Anatomy & Physiology part 2

Action Potential

Action Potential

• purpose of the action potential is to conduct nerve impulses and send information

• neuron starts positive on outside, negative on inside

• sodium (Na+) rushes into neuron, depolarizing the interior, changing to positive charge inside

• action potential moves down the neuron as more ion channels open and let sodium in

• after action potential passes, cell resets to resting potential

Synapses

• neurotransmitter - chemical messenger released by axon into synaptic cleft

• ion channel - gates in next neuron that open and allow ions like sodium to rush in

• synaptic cleft - space in between two neurons

Brain Structure and Function

• cerebral cortex - control voluntary skeletal muscle, intellectual and emotional processing

• thalamus - relays impulses to cerebral cortex

• hypothalamus - regulation of autonomic nervous functions, regulates temp, water balance, food

• limbic system - mediates emotional response

• medulla oblongata - relays sensory input, controls HR, respiratory rate

• cerebellum - smooths skeletal muscle movements, regulates balance and posture

Muscular System

• movement

• maintain posture

• stabilizing joints

• generating heat

• control/regulation

Sliding Filament Model - model of muscle contraction

• calcium - activates binding sites on actin filament

• myosin - protein with head that attaches to actin and performs power stroke (thick filament)

• actin - protein that myosin head pulls in power stroke, causing muscle to shorten (thin filament)

• sarcomere - basic unit of muscle contraction, shortens as actin filaments are pulled toward center