Muscle and movement Flashcards
(18 cards)
What are the four types of tissue?
Muscle, connective, epithelial and nervous
What are the 3 types of action potentials?
Pacemaker, cardiomyocyte and neuromuscular junction
Muscle classification
Striations, skeletal and control (involuntary or voluntary)
Cell shape and appearance of smooth muscle cells
Single
Uninucleate
No striations
Fusiform
Attached to bone and some facial muscles
Cell shape and appearance of skeletal muscle cells
Single
Very long
Cylindrical
Multinucleate
Obvious striations
Cell shape and appearance of cardiac muscle cells
Uninucleate or binucleate
Striations
Branching chains of cells
Features of skeletal muscle
Contraction of the whole muscle
Attached to bones and tendons
Somatic (voluntary) nervous system
Unbranched myocytes
Contraction is controlled by motor units
The size and number of motor units being stimulated is important in determining the strength of contraction
Composed of specialised cells called myocytes
Myocytes are characterised by protein filaments called actin and myosin
Motoneurons send signals to skeletal muscle
Features of cardiac muscle
Autorhythmic cells (will generate their own action potential), this signal passes from cell to cell and triggers contraction in the contractile cells
Autonomic (involuntary) nervous system
Branching myocytes which connect at intercalated discs
Features of smooth muscle
Controlled by action potentials
Phasic smooth muscle is found in the uterus or GI tract (characterised by rhythmic movement and contractions)
Peristalsis in the GI tract is used to move food along (muscles contract in phases at different points)
Tonic smooth muscles are controlled by electrical, chemical and mechanical signals. These are found in the blood vessels and airways. They constrict and dilate
Controlled by autonomic nervous system
Located in the walls of internal organs
Spindle shaped myocytes
Fast twitch muscle
Uses anaerobic respiration
Provides short bursts of speed
Fires rapidly
Fatigues more quickly
Slow twitch muscle
Aerobic respiration
Continuous energy
Higher concentration of myoglobin so darker in colour
Higher endurance
Fires slowly
Myasthenia gravis
Autoimmune disorder
Post synaptic membrane of the muscle cell isn’t folded so there’s less receptor sites resulting in a small EPP
Symptoms include drooping of the mouth, eyebrows and eyes
Neuromuscular junction
Arrival of an action potential
Depolarisation of the presynaptic membrane
Opening of voltage gated calcium ion channels
The increase of intracellular calcium leads to the release of synaptic vesicles containing Acetylcholine
The post synaptic membrane of the muscle cell is highly folded to increase surface area therefore the number of Ach receptors
Binding of Ach receptors on ligand gated ion channels
Increase of potassium and sodium conductance via non-selective ligand gated ion channels
This leads to the generation of the end plate potential (EPP)
Leading to an action potential
Sliding filament model
Rise of intracellular calcium ions
Calcium ions bind to troponin which moves tropomyosin away from myosin binding sites on actin (this is called the cross bridge cycle)
Cross bridge formation
Power strokes where ADP is released from myosin and releases energy
Cross bridge detachment where ATP binds with myosin
Reactivation of myosin head (ADP + Pi)
Myosin = thick filaments
Actin = thin filaments
Types of muscle contraction
Isometric; the length of the muscle fibres stay the same as tension increases
Isotonic; tension remains the same and length of the muscle fibres stay the same
What is tropomyosin?
Regulatory protein which covers the actin myosin binding site in the absence of calcium
What is troponin
A regulatory protein and calcium ion sensor
What is titin
A structural protein which provides elasticity
