct control over, e.g. moving body parts, dancing, typing, etc.

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23
Q

what muscle produces voluntary movements?

A

skeletal muscle (because it is attached to the skeleton)

skeletal muscle cells are long, thin and have a striped appearance. they are sometimes referred to as skeletal muscle fibres, which are interchangeable terms for the same thing.

24
Q

what are motor neurones?

A

any nerve cell that controls movement. its branches (axons) ‘connects’/meets a cell within skeletal muscle and when the motor neurone has been chemically activated (electrical impulse running down its axon), the impulse will therefore cause the muscle’s cells to contract due to the nerve cell and muscle cells connection via its terminal buttons.

neuromuscular junction takes place.

25
Q

name for communication between a motor neurone and a muscle (it’s cells) ?

A

neuromuscular junction (its specific name for a synapse)

26
Q

name of the neurotransmitter released during neuromuscular junction?

A

acetylcholine (ACh). this is what is spilled during neuromuscular junction and once it attaches to the muscle’s dendrite’s surface receptors, causing the movement.

27
Q

what enzyme breaks down ACh and what effect does this have?

A

the enzyme cholinesterase chemically breaks down ACh once it has been used (the movement of the muscle has been carried out), causing it to deactivate.

28
Q

what is the autonomic NS & examples

A

the nerves that belong to the other part of the PNS. these nerves control unconscious processes, involuntary that we have no control over and often have no idea are taking place.

E.g. digestive system, respiratory system, metabolism, urination, etc.

29
Q

examples of what the autonomic NS controls;

A

cardiac muscle
-we cannot directly change our heart rate because the heartbeat is an involuntary process.

smooth muscle
-this is found in the walls of the intestine and blood vessel walls, which allows for contraction and dilation, speed of blood flow and pushing food along

release of substances from glands
-the adrenal glands, which sit on top of each kidney and the sweat glands are controlled by this system, automatically controlling their release of their secretions

30
Q

autonomic subdivisions;

A

sympathetic NS;

  • nerves of this system are involved in processes that use up energy, burn energy, and prepare the body for reaction
  • this system increases BP and heart rate
  • ‘fight or flight’ response

parasympathetic NS;

  • nerves of this system are involved in processes that save energy, build-up the storage of energy and slow the body down
  • reduces BP and heart rate

these systems also differ by releasing different neurotransmitter chemicals

31
Q

autonomic NS subdivisions and the neurotransmitters they release;

A

para
- nerve cells release neurotransmitter ACh to communicate with their target tissue (the same used by motor neurones to communicate with muscle cells)

symp

  • nerve cells release noradrenaline (NA) to communicate with their target tissues.
  • symp nerve cells release ACh when communicating with adrenal glands, which makes them secrete the hormones ACh and Adr (adrenaline).
32
Q

which system of the autonomic subdivisions has more widespread effects?

A

the sympathetic NS has more widespread effects than the para, due to its involvement with the release of hormones.

33
Q

three protective elements of the CNS?

A

skull
-the brain sits inside this bone and it therefore protects its soft tissue

spinal column (stack of vertebrae)
-this is what the spine lies within

Meninges
-three layers of protective tissue that wrap around both the brain and spinal cord

34
Q

layers of meninges

A

In order;

  • Skull
  • Dura Mater; tough layer stuck to the base of the skull
  • Arachnoid Mater; full of blood vessels
  • Sub-Arachnoid
  • Pia Mater; stuck to the surface of the brain and spinal cord
35
Q

sub-arachnoid notes;

A
  • a space filled with the cerebrospinal fluid (CSF), this layer/fluid surrounds the brain & spinal cord
  • meaning this layer acts as a cushion, shock absorber and soaks up some impact of any blows to the head
36
Q

what are cerebral ventricles?

A

these are four structures, all connected and found within the chambers of the brain. they are connected to the subarachnoid space and produce/store CSF which circulates through these ventricles.

37
Q

what is the blood-brain barrier? how does it work?

A

a filter between the bloodstream and brain tissue. it only allows certain materials to cross from the blood into the brain.

glial cells called astrocytes wrap around capillaries in the brain and forma a layer around them. this stops substances from the surrounding bloodstream, including potentially harmful ones) from reaching the brain tissue.

38
Q

glial cells second name and role in the CNS?

A

glial cells are also known as astrocytes and they wrap around capillaries to form a blood-brain barrier.

39
Q

two main function of the spinal cord?

A
  • allows the brain to communicate with the body

* controls reflexes

40
Q

what are cranial nerves and their role?

A

cranial nerves are brain nerves and send messages to muscles in the head and anywhere above the neck

e.g. taste buds, tongue, etc.

41
Q

role of the spinal cord notes;

A
  • messages travel up and down the spinal cord; it is a communication pathway between the brain and rest of the body
  • if the brain wants to send messages anywhere below the neck down, it has send them through the spinal cord
  • spinal nerves take these messages from the brain to the relevant body part, likewise these nerves transport messages from the body, through spinal cord and to the brain
  • it is also a control centre for certain reflexes
42
Q

what are reflexes? and an example;

A

unplanned, unconscious sequence or action

withdrawal reflex

  • when you touch something too hot with your hand, the pain sends messages through nerves that go directly and solely to the spinal cord
  • the spinal cord sends a message directly back, causing the muscle in your arm to pull your hand away

the brain does not control this type of reflex because if it did, it would take too long to react.

43
Q

what is the brain stem?

A

a narrow area of brain tissue (like the stem of a flower) that lies at the base of the brain and connects the brain to the spinal cord (meaning the spinal cord continues on from the brain stem).

44
Q

what are function of the brain stem?

A

the brainstem is involved in controlling processes essential to life.

  • the brain stem contains life-support centres which keep us alive
  • regulates heart rate, BP and respiration
45
Q

what is the cerebellum and its main function?

A

located behind the brainstem and means ‘little brain’, due to its similar structure to the brain itself.

main function- motor coordination. when the brain sends a message to a muscle to move, on its initial journey from the brain, the message detours to the cerebellum to coordinate and smooth out the desired message/movement.

alcohol can affect coordination abilities, as can cerebellum damage.

46
Q

what is the cerebrum and its functions?

A

the biggest part of the brain, making up 70% of the total organ. it has two halves; left & right hemisphere which look similar and have groves on their surfaces.

functions;

  • motor control
  • sensory processing
  • language
  • memory
  • emotion
  • personality
47
Q

what is the hypothalamus? and its functions;

A
  • a tiny structure deep inside the brain
  • it contains the thirst and hunger centres; nerve cells that trigger these sensations
  • regulates and controls body temperature
  • an endocrine centre; helping with regulating hormone release
48
Q

what is the amyglada and its functions?

A

an almond-shaped structure deep within the brain that is concerned with emotion.

  • responsible for generating an appropriate emotional response to your situation
  • responsible for your ability to recognise emotions in others
49
Q

what is the hippocampus?

A

this structure is found deep within the brain and is involved with memory. the name also means sea-horse, due to its similarity in shape.

Taxi Drivers are used to understand this structure, as they have to retain a lot of information to do their job. Brain scans found that they had bigger than usual hippocampus than non-taxi drivers and those who had been in the profession for longer had even bigger ones.

50
Q

cerebral cortex points;

A

very thin, about 2-2.5mm in thickness

jam-packed with nerve cells

you can divide the cortex of each hemisphere into four sections (lobes)

51
Q

what are the four lobes of the brain?

A

frontal lobe (at the front)

parietal lobe (at the top, towards the back)

temporal lobe (at the side)

occipital lobe (at the back)

52
Q

frontal lobe function

A

motor area is located in this lobe, therefore this lobe controls motor functions (movements).

it controls movement on the opposite side of the body, meaning that if someone had a stroke on the left side of their body, they’d experience the effects on the right side and vice versa.

53
Q

parietal lobe

A

somatosensory area of the brain is located here, meaning this lobe is concerned with body sensations. it analyses touch messages but from the opposite side of the body, similar to that of the motor area.

54
Q

temporal lobe

A

the auditory area is located here and this part receives messages from the ears

55
Q

occipital lobe

A

this is the visual area, that receives messages from the eyes

56
Q

two areas only typically found in the left hemisphere of the brain?

A

broca’s area;

  • located in the frontal lobe
  • named after the scientist who identified it
  • responsive for motor control of speech; lip and mouth movement necessary to produce spoken language

wernicke’s area;

  • located nearer back of the brain, half in temporal, half in parietal
  • named after the discover
  • responsible for understanding meaning of language
57
Q

what is the prefrontal lobe?

A

the most mysterious area of the brain, as its so complicated.

located at the front of the brain, right before our forehead

plays a role in our personality, how we interact with one another and how we behaviour in social contexts

prefrontal lobotomies caused a lot of damage to this area.

Physiology (26 decks)

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