Muscle and Nervous Tissue Flashcards
What are the 4 qualities of muscle tissue?
- Excitability - ability to respond to stimuli
- Contractibility - ability to contract e.g.
shorten - Extensibility - ability to stretch without
tearing - Elasticity - ability to return to original shape
Is cardiac muscle striated or involuntary?
Both - its is striated and involuntary
Is skeletal muscle striated or involuntary?
Striated
Is smooth muscle striated or involuntary?
Involuntary
What is the structure of smooth muscle cells?
- Short and spindle shaped - no striations -
Unstriated - Single centrally located nuclei
- Gap junctions between cells
- Able to regenerate by mitosis
- Slow, partial contractions
Where is smooth muscle found?
Found in vessels, organs and walls of hollow organs.
What type of innervation is smooth muscle under?
Under autonomic (involuntary, unconscious) control
What does smooth muscle look like histologically?
Made up of:
- outer longitudinal smooth muscle
- inner circular muscle
- collagen
What does a cardiac muscle cell look like?
Short and narrow
Where is cardiac muscle found in the body?
In the heart and adjacent veins.
Is cardiac muscle striated?
Yes - has striations due to dense arrangement on actin + myosin - its cylindrical with branches
Is cardiac muscle striated?
Yes - has striations due to dense arrangement on actin + myosin - its cylindrical with branching fibres
How many nuclei are present in cardiac muscle?
Has a single central nucleus
What type of cell to cell junctions are present in cardiac muscle ?
Intercalated disks containing gap junctions
- joining cells to allow cell-cell communication for a coordinated output
What type of innervation is cardiac muscle under?
Autonomic control (spontaneous contraction)
- Vagus nerve and sympathetic chain provide parasympathetic and sympathetic innervation to the cardiac muscle and heart rate (Visceral Motor Efferent)
What type of contractions are present in cardiac muscle?
All or none
Does mitosis occur in cardiac muscle?
No
Does regeneration occur in cardiac muscle?
No
What does a skeletal muscle cell look like?
Large and elongated - long cylindrical cells
Where is skeletal muscle located in the body?
Found throughout the body attached to bones via tendons
(voluntary muscle)
Is skeletal muscle striated?
Yes
- has fine black lines running perpendicular to
the fibres
How many nuclei does skeletal muscle have?
Many peripheral nuclei - has long multinucleated parallel cells
What type of control is skeletal muscle under?
Under voluntary (conscious) control - by general somatic efferent (GSE) fibres in the nerves
What type of innervation is skeletal muscle under?
somatic
What type of contraction occurs in skeletal muscle?
All or nothing
Can skeletal muscle undergo mitosis?
No
Can skeletal muscle undergo regeneration?
a limited amount
What is dispersed within skeletal muscle cells to aid recovery?
Satellite cells
What are the 4 components of a myofibril?
- Muscle fiber
- Nuclei
- Sarcolemma
- Mitochondria
What are the 3 components of a muscle ?
- Epimysium
- Perimysium
- Endomysium
What causes muscle contraction?
Overlapping actin and myosin myofilaments
- At rest actin and myosin don’t touch
- Before they contract thick actin filaments
slide past thicker myosin so they overlap
more
What is required for muscle contraction?
ATP and Calcium - proteins can become
unblocked
What causes muscle contraction?
- Chemical energy converted to kinetic energy
- Mitochondria makes ATP
- Sarcoplasmic reticulum loaded with calcium
pumps - and stores calcium - Action potential opens calcium channels -
calcium floods into the cell - Calcium binds with troponin
- Deforms tropomyosin, meaning the myosin
heads can bind to the newly revealed sites
on troponin - ATP –> ADP and P => releases energy
- Myosin heads bind to actin
- Calcium stops flooding into fibre:
- nerve impulse stops
- calcium has been depleted - Calcium unbinds from troponin
How does rigor mortis occur?
There is no ATP to unbind the myosin from the troponin
Muscle remains contracted - fixed in position
rigor mortis = bridge made
What is the nervous system?
A complex network of neurones and associated support cells.
Peripheral vs Central
Autonomic vs Somatic
Motor vs Sensory
What is a neruon?
Nerve cells, specialised cells that conduct electrical impulses
What is the structure of a neurone?
Dendrites - extend from the cell body. They are short with many branches, the points at which nerve impulses are received by the cell. ( the listening part of the cell)
Cell body - located in the central nervous system or arranged in the ganglia of peripheral nervous system
Axon - single nerve fibre which transmits impulses to the distal end.
(Talking part of the cell)
What are the 4 types of neurone?
- Multipolar neurone
- Bipolar neurone
- Pseudo - unipolar neurone
- Unipolar neurone
What are supporting cells called and what do they do?
Glial Cells
Provide support, nutrition, insulation and help with signal transmission in the nervous system
What are the 4 types of glial cells in the central nervous system and their function?
- Astrocytes
- Microglial cells
- Ependymal cells
- Oligodendrocytes
What are the 2 types of glial cells in the peripheral nervous system and their functions?
Satellite cells
Schwann cells
What do Schwann cells do?
- provide a lipid rich insulating barrier - the
myelin sheath
(In peripheral nervous system)
What is the function of satellite cells?
Layer of small cuboidal cells - surround and support neuron cell bodies
(In peripheral nervous system)
What is the function of oligodendrocytes?
Produce an insulating barrier - the myelin sheath
(In peripheral nervous system)
What is the function of oligodendrocytes?
- Engulf and destroy debris - part of the
immune defence against invading
microorganisms
(In central nervous system)
What is the function of ependymal cells?
- Create, secrete and circulate cerebrospinal
fluid - Line ventricles of the brain - line cavities
(In central nervous system)
What is the function of astrocytes?
- communicate between neuron and capillary
- most numerous, cover surfaces
- support, regulate ions
- blood brain barrier - blood to brain
- involved in metabolic exchange between
neurons and blood
(In central nervous system)
What is a neuromuscular junction and where are they located?
Originate at spinal cord or brain stem
Richly innervated by motor neurons
Branch near the muscle and end on individual fibres
Neuromuscular junction / motor end plate
