Noteworthy Nervous System Part 1 The Basics Divided

Noteworthy Nervous System Part 1 --The Basics

Divided into 2 Structural Systems § 1. Central Nervous System (CNS) § Made up of Brain and Spinal Cord § 2. Peripheral Nervous System (PNS) § Made up of Spinal and Cranial Nerves

3 Types of Nervous Cell Tissue § 1. Neurons § 2. Supporting Cells --called Neuroglia (means nerve glue) § 3. Nerves

Nerve § A bundle of neurons and connective tissue.

Nerve Function Classification § **Based on the direction of the nerve impulse (sending of messages) to the CNS** § Sensory: From sense organs to CNS (informers) § Motor: Impulses from CNS to muscle, glands (doers) § Association (integration): Connect sensory and motor (may have many of these in the chain)

Closer Look at Nervous Tissue § A. Neurons § Function: To Transmit electrical and chemical messages § Don’t Reproduce § Made up of a cell body, nucleus, and 2 processes § 1. Axons: Take messages away from the cell body § 2. Dendrites: Take messages toward the cell body

B. Supporting Cells § Functions: Support, Insulate, Protect § Can Reproduce § Collectively called neuroglia--”nerve glue”

6 KINDS OF SUPPORTING CELLS § 1. Astrocytes § 2. Microglia § 3. Ependymal § 4. Oligodentrocytes § 5. Schwann cells § 6. Satellite cells

Astrocytes § Anchor the neurons to blood supply

Microglia § They are Phagocytes that get rid of debris such as dead brain cells and bacteria Neurons stained blue, astrocytes: red and microglia: green

Ependymal § Circulate brain fluid

Oligodendrocytes § Form fatty, insulating covering around nerves of CNS, called myelin sheath)

Schwann cells § Same thing as oligodendrocytes except they are in the Peripheral nervous system not the CNS

Satellite Cells § Act as protective cushioning cells.

Physiology: 3 Basic Functions of the Nervous System § 1. Monitors changes inside and outside the body (this information is called sensory input) § 2. Interprets the sensory input and makes decisions (integration) § 3. Responds by activating muscles, or glands (the response is called the motor output)

Simply Put: 3 Basic Activities of the Nervous System § Take in Sensory Input, § Integrate it, § and Respond.

Examples…. . §Monitor: Sensory Input: See a red light §Interpret: Integration: red means stop §Make decision: Respond: put foot on brake

Noteworthy Nervous System Part 2 --Fun Fun Physiology

Irritability § Ability to respond to a stimulus and convert it to a nerve impulse

Conductivity § Ability to transmit the impulse to other neurons, muscles, or glands

I. Irritability (Electrical) § A. Polarized § Resting or inactive cell § Fewer positive ions inside the cell than outside § Inside is negative, compared to Outside. which is positive

I. Irritability (Electrical) § B. Stimulation § Light excites the eye receptors § Sound excites the ear’s receptors § Pressure excites the cutaneous receptors § Neurotransmitters (chemicals) excite other neurons

I. Irritability (Electrical) § C. Depolarization § Stimulation causes “sodium gates” to open § High concentration of sodium outside, so it rushes in § Now inside is more positive, outside is more negative § Action Potential (Nerve impulse)

I. Irritability (Electrical) § Repolarization § Permeability changes: § Impermeable to sodium § Permeable to potassium

Repolarization (cont. ) § After repolarization, Sodium and Potassium concentrations are restored using a protein pump (ATP)

II. Conductivity (Chemical) § Neurons don’t touch!! They meet the Synaptic Cleft (Synapse)

II. Conductivity (Chemical) § Neurotransmitters--Chemicals that diffuse from one neuron to the next and bind on receptors § If enough neurotransmitter, the whole series of events happens again § Neurotransmitter is cleaned up

Noteworthy Nervous System Part 3 --Rockin’ Reactions and Reflexes

I. Reactions § Voluntary responses to stimulation from the environment § Requires time § Visual: . 25 sec § Hearing: . 17 sec § Touch: . 15 sec

II. Reflexes § A. Characteristics: § Take place without conscious control (often skip brain) § Quick § Purposeful and Involuntary § Always the same (predictable)

II. Reflexes § B. Types § 1. Autonomic Reflexes § Regulate smooth muscles, heart, and glands § EX. Secretion of saliva, change in pupil size (pupillary), digestion, elimination, blood pressure, sweating

II. Reflexes § B. Types § 2. Somatic Reflexes § Regulate skeletal muscles § EX. Knee jerk (patellar), Pulling away from hot stove

II. Reflexes § C. How They Work § 1. Sensory neuron reacts to stimulus § 2. Interneuron in brain or spinal cord reacts § 3. Motor neuron stimulates effector organ

Bravo! For the Bodacious Brain

What’s 3 lbs, pinkish-gray all over, wrinkled like a walnut, and has the texture of oatmeal?

I. Cerebral Hemispheres § Paired (left and right) § A. Anatomy § Gyri and sulci: elevated ridges and shallow grooves § Fissures: deep grooves, separated large regions of the brain § Lobes: sections named after the bones near them

A. Anatomy (cont) § *CORPUS CALLOSUM § Very large nerve tract, connects the two hemispheres, allows the two hemispheres to communicate

B. Functions § Interprets sensory § § § information Initiates voluntary muscle movements Stores information (memory) Uses memory for reasoning Emotion consiousness

II. Diencephalon (interbrain) § Located between cerebral hemispheres and above the midbrain § A. Thalamus: crude recognition of pleasant and unpleasant

B. Hypothalamus § “under the thalamus” § Regulates body temperature, water balance, metabolism, center for emotion (limbic system) § Thirst, appetite, sex, pain, pleasure

B. Hypothalamus (cont) § Pituitary: § Secretes lots of hormones “master gland” § Mammilary bodies: § Reflex center for smell (olfaction)

C. Epithalamus § Pineal Body § Regulates day and night cycles § Choroid plexis: § Knots of capillaries that make cerebrospinal fluid

III. Brain Stem § A. Midbrain § Corpora Quadrigemina § Reflex center for vision and hearing § B. Pons § Regulates depth and rate of breathing

III. Brain Stem § C. Medulla Oblongata § Merges into the spinal cord § Controls heart rate, blood pressure, breathing, vomiting § All nerve fibers connecting brain and spinal cord go through it

IV. Cerebellum § Looks like cauliflower § Precise timing for skeletal muscle activity § Controls balance and equilibrium

V. Protection…. Meninges § A. Dura Mater § “tough or hard mother” § Double layer, one attached to inner surface of skull § Blood vessels

V. Protection…Meninges § B. Arachnoid Mater § “spider”, looks like spiderwebs § Surrounds spinal cord § No blood vessels

V. Protection…Meninges § C. Pia Mater § “gentle mother” § Thin blood vessels § Nourishes cells of the brain and spinal cord, attaches to surface

V. Protection § D. Cerebrospinal fluid § Made from blood in the brain (choroid plexus) § Watery cushion (about half a cup) § Protects from blows and other trauma § Glucose, proteins, Na. Cl

Protection § E. Blood-brain barrier § Capillaries of the brain are least permeable in body § Water, glucose, amino acids easily pass through § Waste and most drugs not allowed to pass § Useless against fats, respiratory gases, fatsoluble molecules like alcohol, nicotine, anesthetics