University of Iowa: Fundamentals of Human Physiology, Exam 2 | Quizlet

Nervous System

Consists of:

-CNS

-PNS

CNS

-Brain and Spinal cord

-Function in control and integration

PNS

-Cranial nerves and spinal nerves

-Motor and sensory

Neurons

Nerve cells that conduct electrical signals

Neuroglia

-Majority of all nerve tissue cells

-Support neurons

Parts of neuron

-Dendrites

-Cell Body

-Axonal hillock

-Axon

-Axon terminal

Myelin

-Protective coating over the axon

-Makes the message through the axon flow faster and smoother

Types of neurons

-Afferent

-Efferent

-Interneurons

Afferent neurons

Carry signal away from the sensors

Efferent neurons

ANS; Sends info from CNS to trigger motor response

Interneurons

CNS; Communicate between sensory and motor neurons

Neuroglia

Non conducting cells; PNS and CNS; aid the neurons

Types of Neuroglia

-Schwann cells

-Oligodendrocytes

-Astrocytes

-Microglia

-Ependymal cells

Schwann cells

PNS; makes myelin

Oligodendrocytes

CNS; makes myelin

Astrocytes

-Form part of the blood-brain barrier

-Help make glucose for neurons

-Absorb extra neurotransmitters

Microglia

Part of the immune system in the brain

Ependymal cells

Help form CSF

Nerves and muscles

Excitable tissues

Negative

Inside of a cell is ____________ relative to the outside.

-70mV

Resting cell potential

K+

Cell is permeable to ____.

Na+

Cell is impermeable to ____.

Equilibrium

At resting potential, neither K+ or Na+ are in ______________.

Polarization

When membrane potential is other than 0mV

Depolarization

What the charge is less negative than resting membrane potential

Repolarization

When the membrane returns to resting potential

Hyperpolarization

When the cell is more negative than resting membrane potential

Types of Potential

-Graded

-Action

Graded potential

-Magnitude varies with stimulus strength

-Decremental

-Depolarizing v. Hyperpolarizing

-Used for short distances

Action potential

-Brief, rapid, and large changes in membrane potential

-All or none law

-Must reach threshold potential

-Not decremental

-Begins at axon hillock

Action potential sequence

-Depolarization

-Peak

-Repolarization

-After hyperpolarization

-Return to resting potential

Depolarization

-Voltage-sensitive Na+ channels open

-Reaches threshold and induces more Na+ channels to open

Peak

-Na+ channels close (inactivate)

-Voltage-gated K+ channels open

Repolarization

K+ leaves neuron

After hyperpolarization

K+ still slowly leaving

Regeneration

PNS only;

-Cut axon is degenerated

-Tube is formed by Schwann cells

Leaky channels

Channels that are always open

Ligand gated channel

When a molecule binds to it to open gate

Voltage gated channel

Changing in the RMP triggers opening of channel

K+

Has Leaky and Voltage gated channels

Positive Na+ feedback cycle

-Passive spread of current from adjacent site already depolarized

-Depolarization

-Opening of some voltage gated Na+ channels

-Influx of Na+

Refractory Period

-Absolute

-Relative

Absolute (RP)

When the potential can no longer send more messages because the sodium channels are inactive

Relative (RP)

After absolute that forces a strong signal to be sent to reach threshold

Propagation

-Action potential opens voltage gated Na+ channels

-Stimulus for depolarization of next adjacent region triggering an AP at the segment

-AP are produced continuously along the plasma membrane of unmyelinated axons

Saltatory conduction

-AP jumps from one node to the next

-Increase AP time by 50

Synapse

-A communication junction between a neuron and either another neuron or a muscle or gland cell

-Stimulates physiological changes

Types of synapses

-Chemical

-Electrical

Chemical

Most common type of synapse

Anatomy of a synapse

-Presynaptic neuron

-Synaptic cleft

-Postsynaptic neuron

Synaptic sequence

-AP triggers opening of Ca2+ channels

-Ca2+ rushes in

-Ca2+ induced exocytosis of synaptic vesicles

-Neurotransmitter binds to receptors on postsynaptic cell membrane

-Opens ligand gated ion channels

-Induces a synaptic potential in postsynaptic cell

Excitatory postsynaptic potential (EPSP)

Potential when the postsynaptic cell membrane depolarizes

Inhibitory postsynaptic potential (IPSP)

When the postsynaptic cell membrane hyperpolarizes

EPSP

Opens Na+ channels

IPSP

Opens Cl- channels

G Protein coupled channels

-Neurotransmitter receptor is separate from the protein that serves as the ion channel

-Alpha sub unit moves over

Catecholamines

-Uses cAMP as second messenger

AChE

-Found in synaptic cleft

-Functions to break down Ach into component parts, which are then taken back into the presynaptic cell for reuse

Neuron Communication

-Convergence

-Divergence

Summation

When one synapse is not enough to get an effect and needs to add the input together

Types of summation

-Temporal

-Spatial

Temporal summation

-Time

-Two quick firings of one neuron

Spatial summation

Firing of two proximal excitatory neurons

Protection of the CNS

-Bone

-Meninges

-CSF

CNS bone

-Cranium

-Vertebral column

Meninges

-Dura mater

-Arachnoid mater

-Subarachnoid space

-Pia mater

CSF

-Found in ventricles in brain

-Formed by ependymal cells in the chorioid plexuses

Function of CSF

-Buoyancy

-Protection

-Maintenance of chemical environment

Cerebrum

-Largest portion of brain (80%)

-Divided into 2 cerebral hemispheres that are connected by the corpus callosum

Cerebral Cortex

-Grey outside and white inside

-5 lobes

Frontal lobe

Contains the motor cortices and is responsible for executive reasoning

Parietal lobe

-Contains the somatosensory cortices

-Responsible for the perception of senses

Temporal lobe

-Auditory cortex

-Perception and interpretation of auditory stimuli

Occipital lobe

Visual cortex

Insula

-integration of sensory information with visceral responses

-Assessing body states

PET

-Produces a 3D image of functional processes in the body

-Involves an injection of a radionuclide tracer

MRI

-Protons are charged and spin

-Uses a magnet to develop a picture

EEG

-Detects brain waves using sensors placed on the head

Lateralization

The idea that cerebral hemispheres are specialized and contralateral

Left hemisphere

-Usually dominant

-Language

-Analytical ability

Right hemisphere

-Visuospatial

-Patterns

-Maps

Found in left hemisphere

-Broca's area

-Wernicke's area

Broca's area

Coordinates complex fine motor functions involved in speech

Wernicke's area

Responsible for the ability to comprehend language and formulate words

Aphasia

A disturbance in comprehension and expression of language

Broca's aphasia

Aphasia where:

-Speech is poorly articulated

-You understand what is spoken, but have difficulty responding

Wernicke's aphasia

Aphasia where:

-You speak easily with made up and real words

-Can't understand spoken or written language

Basal Nuclei

Masses of grey matter located deep within cerebrum

Functions of basal nuclei

-Suppressing useless or unwanted patterns of movement

-Modifying ongoing activity in motor pathways

-Release dopamine

Limbic system

Group of cerebral nuclei

Functions of the limbic system

-Emotion

-Aggression

-Fear

-Sex drive

-Goal Directed behavior

Short term

Memory <30 seconds

Long term

Memory >30 seconds

Non declarative memory

Memory of simple skills

Declarative memory

Memory of facts and events

Temporal lobe

Converts short term memory into long term memory with the help of sleep

Emotional

If the memory has an __________ component, the amygdala is involved in memory formation.

Alzheimers

-Loss of neurons

-Accumulation of tangles and amyloid plaques

Diencephalon

Consists of:

-Thalamus

-Hypothalamus