W4 - Muscle Structure And Function Flashcards
How many muscles are in the human body?
650
What three things can muscles be divided into?
Cardiac muscle
Skeletal muscle
Smooth muscle
What are the functions of muscle tissue?
To produce body movements
To stabilise body positions
To regulate organ volumes
To move substances within the body
Produce heat
Name five properties of muscle tissue
Excitability = respond to chemicals released from nerve cells
Conductivity = the ability to propagate electrical signals over membrane
Contractility = the ability to shorten and regenerate force
Extensibility = the ability to stretch without damaging the tissue
Elasticity = the ability to return to its original shape after being stretched
What does skeletal muscle tissue attached to?
Bone
Skin
Fascia (the skeletal system) via tendons/aponeuroses
What does skeletal muscle tissue look like? And what is it responsible for?
Striated with light and dark bands visible with scope
It is responsible for voluntary control of contraction and relax relaxation
Name the functions of skeletal muscle
Produce skeletal movement
Maintain body position
To support soft or hard tissues
To guard body openings
Maintain body temperature
Stores nutrient reserves
Proprioception
What is the structure of skeletal muscle (connective tissues)
Three layers: epimysium (outer), perimysium, endomysium
What does the epimysium layer of connective muscle tissue do?
Surrounds the whole muscle
It is an exterior collagen layer
Connects to deep fascia
And separates muscle from surrounding tissues
What does the perimysium layer for connective muscle tissue do?
Surrounds muscle fibre bundles (fascicles)
Contains blood vessels and nerve supply to fascicles
What does the endomysium layer of connective muscle tissue due?
Surrounds individual muscle cells (muscle fibres)
Contains capillaries and nerve fibres contacting muscle cells
Contains satellite cells (stem cells) that repair damage
What is the structure of skeletal muscle for nerves and blood vessels?
Nerves
A collection of muscle cells are supplied by a motor neuron
One motor neuron has a muscle fibre that it applies = this is called a motor unit
Each muscle cell is supplied by a terminal branch of a motor neuron
Blood vessels
Muscles have extensive vascular systems that supply large amounts of oxygen nutrients and carry waste products away
Each muscle cell is in contact with one or two capillaries
What is the structure of a skeletal muscle fibre?
The sarcolemma
Transverse tubules
Sarcoplasmic reticulum
A triad
Myofibrils & myofilaments
Sarcomeres
What is the sarcolemma
Cell membrane of a muscle cell
It is surrounded by sarcoplasma (which is filled with myofibrils and myoglobin)
What do the transverse tubules do
Filled with extra cellular fluid
Carry muscle action potentials down into the cell
Allows the entire muscle fibre to contract simultaneously
Mitochondria lie in rose throughout the cell
What is the sarcoplasmic reticulum
A membrane structure that surrounds each myofibril
Helps transmit action potential
Stores calcium in a relaxed muscle
Releases calcium to trigger muscle contraction
What is a triad in muscle contraction?
Formed by 1 T-tubule and 2 terminal cisternae
Release calcium ions into sarcomeres to begin muscle contraction
What is the structure of a sarcomere (myofibril)
I band = only contains actin
A band = only contains myosin
M line = middle line
H zone = only has myosin
Z disc = separate sarcomeres
Name the three proteins that are responsible for the three actions of muscle contraction
Contraction = actin & myosin
Regulation = troponin & tropomyosin
Structural = titin, myomesin, nebulin and dystrophin
