Unit 1 - Intro to Physiology

Question 1

The wall of the alveolus (air sac) in the lung is composed of which type of epithelium?

Answer 1

simple squamous epithelium

This single layer of squamous cells is ideal for the diffusion of gases in the lungs.

Question 2

The proximal tubule of the nephron in the kidney is composed of which type of epithelium?

Answer 2

simple cuboidal epithelium

Simple cuboidal cells line the kidney tubules (nephrons) so that secretion and absorption can take place.

Question 3

The epithelium of the esophagus is composed of which type of epithelial tissue?

Answer 3

stratified squamous epithelium

This epithelium protects underlying tissues from the wear and tear of constant swallowing in the esophagus.

Question 4

Which part of the neuron (a specialized nerve cell) receives signals from other cells and is also the main metabolic region of the neuron?

Answer 4

soma

The soma or cell body receives inputs (signals) from other cells and sends the information to the axon. But unlike a dendrite, it is also the main metabolic and nutritional center of the cell.

Question 5

Which of the three muscle cell types has multiple nuclei?

Answer 5

skeletal

Skeletal muscle cells are elongated and many can be quite long; therefore, they have multiple nuclei.

Question 6

Which muscle cell type has visible striations but is not under voluntary control?

Answer 6

cardiac

Cardiac cells, like skeletal cells, have visible striations but are not under voluntary control.

Question 7

What is excitable tissue?

Answer 7

Excitable tissue is made of cells that can alter their membrane potentials in response to a stimuli and generate action potentials. Excitable cells include neurons, muscle cells, and beta cells of the pancreas.

Question 8

Which form of cell-to-cell communication uses the direct transfer of electrical and chemical signals?

Answer 8

Gap-junction signaling

Question 9

What is the name for a competing ligand that binds to a receptor and causes the same response as the primary ligand?

Answer 9

agonist

Question 10

Neurons that lie entirely within the CNS are called?

Answer 10

interneurons

Question 11

Which glial cells have extensions that contact blood vessels in the brain?

Answer 11

astrocytes

Question 12

A collection of neuronal soma in the PNS (outside the CNS) is called a _______ and within the CNS is called a _______.

Answer 12

ganglion (pl. ganglia); nucleus

Question 13

Concentration gradients exist across the cell membrane. Specifically, there are more ________ inside and more ________ outside the cell membrane.

Answer 13

K+ ions; Na+ ions

Question 14

The plasma membrane of a neuron is more permeable to _________.

Answer 14

Potassium (K+) ions

Question 15

Resting membrane potential being negative (-70 mV) depends on what factors?

Answer 15

-the greater number of potassium leak channels
-the greater permeability of the plasma membrane to K+ ions
-the concentration gradient for Na+ ions

Question 16

A neuron under the influence of a neurotransmitter that opens K+ ion
channels will ______________.

Answer 16

be less likely to fire an action potential

Question 17

An action potential starts at the trigger zone of efferent neurons & interneurons. This is the _______ and _______.

Answer 17

the axon hillock; initial segment

Question 18

In myelinated axons, action potential occurs at the ________ and they propagate ________.

Answer 18

nodes of Ranvier; rapidly

Question 19

Action potential propagation in myelinated axons is known as
________.

Answer 19

saltatory conduction

Question 20

This type of tissue provides structural support and barriers.

Answer 20

connective tissue

Question 21

How do neurons transmit electrical impulses?

Answer 21

via energy stored as an electrochemical gradient

Question 22

Initiating ions to enter a cell is accomplished through the binding of ____________ to __________ ___________ that open _____ ___________.

Answer 22

neurotransmitters; membrane receptors;
ion channels

Question 23

How does the membrane potential return to the resting level?

Answer 23

K+ ions leave the cell (falling phase of action potential)

Question 24

Why can’t an action potential be generated during the absolute refractory period?

Answer 24

The Na+ channel is in an inactive state

The membrane must depolarize before the Na+ channel can return to its normal resting state

Question 25

Why does it take a suprathreshold stimulus to generate an action potential during the relative refractory period after hyperpolarization?

Answer 25

K+ channels are still open, so more Na+ is needed to reach threshold stimulus

Question 26

Why is the refractory period important?

Answer 26

It sets the direction for the flow of current, prevents temporal summation and prevents the action potential from going backwards.

Question 27

What determines how fast an action potential can travel along a neuron?

Answer 27

-diameter of the axon
-resistance of the axon membrane to ion leakage out of the cell (insulating the axon using myelin sheath reduces ion flow out of cell and speeds conduction)