BMS 100 - Chapter 13 Outline

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Vessels
1. Arteries - carry blood, under high pressure, away from the heart, toward organs
2. Capillaries
   1. are located within organs
   2. capillary walls are made of a single layer of cells (for easy passage of gases, etc.)
3. Veins - carry blood, under low pressure, from organs back to the heart

Structure of the Heart (p. 325)
1. heart wall - has three layers, including the myocardium (heart muscle)
2. heart chambers: two atria and two ventricles
   1. atria receive blood from veins and deliver blood to ventricles
   2. ventricles pump blood into arteries
3. “right heart” = right atrium (RA) + right ventricle (RV)
4. “left heart” = left atrium (LA) + left ventricle (LV)

Paths of Circulation (p. 346)
1. Pulmonary circuit - consists of vessels that carry blood from the heart to the lungs and back to the heart
   • while passing through lungs, blood becomes oxygenated
2. Systemic circuit - consists of vessels that lead from the heart to all organs except the lungs and back to the heart.
   • while passing through organs other than lungs, blood becomes relatively deoxygenated

Path of Blood through the Heart
1. LV pumps oxygenated blood into the aorta
2. systemic arteries = aorta & branches of aorta
3. systemic arteries carry ox. blood to all organs, which absorb some of the oxygen from the blood (blood becomes "deox.")
4. systemic veins collect deox. blood from all organs and return it to RA
5. RA receives deox. blood, mainly from the superior vena cava and inferior vena cava, and delivers it to RV
6. RV pumps deox. blood into the pulmonary trunk
7. pulmonary trunk branches into pulmonary arteries, which lead to lungs
8. pulmonary veins collect ox. blood from lungs
9. pulmonary veins return blood to LA
10. LA delivers blood to LV

• Questions
  1. Which side of the heart contains oxygenated blood?
  2. For each of the following, state whether the blood contained is oxygenated ("ox") or deoxygenated ("deox"): systemic artery, systemic vein, pulmonary artery, pulmonary vein.

Heart Actions & Cardiac Cycle (p. 330)
1. both atria contract simultaneously, and both ventricles contract simultaneously
2. systole = contraction of a heart chamber
3. diastole = relaxation of a heart chamber
4. cardiac cycle
   1. ventricular systole (approx. 0.3 sec.) – both ventricles contract
      • systolic pressure = pressure in arteries when ventricles contract
   2. ventricular diastole (approx. 0.5 sec.) – both ventricles relax
      • diastolic pressure = pressure in arteries when ventricles relax
      • atrial systole occurs during the last 0.1 sec. of vent. diastole
5. Click here for a Cardiac Cycle Animation.
6. heart valves
   1. atrioventricular (AV) valves - are located between atria and ventricles
      • closed during ventricular systole to prevent backflow from ventricles (higher pressure) to atria (lower pressure)
   2. semilunar (SL) valves - are located between arteries and ventricles
      • closed during ventricular diastole to prevent backflow from arteries (higher pressure) to ventricles (lower pressure)
   3. Choose "open" or "closed" as appropriate (blood should never flow "backwards"):

      	ATRIAL PRESSURE	AV VALVES	VENTRICLAR PRESSURE	SL VALVES	ARTERIAL PRESSURE
      SYSTOLE	< vent. P.	open or closed?	high	open or closed?	< vent. P.
      DIASTOLE	> vent. P.	open or closed?	low	open or closed?	> vent. P.

   4. heart sounds are due to “shock waves” produced when blood collides with a closing valve
      • at beginning of vent. systole, AV valves close - causes first heart sound (S1)
      • at beginning of vent. diastole, SL valves close - causes second heart sound (S2)

Blood Supply to the Heart (Coronary Circulation)
1. coronary arteries - the first branches of the aorta, contain ox. blood
2. coronary arteries "branch out" and branches penetrate into heart wall
3. gas exchange occurs through the walls of capillaries located in the myocardium
4. deox. blood is collected by veins and returned to the RA

Cardiac Conduction System
1. cardiac muscle fibers within a chamber are connected into a network
2. if any part of the network is stimulated, the whole network contracts as a unit
3. cardiac conduction system - initiates and conducts electrical impulses
   1. sinoatrial node (SA node, pacemaker) - initiates electrical signal; signal spreads throughout atrial myocardium and to...
   2. atrioventricular (AV) node - relays signals to "bundles" and finally to fibers in ventricular myocardium
4. Click here for a Conduction System Animation.

Blood Pressure (p. 342)
1. BP = cardiac output X resistance
   • cardiac output = heart rate X stroke volume
   • resistance is affected by the diameter and the length of the vessels
2. Why must BP be maintained within a certain range?
   • BP too high - vessels may rupture
   • BP too low - not enough pressure to force blood through organs

Chapter 13 Questions at OLC - 4, 5, 7, 10, 11, 12, 14, 15, 19, 21, 26, 29, 31, 33, 34, 35, 36, 37, 38 Spring 2011