(2h) Transport in humans

Name 4 components of the blood

RBC, WBC, platelets, plasma

RBC function

Carry oxygen molecules from lungs to cells

White blood cells function

Part of the immune system - engulf pathogens or produce antibodies

What are the 2 types of white blood cell

Phagocytes, lymphocytes

Platelets description

Small fragments of cells

Platelets function

Form blood clots at wounds

Plasma description

Straw coloured liquid

Plasma function

Transport components in blood

What does the plasma transport?

Carbon dioxide, digested food, urea, hormones and heat energy

Name 3 adaptations of RBCs which make them suitable for the transport of oxygen.

Biconcave disc shape, absence of nucleus, presence of haemoglobin

How is the absence of a nucleus helpful to the RBC

Allows more space for haemoglobin to be packed in

Why does being full of haemoglobin make RBCs suitable for carrying oxygen

Haemoglobin is a protein that binds to oxygen so this allows each cell to carry a large amount of oxygen for efficient transport to respiring cells

How does the biconcave disc shape adapt RBCs for carrying oxygen

Gives a large SA:V ratio to maximise diffusion of oxygen in and out of the cell

What do phagocytes do

Engulf pathogens and release digestive enzymes to digest it

What do lymphocytes do

Release antibodies specific to the pathogen

How do phagocytes detect pathogens

They have a sensitive cell surface membrane that can detect chemicals produced by pathogens

Is phagocytosis a specific immune response?

No, it’s non-specific

What are antibodies?

Proteins with a shape that is complementary to the antigens on the surface of the pathogen

What kind of cell produces antibodies?

Lymphocytes

How do antibodies work?

They attach to antigens and cause agglutination of pathogens so they cannot move easily, allowing phagocytes (chemicals have been released to signal) to engulf them

What happens after the immune response?

The patient retains antibodies specific to that pathogen + memory cells

What are memory cells?

Lymphocytes that recognise the pathogen

What do memory cells do if the patient encounters the same pathogen again?

Produce larger quantities of the required antibody in less time which can fight off pathogen before symptoms occur

What do vaccines contain?

A dead or weakened form of the pathogen

How do vaccines work?

Correct antibodies produced and memory cells retained, but no symptoms suffered

What is herd immunity?

By immunising a large proportion of the population, the spread of the pathogen is greatly reduced as there are less people to catch the disease from

2 advantages of vaccines

Have eradicated many diseases so far and reduced occurrence of many. Epidemics can be prevented through herd immunity.

2 disadvantages of vaccines

Not always effective in providing immunity. Bad reactions can occur.

Do platelets have a nucleus?

No

Where are platelets produced?

Bone marrow

How do platelets create a blood clot?

Release chemicals causing soluble fibrinogen proteins to convert into insoluble fibrin. This forms an insoluble mesh across the wound, trapping RBCs and forming a clot

Why are blood clots important?

Prevent further blood loss from a wound. Eventually dry into a scab, preventing entry of microorganisms.

Why is the left ventricle more muscular than the right?

Has to pump blood at high pressure to whole body

Function of the septum/having separate chambers

Separate oxygenated and deoxygenated blood

Function of valves

Prevent the backflow of blood

Where are the coronary arteries

Branch off from aorta

Function of coronary arteries

Supply cardiac muscle tissue with oxygenated blood for aerobic respiration + muscle contraction

Describe the passage of deoxygenated blood

vena cava > right atrium > tricuspid valve > right ventricle > semilunar valves > pulmonary artery > lungs

Where are the tricuspid valves?

Between atrium and ventricle

Where are the semilunar valves?

Between ventricle and pulmonary artery/vein

Describe the passage of oxygenated blood

lungs > pulmonary vein > left atrium > left ventricle > aorta > body

Why does exercise affect heart rate?

Muscles need to respire more rapidly to provide energy for muscle contraction so cells require faster delivery of O2 + glucose, and removal of waste product CO2

How does exercise affect heart rate

Heart rate and volume pumped out from heart increases

How and why does adrenaline affect heart rate

Heart rate increases, delivering more oxygen to respiring muscle cells preparing the body for movement, and diverting blood away from digestive system

What is coronary heart disease?

Layers of plaque (fatty deposits), mainly formed from cholesterol, build up inside the coronary arteries

What are sources of cholesterol?

Dietary cholesterol from animal products; cholesterol synthesised by the liver

What happens if the coronary artery gets blocked by plaque?

Loses elasticity and cannot stretch to accommodate blood > reducing blood flow through artery > lack of oxygen for cardiac muscle tissue

What can partial blockage of the coronary artery result in (symptom)?

Severe chest pains (angina)

What can complete blockage of the coronary artery cause (symptom)?

Heart attack as cardiac muscle cells cannot respire aerobically

How can you treat coronary heart disease?

Stent to increase width of coronary artery’s lumen; statins to lower blood cholesterol

Name 4 risk factors of CHD.

Obesity; high blood pressure; high cholesterol; smoking

How does obesity increase risk of CHD?

Carrying extra weight puts strain on heart to pump blood to cells

How does high blood pressure increase risk of CHD?

Increases force of blood against artery walls leading to damage of vessels

What might cause high blood pressure?

High levels of salt; nicotine

How does high cholesterol increase risk of CHD?

Speeds up the buildup of fatty deposits in arteries

What might cause high cholesterol?

Diet rich in saturated fat and animal products e.g. eggs

Why does smoking increase risk of CHD?

Causes high blood pressure, narrowing of the arteries and buildup of plaque

What do arteries do?

Carry oxygenated blood away from heart towards respiring cells

What are arterioles?

Blood vessels connecting arteries to capillaries

Name 3 adaptations of arteries

Muscular walls; elastic fibres; narrow lumen

Why do arteries have muscular walls?

To carry blood at high pressures

Why do arteries have elastic fibres?

Allow them to stretch to withstand high pressure

Why do arteries have a narrow lumen?

Help maintain high pressure

What do veins do?

Carry deoxygenated blood towards the heart

Name 3 adaptations of veins

Thin walls; valves; wide lumen

Why do veins have a wide lumen?

To allow low pressure blood to flow through

Why do veins have valves?

Prevent backflow of deoxygenated blood

Why do veins have thin walls?

They don’t need to withstand high pressures

What are venules?

Connect capillaries to veins

What do capillaries do?

Carry blood at low pressure within tissues

Do capillaries carry oxygenated or deoxygenated blood?

Both

Name 2 adaptations of capillaries

One cell thick walls; permeable walls

Why do capillaries have one-cell-thick walls?

Create a short diffusion distance

Why do capillaries have permeable walls?

So substances can easily move into/out of capillary

What is a double circulatory system?

Two circuits: one between lungs and heart, one between heart and body

Why do mammals require a double circulatory system?

Metabolic rate is higher so they need faster circulatory system

What is the function of the circulatory system?

Carry oxygen and nutrients to cells, remove waste products

Which blood vessel carries blood from the body towards the heart?

Vena cava

What blood vessel connects the liver and the heart?

Hepatic artery/vein

What blood vessel carries blood to/from the kidneys?

Renal artery/vein

What blood vessel carries blood to/from the lungs?

Pulmonary artery/vein