The Circulatory System & The Heart

Open circulatory system (definition)

Heart pumps blood into vessels that are open ended, blood leaves the vessels and flows around the cells before re-entering blood vessels.

Open circulatory system (Examples)

Insects, spiders, snails, slugs

Closed circulatory system (definition)

Blood remains in a continuous system of blood vessels e.g. animals

Advantages of a closed system

Blood can be pumped faster (nutrients & oxygen delivered faster, allows organism to be more active). Blood flow rate to different organs can be changed

Name the three blood vessels

Arteries. Veins. Capillaries

Artery Structure

No valves. Narrow lumen. Thick wall

What is the outside, inelastic layer of blood vessels made of?

Collagen

What is the middle layer of blood vessels made of?

Muscle and elastic fibre

What is the name of the cells that surrounds the lumen?

Endothelium

Vein Structure

Wide lumen. Thin walls. Has valves

Function of valves

Prevent the backflow of blood

Capillaries (Structure & Function)

Thin walls (One cell thick to exchange materials between blood and cells). Connects veins to arteries

Name the places blood goes as it travels through the body, starting at the artery

Artery - arteriole - capillary - venule - vein - heart

Draw a diagram of a vein

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Draw a diagram of an artery

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Where is the heart located?

Thoracic cavity (between the lungs and above the diaphragm)

What is the heart made of?

Cardiac muscle

What is cardiac muscle?

An involuntary muscle that is slow to fatigue

What is the pericardium?

A double membrane that surrounds the heart

Function of pericardium fluid

Helps reduce friction when the heart beats

Why does the left ventricle have thicker walls?

Pumps blood all around the body

Why does the right ventricle have thinner walls?

Pumps blood to the lungs

Draw a diagram of the heart

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Aorta (What is it? & Function)

Main artery. Carries oxygenated blood away from the heart to the body

Vena Cava (What is it? & Function)

Main vein. Carries deoxygenated blood from the body to the right atrium

Pulmonary Artery (Function)

Carries deoxygenated blood to the lungs

Pulmonary Vein (Function)

Carries oxygenated blood from the lungs to the left atrium

What are the names of the two circuits?

Pulmonary circuit. Systemic circuit

Pulmonary circuit

Heart - pulmonary artery (right side) - lungs - pulmonary vein (left side) - heart

Advantages of two circuits

Allows for deoxygenated blood and oxygenated blood to be kept separate. Ensures blood pressure remains high enough to reach all parts of the body

The superior and inferior vena cava

Split in two. One Vena cava collects blood from the head (superior vena cava). Other collects it from the rest of the body (inferior vena cava)

Anagram for remembering which side of the heart carries oxygenated/deoxygenated blood

LORD (Left Oxygenated, Right Deoxygenated)

What is a portal system?

A blood pathway that begins and ends in capillaries

What two parts is the hepatic portal system between?

Capillaries in small intestine and capillaries in liver

Function of hepatic portal system

Nutrients from small intestine move directly to the liver for processing

Hepatic artery (function)

Carries blood from aorta into the liver

Hepatic portal vein (function)

Carries nutrients from small intestine to liver

Hepatic vein (function)

Carries deoxygenated blood with nutrients away from the liver

What supplies oxygenated blood to the heart?

Coronary arteries

Where do the coronary veins return blood?

Directly into the right atrium

Where do coronary arteries originate?

Base of the aorta

What is a common cause of a heart attack?

Blockage of the coronary arteries

Bicuspid valve location

Between left atrium and left ventricle

Bicuspid valve function

Prevents back flow of blood into left atrium

Tricuspid valve location

Between right atrium and ventricle

Tricuspid valve function

Prevents back flow of blood into right atrium

Semi-lunar valves location

At the base of arteries

Semi-lunar valves function

Prevents back flow of blood into heart

What causes the flow of blood through the heart?

The alternate contraction and relaxation of the heart muscle

Alternate name for a heartbeat

Cardiac cycle

What is diastole?

Relaxation of cardiac muscle

What is systole?

The contraction of cardiac muscle

First stage of the cardiac cycle

Blood enters through the vena cava and pulmonary vein. Atria and ventricles are in diastole

Second stage of the cardiac cycle

Pacemaker (SA node) sends out waves of electric impulses across the walls of the atria.

Third stage of the cardiac cycle

Atria are in systole, pressure of blood causes bicuspid and tricuspid valves to open. Blood enters ventricles

Fourth stage of the cardiac cycle

AV node carries impulses to the ventricles. Ventricles now in systole. Pressure causes semi-lunar valves to open and blood enters the aorta and pulmonary artery. Ventricles relax

What is the full name of the SA node?

Sinoatrial node

What is the full name of the AV node?

Atrial-ventricular node

Where is the SA node located?

Embedded in the top of the right atrium

Where is the AV node located?

Located in the septum between the right atrium and right ventricle

where can the pulse be felt and why?

In the wrist or neck as the arteries are close to the skin

Blood pressure (definition)

The force exerted by the blood against the walls of blood vessels (mainly arteries)

What does high blood pressure (hypertension) indicate?

The blood is struggling to move freely throughout blood vessels

What causes high blood pressure?

Blockage in arterioles and small arteries

How do medical professionals take blood pressure?

Record the pressure needed to stop the flow of blood in the major artery in the upper arm

What is the average blood pressure?

120/80

How to maintain a healthy heart

Exercise regularly (strengthens heart). Reduce fat, sugar, salt in diet to reduce heart attack risks and obesity. Don’t smoke

How does smoking effect the heart?

CO (carbon monoxide) reduces the blood’s ability to carry oxygen. Nicotine increases blood pressure

Describe how blood is moved through the veins

Moved by the contraction of skeletal muscles and the opening and closing of valves