NERVOUS SYSTEMNervous system !!!

The nervous system begins pre-natally…

It eventually develops into the spinal chord with a specialized extension, the brainstem

The posterior portion of brain stem develops the more specialized cerebellum, and the anteriorDevelops the cerebral hemispheres

THE CENTRAL NERVOUS SYTEMComprises two parts: the brain and spinal chordEncased in bone for protection. In addition, Cerebrospinal fluid circulates inside and around the brain for additional protection

Brain – the organ that directly controls our thoughts,

emotions and motivations.Spinal cord – a series of interconnected neurons Extending from the brain to the center of the back.It carries information to and from the brain

the two directional communication in the nervous system involves two different kinds of nerves and neurons…..

Receptors – are structures designed to receive sensory information from the outlyingNerves of the body and transmit that information back to the brain thru the spinal chord

Effectors – transmit motor information about how the body should act in response to theInformation it receives that usually comes from the brain

The Peripheral Nervous System

Comprises all of the nerve cells except those of the brain and the spinal cord.The primary job of the PNS is to relay information between the CNS and the receptorsAnd effectors lying outside the CNS.

The PNS connects with the receptors in both our external sensory organs and our Internal body parts.

it connects with the effectors that produce Movement, speech and so on.

The PNS comprises of two main parts:

Somatic nervous system – controls quick and conscious movement of skeletal

muscles. these muscles are attached directly to the bone and allow us to move. We have voluntary control over the muscles served by the somatic system

Autonomic nervous system – controls movement of our non skeletal muscles (heart and smooth muscles). The smooth muscles include those of the blood vessels and the internal body organs

the Autonomic system is divided into two parts…..

Sympathetic nervous system - is concerned primarily with ‘catabolism,’ the process by which your body captures

stores, and uses energy and materials from food and eliminate wastes

Parasympathetic nervous system – concerned with ‘anabolism,’ the process that stores energy in the body.

These two systems tend to work in tandem….

T h e b r a i nStructures and functions

forebrain-Located toward the top and front of the brain - comprised of two parts: the telencephalon and diencephalon

Telencephalon:- three parts

~ the cerebral cortex (outer layer of cerebral hemisphere)plays vital role in our thinking

~ the basal gangliaa collection of nerves crucial to motor functions

~ the limbic systemimp. to emotion, motivation and learning. Comprises of3 interconnected cerebral structures

a. hippocampus- plays an essential role in the formation of memories

b. amygdala- plays a role in anger and aggression

c. septum- involved in anger and fear

Diencephalon- between the telencephalon and midbrain- comprises the thalamus and hypothalamus

Thalamus- relays incoming sensory information thru projection fiber to the appropriate region in the cortex

Hypothalamus- involved in water balance in tissues and bloodstreams. It controls much of the autonomicnervous system and endocrine system

also involved in temp. regulation. interacts with and is sometimes viewed as part of the limbic system

therefore involved in behavior related to survival : fighting, feeding,fleeing, mating.

hypothalamus

the main source of control for visual and auditory Information. The reticular activating system of the midbrainRegulates state of consciousness, including sleep, wakefulnessArousal, and attention, as well as breathing and heartbeat

Midbrain

hindbrain

Most rearward portion of the brain

1.Medulla oblongata- part of the reticular activating system helps control heartbeat, breathing,

swallowing, digestion

2. pons- serve as a kind of relay station for signals passing from one part of the brain to another.

3. cerebellum- involved in bodily coordination, balance,andmuscle tone.

fin