heart and circulatory system

The circulatory system is a system of…

Blood vessels, the heart, valves

What type of blood does the right side of the heart pump and what is the circuit called?

Deoxygenated, pulmonary circuit

What type of blood does the left side of the heart pump and what is the circuit called?

Oxygenated, systemic circulation

Deoxygenated blood flows through the…

Right atrium then right ventricle

Oxygenated blood flows through…

The left atrium then the left ventricle

What makes up blood?

Red and white blood cells, platelets, dissolved substances

What does plasma transport?

Blood cells, waste carbon dioxide, urea, small soluble products of digestion

How are red blood cells adapted?

Biconcave discs - more surface area to volume ratio

Packed with haemoglobin - binds with oxygen to form oxyhaemoglobin

No nucleus - more space for haemoglobin

What are lymphocytes and what do they do?

They are a type of white blood cell that form antibodies against microorganisms and release antitoxins against their poisons.

What are phagocytes and what do they do?

They are a type of white blood cell that engulf and digest invading bacteria and viruses via phagocytosis.

What are platelets and why are they important?

They are small fragments of cells without nuclei that are crucial to helping blood clot.

What is blood clotting and how does it work?

Series of enzyme-controlled reactions

Convert fibrinogen to fibrin

Forms network of protein fibres to stop you from bleeding out

What do arteries do?

They carry blood at high pressures away from the heart.

What causes pulse?

The stretching of the arteries as blood is forced through them.

How are arteries adapted for their function?

Muscular walls with elastic fibres that are thicker than lumen - strength and stretch

What do veins do?

Carry blood to heart using skeletal muscles.

How are veins adapted?

Thin walls compared to lumen size - blood flows at low pressure

Bigger lumen - maintain blood flow despite lack of pressure

have valves - stop back flow of blood

What do capillaries do?

Travel close to cells for exchanging substances

How are capillaries adapted?

Thin, permeable walls for exchanging substances

Many of them together - maintain constant concentration gradient

How is blood pumped?

1. Blood flows into left atrium via vena cava and into right atrium via pulmonary vein

2. Atria contract to punch blood into ventricles

3. Ventricles contract → blood into pulmonary artery on right and aorta on left

Which ventricle has thicker walls and why?

Left

Develops pressure to force blood through arterial system but blood from right ventricle goes to lungs where high pressure would damage capillaries

What controls resting heart rate?

A group of cells in right atrium

They send small electrical impulses to surrounding muscle cells causing them to contract

What do coronary arteries do?

Supply the heart’s own supple of oxygen-rich blood

What is coronary heart disease and what are its implications?

A heart disease in which the coronary arteries become narrow usually due to a buildup of fatty material. This means that the heart gets less oxygen which can cause pan, heart attacks and death.

How do stents work?

They are a thin metal mesh

Placed inside artery

Tiny ballon inflated to open up blood vessel and stent

Ballon removed but stent stays to allow blood to flow freely

Advantages and disadvantages of stents

Can be used almost anywhere

Some release drugs to stop blood clotting

Expensive

What is bypass surgery?

Doctors replace part of coronary artery with bits of veins from other areas

Advantages and disadvantages of bypass surgery

Can work in places that stents don’t work

Expensive

Involves risks of general anaesthetic

What do statins do?

Reduce cholesterol levels to slow down rate of fatty material being deposited in coronary arteries

Valves withstand a lot of pressure. What can this cause?

Leaky valves - valves may start to leak or not open fully, making the heart less efficient

Mechanical vs biological valves

M- last very long. B- only 12-15 yrs

M- medicine rest of life B- no medicine

What happens if your natural pacemaker stops working properly?

Too slow - not enough oxygen

Too fast - heart cannot pump blood properly

What is an artificial pacemaker?

An electrical device implanted in the chest used to make heart rates regular.

Sends strong, regular electrical signals to heart to stimulate beating

Downside of artificial pacemakers

Regular medical checkups throughout life

Advantages and disadvantages of artificial hearts

Can sustain people whilst they wait for donors

Can be used to give diseased heart a rest

Need lots of machinery - most have to stay in hospital

Risk of blood clotting

Require lots of resources and super expensive