Bio Exam 2

Central Nervous System

consists of brain and spinal cord

Peripheral Nervous System

consists of nerves, which lie outside the CNS

Does the nervous system or endocrine system have faster responses?

Nervous system

What two types of cells does the nervous system contain?

neurons and neuroglia

Neurons

transmit nerve impulses

Neuroglia

support and nourish neurons

Neuroglia in the CNS

microglia, astrocytes, oligodendrocytes

Neuroglia in the PNS

Schwann cells

Sensory nuerons

sensory receptors respond to stimuli by generating nerve signals that travel via the PNS to the CNS

Interneurons

the CNS sums up the input it receives from all over the body, stores memories, and creates motor responses.

Motor neurons

Generates motor output, which travels from the CNS via the PNS to the muscles, glands, and organs.

What are the three structures of a neuron?

Cell body, dendrites, and axon

Cell body

contains nucleus and other organelles

Dendrites

extension of the cell body that receives signals

Axon

portion of a neutron that conducts nerve impulses.

Individual axons are nerve fibers and collectively they form a nerve

True

What does the myelin sheath do?

covers some axons and acts as an insulator

Node of Ranvier

space between myelin sheaths

Which axons usually have a myelin sheath?

Long axons

Why is Gray Matter of CNS gray?

Because it does not contain myelinated axons

Why is white matter of the CNS white?

Because it contains myelinated axons

Nerve Signals

electrochemical changes that convey information within the nervous system

Resting potential

The potential energy of a neuron at rest

Why does resting potential exist?

because the plasma membrane is polarized

What must neurons do in order to be able to send nerve signals?

Maintain their resting potential

What does the sodium potassium pump do?

pumps Na+ out of the cell and K+ into the cell (the neuron)

Nerve signals are also called....

Action potentials

A stimulus is a .....

Change that activates a neuron

Threshold

The minimum voltage that must be reached to produce an action potential

Depolarization

equal to -55 mV

Action potentials are "all or nothing"

True

When does the action potential happen completely?

When the threshold is reached

Gated channels open when...

depolarization occurs

refactory period

a period of inactivity after a neuron has fired

What does a refractory period ensure?

the one-way direction of the signal from the cell body down the length of the axon

Axons branch into endings called....

axon terminals

synapse

Gap between neurons

synaptic cleft

small gap that separates the sending neuron from receiving the neuron

neurotransmitter

transmits information across a synapse

Excitation

if a neurotransmitter causes sodium gates to open = tries to bring the cell to a threshold

Inhibition

if a neurotransmitter causes potassium ions to exit, or chloride ions to enter the receiving neuron= try to prevent the cell from reaching threshold

What tries to prevent the cell from reaching threshold?

inhibitor

What tries to bring the cell to reach threshold?

Excitation

Integration

summing up of multiple incoming excretory and inhibitory signals

After a response....

neurotransmitter is removed to prevent overstimulation

Skull (cranium)

brain

Vertebral column

spinal cord

both the brain and spinal cord are wrapped in membranes known as...

meninges

meningitis

infection of the meninges

Cerebrospinal fluid

Fluid in the space between the meninges that acts as a shock absorber that protects the central nervous system.

cerebrospinal fluid is found in the...

four ventricles of the brain and central canal of spinal cord

spinal cord

extends from the base of the brain through the foramen magnum

spinal nerves

protect from the cord through small openings called intervertebral foramina.

Intervertebral disks

separate vertebrae

Spinal nerves are a part of which nervous system?

peripheral nervous system?

Paralysis

a loss of sensation and voluntary control

What acts as a gateway for pain and other sensory signals?

spinal cord

Motor signals from the brain pass down the...

spinal cord and out to the muscles

paraplegia

if damage in thoracic region of spinal cord, lower body and legs paralyzed

quadriplegia

if damage in the neck region, all four limbs are paralyzed

Center for thousands of reflex arcs

spinal cord

What are the four regions of the brain?

cerebrum, diencephalon, brainstem, cerebellum

cerebrum

Largest part of the brain; responsible for voluntary muscular activity, vision, speech, taste, hearing, thought, and memory.

Frontal lobes

primary motor area; reasoning, planning, critical thinking; motor speech area; primary olfactory area

Parietal lobes

primary somatosensory area; processing of taste

occipital lobes

visual processing area

temporal lobes

auditory processing

Primary motor area is in which lobe?

Frontal lobe

lack of oxygen during birth can damage...

motor areas, and can cause cerebral palsy

Voluntary signals to skeletal muscles begin in the....

primary motor area

Which lobe is the primary somatosensory area?

parietal lobe

Sensory information from the muscles and skin arrive in the...

parietal lobe

basal nuclei (ganglia)

masses of gray matter (neurons) deep within the white matter

what do basal nuclei do?

integrate motor commands to ensure the proper muscle groups are stimulated or inhibited

What ensures that muscle movements are coordinated and smooth?

basal nuclei (ganglia)

Parkinsons disease

degeneration of neurons in the basal nuclei

Hypothalamus

regulates hunger, sleep, thirst, body temp, water balance, and controls the pituitary gland

Thalamus

receives all sensory input and sends it to the appropriate areas of cerebrum.

What sensory input does the thalamus not receive?

sense of smell

cerebellum

maintains posture and balance,

what does the cerebellum produce?

smooth, coordinated, voluntary movements

What are the two parts of the brain stem?

medulla oblongata and reticular formation

Medulla oblongata

reflex centers for our heartbeat, breathing, and blood pressure

Reticular Formation

arousal and alertness

Limbic system

integrates emotions with higher mental functions (reasoning and memory)

Amygdala

creates the sensation of fear; association of memories with fear

Hippocampus

plays a crucial role in learning and memory

Alzheimer's disease

neurodegenerative disease of memory (hippocampus) ; reasoning (frontal lobe); and language (parietal lobe)

Cranial nerves

arise from the brain (12 pairs)

The force of contraction of a whole muscle can be increased by

Increasing the number of motor units

Which of these pathways provides the quickest means to produce ATP for muscle contraction?

creatine phosphate

Fast twitch fibers have fewer mitochondria than slow twitch fibers

True

Spinal nerves

arise from the spinal cord (31 pairs)

Slow twitch fibers are useful in exercise such as sprinting and weight lifting.

False

dorsal root contains which type of axons?

sensory axons

ventral root contains which type of axons?

motor axons

Reflexes

automatic response to a stimulus

Somatic system

serves the skin, skeletal muscles, and tendons

not all somatic motor actions are voluntary ... some are..

automatic

Gliall cells wrap around axons to form this structure which increases how fast the action potential traverls down the axon

myelin sheath