Biology Chapter 8

Nervous system

One of the most amazing designs in God’s living creation

Central nervous system

Includes the brain and the spinal cord, which are both encased in bone for protection

Peripheral nervous system

Consists of the nerves that branch from the brain and spinal cord

Brain

Protected by cranium, the principal organ of the nervous system; chief organ of the mind

Spinal cord

Brain communicates with most of the body thru this, a thick bundle of nerve fibers located within the spinal cavity; (thirty-one pairs of spinal nerves)(12 cranial)

Meninges

The spinal cord and brain are covered by a triple layer of protective tissues known as this; has three layers (see p117)

Cerebrospinal fluid

A clear fluid that circulates through the fibers of the arachnoid matter, cushioning the brain when bump your head

Glial cells and neurons

The two basic kind of cells that make up the Brian and spinal cord

Gray matter

Found within the brain and spinal cord, consists largely of the cell bodies of neurons and is gray bc call bodies lack the white, specialized covering known as myelin

White matter

Comprised of axons and glial cells that are white bc of their myelin content

Ganglia

Neuron bodies are found only in the brain, spinal cord, and this; masses of cell bodies

Plexus

A network of interconnected nerve fibers going to or from a region

Nerve center

A group of cell bodies in the Brian of spinal cord is known as this

Sensory neurons

Neurons that transmit information to the CNS from the senses of sight hearing taste touch and smell and pain signals

Motor neurons

Neurons that relay signals form the CNS to the other parts of the body

Interneurons

Found only in CNS, relay signals between neurons or groups of neurons and are responsible for the processing of information by the brain like the logic circuits of a computer

Blood-brain barrier

Tightly sealed capillary walls, protect CNS from being permanently damaged during every illness (brains white blood cells are microglia, protects brain from infection)

Meningitis

When invading microorganisms enter the nerve tissue and infect the meninges they cause this disease may cause coma (a state of prolonged unconsciousness)

Poliomyelitis

A serious disease that attacks the spinal cord caused by virus that enters the motor neurons of the spinal cord and destroys some of them

Nerves

Bundles of nerve fibers(AXONS) branching from the brain and spinal cord

Cranial and spinal nerves

12 and 31 pairs

Mixed nerves

Nerves that contain both sensory and motor fibers

Sensory nerve fibers

Carry impulses of light, taste, sound, touch, pain from other parts of the body to the spinal cord and brain for analysis

Motor nerve fibers

Carry impulses from the brain and spinal cord to produce action in muscles and organs

Autonomic nervous system

The part of the PNS that controls the heart and other internal organs (involuntary)

Sympathetic division

Responds to your body’s needs during increased activity and emergency situations by causing heartbeat and breathing rates to increase, thus supplying more blood to your body so that you can respond quickly

Parasympathetic division

Acts as a balance to counteract actions of the sympathetic division when the emergency is over and your nervous system detects the need to slow down this does that

Schwann cells

The axons extending from the nerve cell bodies of peripheral nerves are surrounded by special glial cells called this which produce layers of myelin sheathing that acts much like the insulation on an electrical wire (Myelin needed actions, transmit nerve impulses, much faster than axons lacking a covering)(in brain oligodendrocytes are special glial cellsp122)

Multiple sclerosis

A disease of the brain and spinal cord where the bodies immune system attacks the glial cells; the myelin sheaths deteriorate and are replaced by scar tissue, forming hard patches that cannot be repaired

Paralysis

The inability of the muscles to move

Action potential

This wave of electrical activity is propagated by fast, acting voltage-sensing ion gates, that quickly open and close, allowing sodium and potassium ions to briefly flow into and out of the cell; a brief pulse of positive charge

Synapse

The axon of a neuron ends at this; an enclosed junction between two neurons or neuron and another cell (neurotransmitter when action potential reaches this)

Parkinson’s disease

One serious disease of the nervous system that affects the patient’s control of posture and movement where the patient lacks dopamine

Reflex

The simplest act of the nervous system, a quick automatic response (reflex arc)

Brain

The largest most important part of the nervous system

Cerebrum

The largest part of the brain and is the physical organ that helps you in the areas of consciousness, memory voluntary actions, thinking and intelligence

Hemispheres

The cerebrum consists of two halves called the right and left (left is connected to right side of body and vise versa)

Corpus callosum

The two hemispheres communicate with each other through this; a mass of nerve fibers, called this located at the base of the cerebrum

Cerebral cortex

Much of the brains, grey matter is located here which is also the outer layer of the cerebrum

lobes

The convolutions of each of the cerebral hemispheres are divided by grooves into various regions, or this that correspond to the major bones of the cranium

Frontal lobes

Front of this is associated with personality, judgment and self-control; the rear portion of this is called the motor area because it controls voluntary movement of the skeletal muscles

Parietal lobes

Located behind the frontal lobe, they analyze the senses on their respective sides of the body to allow us to feel sensations such as temperature, pressure and pain

Occipital lobes

The sense of vision is interpreted by this which is located at the back of the brain

Temporal lobes

Located on either side of the brain and is associated with the senses of hearing taste and smell

Cerebral palsy

Damage to the cerebral motor area before or shortly after birth is known as this; ranging from inability to walk to poor speech, etc.

Cerebellum

The second largest brain region, the convolutions are much smaller than that of the cerebrum; most complex muscle coordination is handled by this (One being swimming)

Brainstem

Located between the cerebrum and spinal cord, consists of the medulla oblongata pons and midbrain

Medulla oblongata

The lowest part of the brain stem contains nerve centers that monitor and regulate breathing heartbeat, blood pressure, etc. all major sensory and motor pathways between the body and the cerebral crossover in this part of the brain, (which is why the left cerebral hemisphere controls the right hand instead of the left hand)

pons

Above the medulla oblongata, which Links the cerebrum with the cerebellum, assists medulla oblongata in breathing

Midbrain

Above the pons, nerve centers in the midbrain help coordinate the movements of both eyes adjust the size of the pupils in response to the light and operate the lens muscles to focus the eyes on the object of your attention

Reticular formation

Within the brain stem lies this intricate network of neurons; It’s most important function is serving as the “master switch “of the cerebrum.

Limbic system

A number of complex brain structures like clustered around the brain stem at the core of the brain, surrounded by the cerebrum; neurobiologist sometimes referred to these structures collectively as this, it’s involved in coordinating the activity of the different parts of the brain

Thalamus

At the uppermost, end of the brain stem; this acts like a switchboard routing activation signals from the reticular formation and sensory impulses from various parts of the body to the appropriate areas of the cerebral cortex

Hypothalamus

Just below the thalamus, this is the control unit for your body‘s automatic system; this is also responsible for the physical effects of emotions, such as rage and fear

Behaviorism

According to this philosophy, a person‘s actions can be completely explained as responses to particular stimuli

Sensorineural deafness

Repeated or prolonged exposure to accessible loud sound results in a form of partial or complete hearing in loss known as this; Repeated exposure to sounds that exceed 90 to 100 dB

REM sleep

Occurs when the sleepers closed eyes show rapid movements as though he were watching the events of a dream

Alcohol

One of the most commonly abuse drugs in the world today

Neuritis

Degeneration and inflammation of nerves caused by alcohol

Whiplash

If the spinal nerves protruding from the spinal cord in the neck are injured, this has occurred, resulting in pain, muscle spasm, and limited motion

Sciatica

A condition characterized by pain in the lower back and back of a thigh, is caused by a pinching of the sciatic nerve of the lower spinal cord

Stroke

The most common serious injury of the nervous system, a leading cause of death throughout the world, caused by an internal blockage or rupture of a blood vessel in the brain

Concussion

Minor brain injury, Can cause headache, disorientation, brief unconsciousness, and amnesia

Tetanus

A serious disease that affects the nervous system commonly known as a lockjaw because severe spasms of the jaw muscles, make it hard to open the mouth; caused by exposure of bacteria in a wound

Acute confusion

One of the most common mental disorders in the elderly is this disturbance of the brain caused by physical illness everywhere in the body

Alzheimer’s disease

Has symptoms similar to dementia but more severe, these patients become physically as well as intellectually disabled

Epilepsy

One of the most common neurological disorder that affects people of all ages is this condition; Motor neurons may misfire, causing muscle convulsions, neurons may fire over and over

Sensory receptors

information of world around you is obtained and relayed to the spinal cord brain by living sensors known as this

Somatic senses

Include all the senses of your skin primarily touch and temperature

Special senses

Sight, hearing smell, taste and balance are provided by a second group of neurons located in intricately designed sense organs

Pain receptors

A bear dendrite that reacts to a certain type of strong stimulus

Mechanoreceptors

The sensory receptors responsible for sensations of touch and Pressure

Thermoreceptors

Response to temperature changes

Chemical senses

The sense of taste and smell are these which is a result from the stimulation of chemo receptors on the tongue and in the nose

Taste buds

The organs responsible for taste are these which are chemo receptors on the tongue that detect dissolved chemicals in the mouth

olfactory nerve

The nose is sensory receptors are located in the upper part of the nasal cavity and are connected to the brain by this

Outer ear

Part of the year that is open to the outside of the body contains the auricle ear canal and eardrum

Middle ear

The chamber containing the malleus, incus and stapes

Inner ear

As a vibrations pass through the stapes, they enter this the actual organ of hearing

Bone conduction

The inner ear also receives vibrations from the jawbones. This type of hearing is known as this.

Eustachian tube

Ear infections occur when microbes from the throat travel up to this in the middle ear

Socket

Known as orbit, provides the surrounding protection of heavy bone to eye

Lacrimal glands

Tears are produced by this which are under the upper eyelid on the side away from the nose; tears contains an enzyme known as lysozyme and water

Extrinsic muscles

Attached to the Each eye is a set of six muscles or this, which move the eye

Sclera

The tough outer layer of tissue that provides protection and the supporting frame for the interior of the eye

Cornea

At the front of the eye the opaque sclera is replaced by a transparent portion called this, the area through which light enters the eye

uvea

The largest portion of this, the middle layer of tissue is the choroid a layer of connective tissue rich in blood vessels, which becomes the ciliary body; Contains Iris at the front of the eye

Retina

The innermost layer of the eye is the most delicate part of the eye, and the most important for vision

Rods and cones

The rods are long, thin cells While the cones are slightly shorter and Thicker; in the light sensitive layer of the retina are these two kinds of cells(cones is for color rod is for lights)

Fovea

The layer of nerve cells is also slightly thinner in this region for in a small depression on the retina called this

Blind spot

The point on the retina where the optic nerve leaves the eyeball

Optic chiasm

As the optic nerves leave the retina, they curve inward toward the center of the head, where they meet at a point called this located just beneath the front of the hypothalamus

Rhodospin

The substance and rod cells that absorbs light, which consists of a molecule derived from vitamin A suspended in a protein framework

Persistence of vision

The phenomenon in which an image or picture of an object on the retina persist about a 10th of a second after the object is gone, explains why a flashlight appears to leave a share of light when move rapidly in the dark

Aqueous humor

Between the cornea and the iris and lens is a space filled with a clear fluid called this, which is produced from blood circulating in the ciliary body; it’s most important function is helping to keep the eyeball reasonably firm and in the proper shape

Lens

The part of the eye that focuses the rise of light passing through it

Accommodation

The increase in the curvature of the lens to focus on nearby objects is this

vitreous humor

Between the lens and the rear of the eye is a space filled with this, a transparent jelly like substance that is about 98% water

Nearsightedness

Myopia, the ability to see only near objects clearly

Farsightedness

Hyperopia, a person who is This sees objects at a distance better than those that are nearby can be corrected by convex lenses