Veterinary Physiology Lecture 2

Front 1

Pumping function of the heart is dependent on

Back 1

muscle contraction.

Front 2

Cardiac muscle contraction must be

Back 2

coordinated.

Front 3

Four unique properties of cardiac muscle:

Back 3

1) Fibers branch

2) Connect at intercalated disks

3) Intercalated disks allow cardiac myocytes to be electrically and mechanically linked

4) Self-excitable

Front 4

Cardiac muscle cells are ______ & _______ linked.

Back 4

electrically & mechanically

Front 5

The name for cardiac muscle cells "acting as the same cell"

Back 5

Functional syncytium

Front 6

Intermediate filaments are ______ ________

Back 6

primarily desmin

Front 7

Titin is the ______ most abundant protein in cardiac muscle.

Back 7

3rd

Front 8

Titin is considered a "giant" protein, consisting of _______ amino acids.

Back 8

30,000

Front 9

Titin links the ___ line and the ____ line.

Back 9

Z line and M line.

Front 10

Titin has a role in muscle stiffness and acts as a

Back 10

spring.

Front 11

What are the steps in excitation contraction coupling?

Back 11

1. AP in cardiac contractile cell.

2. Travels down T tubules.

3. Entry of small amount of Ca2+ from ECF; Releas of large amount of Ca2+ from SR

4. Increase of cytosolic Ca2+

5. Troponin-tropomyosin complex in thin filaments pulled aside.

6. Cross-bridge cycling between thick and thin filaments.

7. Thin filaments slide inward between thick filaments.

8. Contraction.

Front 12

What are the key Ca2+ handling contraction proteins?

Back 12

1) L-type Ca2+ channel (dihydroyridine receptor)

2) SR Ca2+ release channel (ryanodine recepter)

Front 13

What are the key Ca2+ handling relaxation proteins?

Back 13

1) SR Ca2+-ATPase (SERCA)

2) NA+-Ca2+ exchanger (NCX)

3) Plasma membrane Ca2+ pump

Front 14

L-type Ca2+ channel

Back 14

Plasma membrane, voltage activated, allows Ca2+ into cytoplasm

Front 15

SR Ca2+ release channel

Back 15

SR membrane, releases Ca2+ from SR for contraction (CICR)

Front 16

SR Ca2+-ATPase

Back 16

SR membrane, pumps Ca2+ back into SR; 2nd largest user of ATP in cardiac muscle.

Front 17

Na+-Ca2+ exchanger

Back 17

plasma membrane, transports Ca2+ out of cell and Na+ in

Front 18

Plasma membrane Ca2+ pump

Back 18

transports Ca2+ out of cell

Front 19

The regulatory Ca2+ handling proteins are

Back 19

1. Phospholamban

2. Calsequestrin

Front 20

Phospholamban

Back 20

inhibits SERCA. Phosphorylation by PKA or CaMKII blocks inhibition, causing faster relaxation.

Front 21

Calsequestrin

Back 21

Ca2+-binding protein in SR. Helps the SR contain a large amount of Ca2+ (18-50 Ca2+ ions per molecule)

Front 22

Mutations in sarcomeric and Ca2+ handling proteins are implicated in _________

Back 22

disease, eg titin and dilated cardiomyopathy

Front 23

Smooth muscle makes up the

Back 23

walls of hollow organs and tubes

Front 24

Smooth muscle is ______ or _______

Back 24

phasic or tonic

Front 25

Phasic

Back 25

contracts in bursts. For propelling contents through an organ (uterus, GI tract)

Front 26

Tonic

Back 26

partially contracted at all times. For maintaining pressure (vasculature)

Front 27

Vascular Smooth Muscle makes up the

Back 27

majority of the vessel wall (except in capillaries)

Front 28

Vascular SMC regulates

Back 28

vessel diameter and thus flow

Front 29

Vascular SMC of small arteries and arterioles is key site for

Back 29

blood pressure & flow regulation

Front 30

Vascular SMC is _____, ________, and _______.

Back 30

Tonic, single-unit, and myogenic.