Chapter 13 - Blood, Heart, and Circulation

Circulatory System: definition, components, and relation to the cardiovascular system

• definition: organ system that transports molecules and other substances over long distances between cells, tissues, and organs

• components:

  • heart

  • blood vessels

  • blood

  • lymph

• relation to cardiovascular system: shares heart, vessels, and blood as components

composition of blood, volume of blood

• plasma: fluid portion of blood, contains water, ions, proteins, nutrients, gases, hormones, wastes, etc.

• formed elements: solid portion of blood, contains erythrocytes, leukocytes, and platelets

• volume of blood: 5.5 L

hematocrit and hemoglobin

• hematocrit: % of volume composed of RBCs

• hemoglobin: (g/mL), transports oxygen

Trace pulmonary and systemic circulation

Pulmonary circulation:

• RV —> pulmonary SL —> pulmonary trunk —> pulmonary arteries —> lungs (gas exchange) —> pulmonary veins —> left atrium

Systemic circulation

• LV —> aortic SL —> aorta —> arteries —> arterioles —> capillaries —> venules —> veins —> venae cavae —> right atrium

All the valves of the heart (try before you buy)

• tricuspid (right atrioventricular) valve

  • connects RA and RV

• pulmonary semilunar valve

  • connects RV to pulmonary trunk

• bicuspid (mitral) (left atrioventricular) valve

  • connects LA to LV

• aortic semilunar valve

  • connects LV to aorta

Definition of Systole and Diastole, and duration of each

• systole: ventricular contraction and blood ejection, 0.3s

• diastole: ventricular relaxation and blood filling, 0.5s

heart sounds, and what they mean

• first sound: soft, “lub”

  • AV valve closure

  • beginning of systole

• second sound: loud “dub”

  • SL valve closure

  • beginning of diastole

Cardiac cycle through the perspective of systole and diastole (start at systole)

1. isovolumetric contraction

2. ejection of blood into aorta and pulmonary trunk - 2/3 of end-diastolic volume

3. isovolumetric relaxation

4. ventricular pressure becomes lower than atrial pressure, so blood flows into ventricles

5. atrial contraction delivers final amount of blood, end-diastolic volume.