Introduction to Human Physiology and mosyly nerons

Physiology

Study of biological function and body mechanisms.

Homeostasis

Dynamic constancy of internal body environment.

Scientific Method

Systematic approach for scientific investigation.

Hypothesis

Testable prediction based on observations.

Clinical Trials

Phased testing of drugs on humans.

In Vitro

Experiments conducted in a controlled environment.

In Vivo

Experiments conducted in living organisms.

Molecule

Smallest unit of a chemical compound.

Cell

Basic structural and functional unit of life.

Tissue

Group of similar cells performing a function.

Organ

Structure composed of multiple tissue types.

System

Group of organs working together.

Organism

Complete living entity with functioning systems.

Muscle Tissue

Specialized for contraction and movement.

Nervous Tissue

Composed of neurons for communication.

Epithelial Tissue

Covers surfaces and lines hollow organs.

Connective Tissue

Supports and connects different body parts.

Skeletal Muscle

Voluntary muscle controlled consciously.

Cardiac Muscle

Involuntary muscle found in the heart.

Smooth Muscle

Involuntary muscle in hollow organs.

Negative Feedback System

Regulates controlled variables to maintain homeostasis.

Positive Feedback System

Reinforces changes in a controlled variable.

Baroreceptor

Detects changes in blood pressure.

Pancreatic Cells

Regulate blood sugar through insulin production.

Controlled Variable

Factor being regulated in a feedback system.

Control Center

Processes information and determines response.

Effector

Carries out response to restore balance.

what do nodes of Ranveer do Conduction in a Myelinated Neuron?

Nodes of Ranvier allow Na+ and K+ to cross the membrane, and Action potentials "leap" from node to node

Conduction of Nerve Impulses step 1

action potential

occurs at a given point on a

neuron membrane,

Conduction of Nerve Impulses step 2

voltage -

gated Na+ channels open as a

wave down the length of the

axon.

Conduction of Nerve Impulses step 3

action potential at one

location serves as the

depolarization stimulus for the

next region of the axon

Conduction of Nerve Impulses step 4

Conduction with no decrement. (ction potentials at one location on a neuron membrane serve as the depolarization stimulus for the next region of the axon)

Action Potentials

Refractory Periods

Action potentials can only increase in

frequency to a certain point. There is a

refractory period after an action

potential when the neuron cannot

become excited again.

when does absolute refractory occur

The absolute refractory period occurs

during the action potential. Na+

channels are inactive (not just closed)

when does relative refractory occur

The relative refractory period is when K+ channels are still open. Only a very strong stimulus can overcome this.

Each action potential remains a

separate__________________ event

all-or-none event.

A stronger stimulus will make action potentials occur ___________

frequently. (frequency modulated)

more

what is frequency modulated

how a stronger stimulus affects action potentials

A stronger stimulus may also activate ___________ neurons in a nerve.

This is called recruitment

more

Recruitment is the process

where a stronger stimulus can activate more neurons in a nerve

All-or-None Law

1. Once threshold has been

reached, an action potential

will happen.

2. The size of the stimulus will

not affect the size of the

action potential, it will

always reach +30mV.

3. The size of the stimulus will

not affect individual action

potential duration.

Voltage-Gated K+ Channels

At around +30mV, voltage-gated K+ channels open, and K+ rushes out

of the cell following the electrochemical gradient.

what do k gated channels do

makes the cell repolarize back toward the potassium equilibrium

potential.

what are k channel goals in repolarizing the cell

Repolarization actually overshoots resting potential and gets down to −85mV. Na+/K+ pumps quickly reestablish resting potential.

what do nodes of Ranveer do Conduction in a Myelinated Neuron?

Nodes of Ranvier allow Na+ and K+ to cross the membrane, and Action potentials "leap" from node to node

Conduction of Nerve Impulses step 1

action potential

occurs at a given point on a

neuron membrane,

Conduction of Nerve Impulses step 2

voltage -

gated Na+ channels open as a

wave down the length of the

axon.

Conduction of Nerve Impulses step 3

action potential at one

location serves as the

depolarization stimulus for the

next region of the axon

Conduction of Nerve Impulses step 4

Conduction with no decrement. (ction potentials at one location on a neuron membrane serve as the depolarization stimulus for the next region of the axon)

Action Potentials

Refractory Periods

Action potentials can only increase in

frequency to a certain point. There is a

refractory period after an action

potential when the neuron cannot

become excited again.

when does absolute refractory occur

The absolute refractory period occurs

during the action potential. Na+

channels are inactive (not just closed)

when does relative refractory occur

The relative refractory period is when K+ channels are still open. Only a very strong stimulus can overcome this.

Each action potential remains a

separate__________________ event

all-or-none event.

A stronger stimulus will make action potentials occur ___________

frequently. (frequency modulated)

more

what is frequency modulated

how a stronger stimulus affects action potentials

A stronger stimulus may also activate ___________ neurons in a nerve.

This is called recruitment

more

Recruitment is the process

where a stronger stimulus can activate more neurons in a nerve

All-or-None Law

1. Once threshold has been

reached, an action potential

will happen.

2. The size of the stimulus will

not affect the size of the

action potential, it will

always reach +30mV.

3. The size of the stimulus will

not affect individual action

potential duration.

Voltage-Gated K+ Channels

At around +30mV, voltage-gated K+ channels open, and K+ rushes out

of the cell following the electrochemical gradient.

what do k gated channels do

makes the cell repolarize back toward the potassium equilibrium

potential.

what are k channel goals in repolarizing the cell

Repolarization actually overshoots resting potential and gets down to −85mV. Na+/K+ pumps quickly reestablish resting potential.

Voltage-Gated Na+ Channels

(Depolarization) open when the membrane reaches what ?

These channels open if the

membrane potential depolarizes to

−55mV.

what happens when the Voltage-Gated Na+ Channels are opened for

(Depolarization) ?

Sodium rushes in due to the

electrochemical gradient. More Na+ channels are open.

when and why are Voltage-Gated Na+ Channels

(Depolarization) deactivated?

Voltage-gated Na+ channels are deactivated at around +30mV, which prevents more sodium ions from flowing in

Changes in membrane potential are

controlled by changes in the flow of ions

through channels. name them and their functions

K+ has two types of channels:

1) Not gated (always open), sometimes called K+ leakage

channels

2) Voltage-gated K+ channels, open when a particular

membrane potential is reached, closed at resting

potential

b. Na+ has only voltage-gated channels that are

closed at rest, the membrane is less permeable

to Na+ at rest.

At rest a neuron is considered _________ when

the _______ is more________ than the __________

polarized, inside, negative, outside

depolarization

When the membrane potential inside the cell

increases (becomes more positive)

Depolarization occurs

when

positive ions enter the cell (usually Na+).

Excitatory.

A return to resting potential is called

repolarization

hyperpolarization

When the membrane potential inside the cell

decreases (becomes more negative)

Hyperpolarization

occurs when

positive ions leave the cell

(usually K+) or negative ions (Cl−) enter the

cell. Inhibitory.

Altering Membrane Potential

Neurons and muscle cells can change their

membrane potentials, excitability or irritability, Caused by changes in the permeability to

certain ions

If a sodium channel is open

sodium ions will flow inside the cell due to the concentration difference

If a potassium channel is open

potassium is going to flow outside

If a channel is open for chloride

chloride is going to flow in

If a channel is open for calcium

calcium is going to flow in

Central nervous system (CNS)

Brain and spinal cord

Peripheral nervous system

(PNS)

Nerves, ganglia, and nerve plexuses (outside of the CNS)

Interneuron

Multipolar neuron located entirely within the CNS

Sensory neuron (afferent

neuron)

Neuron that transmits impulses from a sensory receptor into

the CNS

Motor neuron (efferent

neuron)

Neuron that transmits impulses from the CNS to an effector

organ, for example, a muscle

Nerve

Cablelike collection of many axons in the PNS, may be

"mixed" (contain both sensory and motor fibers)

Somatic motor nerve

Nerve that stimulates contraction of skeletal muscles

Autonomic motor nerve

Nerve that stimulates contraction (or inhibits contraction) of

smooth muscle and cardiac muscle and that stimulates

glandular secretion

Ganglion

Grouping of neuron cell bodies located outside the CNS

Nucleus

Grouping of neuron cell bodies within the CNS

Tract

Grouping of axons that interconnect regions of the CNS

Schwann cells

PNS ,Also called neurolemmocytes, produce the myelin sheaths

around the myelinated axons of the peripheral nervous

system, surround all PNS axons (myelinated and

nonmyelinated) to form a neurilemmal sheath

Satellite cells

PNS, Support functions of neurons within sensory and

autonomic ganglia

Oligodendrocytes

CNS, Form myelin sheaths around central axons, producing

"white matter" of the CNS

Microglia

CNS, Phagocytose pathogens and cellular debris in the CNS

Astrocytes

CNS, Cover capillaries of the CNS and induce the blood-brain

barrier, interact metabolically with neurons and modify

the extracellular environment of neurons

Ependymal cells

CNS, Form the epithelial lining of brain cavities (ventricles)

and the central canal of the spinal cord, cover tufts of

capillaries to form choroid plexuses—structures that

produce cerebrospinal fluid

In the CNS the myelin sheath is

produced by ___________________.

oligodendrocytes

In the CNS, the myelin sheath is

produced by .

oligodendrocytes.

what is this

oligodendrocyte

Myelin gives these tissues (axons) a white color = white matter. t or f

t

Gray matter is cell bodies and

dendrites which lack myelin sheaths. t or f

t

All axons in the PNS are

surrounded by a sheath of_____________ cells called the

____________ or sheath of

______________

Schwann, neurilemma, Schwann

Gaps between Schwann

cells

called nodes of, Ranvier