Anatomy of the Nervous SystemThe Nervous System

is the master controlling and communicating system of the body. CONTROLS and COORDINATES ALL ESSENTIAL FUNCTIONS of the Human Body. consists of the brain, spinal cord, sensory organs, and all of the nerves that connect these organs with the rest of the body.

Nervous System Physiology Functions of the Nervous System

1. Sensory nerves gather information from inside the body and the outside environment. The nerves then carry the information to central nervous system (CNS).

2. Integration . Sensory information brought to the CNS is processed and interpreted.

3. Motor nerves convey information from the CNS to the muscles and the glands of the body.

Two Major of the Nervous System *Central Nervous System *Brain*Spinal cord*Peripheral Nervous System*Cranial Nerves *Spinal NervesDivided into: * Somatic Division * Autonomic Division-Sympathetic-Parasympathetic

Nervous Tissue-made of principal kinds of cells:1.Neurons -aka nerve cells-transmit nerve impulses 2.Neuroglia-aka glial cells-supports & nourishes the neuronsa.Schwann cells-wraps the axon & dendrites in the PNS forming myelin sheathb. Oligodendrocytes -found only in brain & spinal cord-Nodes of ranvier-small gaps interrupts the myelin sheath.

3.Microglia

-CNS protection against various types of pathogenic factors 4. Astrocytes -’star cell’-provides framework for migrating neurons that will form the brain embryo. Synapses

- Gaps between the axon and dendriteSynaptic knob- terminalSynapses consist of: *presynaptic ending -where neurotransmitters are made*post synaptic ending -has neuroreceptors in the membrane*synaptic cleft- space between the presynaptic and postsynaptic endings-Action potentials cannot cross the synaptic cleft-Nerve impulse is carried by neurotransmitters

Structure of a Neuron A. CELL BODY -where the nucleus/organelles are found.B.DENDRITE short extensions that receives signalsC.AXON -conduct nerve impulses away from the cell body 3 basic classes of neurons*Afferent neurons-send impulses towards the CNS away from the PNS*Efferent neurons-carry signals from the CNS to the cells in the pePNS *Interneurons-lying entirely within the CNS

Nerves - a combination of axons and dendrites of several neurons along with blood vessels and connective tissue. Kinds of Nerves

Sensory- made of sensory neurons. Ex: optic nerves

Motor- made of motor neurons. Ex.autonomic nerves

Mixed –combination of sensory & motor neuron Ex. Peripheral nerves like the sciatic nerves in the legs

The Central Nervous System (CNS)-it controls the biological processes of our body and all conscious thought.

-consist of the brain and spinal cord-processing center for the nervous system- main “trunk line” is the spinal cord

- “control center” is the brain

Brain= 1.4 k (with CSF)=80g (without CSF)

Frontal Lobe- talk,move,reason out,plan & solve problem.-located at the front of the brain and is associated with reasoning, motor skills, higher level cognition, and expressive language

Parietal Lobe- body/skin sensation, pain perception, spatial- located in the middle section of the brain and is associated with processing tactile sensory information such as pressure, touch, and pain.Damage to the parietal lobe can result in problems with verbal memory, an impaired ability to control eye gaze and problems with language.

Occipital Lobe – processing & interpreting visual information- located at the back portion of the brain and is associated with interpreting visual stimuli and information.

Temporal Lobe- hearing & recognizing sound-located on the bottom section of the brain.

Gyri-bump (pl. gyrus)Sulci-line/groove (pl.sulcus)Fissure –gyri + sulciCentral fissure- aka Fissure of Rolando

a. Longitudinal fissure – It is the largest fissure; separates the cerebral hemisphere

b. Central fissure & Lateral Fissure - these fissures partially divide each hemisphere into four lobes: the frontal lobe, parietal lobe, temporal lobe, and occipital lobe.

PROTECTS THE BRAIN ALONG W/ THE SKULL

*Dura mater- hard mother-outermost part-tough, inflexible & leather-like-keeps the CSF

*Arachnoid mater – soft, attached to the inside of the dura & surrounds the brain & spinal cord

*Pia mater- innermost part-delicate, thin fibrous tissue that is impearmeable to fluid.

FOREBRAIN Thalamus- sensory & motor sys. ,switching

center Hypothalamus-eating, drinking, body

temperature, blood pressure, heart beat,sex-autonomic fxn, endocrine fxn,

motor fxn, food & water intake ,sleep-wake cycle

-responsible for controlling hunger, thirst, emotions, body temperature regulation, and circadian rhythms. The hypothalamus also controls the pituitary gland by secreting hormones, which gives the hypothalamus a great deal of control over many body functions.

Hippocampus- storing of memory Amygdala-fear, anger, other emotions Basal Ganglia- planning and producing movement Limbic system- involved in fighting, fleeing, feeding, sex

MIDBRAIN -smallest region of the brain that acts as a sort of relay station for auditory and visual information.-part when Parkinsons disease develop-controls the visual and auditory systems as well as eye movement.

Portions of the midbrain called the red nucleus and the substantia nigra are involved in the control of body movement.

The darkly pigmented substantia nigra contains a large number of dopamine-producing neurons are located. The degeneration of neurons in the substantia nigra is associated with Parkinson’s disease.

HINDBRAIN Cerebellum-

o Coordinationo Attentiono Postureo Estimating time

Reticular information- awake and alert, descending for autonomic nervous system

Medulla – breathing , swallowing, blood circulation

Pons- bridge between brainstem & cerebellum ,sleep control, facial muscles

NEUROTRANSMITTERS

Neurotransmitters are an essential part of our everyday functioning. While it is not known exactly how many neurotransmitters exist, scientists have identified more than 100 of these chemical messengers.

What effects do each of these neurotransmitters have on the body? What happens when disease or drugs interfere with these chemical messengers? The following are just a few of the major neurotransmitters, their known effects, and disorders they are associated with.

Acetylcholine: Associated with memory, muscle contractions, and learning. A lack of acetylcholine in the brain is associated with Alzheimer’s disease.

Endorphins: Associated with emotions and pain perception. The body releases endorphins in response to fear or trauma. These chemical messengers are similar to opiate drugs such as morphine, but are significantly stronger.

Dopamine: Associated with thought and pleasurable feelings. Parkinson’s disease is one illness associated with deficits in dopamine, while schizophrenia is strongly linked to excessive amounts of this chemical messenger.