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1st yr-Med 2022-2023 > BMC L1 > Flashcards

BMC L1 Flashcards

1
Q

Functions of Nervous System

A

Sensory input: Recieves / gathers info

Intergration: Nervous system processes recieved sensory info + decides what to do at each specific moment

Motor output: Nervous system activates effector organ to produce response

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2
Q

What problems could arrise if the nervous system started to function incorrectly?

A

Disease

Injuries

Develpment problems

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3
Q

Central Nervous System

A

Brain + Spinal Cord
Conctrol centre - computes + controls info
Intergration
Protected by BBB - Blood Brain Barrier
Brain is housed in + protected by cranial cavity
Spinal cord is protected by vertebrae
Choroid plexus: ventricles which produce CSF
Meninges: enclose on both sides of brain + spinal cord

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4
Q

Peripheral Nervous System

A

Nervous system that is not part of CNS. Nervous systen outside of CNS. All the nerves + ganglia outside of aCNS

Consists of spinal nerves + cranial nerves
Spinal nerves: carry impules from spinal cord
Cranial nerves carry impulses from brain

Allows communication between human body and CNS. Allows communication between organs + limbs and CNS

PNS not protected by BBB

PNS not protected by vertebrae / skull

PNS has two functional divisions:
-afferent division
-efferent division

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5
Q

Afferent / Sensory Division of PNS

A

Where nerve fibres (axons) which transmit impulses to froms sensory receptors to CNS.

Two types of these sensory receptors:

Somatic sensory fibres: transmit impulses from skin, skeletal muscles, joints

Visceral sensory fibres: transmit impulses from visceral organs to CNS

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6
Q

Effererent / Motor Division of PNS

A

Where nerve impulses transmit impulses from CNS to effector organs. This activates effectors to produce a response. For example, a muscle contracts or gland secretes hormone

Motor division of PNS also has two subdivisions:

Somatic Nervous Systsem

Autonomic Nervous System

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7
Q

Somatic Nervous System

A

Part of motor division of PNS that controls voluntary activity / movement (voluntary activity under conscious control)

Consists of somatic motor nerve fibres which send electrical impulses from CNS to skeletal muscles

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8
Q

Autonomic Nervous System

A

Part of motor division of PNS that controls involuntary activity / movement

Consists of visceral motor nerve fibres which regulate/control glands, smootg + cardiac muscle

The autonomic nervous system has two subdivisions:

Symathetic: Fight / Fright
Parasympathetic

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9
Q

Afferent

A

To carrry towards

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10
Q

Efferent

A

To carry away

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11
Q

Inputs

A

Travel from sensory recpetors to CNS via afferent nerves

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12
Q

Inputs

A

Travel from sensory recpetors to CNS via afferent nerves

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13
Q

Outputs

A

Travel from CNS to effectors via efferent nerves

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14
Q

Levels of organisation of Nervous System

A

DIAGRAM L1

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15
Q

Two types of cells which make up nervous tissue

A
  1. Glial cells / Neuglia: “Supporting cells”
    Surround delicate nerve cells + suppory them
  2. Neurones: Nerve cells which are excitable. This means that they can respond to stimuli by changing their membrane potentials. They can transmit electrical impulses
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16
Q

What are the two key neurotransmitters in the PNS?

A
  1. Noradrenaline
  2. Acetylcholine
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17
Q

What are the 2 types of tisssue that make up nervous system?

A
  1. Connective tissue
  2. Blood vessels
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18
Q

Describe the structure of a neurone

A
  1. Dendrites
  2. Axon
  3. Cell Body
  4. Nucleus
  5. Nucleolus
  6. Nissl Bodies
  7. Axon Hillock
  8. Axon Terminal
  9. Neurilemma
  10. Schwann Cell / One internode
  11. Node of Ranvier
  12. Terminal Branches
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19
Q

Function of dendrites

A

Dendrites recieve incoming signals/electrical impulses + carry them towards cell body. They are the receptive + input region.

Dendrites also increase the surface area for recieving incoming signals because there are many of them

20
Q

Function of axons

A

Axons generate + transmit signals/electrical impulses + carry them away from cell body

21
Q

Structure of dendrite

A

They are rough - due to dendritic spines
Can have ribosomes
Cannot have myelin
There are many dendrite
Branch near cell body

22
Q

Structure of axons

A

They are smooth as no dendritic spines
No ribosomes
Can be myelintated
One axon
Branch further from cell body

23
Q

Function of terminal branching

A

Forms junctions with other nerve cells

24
Q

CNS vs PNS terminology

A

Nuclues: Bundle of neurones in CNS
Ganglion: Bundle of neurones in PNS
Tract: Bundle of axons in CNS
Nerve: Bundle of axons in PNS

25
Q

Soma

A

Soma is nerve cell body
Consists of prominent nucleulus and nissl bodies

26
Q

Organelles

A
  1. Cytosol: K+ reach solution inside cell, conataining enzymes for metabolism
  2. Nucleus: DNA maintence, RNA transcription, control of cell activities
  3. Nucleolus: Production of pre-ribosome
  4. Polyribosomes: Lots of free ribosomes attached to one strand of mRNA which produce multiple copies of same protein
  5. Mitochondria:
    Production of energt from glucose substances. Also release adenosine triphosphate
  6. Golgi Apparatus:
    Processing, packaging, sorting + modifications of proteins
  7. Rough ER:
    Translation + folding of new proteins
  8. Nissl bodies: Granules of rough ER. Unique to neurones. Have free ribosomes attached. Site of protein synthesis
27
Q

Functional Classification of neurons

A

Classing neurons based on the direction they transmit electrical impulses relative to CNS

28
Q

Sensory Neurones

A

Carry electrical impulses from sensory receptors to CNS

Soma not in CNS

Example of sensory receptors: Pressure receptors, pain recpetors, proprioreceptors

29
Q

Motor Nuerones

A

Carry electrical impulses from CNS to effector organs

Soma in CNS

Somatic motor neurone involved in locomotion

Effector organs produce a response to stimulus when activated + include muscle + glands

30
Q

Interneurones

A

Carry electrical impulses from sensory neurones to motor neurones

Full cell body in CNS

31
Q

Sensory Neurone Structure

A
  1. Long dendrites, short axon
  2. Dendrite + cell body not in spinal cord but in dorsal root ganglia
32
Q

Internuerone Structure

A
  1. Short dendrite, long/short axon
  2. Full cell body in CNS
33
Q

Structural classifications of neurones

A

Neurones classified based on how many processes extend from the central body

34
Q

Multipolar Neurones

A

Multiple processes
Many dendrites
One axon

Most common in humans
Allows for multiple connections
Mostly interneurones, some motor neurones

35
Q

Bipolar Neurones

A

2 processes
Many dendrites
One axon

FUSED DENDRITES, DENDRITES FUSED WITH ACTIONS
RARE IN HUMANS
FOUND IN SENSORY ORGANS (SMELL, EYES, EARS, TASTE)

Most do not generate action potentials, those that do do not have a universal trigger point

All sensory neurones

36
Q

Unipolar Neurones

A

1 Process
No denrites
One axon

Found in PNS, dorsal root ganglia, cranial nerve ganglia

1 SHORT SMALL PROCESS WITH 2 BRANCHES

BRANCH 1: Peripheral branch: Peripheral process (usually associated with sensory receptors)

Branch 2: Central Branch - Central process, branches into CNS

Mostly sensory neurones, some interneurones

37
Q

3 Regions of Neurone

A
  1. Receptive region: recieves signal
  2. Conductive region: Transmits electrical impulse/signal
  3. Secretory region: secretes neurotransmitters
38
Q

Neuroglia / Glial Cells

A

Supporting cells
6 types, 4 in CNS, 2 in PNS

39
Q

Ependymal cells

A
  1. Found in chloroid plexi of ventricles
  2. Line the cerebospinal fluid-filled cavities
  3. Filter blood to produce CSF
  4. Seperate interstital fluid of fluid filled cavities
  5. Similar to epithelial cells, can have different shapes, can be squammus or columnar
  6. Can be cilliated
40
Q

Oligodendrocytes

A
  1. Have processes which form myelin sheath around CNS nerve fibres
  2. Myelin sheath insulates neurone axons
  3. Oligodendrocytes have fewer processes than astrocytes
41
Q

Astrocytes

A
  1. Most abundant glial cells in CNS
  2. Surround neurones, synaptic endings + capillaries

Function:

  1. Provide mechanical support
  2. Maintain neuronal spacing
  3. Guide migration of new neurones
  4. Control micro-chemical environment of brain
  5. Alter permeability of capillaries for ions

NOT BBB - Blood Brain Barrier - formed by tight junctions between epithelial cells of capillaries and basal membrane of capillary

42
Q

Satellite cells

A
  1. Surround neurone cell bodies in PNS
  2. Functional equivalent of astrocytes in PNS
43
Q

Schwann Cells

A
  1. Functional equivalent of oligodendrocytes in PNS
  2. Tightly wrap around neurones in PNS, and around the thicker neurones, they form myelin sheath
  3. One schwann cell = one internode
  4. Gaps between myelin sheath - nodes of ranvier, sites of ion exhange
  5. Schwann cells allow recognition of damaged nerve cells
44
Q

Microglia

A
  1. Defensive cells in CNS
  2. Similar to macrophages
  3. Travel to injured neurones
  4. Phagocytises neuronal debris, microorganisms

This protection provided by microglia is very important as the immune system has limited access to the CNS

45
Q

Myelin

A
  1. Fatty white substance which surrounds axons
  2. 70% lipid, 30% protein
  3. 30% protein is myelin basic protein (MBP)
  4. Myelinated axons are white, hence “white matter” in brain

Myelin surrounds long + large diameter axons:

  1. Protects
  2. Insulates
  3. Increases speed of signal
46
Q

How do schwann cells form myelin sheath/ myelinate axon?

A
  1. Schwann cell ENVOLOPES axon
  2. Schwann cell then ROTATES around axon
  3. Plasma membrane of schwann cell then LOOSELY wrap around axon in succesive layers
  4. Cytoplasm of schwann cell forced between the two membranes
  5. These membranes wrapping tightly around axon forms myelin sheath

1st yr-Med 2022-2023 (57 decks)

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