nerves presentation pt. 2

Jennie May & Yasmin Ali

Nerves Presentationpt. 2

Coordinates the activities between the various parts of the human body.

The central nervous system includes: Brain

Controls movement, sensation, thinking, memory, speech. (In depth detail of brain will be further on)

Spinal Cord Transmits messages back and forth between

the brain and peripheral nerves.

Central Nervous System

Transfers information to and from the CNS. It also regulates movement and internal environment.

The cells that carry to the CNS are called sensory nervous cells, and those carrying from are called motor nervous cells. And these cells send information due to internal organs or external stimuli.

Peripheral Nervous System

“Left–Right pairs of cranial and spinal nerves with their associated ganglia”

Cranial NervesEmerges from or enters the BrainSensory, motor or mixed nerves. Humans have

12 pairs. Spinal Nerves

Originate in spinal cord and extend below the head.

Consists of all mixed nerves. Humans have 31 pairs.

PNS Structure

Motor Neuron Cells carry the information from the CNS to organs, muscles, and glands.

Motor Neuron cells are divided into two subcategories which are Somatic Nervous System and Automatic Nervous System.

Motor Neuron

It controls :the skeletal muscles and carries to and from

the skeletal muscle due to external stimuli. sensory organs such as the skin.

The Somatic Nervous system is voluntary with exception to reflex reactions.

Somatic Nervous System

Regulates internally through the smooth and cardiac muscles as well as organs of the digestive ,cardiovascular, etc.

This is an involuntary control unlike Somatic. This also carries some exceptions such as the

diaphragm (breathing), bladder muscles, and heart rate, which can all be controlled.

It is further divided into three subsections: Sympathetic DivisionParasympathetic DivisionEnteric Division

Autonomic Nervous System

Sympathetic DivisionControls activities for increased energy generation. Ex:

Flight or Fight. These nerves increase heart rate, dilate pupils, and relax the bladder.

Parasympathetic DivisionServes as the opposite and decreases heart rate,

constricting pupils, and contracting the bladder. These nerves are more for activities that control energy expenditures.

Enteric Division Networks of Neurons in digestive tract, pancreas, and

gallbladder. These nerves can be controlled independently, but are usually regulated by the Parasympathetic and Sympathetic Division.

Autonomic Nervous System Divisions

http://www.youtube.com/watch?v=dOYOdJG0E0s

They are used to respond to stimuli. They help process information from the environment.

Focused more on where the action potentials go rather than what triggers them.

Sensory Reception is the detecting of a stimulus by cells which are called sensory receptors.

Receptors

• Classification–Exteroreceptors•Outside the body–Heat, light, pressure

– Interoreceptors• Inside the body–Blood pressure, body position

Sensory Receptors

MechanoreceptorsTouch, pressure, gravity, stretch, movement

Chemoreceptors Taste and smell

PhotoreceptorsAbsorb light

ThermoreceptorsTemperature changes

ElectroreceptorsElectric stimuli

Sensory Reception

Sensory Transduction Stimulus energy converted into change in

membrane potential.Receptor Potential: The change in membrane

potential Graded potentials via the magnitude and strength

of the stimulus. Results from the opening and closing of ion

channels in the plasma membrane Amplification

Increasing the stimulus energy in sensory pathways

Function of Sensory Receptors

Transmission Identical action potentials (the magnitude

affects the frequency)Integration

Processing of the sensory information Adaptation: decrease in responsiveness to

repetitive stimuli Pain and touch receptors

Function continued…