The Heart Flashcards
What is the main role of the heart?
To pump blood.
Describe the hearts structure.
It is a cone shaped hollow muscular organ, the size of the owners clenched fist.
Where is the heart located?
In the middle of the thoracic cavity.
Under the sternum.
Between the lungs.
Above the diaphragm.
What membrane surrounds the heart?
The pericardium.
What is the role of the pericardium?
It is a membrane that surrounds the heart and prevents friction with nearby organs when the heart contracts.
What muscle is the wall of the heart made of?
Cardiac muscle.
What are the features of cardiac muscle.
It is involuntary.
It contracts strongly- it can shorten.
It does not tire.
Describe the hearts blood supply.
As a living organ of the body, the heart has its own blood supply through the coronary arteries and the cardiac veins.
What is the role of the coronary arteries?
They deliver oxygenated blood to the cardiac muscle wall of the heart.
Where do coronary arteries arise?
From the base of the aorta just beyond the semilunar valve.
What is the role of the cardiac veins?
They drain deoxygenated blood from the cardiac muscle wall of the heart directly to the right atrium.
Distinguish between oxygenated and deoxygenated blood.
Oxygenated blood is high in O2 and low in CO2.
Deoxygenated blood is high in CO2 and low in O2.
What is the region of lowest pressure in the heart and why?
The right atrium as pressure decreases as the right atrium receives blood against the force of gravity from the longer systemic circuit.
What is the region of highest pressure in the heart and why?
The left ventricle is the region of highest pressure as it must pump blood out into the aorta and through the longer systemic circuit.
Why is the wall of the left ventricle thicker?
To pump blood out into the aorta and through the longer systemic circuit.
Describe the structure of the atria.
They are the thin walled upper chambers.
They only pump blood the short but equal distance to the ventricles.
What are the functions of the atria?
They receive blood from the veins and pump it a short distance down to the ventricles.
Describe the structure of the ventricles.
They are the thicker walled lower chambers.
They pump blood through the longer systemic circuit.
What are the functions of the ventricles?
They pump the blood out of the heart into the arteries.
Describe the structure of the septum.
Middle cardiac muscular wall.
What are the functions of the septum?
Keeps oxygenated and deoxygenated blood separate.
Describe the structure of the tricuspid valve.
Has 3 flaps.
What are the functions of the tricuspid valve?
Prevents the backflow of the blood from the right ventricle to the right atrium.
Describe the structure of the bicuspid valve.
Has 2 flaps.
What are the functions of the bicuspid valve?
Prevent backflow of blood from the left ventricle to the left atrium.
Describe the structure of the tendons.
Tough cords.
What are the functions of the tendons?
Hold the tricuspid and bicuspid valves in place.
Describe the structure of the semilunar valves.
Flaps located at the base of the aorta and pulmonary artery.
What are the functions of the semilunar valves?
Prevents backflow to the ventricles following ventricle systole.
What is the pericardium?
It is a double membrane with pericardial fluid.
What is the role of the pulmonary artery?
To carry deoxygenated blood to the lungs from the right ventricle.
Has a semilunar valve to prevent the backflow of blood into the right ventricle.
What is the role of the pulmonary vein?
Returns oxygenated from the lungs to the left atrium.
What is the role of the aorta?
Carries oxygenated blood to the body from the left atrium.
Has a semilunar valve to prevent the backflow of blood into the left ventricle.
What is the role of the superior and inferior vena cava?
Return deoxygenated blood from the body to the right atrium.
Venous blood is carried under low pressure against the force of gravity, hence the need for valves to prevent the backflow of blood.
Describe the pulmonary circuit.
The right ventricle pumps deoxygenated blood to the lungs in the pulmonary artery
At the lungs CO2 is lost and O2 is collected
Oxygenated blood is then returned to the left atrium by the pulmonary veins
Describe the systemic circuit.
The left ventricle pumps oxygenated blood to the body in the aorta.
Blood loses o2 and gains CO2
Deoxygenated blood is then returned to the right atrium by the superiors and inferior vena cava
What are the advantages of double circulation?
Oxygenated and deoxygenated blood are kept separate- generates a high blood pressure which supplies all body cells with o2 and nutrients like glucose
Organism is more active with a high metabolic rate
What is single circulation?
Heart pumps blood to the body and returns it to the heart in a single circuit e.g fish
What is the disadvantage of single circulation?
Generates only a low blood pressure so the organism is less active due to a low metabolic rate
What is a portal system
Begins and ends in capillaries
What is an example of a portal system
Hepatic portal vein
Connects the capillaries in the intestine to the capillaries in liver
Carries deoxygenated blood rich in co2 and nutrients such as glucose and amino acids to the liver
It does not transport lipids
Carbon dioxide levels are usually higher in venous blood than in arterial blood, explain why this is the case
Venous blood collects carbon dioxide as it drains blood from cells
Carbon dioxide is produced during respiration
what is the SA node?
The sino atrial node/ pace maker
What is the AV node?
The Atrio ventricular node
What is systole
Contraction of the heart muscle
What is diastole
Relaxation of the heart muscle
Where is the SA node located
It is located in the wall of the right atrium
What is the role of the SA node?
Controls the heartbeat
Generates impulses
Impulses cause the atria to contract
Initiates a wave of muscular contractions through the heart from atria to ventricles
Where is the AV node located
In the septum between the right atrium and right ventricle near the tricuspid valve
What is the role of the AV node?
Generates impulses which cause the ventricles to contract-ventricle systole
What is the rate at which the pacemaker operates influenced by?
Nerves from the brain which connect to the pacemaker
Hormones such as adrenaline
What are the factors that increase the heart rate?
Exercise
Temperature
Shock
What are the factors that decrease the heart rate
Sleep
Relaxation
Alcohol
Describe the stages of the heart beat
Describe how blood flow through the heart is maintained
The functioning of the SA AND AV nodes in relation to systole and diastole periods in the heart cycle.
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Write notes on the sounds created during the cardiac cycle
Lub and dub sound is caused by the valves closing.
The lub sound is quieter and longer and is caused by the closing of the tricuspid and bicuspid valves
The dub sound is louder and shorter and is caused by the closing of the semilunar valves
What is the pulse
The expansion and contraction of an artery,
A wave of vibrations that pass down the walls of arteries when the aorta expands following a ventricular contraction
Where is the pulse located
Wrist
Temple
Neck
As the artery is close to the skin surface
What is the average pulse rate
72bpm
What is exactly being measure when a persons blood pressure is being taken
The force exerted by blood against the inner walls of arteries
How is blood pressure measured?
In an artery in the upper arm using a sphygmomanometer
What two pressures are measured
Systolic pressure as the ventricles contract
Diastolic pressure as the ventricles relax
What’s hupertension
High blood pressure can lead to heart attacks and strokes
