Section 7 Flashcards
Functions of the CV system (5)
- deliver O2 to tissue
- deliver deoxygenated blood to lungs
- transport heat from core to skin
- deliver nutrients to tissues
- transport hormones to tissues
Describe heart structure (2)
striated lattice-like. Pulmonary Circuit (Right side) Systemic Circuit (Left side)
Pulmonary Circuit
Right side;
right atrium receives blood from body (deoxygenated). Right ventricle sends blood to lungs.
Systemic Curcuit
Left side;
left atria receives blood rom lungs (oxygenated). Left ventricle sends blood to body.
Arterial System
aorta, arteries, and arterioles
moves blood front heart to tissues.
High pressure w/ elastic recoils.
Endothelial lining (lack of is an early sign of cardiovascular disease), smooth muscle, and connective tissue (anchors it into place).
Cardiorespiratory System (3)
Arterial System
Capillaries system
Venous System
Capillaries System
(fiber type dependent)
Store quite a bit of blood.
Exchange vessel are 7-10 m in diameter.
Contain 6% of total blood volume.
Pre-capillary sphincters regulate flow.
Venous System
coronary sinus, venules, and veins
Blood movement from tissue to heart (assisted by one-way valves).
Low pressure, thinner-walled collection and return tubes. Serve in capacitance role (about 2/3 of blood on the venous side).
When sitting, 60-65% of our blood is between our hips and downward.
Myocardium
Contractile portion of the heart responsible for force. Intercalated discs intercellular connections that permit the transmission of electrical impulses between fibers. The heart contracts as a unit (“functional syncytium”). Highly aerobic with high capillary and mitochondrial density.
Heart muscle receives blood from the R and L coronary arteries.
Myocardial Circulation
Coronary arteries branch off the ascending aorta.
Right coronary artery (RCA) supplies predominantly the right atrium and ventricle.
The left coronary artery (LCA) supplies the left atrium and ventricle and small portion of the right ventricle.
Myocardial O2 use at REST
~70-80% available O2.
Myocardium has higher mitochondrial density than Type 1 fiber.
This allows heart to utilize: glucose, lactate (fuel for heart), and fatty acids (produce more ATP at rest).
Lactate>pyruvate>Acetyl-CoA>combusts thru Krebs and ETC
Endurance exercise increases: use of lactate and FFA for fuel, which decreases use of carbs
Myocardial O2 use during EXERCISE
flow must increase to meet O2 demand
flow may increase 4-6x during strenuous-near max exercise.
Increase in CO= heart is working very hard
Myocardial Workload Assessment
Rate - Pressure or Double Product: Systolic Blood Pressure (SBP) x HR.
If this number is high, that means the heart is working hard.
MAP = DBP + 1/3PP
Electrical Conduction System (5)
- SA node initiates the action potential, which sweeps across the atria.
- Slight delay at the AV node to allow the atria to finish pumping blood.
- Impulse is then transmitted to the AV bundle.
- Impulse spreads to contractile fibers of the ventricle.
- Ventricular contraction begins.
Parasympathetic stimulation- decreased heart rate (slower NA influx)
Sympathetic stimulation- increased heart rate (less K efflux)
Auto Rhythmicity
it refers to the electrical activity of the heart & how the heart contracts rhythmically as a result of APs that it generates by itself
Components of blood (5)
Plasma: watery portion consisting of ions, proteins, and hormones.
Cells: red bloods cells, platelets, WBCs.
RBCs: contains hemoglobin for O2 transport
Platelets: blood clotting
WBCs: immune function
Hematocrit
Hematocrit: percentage of blood that’s RBC. Varies person to person (42% males, 38% females).
Hematocrit increase = Viscosity increases.
2 phases of the cardiac cycle and how they relate to BP
Diastolic BP (relax) Systolic BP (contraction)
maintains blood pressure and keeps blood flowing to organs