CIRCULATORY SYSTEM - Weebly



CIRCULATORY SYSTEM

Function:

• _________________________________________

• _________________________________________

• _________________________________________

• _________________________________________

• _________________________________________

• _________________________________________

BLOOD

• A red sticky substance

• Body contains 5L of blood

• Blood with high O2 is bright red; dark red with low O2

Composition: _______________________________

_________________________________________________________

1) Plasma

2) Erythrocytes (red blood cells)

3) Leukocytes (white blood cells)

4) Thrombocytes (platelets)

Blood Types

• Determined by the presence or absence of antigens

• Antigen – a molecule recognized as foreign by the immune system. Causes the body to release antibodies.

• Antibody – a protein that recognizes an antigen

|Blood Type |Antigen Present |Antibody Present |

|A |A |B |

|B |B |A |

|AB |A and B |None |

|O |None |A and B |

Universal Donor – Type O – has no antigens

Universal Receiver – Type AB – has both antigens, no antibodies

BLOOD VESSELS

|Arteries |Capillaries |Veins |

| |Exchange of materials between blood and tissues | |

| | | |

| |Thin walls 1 cell layer thick | |

| | | |

| |1 cell at a time | |

| | | |

| |No valves | |

| | | |

| |Move blood at low speed. Cells move single file | |

| | | |

| |Low pressure | |

| | | |

| |Links arterioles and venules | |

| | | |

Flow of Blood through the Heart

Pulmonary Circulation – ____________________________________________

Systemic Circulation – _______________________________________________

Coronary Circulation – ______________________________________

Supplies the heart muscle with oxygen and nutrients

1. _________________ blood flows into the right atrium from the inferior and superior vena cava

2. Right atrium pumps blood through the tricuspid valve (atrio-ventricular valve) into the right ventricle

3. Blood is pumped out through the semi-lunar valve to the pulmonary artery to the lungs

4. Blood picks up oxygen (gets rid of CO2) at the alveoli

5. ____________blood returns to the heart through the pulmonary vein and enters the left atrium

6. Left atrium pumps blood through the bicuspid valve (A-V valve) into the left ventricle

7. Blood is pumped through the semi-lunar valve to the aorta and out to the coronary arteries and the rest of the body.

• The entire cycle takes about 20 seconds

• The heart is a double pump. Deoxygenated blood on the right, oxygenated blood on the left.

• The fetal heart has a hole between the left and right atrium to exchange oxygenated and deoxygenated blood.

Control of the Heartbeat

➢ Cardiac muscle contracts spontaneously

➢ The heart beat is _________________(_________________) and is under _____________________ control

➢ Originates in the __________________ (SA node) located in the right atrium. ( ____________

➢ Sends a nerve impulse that causes contraction of the atria

➢ This impulse spreads to the _____________________ (AV node), then to the Bundle of HIS down to the apex of the heart and to the perkinji fibres.

➢ This causes contraction of the ventricles.

➢ Nerves and hormones can slow down or speed up the heart beat (eg. Adrenalin)

➢ An increased CO2 level sensed by medulla in the brain (therefore a greater need for oxygen)

The Cardiac Cycle & Blood Pressure

Cardiac Cycle – the sequence of actions of a heart beat.

One cardiac cycle involves:

Diastole – relaxation or resting of heart chambers.

Systole – contraction of heart chambers

Arterial Diastole

➢ Atria fill with blood.

➢ Pressure forces the AV valves open

Arterial Systole

➢ Atria contract

➢ Blood is pushed into the ventricles

Ventricular Systole

➢ Contraction of the ventricles.

➢ A-V valves close (bicuspid & tricuspid), causing a “lub” sound.

➢ Pressure is increased and forces blood out of the ventricles, opening the semilunar valves.

Ventricular Diastole

➢ Relaxation of the ventricles

➢ Semilunar valves close causing a “dub” sound.

➢ Pressure drops, AV valves open, ventricles fill with blood.

Heart beat sounds: “lub-dub-lub-dub”

Blood Pressure – the pressure exerted on the walls of the arteries.

Systolic Normal Adult = 120 mmHg

Diastolic 80

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