Circulatory System

2 Types pf Circulatory system

  • Open circulatory systems
  • Closed circulatory systems

All Circulatory systems have...


  • A heart
  • Connecting vessels
  • Certain type of circulatory fluid

Closed circulatory systems-

  • Circulatory fluid is blood
  • High blood pressure stimulates movement of oxygen and nutrients
  • 1 or many hearts pump blood into large vessels and branch into smaller ones that come into the organs and tissues

Open circulatory systems-

  • Circulatory fluid is interstitial fluid
  • Lower hydrostatic pressures which means they use less energy
  • When the Heart contracts it pumps hemolymph through circulatory vessels then fluid goes to sinuses to do nutrient exchange

Route of blood flow
1).R atrium
2.)R AV valve
3.)R.ventricle
4.Pulmonary semilunar valve
5.)Pulmonary arteries
6.)lungs for gas exchange in capillaries
6.pulmoney vein
7.)L. atrium
8.)L.AV valve
9.)L.ventricle
10.)Systemic semilunar valve
11.)Aortic artery
12.)Gas exchange in body tissue capillaries
13.)inferior and superior vena cava
14.)R. Atrium

3 Steps of Cardiac Cycle

  • Atrial and ventricular diastole
  • Atrial systole and Ventricular diastole
  • Ventricular systole and Atrial diastole

Atrial systole and Ventricular diastole Atrium contracts and pumps blood into ventricle

Ventricular systole and Atrial diastole Ventricle pumps blood through semilunar valve into the large blood vessels

Atrial and ventricular diastole
Atrium and Ventricle are both in relaxation

Vasodilation: Blood vessels become larger in diameter , and cause a increase in blood flow ,which decrease blood pressure -> Can help with hypertension , Your heart doesn't have to pump as hard, reducing your blood pressure

Vasoconstriction: Blood vessels become Smaller in diameter , and cause a decrease in blood flow, which increase blood pressure

Heart beat : is the heart contracting and is controlled by intrinsic and extrinsic (2 types of controllers ) Extrinsic= medulla oblongata Intrinsic= pacemaker cells

Intrinsic: Pacemaker cells
4 steps of pacemaker cells
SA node in atria -> Signals a delay of atria emptying into ventricle at AV node -> electrical impulses spread to heart apex through purkinje fibers to ventricle -> then ventricles , which cause contraction in unison

Extrinsic: medulla oblongata
Sympathetic = increase in BP
Parasympathetic = decrease in BP

EKG: detects movements of heart electrical impulses and displays those contractions and relaxation on a graph , to show the stages of cardiac cycle

3 Types of Blood vessels structure/Function

How to measure blood pressure:
Cuff is inflated to close of arteries
Cuff is gradually deflated
When you hear first beat thats systolic pressure, but when you can't hear beat thats diastolic pressure

Capillaries: 2 cell layer thick so diffusion is constantly happening , very thin , smallest diameter

Arteries: thick 3 layer of (endothelium, smooth , connective tissue) can dilate or contract {Highest Pressure}

Vein: thin layer of (endothelium, smooth and connective tissue) has valves to stop back flow of blood {Lowest pressure}

How do molecules in blood get into interstitial fluid? Through diffusion to move particles through body by passive transport
2 mechanisms to control liquid movement ..
Blood pressure = fluid move out of capillaries into tissues (Hydrostatic)
Blood proteins = pull fluid back into capillaries and out of tissue(Osmotic)


Lymphatic system: have vessels to prevent back flow to maintain liquid movement through the body, lymph nodes filter lymph and store immune system cells