Ch.10-11 muscular system Flashcards
What are the 3 types of muscle tissue
- Skeletal muscles
- associated with bones
- Smooth Muscle
- visceral organs (liver, stomach ect)
- Cardiac muscle
- heart muscle
Describe the characteristics of skeletal muscle tissue
- undergoes voluntary contractions due to concious control by CNS
- somatic nervous system
- muscle cells called muscle fibers
- striated muscles (under microscope)
- light and dark bands alternate
- multinucleated, large cylindrical cells
What are the functions of skeletal muscles?
- Motion
- gross and fine movements involving most of the body or localized function
- relies on integration between bones, joints, and skeletal muscles
- Stabilize Body positions
- postural skeletal muscles
- provide sustained contraction while awake to stabilize joints and maintian body position
- Movement of Substances
- moves blood in veins and lymph back to heart
- swallowing initially involves a contraction of skeletal muscles
- Thermogensis
- muscles generate heat when glucose is oxidized by mitochondria in muscle fibres to produce atp
- shivering is a form of thermogensis
How are skeletal muscles fibers stimulated?
by neurotransmitters from motor neurons to contraction
Describe the gross anatomy of muscle fibers
- Skeletal muscles
- Fascia
- Tendons
What do skeletal muscles consist of
- muscle cells
- neurons and sensory receptors
- connective tissue coverings
- blood vessels
- lymphatic vessels
Describe Fascia
- covers muscles
- sheets of dense irregular connective tissue
- 2 types of fascia
- Superficial
- Deep
Describe superficial fascia
seperates the muscle from skin
Describe deep fascia
surrounds muscle to hold it in place
Describe tendons
- cords of connective tissue attach muscle to bone
Describe ligaments
Cords of Connective tissue connect bone to bone
Describe the microscopic anatomy of muscle cells
- Muscle fibers
- Facicles
- Sarcolemma
- Mitochondria and nucleus
- pushed to edge of cell
- Sarcoplasmic reticulum
- Myofibrils
- filaments
- Sarcomeres
Describe muscle fibers
Individual muscle cells
Describe fascicles
bundles of mucle cells/fibers that are grouped together
Describe Sarcolemma
plasma membrane covering for the muscles
Describe sacrcoplasmic reticulum
key organelle in muscle cells that store calcium ions needed for contraction
Describe microfibrils
- cytoplasm of muscle cells
- full of proteins arranged in threadlike cylinders
Describe Filaments
- provide a striated appearance of muscle cells
- Thick filaments
- composed of protein myosin
- thin protein
- composed of the protein actin
Describe sacromeres
basic functional units of striated muscle fibers in a repeated arrangement of filaments
What is the neuromuscular junction
- synapses between a motor neuron and a skeletal muscle fiber
- typically at the midpoint of a cell
- site of an action potential
What is an action potential
nerve impulse from neuron, transmits an electrical impulse indirectly to a cell without touching it
What are neurotransmitters
- chemicals that are released from synaptic vessels of the synapic end bulb and are diffused across the synaptic cleft
What is the name for the neurotransmitter that is released by muscle?
Acetylcholine
What is the specialized region of the muscle cell membrane associated with the neuromuscular junction
- motor end plate
- possesses receptors for acetylcholine
Describe the simplified steps required for a muscle contraction
- action potential travels along axon and the neuromuscular junction
- acton potential triggers release of acetylcholine from synaptic end bulb of axon
- Acetylcholine diffuses across synapic cleft to bind receptors on the cell membrane of muscle fibers
- this triggers action potential in teh muscle fibers which release calcium ions from the sarcoplasmic reticulum, which leads to contraction
- energy as ATP is required for contraction
What are the energy sources for skeletal muscle
- Free ATP
- Creatine Phosphate Stores
- Glycogen Stores
- Blood Glucose
Describe Free ATP
- found in cytosol of muscle cell
- can supply contractions for approximately 2 seconds
Describe creatine phosphate stores
- Stores excess ATP in muscle cells as creatine phosphate in relaxed muscles
- can supply the cell for approximately 13 seconds
Describe Glycogen stores
- utilized during anaerobic cellular respiration
- supplies cells for 30-40sec
- lactic acid is a biproduct
Describe blood glucose as an energy source for skeletal muscle
- delivered by cardiovescular system
- used during areobic cellular respiration
- used for prolonged activity
- requires oxygen
What attaches muscle to bone?
Tendons
Define origin of a muscle cell
- attachment to stationary bone
- usually the proximal end of the bone
Define Insertion of muscle
- muscle Attachment point to the moveable bone
- usually distal end of the bone
Define Belly
Portion of muscle between tendon or insertion and origin