Physiology of Exercise

important in initiating movement od sustained and repetitive nature

ex: arm swinging during walking

Thalamus: important for sensory integration. Regulates what sensory input reaches the conscious brain and is very important for motor control.

Hypothalamus: responsible for maintaining homeostasis by regulating almost all processes that affect body's internal environment

• crucial role in coordinating movement
• Assists function of primary motor cortex and basal ganglia
• Facilitates movement patterns by smoothing out movement

• Composed of midbrain, pons, and medulla oblongata
• Connects the brain and spinal cord
• Contains the major autonomic centers that control respiratory and cardiovascular systems

• Lowest part of brain stem
• Composed of tracts of nerve fibers that allow 2-way conduction of nerve impulses
• Sensory (afferent) fibers carry neural signals from sensory receptors (skin, muscles, joints) to upper levels of CNS
• Motor (efferent) fibers from the brain and upper spinal cord transmit action potentials to end organs (muscles, glands)

• Contains 43 pairs of nerves: 12pairs of cranial nerves & 31 pairs of spinal nerves

Sensory Division 

Motor Division

continuously convey info to CNS concerning body’s constantly changing status, position and internal/external environment

Receives info from five primary types of receptors

1. Mechanoreceptors: respond to mechanical forces such as pressure, touch, vibrations, or stretch
2. Thermoreceptors: responds to changes in temperature
3. Nociceptors: respond to painful stimuli
4. Photoreceptors: respond to electromagnetic radiation (light) to allow vision
5. Chemoreceptors: respond to chemical stimuli, from food, odors, change in blood or tissue concentrations of substances like oxygen, carbon dioxide, glucose and electrolytes

Once CNS processed info receives from sensory division, it determines how body should respond to input.

• Controls the body’s involuntary internal functions (heart rate, blood pressure, lung function)

Sympathetic Nervous System

Parasympathetic Nervous System

Fight or Flight

Rest & Digest

Causes decresed heart rate, constriction of coronary vessels, and bronchoconstriction

• Sensory stimulus is received by sensory receptors
• Sensory action potential is transmitted along sensory neurons to CNS
• CNS interprets the info and determines which response if most appropriate or reflexively initiates a motor response
• The AP for response are transmitted from CNS along a-motor neurons
• The motor AP is transmitted to a muscle, and response occurs

preprogrammed response

•  group of specialized muscle fibers found between regular skeletal muscle fibers referred to as extrafusal (outside the spindle)
• Consists of 4-20 small specialized intrafusal (inside the spindle) fibers and the nerve ending, sensory and motor associated with these fibers

control intrafusal fibers

extrafusal fibers

• Encapsulated sensory receptors through which a small bundles of muscle tendon fibers pass
• Trigger a reflex that inhibits contraction if tendon fibers are stretched from high muscle tension 

composed of the rain and spinal cord

divided into sensory (afferent) nerves and motor (efferent) nerves

responsible for informing the CNS about what is going on within and outisde the body

are responsible for sending information from the CNS to various tissues, organs, and systems of body in response to signals coming in from sensory division.

composed of two parts, the autonomic nervous system and somatic nervous system. 

basic structural unit of nervous system.

• cell body- contains nucleus
• dendrite- many in one neuron- neurons receivers
• axon- only one axon in neuron

axon splits ino numerus end branches which go into tiny bulbs known as this

used for communication between a neuron and another cell.

 electrical signal that arises when stimulus is strong enough to substantially change the normal electrical charge of the neuron

electrical potential difference caused by uneven separation of charged ions across membrane. -70mV

1. Cell membrane is mre permeable to K+ than to Na+ , so K+ moves more freely

2. Sodium-potassum pumps in neuron membrane, which contain Na+-K+ adenosine triphosphatase, maintain imbalance on each side of membrane by actively transporting potassium ions in and sodium ions out. 

occurs any time the charge difference becomes more positive than the RMP -70mV, moving closer to zero. 

charge difference across membrane increases, moving from RMP to even more negative value, then membrane becomes more polarized

membranne potential changes from RMP about -70mV to value about +30mv and then rapidly returns to resting value. Lasts about only 1ms

membrane voltage which graded potential becomes an action potential

Any depolarization that does not reach threshols will not result in action potentiall but any time depolarization reaches or exceeds threshold, action potential will result. 

when segment of axons sodium gates are open and in process of generating action potential, unable to respond to another stimulus. 

axons of many nerons covered with sheath formed by myeln, a fatty substance that insulates the cell membrane.