Please enable JavaScript.
Coggle requires JavaScript to display documents.
Circulatory System (Maintaining the heart beat (rate of heart contractions…
Circulatory System
-
Cardiac cycle
-
Important Key Terms:
Systole- contraction phase of cardiac cycle
contraction= pumps blood out
Diastole- relaxation phase of cardiac cycle
relaxation= fills with blood
First stage:
Atrial and ventricular diastole- during relaxation phase, blood returning from large veins flows into atria and then into ventricles through AV valves
Second stage:
Atrial systole and ventricular diastole- a brief period of atrial contraction then forces all blood remaining in atria into ventricles
Third stage:
Ventricular systole and atrial diastole- during the remainder of the cycle, ventricular contraction pumps blood into large arteries through semilunar valves
3 types of blood vessels
Capillary
- endothelium (one layer of endothelial cells) + basal lamina
- smallest in diameter (just barely bigger than a red blood cell
- very thin walls for optimal diffusion
Artery
- endothelium + thick layer of smooth muscle + thick layer of connective tissue
- hormones and nervous system signals act on arteries to dilate or constrict arteries to control blood flow to different body parts
Vein
- endothelium + thin layer of smooth muscle + thin layer of connective tissue
- also contain valves to maintain unidirectional blood flow even with low blood pressure
Blood pressure in heart contraction cycle:
- High pressure occurs when blood is pumped away from the heart
- leaving ventricles
- in arteries
- Low pressure occurs when blood has finished traveling through capillaries and re-enters veins to go towards the heart
- traveling towards atria
- in veins
Vasoconstriction and vasodilation both parts of homeostatic mechanism regulate arterial blood pressure by altering diameter of ventricles
-
-
-
-