Y11 Human Bio (ALL FLASHCARDS)

What is the main function of the heart?

The primary function of the heart is to pump blood around the body

What are the four chambers of the heart?

right atrim, left artrium, right ventricle, left ventricle

What is the difference between the atria and ventricles?

Atria are the upper chambers that collect blood entering the heart, while ventricles are the lower chambers that pump blood out of the heart.

What is the function of the septum?

The septum separates the left and right sides of the heart and prevents the oxygenated blood and deoxygenated blood from mixing.

What is the myocardium?

The myocardium is the muscular wall of the heart, which is responsible for pumping blood.

Why is the left ventricle thicker than the right ventricle?

The left ventricle pumps blood around the body, which means it needs more muscle to generate a higher pressure.

What is the function of the pericardium?

The pericardium is a protective membrane around the heart which contains lubricating fluid that reduces friction during the beating of the heart.

Which side of the heart pumps deoxygenated blood?

The right side

Which side of the heart pumps oxygenated blood?

The left side

What is the function of the vena cava?

The vena cava returns deoxygenated blood from the body to the right atrium

What type of blood does the vena cava carry?

deoxygenated blood

What is the function of the pulmonary artery?

It carries deoxygenated blood from the right ventricle to the lungs

Why is the pulmonary artery unusual?

It is the only artery that carries deoxygenated blood

What happens in the lungs?

Gas exchange occurs, carbon dioxide leaves the blood and oxygen enters the blood.

What is the function of the pulmonary veins?

They carry oxygenated blood from the lungs to the left atrium

Why are pulmonary veins unusual?

They are the only veins that carry oxygenated blood

What is the function of the aorta?

The aorta carries oxygenated blood from the left ventricle to the body

What are coronary arteries?

They are blood vessels that supply oxygenated blood to the heart muscle

What are the main heart valves?

Tricuspid valve, Bicuspd valve, pulmonary semilunar valve, arotic semilunar valve

Where is the tricuspid valve located?

Between the right atrium and right ventricle

Where is the bicuspid valve located?

Between the left atrium and left ventricle

Where is the pulmonary semilunar valve located?

Between the left ventricle and aorta

Describe the pathway of blood through the heart

Vena cava, right atrium, tricuspid valves, right ventricle, pulmonary valve, pulmonary artery, lungs, pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, aorta, body

What is a double circulatory system?

A system where blood passes through the heart twice in one complete circulation.

What is the pulmonary circut?

The movement of blood between the heart and the rest of the body

What is the role of the heart valves?

Heart valves ensure one way blood flow.

How do valves ensure one way blood flow?

Valves open when pressure behind them is higher and close when pressure in front of them becomes higher.

How does the structiure of the heart support it’s pumping function?

Thick muscular walls generate pressure, while valves prevent backflow. Seperate chambers keep oxygenated blood and deoxygenated blood apart via the septum, and the thicker left ventricle generates high pressure for systematic circulation.

What is atherosclerosis?

The buildup of plaque on the artery walls, causing arteries to narrow and harden

How does atherosclerosis affect blood flow?

It restrict blood flow, and reduces oxygen delivery to tissues.

What can atherosclerosis lead to?

Heart attacks, strokes and peripheral artery disease.

What are common causes of atherosclerosis?

High cholestorol, smoking, high blood pressure and diabetes.

What is valve stenosis?

Valve stenosis is narrowing of a heart valve, reducing blood flow.

What is valve regurgitation?

When a valve leaks, allowing blood to flow backwards.

How can coronary artery blockage affect the heart?

It reduces oxygen supply to the heart muscle, potentially causing a heart attack.

What does ‘myogenic’ mean?

The heart can generate its own electrical signals without input from the brain

What is the role of the ‘SA node’?

The sinoatrial node acts as the hearts natural pacemaker and starts the heartbeat.

Where is the SA node located?

In the right atrium near the vena cava

What is the role of the AV node?

The atrioventricular (AV) node delays the electrical signal before passing it to the ventricles.

What is the role of the Bundle of His?

It carries the electrical signal through the ventricles causing ventricular contraction

What is the role of Purkinje fibres?

They spread the electrical signal through the ventricles causing ventricular contraction

What is the pathway of electrical conduction through the heart?

SA node ——> AV node ——> Bundle of His ——> Purkinje fibres

Why is there a delay at the AV node?

The delay allows the ventricles time to fill with blood before they contract

Why must electrical signals travel in the correct order?

So the atria contract before the ventricles, ensuring efficient blood flow

What is an arrhythmia?

An abnormal heart rhythm

What can happen if the conduction system is damaged?

The heart may beat too fast, too slow or irregularly

What is fibrillation?

Disorganised, irregular contractions of the heart muscle that reduce effective pumping

What is the purpose of a defibrillator?

To deliver an electrical shock that resets the heart to a normal rhythm

Why are artificial pacemakers used?

They maintain a regular heartbeat when the heart’s natural conduction system fails

What is the cardiac cycle?

the cardiac cycle is the sequence of events that occurs during one complete heartbeat, including contraction and relaxation of the heart

What is systole

the contraction phase of the heart

what is diastole

diastole is the relaxation phase of the heart

What happens during atrial systole

The atria contract and push blood into the ventricles while the ventricles are relaxed

What happens during cardiac dyastole

All chambers relax and refill with blood before the next heartbeat

Why is there no pause between cardiac cycles?

The heart works continuously so blood keeps flowing around the body

in what order do the chambers contract during the cardiac cycle?

The atria contract first, then the ventricles contract, then all chambers relax

What causes heart valves to open and close

pressure changes inside the heart chambers

What happens to pressure when chamber volume decreases

pressure increases

What happens to pressure when chamber volume increases?

Pressure decreases

When do atrioventricular (AV) valves open?

When atrial pressure is higher than ventricular pressure

When do atrioventricular (AV) valves close?

When ventricular pressure becomes higher than atrial pressure

When do semilunar valves open?

When ventricular pressure becomes higher than artery pressure

When do semilunar valves close?

When artery pressure becomes higher than ventricular pressure

What causes the first heart sound ‘lub’

Closure of the atrioventricular valves at the start of ventricular systole

What causes the second heart sound ‘dub’?

Closure of the semilunar valves that the start of ventricular diastole.

Why are heart sounds important?

They indicate the valves are closing properly and the cardiac cycle is functioning normally

How does strong ventricular systole afftect blood pressure?

It creates higher systolic pressure and pumps out more blood

How does efficiant diastole improve heart function?

It allows more time for ventricular filling, increasing stroke volume

How does a very fast heart rate reduce efficiancy?

Diastole becomes shorter, so the ventricles fill with less blood.

How does a slower heart rate improve efficiency?

More filling time allows greater stroke volume and more effective pumping

How does valve malfunction reduce heart efficiency

Backflow reduces pressure efficiency and decreases cardiac output

what is stroke volume?

The amount of blood pumped out of a ventricle in one contraction

What is cardiac output?

The total amount of blood pumped by the heart per minute.

How can heart faliure affect the cardiac cycle?

Weak contractions recuce pumping efficiency and blood circulation around the body

What is an ECG?

An electrocardiogram (ECG) is a recording of the hearts electrical activity

What does the P wave represent?

Atrial contraction

What does the QRS complex represent?

Ventricular contraction

What does the T wave represent?

Ventricular relaxation

Why is the QRS complex larger than the P wave?

The ventricles have more muscle mass than the atria

What do the flat sections of an ECG represent?

Periods when the heart chambers are filling with blood

What is tachycardia?

An abnormally fast heart rate

What is bradycardia?

An abnormally slow heart rate

What is fibrillation on an ECG?

Irregular, unsynchronised electrical activity in the heart

How can ECGs help diagnose heart disorders?

They reveal abnormal electrical patterns linked to heart problems

What are the main structures of the pulmonary system?

Trachea, bronchi, bronchioles, alveoli, diaphragm, ribs, intercostal muscles, and pleural membranes

What is the function of the trachea?

It carries air to and from the lungs

What is the function of the cartilage rings in the trachea?

They keep the airway open

What are bronchioles?

Small branching airways inside the lungs

What are alveoli?

Tiny air sacs where gas exchange occurs

what is ventilation?

The mechanical process of breathing air into and out of the lungs

What happens during inhalation?

• External intercostal muscles contract

• Rib cage moves up and out

• Diaphragm contracts and flattens

• Lung volume increases

• Pressure decreases

• Air moves into the lungs

What happens during exhalation?

• External intercostal muscles relax

• Rib cage moves down and in

• Diaphragm relaxes and domes upward

• Lung volume decreases

• Pressure increases

• Air moves out of the lungs

Why does air enter the lungs during inhalation?

Pressure inside the lungs becomes higher than atmospheric pressure.

Why does air leave the lungs during exhalation?

Pressure inside the lungs becomes higher than atmospheric pressure

How does increased ventilation affect oxygen delivery?

More oxygen enters the alveoli and diffuses into the blood, increasing oxygen delivery to tissues

How does reduced ventilation affect the body?

Less oxygen enters the blood and carbon dioxide removal decreases

Where does gas exchange occur in the lungs?

In the alveoli

What is diffusion?

The passive movement of particles from high concentration to low concentration

What is a concentration gradient?

A difference in concentration between two areas

How does oxygen move during gas exchange?

Oxygen diffuses from the alveoli into the blood