Human Anatomy Quiz 15: Channels & Membrane at Rest

action potential

What is a nerve impulse the same thing as?

membrane potential, specific ion channels

What does the production of nerve impulses depend on?

the separation of ions across the membrane leading to an electrical voltage difference

What is membrane potential?

move down their concentration gradient

What will ions do when ion channels are open?

charge, + towards - and vice versa

What do ions move down this concentration gradient according to? What does that mean?

gates, they open and close in response to a stimulus

What do ion channels act as? What does that mean about their functionality?

leakage channels, voltage gated channels, ligand gated channels, mechanically gated channels

What are the four types of ion channels?

randomly alternate between opened and closed

What do leakage channels do?

K channels

Are there usually more K or Na channels?

K channels

Are K or Na channels leakier?

higher membrane permeability to K

What is the result of the greater likelihood of leakage of K channels?

change in membrane potential (voltage)

What do voltage gated channels open and close in response to?

specific molecules that bind to the channels

What do ligand-gated channels open and close in response to?

neurotransmitter

What is an example of a specific molecule that could bind to a ligand-gated channel, resulting in the opening and closing of it?

mechanical stimulation

What do mechanically gated channels open/close in response to?

vibration, pressure, stretch

What are three examples of mechanical stimulation?

because of build up of negative ions just inside the neuron cell membrane and the positive ions outside

Why does resting membrane potential exist?

potential energy

What is separation of charges a form of?

\-70 mV

What does separation of charges measure about in a typical cell?

K, many anions, phosphates, amino acids

What is the dominant cation inside of the cell? What is also present inside of a cell? Such as?

false

True or False: K cannot leak out of the cell

true

True or False: Anions cannot leak out of the cell

Na

What is the dominant cation outside of the cell?

at rest

When does the inside of a neuron’s membrane have a negative charge?

negative

At rest, what kind of charge does the inside of a neuron’s membrane have?

pump sodium out of the cell and potassium into the cell

What does a Na+/K+ pump in a cell membrane do?

potassium

What is the cell membrane more leakier to: sodium or potassium?

inside of the membrane builds up a net negative charge relative to the outside of the membrane

What is a result of potassium ions leaking out of the cell?

when a stimulus causes a ligand or mechanically gated channel to open or close

How do graded potentials arise?

type of ion channel opened

What does the hyperpolarization or depolarization of a membrane depend on?

hyperpolarized

When a membrane becomes more negative it is…

depolarized

When a membrane becomes more positive it is…

they vary in size depending on the strength of the stimulus

Why are signals graded?

more gates to be open

What does a large stimulus cause?

it is localized, it is only useful for communication over short distances

What is significant about ion flow? What does that mean?

ion flow

What is usually present in dendrites?

small potentials are often summed

What occurs at the axon hillock?