Anatomy - Unit 9

• 1. MOVEMENT
• 2. STABILITY
• 3. CONTROL OF OPENINGS
• 4. HEAT PRODUCTION
• 5. COMMUNICATION

• 1. EXCITABILITY
• 2. CONDUCTIVITY
• 3. CONTRACTILITY
• 4. EXTENSIBILITY
• 5. ELASTICITY

to create action potential

to conduct an action potential. So it can spread through the cell

can shorten/contract

ability to stretch between contractions

tendency to return to the original length when tension is released.

• 1. SKELETAL MUSCLE
• 2. SMOOTH MUSCLE
• 3. CARDIAC MUSCLE

• Attached to bones
• Striated appearance
• Voluntary control
• Results in bodymovement/ balance

• Blood vessels, glands, airways, digestive/ urinary/ reproductive tracts
• Non-striated
• Involuntary
• Results in internal organ movement & glandular
• secretions

• Only in the heart
• Less pronounced striations; Intercalated discs
• Involuntary

1 somatic efferent neuron + many muscle fibers

Action Potential travels down neuron → terminal/ synaptic knob → opens voltage-gated CA++ channels → Ca++ enters → exocytosis of synaptic vesicles that contain ACh → ACh released into synaptic cleft → ACh binds Rc's on muscle cell→ opens Na+ channels → Na+ in: depolarization (local potential) to threshold → Action Potential on sarcolemma [voltage-gate Na+ & K+ channels] → AP travels into T-Tubules → Activates SR to release Ca++ → Ca++ bind troponin → tropomyosin moves → Actin & myosin can bind Myosin head takes ATP → Myosin head goes into high energy position. ADP + Pi (Tri- to Di- + one p) → Myosin (hi energy) binds Actin → Myosin releases ADP & Pi and returns to low energy position. called “Power Stroke”→ Sarcomere shortening /muscle contraction → Myosin binds ATP → releases Actin

• 1. Creating High-Energy position of myosin cross-bridge so it can bind actin
• 2. Releasing myosin cross-bridge from the actin once the power stroke has occurred
• 3. Pumping Ca++ back into the SR once contraction is over

• needs oxygen and glucose
• high activityEndurance
• Most efficient & highest yield of ATP: one cycle gives 36 ATP.

• medium activity
• No O2 present
• Low yield of ATP & Lactic Acid by-product 2 per cycle.

• low activity
• Phosphate storage molecule
• Gives up phosphate molecule to ADP → ATP Used in short bursts of energy (100 m dash)

• Aerobic Metabolism
• Anaerobic Metabolism
• Creatine Phosphate

Decrease in muscle mass due to decreased activity

Increase in muscle mass due to increased activity

Increase protein synthesis in musclesResults in hypertrophied muscles

is a natural steroid found in higher quantities in males that results in larger muscle mass in males vs. females

• weakness.
• Loss of muscle contractility due to prolonged use of muscle.
• Caused by low ATP, build up of lactic acid which lowers enzyme ability.
• Neurons can run out of ACh. CNS can get tired of stimulating.

Create muscle tension, but do not change length of muscle

Result in changing length of muscle and movement

• Duchenne's
• Sex-linked recessive disease
• Lack muscle protein DYSTROPHIN
• Muscles degenerate, weaken, & atrophy
• Replaced by fat & scar tissue

• Autoimmune disease
• Antibodies against ACh receptors in NM Junction
• Muscles are less sensitive to ACh & become weakened

• Irritation of the tibialis anterior muscle
• Caused by overuse without conditioning

• AKA pulled muscle
• Excessive stretching of a muscle due to overuse/abuse

cell membrane

• Cytoplasm
• multiple nuclei
• glycogen - sugar
• myoglobin
• t-tubules.
• SR

• infoldings of sarcolemma.
• Tell SR when to release Calcium

smooth ER of the muscle fiber - stores calcium

bundles of proteins inside the muscle fiber made of myofilaments

• thick
• thin

made of 1000's of myosin

• made of two beaded strands. Each contain:
• Actin
• Troponin: binds calcium
• Tropomyosin: blocks actin from myosin

• dark
• thick and thin
• h-band

• light
• thin only
• z-line

• lighter
• in the middle
• no thin

connect thin