Lecture Overview Of Cardiovascular Flashcards
What does the CVS consist of?
Heart, blood, and blood vessels (arteries, veins, capillaries)
What is the flow of blood?
Heart/ lungs, arteries, arterioles, capillaries, venules, veins and heart
Primary function of the CVS?
Distribution of dissolved gases and other molecules for nutrition, growth and repair
How is blood pumped to the heart?
Deoxygenated blood returns to the right heart, oxygenated in lungs and retuned to the left heart and the, pumped to the entire body
Secondary functions of the CVS
Circulating hormones on NTs
Thermoregulation
Mediation of inflammatory and host defense responses against invading microorganisms
What happens during BV dilation (vasodilation)?
Increased heat loss across the epidermis
What happens during BV (vasoconstriction)
Heat conservation
Epicardium
Is real layer of the serous pericardium
Myocardium
Spiral bundles of cardiac muscle cells
Fibrous skeleton of the heart; interlacing layer of CT
What are the functions of myocardium?
Anchors cardiac muscle fibers
Supports great vessels and valves
Limits spread of action potentials to specific paths
Endocardium
Continuous with endothelial lining of blood vessels
Cardiac skeleton
Annulus fibrosis
Forms and anchors valves
Partitions atria and ventricles
What are the 2 pumps of the heart?
Left side: main pump
Right side: boost pump
Systemic circulation
The left heart and all systemic arteries, capillaries and veins
The left ventricle will pump blood to all organs of the body except the lungs
Pulmonary circulation
The right heart and pulmonary artery, capillaries and veins
Right ventricle pumps blood tot the lungs
Central circulation
The pulmonary circulation and the heart
How are the pulmonary and systemic circulation arranged?
In a series
Blood must pass through the pulmonary vessels between each passage through the systemic circuit
When does the contraction of a cardiac muscle occur?
After an action potential
How is the AP initiated by?
Spontaneously by pacemaker cells and propagated throughout the heart by way of the conducting system and gap junctions
Where do most cardiac muscle cells remain stable?
Resting membrane potential
Pacemaker cells
Cardiac cells that depolarize spontaneously toward threshold
They initiate heartbeats
Wilhelm His Jr.
1863-1934
Discovered Bundle of His
First to recognize intracranial origin of heartbeat
Sinus Node (SA node)
Small, flattened, ellipsoid strip of specialized cardiac muscle
No contractile muscle filaments
Where are SA nodes located?
In the superior wall of the right atrium below and lateral to the opening of the superior vena cava
Anteriorinteratrial band (Bachman’s bundle)
Internodal pathway
Passes through the walls of right atrium to left atrium
What are the internodal pathways?
Anteriorinteratrial band, anterior, middle and posterior
How do the other 3 internodal pathways run?
Curve through areas of the right atrial wall and terminate in the AV node
AV node
Located in the dorsal wall of the right atrium behind the tricuspid valve
Bundle of His (AV Bundle)
Passes downward in the ventricular septum toward the apex of the heart driving into left and right bundle branches
AP conduction velocity of the SA and AV node?
0.02-0.01 m/s (slowest)
60-100
40-55 (AV node will take over if SA not working)
AP conduction velocity of the pathways?
1 m/s
AP conduction velocity of atrial and ventricular muscles
0.5 m/s
AP conduction velocity and pacemaker rate of bundle of His and the lest and right bundle branches
2 m/s
25-40
AP conduction velocity and pacemaker rate of purkinje fibers
4 m/s (fastest)
25-40
Where does Norma, excitation originate?
In SA node then propagates through both atria
Heart contraction
- Atrial excitation begins at 0 when one SA node cell fires and AP
- Within 0.1 seconds, the AP propagates across the atrias and contraction starts
- AP propagates across the atria and depolarizes the cells in the AP nose at 0.04 sec
- AP arrives at the ventricular apex 0.17 sec and takes 0.13 sec for AP to travel through the AV node and bundles
- Ventricular depolarization is complete by 0.22 and both ventricles contract and atria have depolarized and are relaxing
What is each cardiac muscle smell made of?
A few hundred myofibrils
Myofibrils
Each one has a A band, I band, Z disk forming a sarcomere
Sarcomere
Contractile unit of the muscle fiber
~0.1 mm (100um) long
Intercalated disks
Cell membranes that separate individual cardiac muscle cells from each other
What is formed for rapid diffusion of ions between fibers?
Cells membranes fuse and from permeable GJs at each intercalated disc
Where do cardiac muscles contract?
In the syncytium since the action rapidly spreads across the organ
What are the 2 syncytia?
Atrial syncytium (walls of 2 atria)
Ventricular syncytium (walls of 2 ventricles)
