Chemistry of Muscle Contraction

• _______ is the energy source for actin and myosin to contract. – Produced by the many _____________.

– ATP that has become ADP can recharge back to ATP when creatine phosphate (CP) splits and donates a phosphate.

– Glucose and oxygen are also needed for contraction. • Stored in form of glycogen and myoglobin for aerobic metabolism.• Anaerobic metabolism produces __________ acid

Heat Production• Muscular activity is one of the major heat-generating

mechanisms that the body uses to maintain its temperature.• Shivering (small spasms of contraction) helps to prevent

hypothermia

Cardiac Muscle

• Also known as ______________ due to lack of conscious control ________________ and _______________ due to microscopic appearance– Contain myofibrils

• Only found within the heart (walls) • Much smaller than skeletal muscles cells and only

contain one nuclei per cell • Are longer than wide and have multiple branches

forming a network of cells.

– Contain _________ _________- gap junctions where cells attach one to another.• Transmit impulses from cell to cell.• This allows entire groups of cells to

contract together at the same time.• Dark, transverse

Physiology of Cardiac Muscle

• No external nerve stimulation required to contract.

– Rate and rhythm of contraction is due to (SA node) _______ ______ (pacemaker) of heart located in the wall of the right atrium.

– Impulse follows a controlled path through the conduction system of the heart.

• Groups of cardiac muscle cells that touch adopt the contraction rate of the most rapid cell.

• Cardiac cells contract in rapid, wavelike fashion down a controlled path.– This helps to squeeze blood out of

chambers of the heart

Nerve Supply of Heart

• Heart rate is modified by Autonomic Nervous System– Sympathetic and Parasympathetic Nervous

Systems

1. Sympathetic fibers stimulate heart to beat harder and faster as part of "fight or flight response”

2. Parasympathetic fibers inhibit cardiac function, causing heart to beat more slowly and with less force, part of “feed or breed” response.

Smooth Muscle

• Also known as ______________ due to lack of conscious control ________________ and _______________ due to lack of striations.

• Found in two forms:– _________________ smooth muscle

• Large sheets of cells in the walls of some hollow organs

– _________________ smooth muscle• Small, discrete groups of cells make delicate

movements.

Smooth microscopic muscle anatomy

• Small with single nucleus.

• Actin and myosin are present, but are not arranged in parallel.

– criss-cross cell and are attached to __________ bodies that are similar to Z lines of skeletal muscle.

– Cell balls up as it contracts

Visceral Smooth Muscle

• Found in walls of many soft internal organs that are known as viscera.

• Instead of fine movements, work in waves of motion.

• Does not need external stimulation.– If stretched, will contract more

strongly.

• __________ nervous system decreases activity, __________ nervous system increases activity

Multiunit Smooth Muscle

• Individual cells or small groups of cells that produce fine and delicate movements– Ex: blood vessel walls, within

the eye, small airways

• Also under influence of the autonomic nervous system