NURS 301 Lecture Notes - Lecture 3: Skeletal Muscle, Cardiac Muscle, Muscle Tissue
Cardiac muscle tissue
Only found in heart
-
Striated
Single nucleus
○
Short, stumpy, slightly branched
○
-
Involuntary activity that never stops
-
Skeletal muscle tissue
Attached to bones
-
Striated
Overlapping arrangement of contractile proteins
○
Multinucleated myofibers-peripherally located
○
-
Skeletal muscle fibers are long, have multiple nuclei
-
Voluntary activation
Contraction and relaxation under our own controls
○
-
Smooth tissue
Present in most hollow internal organs, except heart
E.g. digestive system
○
-
Non-Striated
Fusiform myocyte
○
One nucleus
○
-
Involuntary
-
Functions of Muscular system
Movement
Movement of individual parts, e.g. exercise
○
Moving from one place to another, e.g. walking
○
Movements of body contents, e.g. breathing, blood
circulation, etc.
○
Communication, e.g. speech, writing, nonverbal body
language
○
-
Stability
Maintaining posture by preventing unwanted muscle
movements
○
Stabilizing joints, keeping bones at joint tight
○
-
Heat production
Skeletal muscles produce as much as 85% of body heat
○
-
Properties of Muscular System
Excitability: exhibition of electrical and mechanical response
Muscle and nerve cells
○
-
Conductivity: conduction of electrical excitation throughout the
entire plasma membrane
Allows muscles to pull on bones or other tissues to create
movement
○
-
Contractility: shortening in response to stimulation
Ability to shorten
○
-
Extensibility: the ability to be stretched
Can stretch 3 times without being harmed
○
-
Elasticity: the ability to recoil to the original length
-
Organization of Skeletal Muscle fibers
Also contains connective and nervous tissue and blood vessels
-
Connective tissue from LARGEST TO SMALLEST:
Deep fascia: sheath of connective tissue that separates
neighboring muscles
○
Epimysium: fibrous connective tissue that surrounds the
entire muscle
○
Perimysium: thick connective tissue that surrounds the
whole fascicle
Each muscle contains several fascicles
§
Also hold blood and nerve vessels
§
Within each fascicle, there is multiple muscle fiber
cells, usually bundled together
Endomysium: surrounds each muscle fiber
Creates room for blood capillaries
®
Allowing nourishment
®
□
§
○
-
Muscle shapes
*based on orientation of their fascicles
Different muscles have different force
-
Circular: form rings around certain body openings
When contract, constrict opening prevents passage of material,
e.g. orbicularis oris
-
Convergent: triangular, fan shaped, broad, e.g. pectoralis major
Fusiform: thick in middle, tapered at each end e.g. biceps brachii
Parallel: thin, all fascicles arranged in parallel to each other, expand
long distances, e.g. satorius
Pennate: feather shaped
Unipennate
All muscle fibers are on the same side of the tendon
○
-
Bipennate
Muscle fibers on both sides of tendon
○
-
Multipennate
Tendon branches within a pennate muscle
○
-
Muscle Attachment
Skeletal muscles attached to bone though connective tissue
component
Direct: little separation of muscle and bone
Muscle tissue emerges directly from bone
○
Collagen fibers of the muscle continue to tendon and from
there, into the perimysium
Strong continuity
§
○
-
Indirect: attachment of muscle to bone through tendon
-
Function of Muscle Groups
Skeletal muscles rarely act independently
Combined actions produced coordinated control of joints
-
Particular muscle can act in different movements
-
Prime mover: the muscle that produced most of the force during
a particular join action
-
Synergistic: stabilize a joint and restrict unnecessary movement
Modify the direction of a movement so that the action of
the primer mover is more coordinated and specific
○
-
Antagonist: a muscle that opposed the primer mover
E.g throwing a dart
Primer mover: triceps
§
Antagonist: biceps
§
○
-
Fixator: a muscle that prevents a bone from moving
Hold it steady, allowing another muscle that is attached to
it to pull to something else
○
-
Structural Hierachy of Skeletal Muscle
From macroscopic to microscopic level
Muscle (whole organ)1.
Fascicle (portion of muscle)2.
Muscle fiber (single muscle cell)3.
Myofibril (muscle cell organelle)4.
Sarcomere (portion of myofibril)5.
Myofilament (part of sarcomere)6.
Closer look at Muscle Fiber
Pulled out from fascicle
-
Filled with myofibril
Filled with parallel proteins called myofilaments
○
-
3 types of myofilaments:
Help muscle tissue contract
Actin: also called thin filament
Binds to head of myosin
○
-
Myosin: thick filament
-
Actin and myosin together are contractile protein
Important in muscle contraction
-
Titin: acts to stabilize thick filament
Center myosin between thin filaments
○
-
Z-lines divide
Neuromuscular Junction
Skeletal muscle never contracts in the absence of nervous
stimulation
-
Motor neurons have cell body in brain and spinal cord
-
Any muscle fiber is only supplied by one motor neuron
-
Terminal branch of nerve fibers
Synapse: where motor neuron approaches muscle fiber
Synaptic vesicles filled with chemicals for
contraction, acetocholine is a neurotransmitter
§
○
When nerve signals arrives at synaptive end
Vesicles releases Ach into synaptive cleft
§
Ach binds to specific receptors at sarcolemma: plasma
membrane of muscle fibers
§
Cascade of events initiates muscle contraction
§
○
-
Online Lecture - Week 3
Friday, April 13, 2018
12:30 PM
Cardiac muscle tissue
Only found in heart
-
Striated
Single nucleus
○
Short, stumpy, slightly branched
○
-
Involuntary activity that never stops
-
Skeletal muscle tissue
Attached to bones
-
Striated
Overlapping arrangement of contractile proteins
○
Multinucleated myofibers-peripherally located
○
-
Skeletal muscle fibers are long, have multiple nuclei
-
Voluntary activation
Contraction and relaxation under our own controls
○
-
Smooth tissue
Present in most hollow internal organs, except heart
E.g. digestive system
○
-
Non-Striated
Fusiform myocyte
○
One nucleus
○
-
Involuntary
-
Functions of Muscular system
Movement
Movement of individual parts, e.g. exercise
○
Moving from one place to another, e.g. walking
○
Movements of body contents, e.g. breathing, blood
circulation, etc.
○
Communication, e.g. speech, writing, nonverbal body
language
○
-
Stability
Maintaining posture by preventing unwanted muscle
movements
○
Stabilizing joints, keeping bones at joint tight
○
-
Heat production
Skeletal muscles produce as much as 85% of body heat
○
-
Properties of Muscular System
Excitability: exhibition of electrical and mechanical response
Muscle and nerve cells
○
-
Conductivity: conduction of electrical excitation throughout the
entire plasma membrane
Allows muscles to pull on bones or other tissues to create
movement
○
-
Contractility: shortening in response to stimulation
Ability to shorten
○
-
Extensibility: the ability to be stretched
Can stretch 3 times without being harmed
○
-
Elasticity: the ability to recoil to the original length
-
Organization of Skeletal Muscle fibers
Also contains connective and nervous tissue and blood vessels
-
Connective tissue from LARGEST TO SMALLEST:
Deep fascia: sheath of connective tissue that separates
neighboring muscles
○
Epimysium: fibrous connective tissue that surrounds the
entire muscle
○
Perimysium: thick connective tissue that surrounds the
whole fascicle
Each muscle contains several fascicles
§
Also hold blood and nerve vessels
§
Within each fascicle, there is multiple muscle fiber
cells, usually bundled together
Endomysium: surrounds each muscle fiber
Creates room for blood capillaries
®
Allowing nourishment
®
□
§
○
-
Muscle shapes
*based on orientation of their fascicles
Different muscles have different force
-
Circular: form rings around certain body openings
When contract, constrict opening prevents passage of material,
e.g. orbicularis oris
-
Convergent: triangular, fan shaped, broad, e.g. pectoralis major
Fusiform: thick in middle, tapered at each end e.g. biceps brachii
Parallel: thin, all fascicles arranged in parallel to each other, expand
long distances, e.g. satorius
Pennate: feather shaped
Unipennate
All muscle fibers are on the same side of the tendon
○
-
Bipennate
Muscle fibers on both sides of tendon
○
-
Multipennate
Tendon branches within a pennate muscle
○
-
Muscle Attachment
Skeletal muscles attached to bone though connective tissue
component
Direct: little separation of muscle and bone
Muscle tissue emerges directly from bone
○
Collagen fibers of the muscle continue to tendon and from
there, into the perimysium
Strong continuity
§
○
-
Indirect: attachment of muscle to bone through tendon
-
Function of Muscle Groups
Skeletal muscles rarely act independently
Combined actions produced coordinated control of joints
-
Particular muscle can act in different movements
-
Prime mover: the muscle that produced most of the force during
a particular join action
-
Synergistic: stabilize a joint and restrict unnecessary movement
Modify the direction of a movement so that the action of
the primer mover is more coordinated and specific
○
-
Antagonist: a muscle that opposed the primer mover
E.g throwing a dart
Primer mover: triceps
§
Antagonist: biceps
§
○
-
Fixator: a muscle that prevents a bone from moving
Hold it steady, allowing another muscle that is attached to
it to pull to something else
○
-
Structural Hierachy of Skeletal Muscle
From macroscopic to microscopic level
Muscle (whole organ)1.
Fascicle (portion of muscle)2.
Muscle fiber (single muscle cell)3.
Myofibril (muscle cell organelle)4.
Sarcomere (portion of myofibril)5.
Myofilament (part of sarcomere)6.
Closer look at Muscle Fiber
Pulled out from fascicle
-
Filled with myofibril
Filled with parallel proteins called myofilaments
○
-
3 types of myofilaments:
Help muscle tissue contract
Actin: also called thin filament
Binds to head of myosin
○
-
Myosin: thick filament
-
Actin and myosin together are contractile protein
Important in muscle contraction
-
Titin: acts to stabilize thick filament
Center myosin between thin filaments
○
-
Z-lines divide
Neuromuscular Junction
Skeletal muscle never contracts in the absence of nervous
stimulation
-
Motor neurons have cell body in brain and spinal cord
-
Any muscle fiber is only supplied by one motor neuron
-
Terminal branch of nerve fibers
Synapse: where motor neuron approaches muscle fiber
Synaptic vesicles filled with chemicals for
contraction, acetocholine is a neurotransmitter
§
○
When nerve signals arrives at synaptive end
Vesicles releases Ach into synaptive cleft
§
Ach binds to specific receptors at sarcolemma: plasma
membrane of muscle fibers
§
Cascade of events initiates muscle contraction
§
○
-
Online Lecture - Week 3
Friday, April 13, 2018 12:30 PM
Document Summary
Skeletal muscle fibers are long, have multiple nuclei. Present in most hollow internal organs, except heart. Moving from one place to another, e. g. walking. Movements of body contents, e. g. breathing, blood circulation, etc. circulation, etc. Skeletal muscles produce as much as 85% of body heat. Conductivity: conduction of electrical excitation throughout the entire plasma membrane. Allows muscles to pull on bones or other tissues to create movement. Elasticity: the ability to recoil to the original length. Also contains connective and nervous tissue and blood vessels. Deep fascia: sheath of connective tissue that separates neighboring muscles. Epimysium: fibrous connective tissue that surrounds the entire muscle. Perimysium: thick connective tissue that surrounds the whole fascicle. Within each fascicle, there is multiple muscle fiber cells, usually bundled together. When contract, constrict opening prevents passage of material, e. g. orbicularis oris. Convergent: triangular, fan shaped, broad, e. g. pectoralis major. Fusiform: thick in middle, tapered at each end e. g. biceps brachii.
