Chapter 11 Ex Phys

Brain and spinal cord

Cranial nerves and spinal nerves

Medulla oblongata, pins, midbrain, cerebellum, diencephalon, telencephalon

Occipital, parietal, temporal, frontal

33 vertebrae, separated by intervertebral discs

3 types of nerves: interneurons, sensory, and motor

Transits impulses downward through the spinal cord

Originates in the brain stem and connect all levels of the spinal cord

31 pairs of cranial nerves (8, 12, 5, 5, 1) and 12 pairs of cranial nerves.

Afferent and efferent neurons

Has somatic and autonomic nervous systems

Epinephrine, norepinephrine, serotonin, histamine, dopamine

Short chain amino acids, endorphins

Monoamines, neuropeptides, nitric oxide

Innervates skeletal muscle, somatic efferent nerve firing excites muscle activation

Maintains constancy in the internal environment. Includes both the sympathetic and parasympathetic nervous systems

Fight or flight response

Rest and relax

420,000 nerves and 250 million fibers. One nerve supplies numerous fibers

Less complex movements have more fibers while more complex moves have more neurons

Less precise movements: 3000 fibers to 1 neuron

Complex movements: 10 fibers to 1 neuron

Contain myelin sheath that insulate and increase rate of impulse transmission

Gap between swann cells that is not covered in myelin which allows for depolarization along the axon

Skeletal muscle fibers and corresponding innervating motor neuron

Functional unit of movement

Each muscle contains many motor units, all attached to one neuron with many fibers

Cell body houses the control center

Axon extends from cord and delivers message to the fibers

Dendrites receive impulses

Myelin sheath

Schwann cells

Provides interface between the end of a myelinated motor neuron and muscle fiber, transmits nerve impulses to fiber,

Twitch: response to single electrical pulse, some units are high Twitch, while others are slow and others are intermediate

Tension: different amounts of tension are made because of several factors.

All or none principal, graduation of force principal, level of motor unit recruitment patterns

All muscle fibers will fire or none will. They wait until the threshold is met

The force of muscle action varies from slight to maximal in one of two mechanisms

Increasing number of motor units recruited or frequency of motor unit discharge

Process of adding Motor units to increase muscle force. Size principle: motor neurons with large axons become recruited as muscle force increases.

The decline in muscle tension or force capacity with repeated stimulation over a given time period.

Specialized sensory receptors that are sensitive to stretch, tension, and pressure in the muscles, joints, and tendons.

Relay critical information about muscular dynamics, limb position, and proprioceotion to conscious and subconscious portions of the central nervous system

Provide mechano-sensory information about changes in muscle fiber length and tension

Connect in series of extrafusalfibers and also are located in ligaments of joints to primarily detect differences in muscle tension rather than length

Comprises the functional unit of the muscle cell. Actin and myosin filaments provide mechanical mechanism for muscle.

Center of A band contains H zone which is a region of lower density. The M line bisects the central portion of the H zone. It contains the most protein structures

Muscle fibers shorten or lengthen because thick and thin myofilaments glide past each other without the filaments themselves changing length

The globular head of the myosin crossbridge provides the mechanical power stroke for action and myosin filaments to glide past each other. During muscle activation, each cross bridge undergoes repeated independent cycles of attachment and detachment to actin

Rapid action potentials

High activity level of myosin ATPase

Rapid rate of calcium release

Generate rapid cross bridge turn over

Exhibits fast shortening speed and a moderate capacity for energy transfer from both anaerobic and aerobic sources.

Represents fast-oxidative-glycolitic fibers

Greatest anaerobic potential and most rapid shortening velocity.

Represents fast-glycolitic fiber

Generate energy for ATP resynthesis by aerobic energy transfer. Low activity level of ATPase, slow contraction speed, lower glycolitic. Resist fatigue