Physio Lecture 11 Questions (Exam 2)

Front 1

Which type of muscle is found in the walls of blood vessels?

Back 1

Smooth muscle

Front 2

What are two major differences in the proteins found in skeletal muscle and smooth
muscle?

Back 2

Smooth muscle DOES NOT have troponin, and has only a very small amount of sarcoplasmic reticulum (SR) structures.

Front 3

Which muscle type(s) can we voluntarily control?

Back 3

Skeletal muscle

Front 4

Which type has the smallest cells?

Back 4

Smooth muscle cells, cardiac are intermediate and skeletal are largest.

Front 5

Which muscle type(s) utilize extracellular calcium for activation of crossbridge binding?

Back 5

Cardiac and smooth muscle cells.

Front 6

Which muscle type has the longest contraction cycle, (actin/myosin binding and release)?

Back 6

Smooth muscles

Front 7

Which muscle type uses ATP most efficiently?

Back 7

Smooth muscles

Front 8

Which muscle type has the greatest ability to develop tension over a wide range of lengths?

Back 8

Smooth muscles

Front 9

Which type(s) have gap junctions?

Back 9

Cardiac and some smooth muscles

Front 10

What are desmosomes?

Back 10

Areas between the cardiac myocytes (cells) where proteins make physical
attachments to link the cells together.

Front 11

What are intercalated disks?

Back 11

These are the areas of
the cell membranes where both the desmosomes and gap junctions are found.

Front 12

What is calmodulin?

Back 12

A molecule that binds Ca++ in smooth muscle cells which will start a cascade of events allowing the cells to contract

Front 13

What is MLCK?

Back 13

"Myosin light chain
kinase" which is the enzyme that is activated by the calmodulin/Ca++ complex, and
causes phosphorylation of the regulatory chains near the myosin head groups which
activates them so that they can bind to the actin molecules.

Front 14

Which cell type(s) use the
enzyme MLCK to initiate contraction?

Back 14

Smooth muscle cells.

Front 15

What is myosin phosphatase and what is its function?

Back 15

It is the enzyme that is responsible for removing the
phosphate group (dephosphorylating) from the regulatory chains near the myosin head group. This enzyme will stop contraction in the smooth muscle cells.

Front 16

What is the difference between single-unit smooth muscle and multiunit smooth muscle?

Back 16

Single unit smooth muscles spread depolarization through gap junctions. Multiunit
smooth muscles have extensive "synapses en passant" from multiple neurons to cause depolarization of the cells of the tissue.

Front 17

How the neural activation different between single-unit smooth muscle and multiunit smooth muscle?

Back 17

Single units smooth muscles have one or only a few neurons which usually modulate the
intrinsic activity of the entire tissue (in other words can speed up or slow down
contraction rates). Multiple unit smooth muscles require neurons to activate the tissue
and multiple unit smooth muscles have many receptors for neurotransmitters covering the entire cell surface, this allows activation via “synapses en passant”.

Front 18

Which type(s) can contract without neural stimulation?

Back 18

Cardiac and smooth muscles

Front 19

What does NO (nitric oxide) do?

Back 19

It causes vasodialation in a localized area of smooth
muscles.

Front 20

What five molecules can cause the synthesis of NO?

Back 20

ACh
bradykinin
histamine
ATP
L-arginine.

Front 21

Which muscle type(s) will change contraction rate in response to hormones?

Back 21

Cardiac and smooth
muscle.

Front 22

Which muscle type(s) have actin and myosin?

Back 22

All three types of muscle.

Front 23

Which muscle types have sarcomeres?

Back 23

Skeletal and cardiac.

Front 24

Which muscle types are striated?

Back 24

Skeletal and cardiac muscle.

Front 25

In which type(s) do action potentials spread from one muscle cell to the next, causing a series of synchronized contractions. (act as a syncytium) ?

Back 25

Cardiac and single-unit smooth
muscle cells.

Front 26

Give an example of a type of muscle and the mechanisms it uses to contract?

Back 26

Cardiac cells and smooth muscles of the reproductive tract have pacemaker potentials; smooth muscle of the GI tract has slowwave potentials.

Front 27

Which type can not tetanize, because of its long refractory period?

Back 27

Cardiac muscles

Front 28

How many types of excitatory cells does the heart have?

Back 28

Two; conducting cells and
contracting cells.

Front 29

Do they produce the same type of depolarization events?

Back 29

no

Front 30

What is a pacemaker potential?

Back 30

It is the result of the inability of the cell membrane to
maintain a resting membrane potential, as soon as the membrane potential repolarizes, it immediately begins to depolarize again

Front 31

What cell type produces a potential with a plateau phase?

Back 31

The contracting cardiac myocytes (cells).

Front 32

Do all cardiac cell potentials
have a plateau phase?

Back 32

No – the pacemaker cells do not have plateaus, but all the
contracting cells do.

Front 33

Why is this plateau phase important?

Back 33

It causes the refractory period
of the contracting cells to be extended to almost the end of the contraction cycle.

Front 34

In considering skeletal muscle cells and cardiac cells, relate the refractory periods of
depolarization events to the actual contraction of the cells.

Back 34

For skeletal muscle cells, the
refractory periods are short enough to allow restimulation before the end of the muscle
cell contraction as this allow for summation (increasing force production) and ultimately tetanus. In cardiac cells, because the refractory period doesn't end until almost the end of the muscles relaxation period, this prevents summation and tetanus from occurring.

Front 35

What
are the important differences about the refractory periods of skeletal and cardiac muscle
cells?

Back 35

The two muscles are used for completely different activities. Skeletal muscle
needs to maintain a contracted state to allow us to lift and move things, so it is important
for skeletal muscle to be able to "tetanize". Cardiac muscle is used to pump blood, and
absolutely must relax in between contractions to allow for the chambers to re-fill, so it is important that cardiac muscle CANNOT summate or tetanize. Therefore, by having
different refractory periods we can either allow for tetanus to occur (in skeletal muscle)
or prevent it from occurring (in cardiac muscle).

Front 36

Calmodulin

Back 36

Ca enters through channels in plasma membrane and binds with Calmodulin, this comples activates MLCK which phophorylates and activates myosin

Front 37

Myosin Phosphatase

Back 37

An enzyme which removes phosphate from the regulatory light change and dephosphoylates myosin so crossbridges can no longer form, is always present in the cytosol

Front 38

Single-unit Smooth Muscle

Back 38

Most abundant type of smooth muscle, made up of muscle fibers that are interconnected by gap junctions so that they become excited and contract as a unit, Spontaneously activated (myogenic), has gap junctions to spread electrical activity, found in walls of hollow organs (digestive, reproductive tracts and urinary tracts)

Front 39

Multi-unit Smooth Muscle

Back 39

Smooth muscle mass that consists of multiple discrete units that function independently of each other and that must be separately stimulated by autonomic nerves to contract, requires nerve stimulation by ANS, NT released along a series of synapses called varicosities in the synapses en passant, found in walls of large blood vessels, bronchioles, eyes, hair follicles

Front 40

Slow Wave Potential

Back 40

Self-excitable activity of an excitable cell in which its membrane potential undergoes gradually alternating depolarizing and hyperpolarizing, found primarily in GI tract, pacemaker activity

Front 41

Latch State

Back 41

Prolonged binding of myosin to actin, maintain force using little energy

Front 42

Syncitium

Front 43

Pacemaker Potential

Back 43

Self-excitable activity of an excitable cell in which its membrane potential gradually depolarizes to threshold on its own, reproductive tract, pacemaker activity

Front 44

Intercalated Disk

Back 44

Joins the adjacent myocardial cells (gap junctions)

Front 45

Desmosome

Back 45

An adhering junction between two adjacent but non-touching cells formed by the extension of filaments between the cells plasma membrance, most abundant in tissues that are subject to considerable stretching, acts like velcro to keep cells together

Front 46

Gap Junction

Back 46

Link between cells, a communicating junction between adjacent cells by small connecting tunnels that permit passage of charge-carrying ions between the cells so that electrical activity in one cell is spread to the adjacent cell

Front 47

Pacemaker Cells

Back 47

Form wiring network that initiates electrical activity in heart and depolarization of all cells in the heart, never obtain a resting potential, do NOT contract, once hyperpolarizes it starts to rise to threshold again, spontaneiously activated, set pace for heart

Front 48

NO (Nitric Oxide)

Back 48

Creates localized reaction that is an important molecule made by endothelial cells in body and causes relaxation in smooth muscle, decreases the amount of Ca and hyperpolarizes the membrane, resulting in relaxation

Front 49

Contractile Cells

Back 49

One of the two types of cells found in the heart, the only contracting cell

Front 50

Plateau Phase

Back 50

Part of the activation where calcium slows down, Calcium plateau (voltage gated Ca channel to allow Ca back inside)

Front 51

MLCK – Myosin Light Chain Kinase

Back 51

Enzyme which phosphorylates the regulatory light chain of the myosin molecule

Front 52

Regulatory Light Chains

Back 52

Myosin II found in smooth muscles, couple proteins wrapped around it, very important for smooth muscle

Front 53

Dense Bodies

Back 53

Found in smooth muscle, actin filaments are anchored to dense bodies

Front 54

Myogenic

Back 54

Spontaneously activated