Lecture 28- Muscle Tissue Flashcards
Three types of muscle tissue
Skeletal muscle- large cells that have striations and are under voluntary control
Cardiac muscle- found only in heart, small striated cells under involuntary control
Smooth muscle- found in walls of hollow organs , small elongated unstriated cells under involuntary control
Muscle functions
Muscles produce movement by acting on bones of the skeleton, pumping blood, forming valves or propelling substances through hollow organs.
Muscles aid in maintaining posture by adjusting the position of the body with respect to gravity.
Muscles stabilize joints by exerting tension.
Muscles generate heat as a function of their
metabolic processes.
Muscles enclose and protect internal organs.
4 Characteristics of muscle tissue
Excitability- the ability to receive and respond to a stimulus.
Contractility- the ability to contract forcibly when stimulated.
Extensibility- the ability to be stretched.
Elasticity- the ability to resume the cells’ original length once stretched.
Endomysium
Surrounds each muscle fibre (skeletal muscle cell)
Perimysium
Surrounds group of muscle fibres (skeletal muscle cells)
Epimysium
Surrounds whole muscles
Each muscle is an organ true or false?
True
What is muscle made up of
Muscle fibres
Blood vessels
Nerves
Connective tissue
Fascia
Supports and surrounds muscle
Muscle Insertion
More movable attachment
Muscle Origin
Less movable attachment
Direct muscle attachments
Epimysium fuses with periosteum or perichondrium
Indirect muscle attachment
Connective tissue wrappings of muscle extend into rope like structure that attaches to bone,cartilage, or fascia
Most common
Skeletal muscle fibres
Large cylindrical cells with multiple nuclei beneath the sarcolemma or plasma membrane
Sarcoplasm
Cytoplasm of muscle cell
Large amounts of glycosomes for glycogen storage
Large amounts of myoglobin, an oxygen binding pigment similar to hemoglobin
When do muscles function aerobically
When there is adequate oxygen and nutrient delivery
What produces creatine?
Skeletal muscles
Cardiac muscle cells
Brain neurons
Direct phosphorylation
Coupled reaction of creatine phosphate and ADP
no oxygen required
1 creatine phosphate produces 1 ATP
Anaerobic pathway
Glycolysis and lactic acid formation
No oxygen required
1 glucose produces 2 ATP and 2 lactic acid
Aerobic pathway
Aerobic cellular respiration of glucose, pyruvic acid, free fatty acids from adipose, amino acids from protein catabolism
Oxygen is required
1 glucose produces 30-32 ATP, CO2 and H2O
Lactic acid fermentation
If oxygen is not available pyruvate converts into lactic acid.
This pathway produces only about 5% the ATP from each glucose, but ATP production occurs 21⁄2 times faster.
Most of lactic acid produced is released to the bloodstream and taken to the liver, heart, or kidneys for use, but lactic acid that remains in the muscle contributes to soreness after exercise.
Glycolytic muscle
Relatively few blood vessels and good for short bursts of intense activity
Oxidative muscle
Has abundant blood vessels and mitochondria for prolonged use
Slow oxidative fibres
contract slowly but are very resistant to fatigue. They are used for things like standing and posture.
Fast oxidative glycolytic fibres
are moderately resistant to fatigue but can also use anaerobic glycolysis. They are used for walking and sprinting.
Fast glycolytic fibres
have few mitochondria and few blood vessels. They are good for short anaerobic motions like lifting and throwing. Most muscle building occurs in these fibres.
