Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

YEAR 1 - Organisation of the Body (Anton) > 6. Excitable Cells: Neural Communication > Flashcards

6. Excitable Cells: Neural Communication Flashcards

1
Q

What are the two main nervous systems?

A
  • Central nervous system
  • Peripheral nervous system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What structures make up the CNS?

A
  • Brain
  • Spinal cord
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What structures make up the PNS?

A

All neuronal elements outside the brain and sponal cord:

  • Cranial and spinal nerves -> Made of sensory and motor nerves
  • Associated ganglia
  • Supporting cells (e.g. Schwann cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Are sensory peripheral nerves divided into autonomic/somatic, parasympathetic/sympathetic, etc.?

A

They are sometimes divided into somatic and visceral afferent fibres, but CHECK THIS.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Draw a diagram to show the divisions of the nervous system.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the embryological origin of the central and peripheral nervous systems?

A
  • CNS -> Neural tube
  • PNS -> Neural crest
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the process by which peripheral nervous system cells develop (in terms of embryology).

A

They undergo:

  • Specification
  • Migration
  • Differentiation
  • Functional specification
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two divisions of the sensory division of the nervous system?

A
  • Somatic sensory
    • Consciously perceived
    • Touch, pain, hearing, etc.
  • Visceral sensory
    • Not consciously perceived
    • Stretch, chemical changes, taste, etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two types of peripheral neurons?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Draw the structure of a reflex arc.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are ganglia?

A

Egg-shaped structures containing cell bodies of neurons and glial cells supported by connective tissue.

i.e. It is where the cell bodies of neurons are.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are unipolar, bipolar and multipolar neurons? Where is each found?

A

This essentially refers to the number of processes (e.g. axons) that come out of the cell body:

  • Unipolar -> Sensory neurons with cell bodies in spinal and cranial nerve ganglia.
  • Bipolar neurons -> Relatively rare. They are sensory neurons found in olfactory epithelium, the retina of the eye, and ganglia of the vestibulocochlear nerve.
  • Multipolar neurons -> Most common. They are located in the central nervous system (brain and spinal cord) and in autonomic ganglia.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where do sensory neurons have ganglia?

A

Near the spinal cord -> These are called DORSAL ROOT GANGLIA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is found in dorsal root ganglia?

A

The cell bodies of sensory neurons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where do sensory neurons usually terminate?

A

At interneurons of the CNS.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are some different categories of sensory neuron receptors?

A
  • Thermoreceptors – Respond to changes in temperature
  • Photoreceptors – React to light
  • Chemoreceptors – Respond to chemicals
  • Mechanoceptors – Respond to pressure, touch vibrations
  • Nociceptors – Respond to pain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where are sensory receptors found?

A

They are found at the ends of sensory neurons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Give some examples of sensory nerve endings and what they detect. [IMPORTANT]

A
  • Meissner corpuscle -> Fine touch
  • Merkel disc -> Touch
  • Pacinian corpuscle -> Coarse touch, Pressure, Vibration
  • Free nerve endings -> Heat, Pain
  • Ruffini endings -> Stretch

Remember:

  • Meissner sounds smooth so it detects smooth touch, while Merkel sounds rough so it detects coarser touch
  • ViP STaR = Vibration is detected by Pacinian corpuscles, while Stretch and Temperature are detected by Ruffini endings
  • Free nerve endings detect heat and pain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What stimulus do Meissner corpuscles detect?

A

Fine touch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What stimulus do Pacinian corpuscles detect?

A

Coarse touch, Vibration, Pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What stimulus do free nerve endings detect?

A

Pain, Heat, Touch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What stimulus do Ruffini’s corpuscles detect?

A

Stretch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What stimulus do Merkel’s disks detect?

A

Touch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Draw the positions and appearance of different sensory nerve endings near the skin.

A

Remember: The two M’s are in the epidermis along with the free nerve endings, while the rest are in the dermis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is this?

A

Pacinian corpuscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is this?

A

Meissner’s corpuscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Compare the motor neurons of somatic and autonomic nervous systems.

A

Somatic motor neurons:

  • Single neuron network
  • Monosynaptic

Autonomic motor neurons:

  • Two neuron network
  • Disynaptic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Compare the neurotransmitters that the somatic, parasympathetic and sympathetic nervous systems use.

A
  • Somatic -> Acetylcholine
  • Parasympathetic -> Acetylcholine (at both synapses)
  • Sympathetic -> Acetylcholine (at ganglion) + Noradrenaline (at effector)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Name the different types of ganglia that the spec mentions. What is found in each?

A
  • Dorsal root ganglia (where sensory neuron cell bodies are)
  • Sympathetic (where postganglionic neuron cell bodies are)
  • Parasympathetic (where postganglionic neuron cell bodies are)
  • Enteric (where postganglionic neuron cell bodies are)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What parts of the body do the sympathetic, parasympathetic and enteric nervous systems provide motor supply to?

A

Sympathetic:

  • Muscles
  • Viscera
  • Cardiac and smooth muscle

Parasympathetic:

  • Viscera
  • Cardiac and smooth muscle
  • No musculo-skeletal supply

Enteric:

  • Intrinsic nervous system of gut
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the pre-ganglionic neurotransmitter?

A

Acetylcholine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Compare the general positions of ganglia in the somatic, parasympathetic and sympathetic nervous systems.

A
  • Somatic -> No ganglia
  • Parasympathetic -> Usually within (or near to) effector organs
  • Sympathetic -> Usually within discrete ganglia closer to the spinal cord (e.g. paravertebral ganglia)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

At what spinal levels do sympathetic and parasympathetic nerves arise from?

A
  • Parasympathetic -> Craniosacral
  • Sympathetic -> Tharcolumbar

Remember: PSP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Describe the different sympathetic ganglia. [IMPORTANT]

A

Paravertebral ganglia:

  • Two paravertebral ganglia run either side of the spinal cord -> Supply multiple organs
  • At the top of these are cervical ganglia -> Supply the head and thorax (heart and lungs)

Prevertebral (i.e. between the paravertebral ganglia and the target organs):

  • Coeliac ganglia -> Supply foregut
  • Superior mesenteric ganglia -> Supply midgut
  • Inferior mesenteric ganglia -> Supply pelvic organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the pre-ganglionic nerves that supply the coeliac, superior mesenteric and inferior mesenteric ganglia (sympathetic)? What body parts do these supply?

A
  • Coeliac ganglion -> Greater splanchnic nerve
    • Supplies the foregut
  • Superior mesenteric -> Lesser splanchnic nerve
    • Supplies the midgut
  • Inferior mesenteric -> Least splanchnic nerves
    • Supplies the pelvic organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are the different cervical ganglia and what do they supply? Is this sympathetic or parasympathetic?

A
  • Superior cervical ganglion -> Head
  • Middle cervical and stellate ganglia -> Heart and lungs

This is sympathetic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What do the sympathetic paravertebral chains allow?

A

They allow nerve fibres to travel to spinal nerves that are superior and inferior to the one in which they originated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Where do the cervical ganglia receive nerve fibres from?

A

They receive fibres from the paravertebral chain, since no nerve roots come from the cervical region.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What exact fibres modulate the enteric nervous system?

A
  • Pre-ganglionic parasympathetic fibres
    • Vagus nerve
    • Sacral fibres
  • Post-ganglionic sympathetic fibres
    • From prevertebral ganglia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What do sacral parasympathetic fibres supply?

A

Meissner’s and Auerbach’s plexus (enteric nervous system), as well as the lower gut and urogenital tract.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Draw the structure of the enteric nervous system.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the role of the enteric nervous system?

A

Coordinates the activities of the gut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are the three types of neuron in the plexuses of the gut wall?

A
  • Sensory
  • Motor
  • Secretomotor -> Induce a gland to secrete a substance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Describe the formation of the autonomic nervous system.

A
  • The peripheral nervous system is derived from the neural crest, which forms when the neural tube closes.
  • These then undergo migration and the time of migration determines the fate of the cells:
    • First cells -> Form the enteric nervous system.
    • Next -> Crest cells migrate through the somites to form the segmental paravertebral ganglia (sympathetic)
    • Finally -> Parasympathetic ganglia and prevertebral sympathetic ganglia form.
  • Pre-ganglionic fibres of the autonomic nervous system are CNS neurons that lie in the intermediate part of the spinal cord and are patterned by Shh signals from the notochord.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Why are the paravertebral chain ganglia arranged segmentally?

A
  • The neural crest migrates through the cranial half of each somite and forms the segmental sympathetic chain ganglia.
  • The caudal half of each somite contains inhibitory molecules that prevent neural crest migration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How is the enteric nervous system formed?

A

Neural crest cells arise from the cervical levels, invade the gut and then colonise the entire gut in a caudal direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is Hirschprung’s disease, what causes it and what are the symptoms?

A
  • Caused by failure of neural crest cells to invade (or survive in) the gut wall
  • This means that the enteric nervous system doesn’t develop fully
  • The symptoms include constipation and megacolon (swelling of the colon and lack of peristaltic movement)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What are the three points where pre-ganglionic nerve fibres terminate in the sympathetic nervous system?

A
  1. Some terminate in the ganglia
  2. Some reach the paravertebral ganglia, go up or down the chain, and then terminate at a different spinal level
  3. Some pass to pre-vertebral/midline ganglia via the splanchnic nerves (without synapsing at the paravertebral chain)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What are midline ganglia?

A

They are pre-vertebral ganglia (sympathetic). [CHECK THIS - DOES IT ACTUALLY MEAN PARAVERTEBRAL?]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What does the sympathetic and parasympathetic supply to the head come from?

A
  • Sympathetic -> From the superior cervical ganglion (at the top of the paravertebral chain)
  • Parasympathetic -> Cranial nerves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Are cranial nevres parasympathetic or sympathetic?

A

Parasympathetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What are the four cranial nerves you need to know about and what number are they?

A
  • III - Occulomotor
  • XII - Facial
  • IX - Glossopharyngeal
  • X - Vagus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Which cranial nerve is the occulomotor nerve and what does it supply?

A
  • III
  • Supplies the iris of the eye (via the ciliary ganglion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Which cranial nerve is the facial nerve and what does it supply?

A
  • VII
  • Supply lacrimal glands and nasal mucosa (via the pterygopalatine ganglion)
  • Supply salivary glands (via submandibular ganglion )
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Which cranial nerve is the glossopharyngeal nerve and what does it supply?

A
  • IX
  • Supplies parotid salivary gland (via the otic ganglion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Which cranial nerve is the vagus nerve and what does it supply?

A
  • X
  • Supplies the organs of the thorax and abdomen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Describe how peristalsis happens.

A
  • Food in gut causes mechanical release of serotonin
  • This stimulates cells in the submucosal plexus which in turn stimulate the myenteric plexus
  • This causes peristalsis to happen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Compare the structures at the effector-end of somatic and autonomic motor neurons.

A
  • Somatic motor neurons end in a synapse (motor end-plate)
  • Autonomic nerves end in varicosities, which are a series of enlargements where neurotransmitter is released onto the effector
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is the exception to the rule that sympathetic post-ganglionic nerves use noradrenaline?

A

Sweat glands receive cholinergic control.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Describe how the adrenal gland relates to the sympathetic nervous system.

A

It is stimulated by pre-ganglionic fibres (by ACh release) to release catecholamines into the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Which nerve innverates the adrenal gland?

A

Greater splanchnic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

How are cardiovascular effects of the sympathetic system coordinated?

A

By CNS control centres.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is Horner’s syndrome and what are the symptoms?

A
  • Caused by lesions of the superior cervical ganglion (that supplies the head)
  • Symptoms:
    • Permanent constriction of the pupil
    • Drooping eyelid (ptosis)
    • A dry face and flushed face
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

How can excessive sweating (hyperhidrosis) be treated?

A
  • Sympathetic chain can be cut to prevent sympathetic stimulation

OR

  • Region injected with Botulinum toxin.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Is crying a sympathetic or parasympathetic action?

A

Parasympathetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

For the heart, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Increased heart rate -> Beta 1 (and beta 2)
  • Increased force of contraction -> Beta 1 (and beta 2)
  • Increased conduction velocity

Parasympathetic:

  • Decreased heart rate
  • Decreased force of contraction
  • Decreased conduction velocity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

For arteries, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Constriction mostly (alpha 1)
  • Dilation of some (beta 2)

Parasympathetic:

  • Dilation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

For veins, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Constriction mostly (alpha 1)
  • Dilation of some (beta 2)

Parasympathetic: None

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

For lungs, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Bronchial muscle relaxation (beta 2)

Parasympathetic:

  • Bronchial muscle constriction
  • Increased bronchial gland secretions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

For the GI tract, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Decreased motility (beta 2)
  • Constriction of sphincters (alpha)

Parasympathetic:

  • Increased motility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

For the liver, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Glycogenolysis (beta 2 and alpha)
  • Gluconeogenesis (beta 2 and alpha)
  • Lipolysis (beta 2 and alpha)

Parasympathetic:

  • Glycogen synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

For the kidney, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Renin secretion (beta 2)

Parasympathetic: None

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

For the bladder, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Detrusor relaxation (beta 2)
  • Contraction of sphincter (alpha)

Parasympathetic: None

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

For the uterus, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Contraction of pregnant uterus (alpha)
  • Relaxation of pregnant and non-pregnant uterus (beta 2)

Parasympathetic: None

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

For the eye, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Dilates pupil (alpha)

Parasympathetic:

  • Constricts pupil
  • Increased lacrimal gland secretions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

For the salivary glands, what is the effect of sympathetic and parasympathetic stimulation? What receptors does the sympathetic nervous system act on?

A

Sympathetic:

  • Viscous salivary secretions (alpha)

Parasympathetic:

  • Watery salivary secretions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What are the major parts of a neuron?

A
  • Cell body
  • Axon
  • Dendrites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What is the difference between axons and dendrites?

A
  • Axon
    • Long process stretching from cell body
    • Responsible for transmitting signals from cell body
  • Dendrites
    • Short cell processes
    • Increase surface area for connecting with other axons and transmit signals to cell body

Remember: Axons Away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Describe the structural appearance of neuron cell bodies.

A
  • Large nucleus
  • Finely dispersed chromatin (indicative of a rich synthetic activity)
  • Abundant rough endoplasmic reticulum (RER) with ribosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What are these purple structures?

A

Nissi bodies -> They are the cell bodies of neurons after they have been stained purple with basic dye.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

What are axons specialised for?

A

Transmission of information away from the cell body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

What is the diameter and length of axons?

A
  • Microscopic in diameter (1μm – 1 mm)
  • Some may extend a meter or even longer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

What are dendritic spines?

A

Plastic structures in dendrites that are implicated in motivation, learning and memory.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

Describe the two types of polarity of neurons.

A
  • Structural
    • One domain specialised to receive incoming signals and the other for sending signals
  • Functional
    • Unidirectional impulse propagation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

What are the three types of cytoskeleton element in neurons and what does each do?

A
  • Microtubulules -> Transport
  • Neurofilaments (a type of intermediate filament) -> Maintain axonal structure
  • Microfilaments -> Allow changes in cell shape and act as scaffold for signal transduction systems
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What molecules make up microfilaments in neurons?

A

Actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What molecules make up microtubules in neurons?

A

Tubulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What maintains neuronal polarity?

A

Bidirectional transport along the axon, using microtubules as skeletal tracks.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What are the two directions of transport in neurons?

A
  • Anterograde -> Towards the tip of axons
  • Retrograde -> Back from the tip of axons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What mechanochemical enzymes allow anterograde and retrograde transport along axons?

A
  • Anterograde (towards the tip of axons) -> Kinesin
  • Retrograde (back from the tip of axons) -> Dynein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What things are transported in a anterograde and retrograde direction along axons?

A
  • Anterograde:
    • Organelles
    • Growth factors
    • Neurotransmitters
  • Retrograde:
    • Endocytosis products to endosomes in cell body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

What cells myelinate axons in the PNS and CNS?

A
  • PNS -> Schwann cells
  • CNS -> Oligodendrocytes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Describe how myelination of an axon by a Schwann cell occurs.

A
  • Numerous layers of a Schawnn cell are wrapped around an axon
  • Each turn forms a lamella of myelin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

What is a mesaxon?

A

A pair of parallel plasma membranes of a Schwann cell, marking the point of edge-to-edge contact by the Schwann cell encircling the axon.

i.e. It is the point where the layers of a Schawann cell wrapped around an axon touch.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

Do non-myelinated axons associate with Schwann cells?

A

Yes, they bury themselves in their cytoplasm (although the Schwann cells do not wrap around the axon like in myelinated axons).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

What do oligodendrocytes do?

A
  • Wrap myelin around several axons at once
  • Found in the CNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

What are some functions of myelin?

A
  • Provides support
  • Facilitates fast axonal conduction
  • Insulation
  • Reduction of electrical capacitance for axons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

What are the gaps between Schwann cells on an axon called?

A

Nodes of Ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

What is myelin made of?

A
  • Phospholipids (70%)
  • Proteins (30%)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

What are 3 protein-encoding genes that are involved in myelin production?

A
  • Protein zero (P0)
  • Myelin basic protein (MBP)
  • Proteolipid protein (PLP)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

How do autoimmune diseases affect the nervous system and what are the symptoms?

A
  • Caused by antibodies to glycosphingolipids
  • Usually triggered by an acute infectious process
  • Myelin regeneration occurs but there may also be axon damage
  • Many patients become completely paralyzed and unable to breathe, 5% die from respiratory paralysis

An example is Guillain-Barre syndrome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

Do peripheral nerves contain just one axon?

A

No, they can contain very many.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

How are neurons arranged in nerves?

A

Each nerve trunk contains:

  • Bundles (fascicles) of fibres consisting of axons and Schwann cells
  • Support cells and blood vessels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

What are the 3 support tissues in nerves?

A
  • Epineurium
  • Perineurium
  • Endoneurium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

What do each of the epineurium, perineurium and endoneurium do?

A
  • Epineurium
    • Outer sheath binds individual nerve fascicles into a nerve trunk
  • Perineurium
    • Surrounds fasicles (bundles of axons)
  • Endoneurium
    • Surrounds axons and Schwann cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

What are the epineurium and endoneurium made of?

A
  • Epineurium -> Type I collagen and fibroblasts
  • Endoneurium -> Longitudinally orientated Type III collagen, fibroblasts and capillaries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

What are the arrows pointing to?

A

Axons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

In spinal nerves, are the dorsal and ventral roots sensory or motor?

A
  • Dorsal is sensory (you can remember this because only sensory neurons synapse in the dorsal root ganglia)
  • Ventral is motor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

Draw the structural organisation of the PNS in a spinal nerve.

110
Q

What different things do ganglia contain?

A
  • Efferent and afferent axons
  • Support cells (satellite cells)
  • Blood vessels
  • Support tissue -> Perineural and epineural sheaths
111
Q

Which cell body is found in autonomic ganglia?

A

The cell body of postganglionic autonomic nerves.

112
Q

Describe the structure of dorsal root ganglia and autonomic ganglia.

113
Q

Draw the structure of a synpase.

114
Q

Can an axon innervate more than one muscle?

115
Q

What is a motor unit?

A

A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron’s axonal terminals.

116
Q

What is the name for the connection between a somatic motor neuron and skeletal muscle?

A

Neuromuscular junction (NMJ)

117
Q

What is the name for the synapse between an efferent neuron and its effector organ in the autonomic nervous system?

A

Neuroeffector junction

118
Q

Draw the structure of a neuroeffector junction.

119
Q

Compare the neurotransmitter release at the NMJ and neuroeffector junction.

A

It occurs from varicosities at the neuroeffector junction and this is much slower and more widespread.

120
Q

What is myasthenia gravis and what are the symptoms it?

A
  • Disease caused by antibodies blocking the AChR so signal is not transmitted
  • Affects control of voluntary muscle:
    • Drooping eyelids
    • Impaired speech
    • Breathing difficulties
    • Blurred vision
    • Muscle weakness in arms and legs
121
Q

Describe the standard diagnostic test for myasthenia gravis. [EXTRA?]

122
Q

Mutations in genes of proteins at NMJ can cause disease. How? How are these treated?

A
  • Dominant mutations in NMJ genes cause disease
  • Use gene silencing to silence mutated allele of these genes -> Allow expression of normal wild type allele.
123
Q

Can nerve axons regenerate?

A
  • Peripheral nerve axons -> Able to regenerate throughout life
  • Central nervous system axons -> Ability to regenerate decreases from birth
124
Q

What cells direct nerve regeneration? How?

A

Schwann cells:

  • When a nerve is damaged or injured the distal part atrophies – Wallerian degeneration
  • Schwann cells divide and form hollow tube enclosed by endonerium
  • Proximal end of the nerve fibre sends out sprouts towards those tubes
  • Sprouts are attracted by growth factors produced by Schwann cells in the tubes Proceeds at 3-4 mm/day
125
Q

What are the 3 types of nerve ending you need to know about?

A
  • Sensory terminals
  • Motor end-plates
  • Sympathetic varicosities
126
Q

Add flashcards on what terminal arbors are.

A

Are they just axon terminals?

127
Q

Describe the segmental organisation of the somatic nervous system.

A
  • There are 43 segments of nerves in the human body:
    • 31 segments of nerves are in the spinal cord
    • 12 segments in the brain stem
128
Q

What are the the symptoms on loss of motor function?

A

Weakness and paralysis

129
Q

What are the symptoms of irritation of sensory fibres?

130
Q

What are the symptoms of damage to sensory fibres?

A

Loss of sensation

131
Q

What is a mixed nerve?

A
  • A mixed nerve is a nerve that contains both afferent and efferent nerves.
  • MOST peripheral nerves are mixed nerves.
132
Q

Where do visceral afferent fibres have their cell bodies?

A

In dorsal root ganglia.

133
Q

What fibres do visceral afferent fibres often run alongside? What is the effect of this?

A
  • Autonomic efferent nerves (since they both run to/from visceral organs)
  • This can elicit involuntary autonomic reflexes (e.g. baroreceptor reflex) or may give sensation and mixed autonomic and voluntary somatic effects (e.g. micturition)
134
Q

What spinal roots levels do sympathetic fibres arise from?

135
Q

What type of cell are adrenal medullary cells (that produce catecholamines)?

A

Modified sympathetic ganglion cells

136
Q

Describe the myelination and speed of somatic and autonomic fibres.

A

Somatic:

  • Mostly myelinated with medium to fast velocity
  • Except unmyelinated slow C-type pain fibres

Autonomic:

  • Pre-ganglionic -> Mostly myelinated with slow to medium velocity
  • Post-ganglionic -> Non-myelinated with slow velocity
137
Q

Nearly all cells have contractile elements. What are they and what are they used for?

A
  • Actin and myosin

Used for:

  • Movement
  • Changing shape
  • Intracellular movement of organelles
138
Q

Nearly all cells have contractile elements (actin and myosin). What makes muscle cells different?

A
  • Contractile machinery is permanently orientated
  • Permits directional movements
139
Q

What are the 3 types of muscle?

A
  • Skeletal muscle
  • Smooth muscle
  • Cardiac muscle
140
Q

What is striated muscle?

A

Muscle tissue that features repeating functional units called sarcomeres.

141
Q

Compare skeletal, cardiac and smooth muscle in terms of whether they are striated or not.

A
  • Skeletal -> Striated
  • Cardiac -> Striated
  • Smooth -> Non-striated
142
Q

Compare skeletal, cardiac and smooth muscle in terms of their nuclei.

A
  • Skeletal -> Multiple nuclei, peripherally located
  • Cardiac -> One nucleus, centrally located
  • Smooth -> One nucleus, centrally located
143
Q

Draw a table to compare skeletal, cardiac and smooth muscle in terms of:

  • Location
  • Appearance
  • Nuclei
  • Innervation
144
Q

In muscle cells, what are the names for these structures:

  • Cell membrane
  • Cytoplasm
  • Smooth endoplasmic reticulum
  • Mitochondria
  • Contractile unit
A
  • Cell membrane -> Sarcolemma
  • Cytoplasm -> Sarcoplasm
  • Smooth endoplasmic reticulum -> Sarcoplasmic reticulum
  • Mitochondria -> Sarcosomes
  • Contractile unit -> Sarcomere
145
Q

What is the name of the process by which muscle cells are generated?

A

Myogenesis

146
Q

Which germ layer are muscle cells derived from?

147
Q

Which part of which germ layer do skeletal muscle cells develop from?

A

Somites (that form from parietal mesoderm, which is made when the lateral plate mesoderm splits into the parietal and splanchnic mesoderm)

148
Q

Describe how skeletal muscle cells form from mesoderm.

A
  • Somites are induced to differentiate into a sclerotome and dermomyotome -> Due to sonic hedgehog (Shh) protein from notochord
  • Progenitor cells of the dermomyotome then form Pax3+/Pax7+ expressing myoblasts that can divide and migrate
  • Myoblasts exit the cell cycle & express transcription factors (MyoD and Myf5) that activate genes for muscle cells
  • Myoblasts fuse to form multinucleate cells, called myotubes
  • Myotubes develop into myocytes (fibres)
149
Q

What are myoblasts?

A
  • Embryonic precursors of myocytes (also called muscle cells).
  • Myoblasts differentiate into muscle cells through a process called myogenesis.
150
Q

What myoblast is a major muscle precursor cell and what cells does it produce?

A

Pax3+/Pax7+ myoblast

151
Q

What are myotubes?

A

The multinucleate tubes formed by the fusion of multiple myoblasts. When they mature, they are myocytes.

152
Q

Describe the order of development of cells in myogenesis.

A
  • Progenitor cells (from dermamyotome of somites)
  • Myoblasts
  • Myotubes
  • Myocytes
153
Q

What is the difference between myocytes, muscle fibres and myofibres?

A

They are all the same. They are different names for a muscle cell.

154
Q

Describe the smaller structures found within myocytes. (i.e. what makes up what makes up what)

A
  • Myofilaments make up myofibrils
  • Myofibrils make up myofibres (muscle cells)
155
Q

Describe the number and location of nuclei in skeletal muscle cells.

A
  • Multiple nuclei
  • Located peripherally
156
Q

What is the diameter and length of skeletal muscle cells?

A
  • 10-100μm diameter
  • Up to 35cm long
157
Q

What are satellite cells and where are they found?

A
  • Regenerative cells
  • Found on the outside of myocytes
158
Q

What is a muscle fibre?

A

It is just another name for a skeletal myocyte (muscle cell).

159
Q

Describe how blood supply exists in muscles.

A
  • Blood vessels penetrate the muscle and form a rich capillary network
  • Runs between and parallel to the muscle fibres
160
Q

What are the two proteins that make up microfilaments? Which is thin and which it thick?

A
  • Actin -> Thin
  • Myosin -> Thick
161
Q

What is a sarcomere?

A

Repetitive sub-units of contractile apparatus.

162
Q

Draw the structure of a sarcomere. Include the names of the different zones.

A
  • A band (dark) -> All of the length of myosin filaments
  • I band (light) -> Just actin filaments
  • Z line -> Where actin attaches
  • H band -> Just myosin filaments
  • M line -> What myosin attaches to
163
Q

What happens to the different zones in a sarcomere when it contracts?

A
  • I (just actin) and H (just myosin) bands are reduced in size
  • A (all of myosin) bands do not change size
164
Q

How many actin filaments surround each myosin filament?

165
Q

What are the 4 main contractile proteins in skeletal muscle?

A
  • Myosin
  • Actin
  • Tropomyosin
  • Troponin
166
Q

In skeletal muscle, which contractile protein has heads?

167
Q

Describe the structure of myosin in skeletal muscle.

A

6 polypeptides twisted to form a fibre helix with globular end, which has ATPase activity and binds to actin.

168
Q

Describe the structure of actin in skeletal muscle.

A

Globular protein which polymerizes into polymeric fibres and contains a myosin binding site .

169
Q

What are tropomyosin and troponin? What is their function in skeletal muscle?

A

Tropomyosin:

  • Fibre-like protein which wraps helically around the actin
  • In relaxed muscle, tropomyosin blocks attachment site for myosin crossbridge, thus preventing contraction

Troponin:

  • Calcium-sensitive globular protein complex attached to end of each tropomyosin molecule
  • Ca2+ binds to troponin -> Knocks tropomyosin off binding site (for myosin head) and initiates contraction cycle
170
Q

Draw a diagram to show how actin, myosin, tropomyosin and troponin interact.

171
Q

What molecule triggers contraction in skeletal muscle and how?

A
  • Ca2+
  • It binds to troponin, causing tropomyosin to be knocked off of actin, so myosin heads can bind and contraction can occur
172
Q

Aside from actin, myosin, troponin and tropomyosin, what are some important proteins involved in a sarcomere of skeletal muscle?

A
  • Titin
  • Alpha-actinin
  • Nuebulin
173
Q

What is titin and what is its function?

A
  • Protein that connects myosin to the Z-line (actin is just anchored to Z-line)
  • It is responsible for the passive elasticity of muscle and maintains sarcomere structure
174
Q

What is unusual about titin?

A

It is the largest protein in the human body.

175
Q

What is another name for titin?

176
Q

What is alpha-actinin and what is its function?

A

Protein that anchors actin to the Z-line.

177
Q

What is usually in a complex with alpha-actinin?

178
Q

What is nebulin and what is its function?

A

Actin-binding protein that regulates the length of actin.

179
Q

Draw the structure of a sarcomere, showing these components:

  • Actin
  • Myosin
  • Troponin
  • Tropomyosin
  • Nebulin
  • Alpha-actinin
  • Titin
180
Q

What are the different energy sources used for muscular contraction? For what length of time can each be used?

A
  • Stored ATP + creatine phosphate -> 8-10 secs
  • Glycolysis -> 90 secs
  • Aerobic respiration -> 2 min+
181
Q

What occurs in muscles when the body cannot produce ATP? Why?

A
  • The actin and myosin cannot dissociate
  • So rigor mortis sets in
182
Q

What are the different classes of skeletal muscle?

A
  • Type I -> Slow twitch
  • Type II -> Fast twitch
    • Type IIa -> Intermediate between fast and slow
    • Type IIb -> Classic fast twitch
183
Q

Compare the structure of slow and fast twitch skeletal muscle.

A
  • Slow twitch -> Abundant mitochondria and extensive blood supply
  • Fast twitch -> Abundant glycogen
184
Q

Compare how slow and fast twitch skeletal muscles can be distinguished histologically.

A
  • Type I (slow twitch) -> Succinate dehydrogenase stains more intensely
  • Type II (fast twitch) -> mATPase stains more intensely
185
Q

What are T-tubules?

A

Invaginations of the sarcolemma (of myocytes) that surround myofibrils.

186
Q

Describe the arrangement of T-tubules and the sarcoplasmic reticulum in skeletal muscle cells.

A
  • T-tubules are invaginations of the sarcoplasmic reticulum that surround myofibrils
  • Each T-tubule is flanked by two terminal cisternae of the sarcoplasmic reticulum (forming a triad):
    • Impulse is conveyed from T tubules to cisternae
    • Triggers Ca2+ release
    • Troponin binds to it and activates actin & myosin
187
Q

What are motor end plates?

A

Another name for neuromuscular junctions.

188
Q

What is a motor unit?

A
  • One motor neuron can supply many muscle cells
  • Together, these form a motor unit
  • Can contract in unison much faster than if each muscle cell individually stimulated
189
Q

Describe briefly synaptic transmission at an NMJ.

A
  • Nerve action potential opens voltage-gated calcium channels.
  • Entry of Ca2+ triggers fusion of synaptic vesicle containing acetylcholine (ACh) with plasma membrane.
  • Ach binds to AChR, causing opening of postsynaptic channels on muscle cell
  • This triggers an action potential
190
Q

What are fascicles?

A

Bundles of muscle fibres (muscle cells) groups together by perimysium.

191
Q

What is the order of the connective tissues that are found in skeletal muscle?

A

Inner to outer:

  • Endomysium
  • Perimysium
  • Epimysium
192
Q

What is the endomysium and what does it surround?

A
  • Surrounds each muscle fibre
  • Composed of reticular fibres and external lamina (basal lamina)
193
Q

What is the perimysium and what does it surround?

A
  • Surrounds bundles (fascicles) of muscle fibers
  • Dense collagenous connective tissue derived from epimysium
194
Q

What is the epimysium and what does it surround?

A
  • Surrounds entire muscle
  • Dense irregular collagenous connective tissue
195
Q

What is the function of the endomysium, perimysium and epimysium in muscle?

A

The collagen transmits mechanical force generated from contraction.

196
Q

What is dystrophin, what is it part of and what is the function? [IMPORTANT]

A
  • Dystrophin is a rod-shaped protein inside muscle cells
  • It is a vital part of the dystrophin-associated glycoprotein complex (DGC)
  • This complex anchors the cytoskeleton of the muscle fibre to the surrounding extracellular matrix, maintaining the mechanical integrity of the cell
197
Q

What is muscular dystrophy and what causes it?

A
  • Mutations in dystrophin gene (frame shift) -> Leads to a truncated unstable form of dystrophin
  • Absence of dystrophin leads to impairment of sarcolemma
  • Force is no longer transmitted from myocytes to bones, so there is reduced movement at joints
  • Symptoms: Muscle weakness and wasting
198
Q

When does muscular dystrophy onset?

A

2 to 6 years

199
Q

What is the inheritance pattern of muscular dystrophy?

A

X-linked recessive

200
Q

Are there different isoforms of dystrophin?

A

Yes, because the gene is very long as has many introns.

201
Q

What are the most common mutations causing muscular dystrophy?

A
  • 60-65% deletions (these occur in hotspots)
  • 5-15% duplications
  • Point mutations
202
Q

What are some treatments for muscular dystrophy?

A
  • Corticosteroids
  • Physiotherapy
  • Cardiac + Respiratory support
  • Palliative care
  • Genetic counseling
203
Q

What are some novel treatment methods for muscular dystrophy?

A
  • Delivery of normal dystrophin gene
    • Hard to do because:
      • Size of dystrophin
      • Needs to be delivered to all muscles
  • Utrophin upregulation
    • Utrophin is a closely related gene to dystrophin
    • Expression is more tightly regulated -> Only in immature muscle and at NMJ
    • Can identify drugs/small molecules to activate utrophin promoter and allow functional replacement of dystrophin
  • Exon skipping – anti-sense oligonucleotides
    • Chemically modified single-stranded nucleic acids are used
    • Hybridise to unique sequence of mRNA
    • This is used to alter the exons are revert to the normal frame (since DMD is caused by frame shift)
204
Q

What are the general symptoms of neuromuscular diseases?

A
  • Spasticity or paralysis
  • Depending on location & nature of problem
205
Q

What are some examples of neurological disorders?

A
  • Motor neuron disease
  • ALS
  • Cerebrovascular accident (stroke)
  • Parkinson’s disease
  • Myasthenia gravis
206
Q

Describe how satellite cells allow for skeletal muscle repair.

207
Q

Is cardiac muscle striated?

208
Q

What is cardiac muscle derived from embryologically?

A

Defined mass of splanchnic mesenchyme and myoepicardiaum mantel.

209
Q

Draw the different layers of the heart wall.

210
Q

What does the endocardium derive from?

A

Vascular endothelial progenitors

211
Q

In the heart muscle, the cardiac myocytes are arranged in layers. What are these called?

212
Q

What is unusual about the shape of cardiac myocytes?

A

They are branched.

213
Q

How many nuclei do cardiac myocytes have?

A

Single, centrally-located nucleus (usually)

214
Q

Do cardiac myocytes have T tubules?

215
Q

What is the distinguishing characteristic of cardiac muscle in histology?

A

The presence of dark transverse lines between cells -> These are intercalated discs.

216
Q

What are intercalated discs?

A

Structures that interface between adjacent cardiac muscle cells and support synchronised contraction.

217
Q

What are the 3 components of intercalated discs?

A
  • Desmosomes
  • Adherens junctions
  • Gap junctions
218
Q

What is the function of desmosomes in intercalated discs between cardiac myocytes?

A

Bind cells together.

219
Q

What is the function of adherens junctions in intercalated discs between cardiac myocytes?

A

Act as anchoring sites for actin filaments.

220
Q

What is the function of gap junctions in intercalated discs between cardiac myocytes?

A

Provide continuity between adjacent cells and allow ions to pass between cells.

221
Q

What is another name for adherens junctions in intercalated discs?

A

Fascia adherens (a.k.a. hemi Z-bands)

222
Q

What is another name for desmosomes in intercalated discs?

A

Macula adherens

223
Q

Overall, what do intercalated discs allow?

A

They allow cardiac muscle to act as a functional syncytium.

224
Q

Summarise simply the structure and functioning of cardiac myocytes.

A

Branching mesh of mononuclear striated cells joined and electrically coupled by intercalated discs (desmosomes and gap junctions: electrically a ‘functional syncytium’).

225
Q

What is meant by cardiac muscle being myogenic?

A

It is self-excitable.

226
Q

Describe briefly excitation-contraction coupling in cardiac myocytes [EXTRA - this is more of a P&P topic].

227
Q

Here is a section of muscle. What type of muscle is it and what do the letters a, d and g show?

A

Cardiac muscle (since this is an intercalated disc):

  • a = Adherens junction
  • d = Desmosome
  • g = Gap junction
228
Q

What are Purkinje fibres made of?

A

Modified cardiac muscle cells

229
Q

Where are Purkinje fibres located?

A
  • In inner ventricular walls
  • Run beneath endocardium
230
Q

What do Purkinje fibres enable?

A

Synchronised contractions of ventricles

231
Q

How do Purkinje fibres appear histologically?

A

They have a pale-staining cytoplasm.

232
Q

What are some structural differences between Purkinje fibres and normal cardiac myocytes?

A
  • Rich in glycogen & mitochondria
  • Contain limited contractile elements
  • No T-tubule system
233
Q

What is DCM? [EXTRA?]

234
Q

What is HCM? [EXTRA?]

235
Q

Are cardiac myocytes repaired?

A
  • They are very slowly turned over with age
  • Less than 50% of cardiomyocytes are replaced during a normal life span
236
Q

Are smooth muscle cells striated?

237
Q

How many nuclei do smooth muscle cells have?

A

They are mononucleate.

238
Q

Describe and draw the shape of smooth muscle cells.

A

They are fusiform: elongated cells that taper at either end.

239
Q

What are smooth muscle cells surrounded by?

A
  • Basal lamina and network of reticular fibers.
  • However, these layers are much thinner and therefore not as well seen as in skeletal muscle
240
Q

Describe the alignment of contractile filaments in smooth muscle cells.

A

They are not arranged parallel, but instead form a sort of lattice.

241
Q

Do the filaments in smooth muscle work in the same way as in striated muscle (skeletal and cardiac)?

A

Yes, they still work by sliding past each other, even though they are not arranged in a regular parallel manner.

242
Q

In smooth muscle, actin and myosin are arranged in a…

243
Q

What are two important attachment points in smooth muscle?

A
  • Focal densities
  • Dense bodies
244
Q

What do focal densities do in smooth muscle cells?

A

Attach actin filaments to the sarcolemma.

245
Q

What do dense bodies do in smooth muscle cells?

A

Attach actin filaments to each other -> They help maintain their alignment.

246
Q

What are dense bodies functionally analogous to?

247
Q

Draw a diagram to show the different contractile proteins and attachment points in smooth muscle cells.

248
Q

What are invaginations of the sarcolemma called in smooth muscle cells?

A

Caveolae -> These are functionally analagous to T-tubules.

249
Q

What is the function of caveolae in smooth muscle cells?

A
  • Involved in fluid and electrolyte transport (pinocytosis)
  • Transmit depolarisation signalto inside the cell
250
Q

What connects different smooth muscle cells?

A

Gap junctions -> Couple adjacent cells chemically and electrically.

251
Q

Compare how cells are connected in skeletal, cardiac and smooth muscle.

A
  • Skeletal -> Cells are long and multinucleate so they aren’t really functionally connected in a significant way
  • Cardiac -> Intercalated discs (made of gap junctions, adherens junctions and desmosomes)
  • Smooth -> Gap junctions
252
Q

Where is smooth muscle found?

A

Found in lining of viscera in:

  • Gut
  • Bladder
  • Uterus
  • Respiratory system
  • Blood vessels
253
Q

Compare the arrangement of smooth muscle cells in the uterus and bowel.

A
  • Uterus -> Loosely arranged
  • Bowel -> Regularly arranged
254
Q

Describe the two functional arrangements of smooth muscle.

A
  • Single unit
    • Function as a unit enabled by electric coupling via gap junctions
    • Allows muscle to behave as syncytium
  • Multiunit
    • Each cell isolated & stimulated independently to enable finer control
255
Q

Give an example of an organ that includes single-unit smooth muscle.

A
  • GI tract
  • Bladder
256
Q

Give an example of an organ that includes multi-unit smooth muscle.

A
  • Iris of the eye
257
Q

Describe the organisation of smooth muscle in the GI tract.

258
Q

Label this. What muscle type is it?

259
Q

What are the two forms of innervation that can trigger smooth muscle contraction?

A
  • Release of neurotransmitter from autonomic varicosities (not NMJs)
  • Visceral muscle pacesetters can spontaneously trigger contraction
260
Q

Does smooth muscle feature motor units?

A

No, because they are innervated by autonomic varicosities, not NMJs.

261
Q

What are some diseases related to smooth muscle?

262
Q

Can smooth muscle cells regenerate?

A

Yes, they retain the highest capacity to regenerate of all the muscle types.

263
Q

What are the two main ways in which smooth muscle can regenerate?

A
  • Smooth muscle cells retain ability to divide, and can increase in number this way
  • New cells can be produced by the division of pericytes that lie along some small blood vessels
264
Q

Can smooth muscle hypertrophy?

265
Q

What cells wrap around smooth muscle and what is their function?

A

Pericytes -> Help regenerate the smooth muscle.

266
Q

What types of myocyte are these?

267
Q

What makes up gap junctions in cardiac muscle? How are they regulated?

A
  • Several connexins join to form a connexon
  • Two connexons form a gap junction
  • These can be regulated by phosphorylation and calcium
268
Q

Are gap junctions selective?

A

No, but they can be regulated by phosphorylation and calcium.

269
Q

Draw the process of formation of gap junctions. [EXTRA]

YEAR 1 - Organisation of the Body (Anton) (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions