Anatomy 11 - Histology of Muscles Flashcards
What is a muscle
A band or bundle of fibrous tissue that has the ability to contract
What are the three types of muscle
Skeletal muscle, cardiac muscle and smooth muscle
Characteristics of skeletal muscle
Striated, voluntary, and contains multiple nuclei
Where do the nuclei of skeletal muscle lie
At the periphery of the fibre, just under the cell membrane
What is the cell membrane known as in uncle cells
The sarcolemma
Groups of muscle fibres are known as
Fascicles
Connective tissue surrounding the muscle as a whole is known as
The epimysium
Connective tissue around each individual fascicle is known as
The perimysium
Connective tissue around each single muscle fibre is known as
The endomysium
What are the smallest contractile fibres in a muscle
Sarcomeres
Hundreds of thousands of sarcomeres join together to form
A myofibril
What does cardiac muscle form
The major parts of the walls of the heart chambers and origins of the great vessels
Characteristic of cardiac muscle
Striated (but not as prominent as skeletal), branch to form a complex network and have a single nucleus
Where is the nucleus of cardiac cells found
Near the centre of the fibres
What do cardiac myocytes have
An intrinsic rhythmic contraction
What do gap junctions allow for
Synchronisation of contraction between cells and allow for waves of electrical excitation to sweep through the tissue
Characteristics of smooth muscle
It is involuntary, visceral, has no visible striations and has a single nucleus
Where is smooth muscle predominantly found
In organs
What are the fibres of smooth muscle like
They are elongated, spindle-shaped cells
The nucleus of smooth muscle
Is cigar-shaped and lies in the centre of each fibre
What muscle fibres allow for contraction
Actin and myosin
The specialised smooth ER in muscle cells is known as
Sarcoplasmic reticulum
What ion is in high concentration in the sarcoplasmic reticulum
Ca++
What neurotransmitter is release in muscle cells
Acetylecholine
What are the tubules within muscle cells known as
Transverse tubules or T-tubules
What lies on either side of the T-tubules
The sarcoplasmic reticulum
What is collectively known as a triad
T-tubule and the two branches of sarcoplasmic reticulum on either side
What does acetylcholine cause to be released in the muscle cell
An action potential
What does the action potential in the muscle cell cause the release of
Ca++
What does the release of Ca++ cause within the muscle fibres
It cause the myosin fibrils to ratchet across the actin fibrils
What are muscles normally connected to bone by
A tendon
The college of the tendon joins the muscle fibres to form a
Myotendinous junction
What anchors the muscle fibres to the tendon
Complex interdigitations
A tendons blood supply is
Poor, which means it is difficult to heal
What provides information on how much stretch/tension there is within the muscle
Specialised sense organs
What are the specialised sense organs in muscles known as
Muscle spindles
What do muscle spindles contain
Special muscle fibres
What are normal contractile muscle fibres known as
Extrafusal fibres
What makes up a motor unit
The motor neurone and all of the muscle fibres it innervates
How does the number of muscle fibres in a motor unit relate to the control
The fewer the number of muscle fibres in a motor unit, the finer the control
What is the synapse of a motor neurone called
The motor end plate
Which type of muscle tissue retains a population of myoblasts
Skeletal
What are myoblasts within skeletal muscle tissue known as
Satellite cells
Where are satellite cells found
Pressed against the outer surface of the sarcolemma, under the surrounding basal lamina
What is the function of satellite cells
Following damage they become active and proliferate to form new muscle fibres
What competes with the newly formed muscle fibres of satellite cells
Scar tissue
In what type of muscle tissue is there only a small population of stem cells
Cardiac muscle tissue
Where is skeletal muscle found
It composes the gross skeletal muscle of the muscular system
Function of skeletal muslce
Too move or stabilise bones and other structures
Where is smooth muscle found
In the walls of the tubes: the gut, respiratory tract, blood vessels and the uterus
It is also found in the iris of the eye
