The Nervous System Flashcards

1
Q

What are the functions of the nervous system?

A

Sensory- input- gathering information to monitor changes (stimuli) occurring inside and outside the body
Integration to process and interpret sensory input and decide if action is needed
Motor- response- initiate action (voluntary and/or involuntary)

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2
Q

What does the nervous system do?

A

Regulates and controls all body activity. It works with the endocrine system to maintain homeostasis

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3
Q

What are the two types of nervous system?

A

Central Nervous System (CNS)- brain and spinal cord

Peripheral Nervous System (PNS)- all nerves outside the CNS

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4
Q

What is a nerve?

A

A bundle of hundreds to thousands of axons associated with connective tissue and blood vessels
Each nerve has sensory (afferent) and motor (efferent) fibres (neurones)
Each nerve serves a specific region of the body

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5
Q

What is a neurone?

A

A single nerve cell
Specialised cells to transmit messages
Major regions of neurones
Cell body- nucleus and metabolic centre of the cell
Processes outside the body- fibres that extend from the cell body (axons and dendrites)
Axons conduct impulses (electrical transmission) away from the cell body
Dendrites conduct impulses towards the cell body

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6
Q

Describe the structure of Neurones

A

Cell body- containing nucleus and organelles
Axons end in axon terminals
Axon terminals contain vesicles containing neurotransmitters
Axon terminals are separated from the next neurone/cell by a gap called the synapse (junction between nerves)
Schwann cells cover some axons (myelinated neurones)
Between Schwann cells are gaps- nodes of Ranvier (NoR)

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7
Q

What is an action potential?

A

An electrical signal that is transmitted along the axon. The action potential hops from 1 NoR to the next

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8
Q

Where are neurotransmitters made?

A

Made in the cell body but stored in the axon terminals

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9
Q

How do neurones communicate with other cells?

A

Chemically:
Chemical messengers known as neurotransmitters are stored in the ‘axon terminals’
When stimulated by an action potential, neurotransmitters are released into the synapse
They diffuse across the synapse then attach to a receptor on the adjacent cell (post synaptic cell)
They then either stimulate or inhibit the post synaptic cell

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10
Q

Describe the features of motor neurones

A

Have cell body at one end and lots of processes (dendrites and axon) leaving the cell body (multi-polar)
They carry impulse from CNS to peripheral (to effectors)

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11
Q

Describe the features of sensory neurones

A

Have cell body on axon, only one process leaving the cell body (axon)
Carry impulse from peripheral to CNS. e.g. information about pain and temperature

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12
Q

What are receptors?

A

Usually proteins to which chemical messengers such as neurotransmitters bind to on the surface of the ‘target’ cell (cell they want to affect)
Once the chemical has bound it can change activity within the cell

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13
Q

Describe the effect of the neurotransmitter noradrenaline

A

Noradrenaline is a neurotransmitter released by the sympathetic nervous system that can bind to the SA node, causing an increase in heart rate

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14
Q

What are neuroglia?

A

Support cells within the CNS
Support, insulate, nourish and protect neurones, also form the ‘blood brain barrier’
For example, Schwann cells which form the myelin sheath in the PNS

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15
Q

Describe the features of the CNS

A

The brain (containing millions of neurons) and the spinal cord (neurones convey impulses towards and away from the brain)
The CNS is protected by the skull (brain) and vertebral column (spinal cord)
Also has a covering of connective tissue which protects and supports

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16
Q

What are the meninges?

A

Three connective tissue membranes that cover and protect the CNS

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17
Q

What are the three layers of the meninges?

A
Dura Mater (double-layered external covering: tough connective tissue)
Arachnoid Layer (middle layer, web-like)
Pia Mater (internal layer, clings to surface of brain)
18
Q

What is cerebrospinal fluid?

A

Fluid that circulates within the brain and around the outside of the brain and spinal cord. Similar to plasma in appearance

19
Q

Where is CSF formed?

A

In the brains ‘ventricles.’ It flows around the surface of the brain and spinal cord in the subarachnoid space

20
Q

What is the function of CSF

A

Provides a watery cushion or shock absorber. It protects the brain and spinal cord from jolts

21
Q

What are the 4 main parts of the brain?

A

Brain stem- continuous with spinal cord and consists of medulla oblongata, pons and midbrain
Diencephalon- consists mainly of thalamus, hypothalamus and pineal gland
Cerebrum- bulk of the brain. On the surface is thin layer of grey matter and underneath is white matter
Cerebellum

22
Q

What protects the brain?

A

Cranium and cranial meninges

23
Q

What is the cortex (cerebrum) responsible for?

A

Higher order function, for example voluntary motor and sensory function, vision, processing language, planning and problem solving
There are also specific areas that deal with sensation (in the somatosensory cortex) Parts regulating movement have been similarly identified in the motor cortex

24
Q

What are the 4 lobes of the brain?

A

Frontal lobe- associated with reasoning, planning, parts of speech, voluntary movement, emotions and problem solving
Parietal lobe- associated with movement, orientation, recognition, perception of stimuli
Occipital Lobe- associated with visual processing
Temporal Lobe- associated with perception and recognition of auditory stimuli, memory and speech
The lobes of the brain are names after the part of the skull that covers these lobes

25
Q

What is the function of the thalamus?

A

The relay station for sensory impulses

Transfers impulses to the correct part of the cortex for localisation and interpretation

26
Q

What is the function of the hypothalamus?

A

Important autonomic nervous system center
Important regulator of hormones of pituitary gland
-Helps regulate body temperature
-Controls water balance
-Regulates metabolism

27
Q

What does the brain stem attach to?

A

Spinal cord

28
Q

What are the parts of the brain stem?

A

Midbrain
Pons
Medulla oblongata

29
Q

What does the medulla oblongata regulate?

A
Heart rate
Blood pressure
Breathing
Swallowing
Vomiting
30
Q

Describe the features of the PNS

A

Consists of cranial nerves and their branches, spinal nerves and their branches, ganglia and sensory receptors
12 Cranial nerves come out from the base of the brain
Thirty-one pairs of spinal nerves exit from the spinal cord (one each side of spinal cord)

31
Q

What is the ganglia (PNS)?

A

A small mass of nervous tissue outside the brain and spinal cord (actually contain cell bodies of neurones)

32
Q

What are sensory receptors (PNS)?

A

Dendrites of sensory neurones that monitor change in the internal or external environment

33
Q

What happens in the sensory pathway (Afferent)?

A
Sensory receptors (end of sensory neurones) detect many different types of stimuli within and outside the body
The sensory neurone carries the impulse (message) to the CNS
The neurones (nerve cells) that carry this sensory information to the CNS are called sensory or afferent neurones
34
Q

What happens in the Central Nervous System (control centre)

A

The CNS integrates (processes) sensory information by analysing and storing some of it. It is the source of thoughts, emotions and memories. Decisions are made for an appropriate response that is done via the motor pathway

35
Q

What happens in the motor pathway?

A

A response is made via motor or efferent neurones. Motor neurones carry information from the brain and spinal cord to body (effectors). The cells and organs such as skeletal muscle fibres and cells in glands that respond to motor neurones are collectively called effectors

36
Q

Describe the reflex arc

A

The most basic and primitive response is called a reflex arc

  • A sensory neurone detects a stimulus
  • This activates a motor neurone at the spinal cord level (the brain is not involved)
  • The motor neurone stimulates an effector such as a muscle or gland
37
Q

What is the organisation of the peripheral nervous system?

A

Peripheral nervous system consists of:
Somatic and autonomic nervous system
Autonomic nervous system has two branches:
Sympathetic and parasympathetic

38
Q

What does the somatic nervous system consist of?

A

Sensory neurones that carry information to the CNS from head, body wall and limbs and from receptors for special senses such as vision, hearing, taste and smell to CNS
-Motor neurones that conduct impulses from the CNS to skeletal muscles only (these motor responses are voluntary (can be consciously controlled)

39
Q

What does the autonomic nervous system consist of?

A
  • Sensory neurones carry information from autonomic sensory receptors located in visceral organs such as the stomach and lungs to the CNS
  • Motor neurones conduct nerve impulses from the CNS to the smooth muscle, cardiac muscle and glands. These motor responses are involuntary (not under conscious control.) These motor parts of the ANS has 2 divisions- sympathetic and parasympathetic divisions
40
Q

What is the effect of the sympathetic system on the body?

A

Helps support exercise or emergency situations- ‘fight or flight’

  • Dilates pupils
  • No effect on tear glands
  • Inhibits saliva production
  • Dilates bronchi
  • Speeds up heart rate
  • Increases blood pressure
  • Inhibits peristalsis
  • Stimulates glucose production
  • Inhibits urination
  • Vasoconstriction
41
Q

What is the effect of the parasympathetic system on the body?

A

Opposite of sympathetic. Helps ‘rest and digest’

  • Constricts pupils
  • Stimulates tear secretion
  • Stimulates saliva production
  • Constricts bronchi
  • Slows down heart rate
  • No effect on blood pressure
  • Stimulates peristalsis
  • Stimulates bile production
  • Stimulates urination
42
Q

Describe the stress response

A

Any stress, psychological or physiological, will trigger the stress response (SAM system)
The stress response (fight or flight) is initiated by the sympathetic nervous system (SNS) which also stimulates the adrenal medulla. The adrenal medulla releases the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine) into the blood. These hormones prolong and intensify effects of the SNS