Neural influences on exercise

Chapter 11

Neuromotor System Organization Neuromotor System Organization

• Central nervous system (CNS)– Includes the brain and spinal cord

• Peripheral nervous system (PNS) – Is comprised of cranial and spinal nerves

Major Neuron ClassificationsMajor Neuron Classifications• Motor (efferent) neurons

– Supply extrafusal and intrafusal skeletal muscle fibers

• Sensory (afferent) neurons – Transmit sensory information from peripheral sensory

receptors to the brain

Peripheral Nervous System Peripheral Nervous System

• Consists of 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal) and 12 pairs of cranial nerves

Neurotransmitters of the BrainNeurotransmitters of the Brain• Neurotransmitters-

chemical messengers• Synapse= gap between

nerves

Somatic Nervous System Somatic Nervous System

• Innervates (voluntary) skeletal muscle

• Somatic efferent nerve firing excites muscle activation

Autonomic Nervous System (ANS)

Autonomic Nervous System (ANS)

• Innervates smooth muscle (involuntary muscle) in the intestines, sweat and salivary glands, myocardium, and some endocrine glands

• Has two distinct divisions– Sympathetic – Parasympathetic

Sympathetic Nervous SystemSympathetic Nervous System• Sympathetic neurons

– Exit the spinal cord and enter a series of ganglia (sympathetic chain) near the cord

– Release norepinephrine

• Activated during flight-or-fight situations– Accelerates breathing and heart

rate – Dilates pupils– Helps redistribute blood flow

from the skin to deeper tissues in anticipation of a perceived challenge

Parasympathetic Nervous SystemParasympathetic Nervous System

• Parasympathetic nerve neurons – Release acetylcholine (cholinergic fibers)– Produce effects opposite of sympathetic fibers

ReflexesReflexes• Autonomic reflex

arc – Monosynaptic

reflex arc

– Polysynaptic reflex arc

• Complex reflexes – Crossed-extensor

reflex

• Learned reflexes

Reflexes• Sensory input• Transmission of

afferent impulses to spinal cord via sensory root

• Causes muscle fibres to contract

Sports reflexes

What happens in each of the players to enable them to catch the ball??

Muscle fibre types

All-or-None Principle All-or-None Principle

• If a stimulus triggers an action potential in the motoneuron, all of the accompanying muscle fibers contract synchronously

• A single motor unit cannot generate strong and weak contractions—either the impulse elicits a contraction or it does not

Lab manuals

• Must be to me by Friday– My office 3.11

• Or 10% penalty per day

• Special consideration

Prac break

• 3 weeks 2nd year prac

• 1 week mid semester break