IGCSE biology - basically everything

What is the name of the part of the heart labelled as 1?

Pulmonary artery

What is the name of the part of the heart labelled as 2?

Vena cava.

What is the name of the part of the heart labelled as 3?

Right atrium.

What is the name of the part of the heart labelled as 4?

Right ventricle.

What is the name of the part of the heart labelled as 5?

Left ventricle.

What is the name of the part of the heart labelled as 6?

Left atrium.

What is the name of the part of the heart labelled as 7?

Pulmonary vein

What is the name of the part of the heart labelled as 8?

Aorta.

Blood is made from:

red blood cells, white blood cells, platelets, and plasma. 55% of blood is plasma.

White blood cells contain:

Lymphocytes and phagocytes.

What is the role of platelets?

To help blood clotting and prevent bleeding.

What per cent of plasma is water?

About 90%

The plasma transports the following things:

• glucose

• Amino acids

• Antibodies

• Chlosterol

• CO2

• Urea

• Lactic acid

• Hormones

• The plasma also distributes heat around the body.

What is the function of red blood cells?

To transport oxygen from the lungs to body tissues and carry carbon dioxide back to the lungs.

How are red blood cells adapted for their role?

They have a biconcave shape to increase surface area for gas exchange, lack a nucleus to maximize haemoglobin content, and contain haemoglobin to bind oxygen to form oxyhaemoglobin.

The innate immune system:

• first line of defence (immediate)

• Non-specific

• No immunological memory

• It doesn’t respond differently the second time you come into contact with a pathogen

• It includes physical barriers like skin and mucous membranes, as well as immune cells such as phagocytes that respond quickly to pathogens.

How does a phagocyte remove bacteria?

A phagocyte removes bacteria by engulfing them through a process called phagocytosis, where the bacteria are enclosed in a vessel and then destroyed by enzymes.

Example of a physical defence:

Ear wax = has acidic environment that kills bacteria. It traps dirt, dust and small object from damaging your ear.

Adaptive immune system

• second line of defence (5-7 days)

• Has immunological memory - your immmune system responds better the second time.

• Just cellular defence - T and B cells (lymphocytes)

• B cells produce antibodies

• T cells kill virally infected cells.

Antigens

A molecule, often a protein or sugar, that is recognized by the immune system as foreign and potentially harmful, triggering an immune response to fight it.

(Fact 1: they are found on the surface of all cells

Fact 2: there are hundreds of thousands of different antigens)

Role of lymphocytes

When they come across a foreign antigen, they will produce proteins called antibodies. Memory cells are also produced in response to a foreign antigen. These remain in the body and remember a specific antigen. Then next time they come into contact with the antigen, they reproduce VERY fast.

What is the role of antibodies?

Antibodies lock onto invading pathogens and mark them out for destruction by other white cells.

1. They stick to antigens

2. They can clump bacteria together and this makes them difficult to reproduce

3. They stick to viruses and this makes them difficult to get inside cells.

What is a vaccine?

Typically, either alive microbe, mild or weakened, or a dead microbe

Therefore, the antigens are present but the ability to cause the disease is not.

• the antigens are present

• Therefore, the lymphocytes multiply

• Some become memory cells.

• If theses memory cells meet the actual pathogens (antigens), they multiply quickly, produce more antibodies and fight the pathogens before you even feel the effects.

Active immunity

You make an immune response either following a real infection or following a vaccine

Passive immunity

You are given antibodies either naturally (in utero) or artificially.

Order of the cardiac cycle.

1. Atrial systole

2. Ventricular systole

3. Diastole

Atrial systole

Atria contract

bicuspid/tricuspid valves OPEN
blood flows into the ventricles

Ventricular systole

Ventricles contract

Bicuspid/tricuspid valves close

Semi-lunar valves open

Blood leaves the heart

Diastole

Heart relaxes

Semi-lunar valves close

Blood enters atria

How does the heart rate change during exercise?

1. More energy so there is more respiration

2. More carbon dioxide in your blood stream and your brain detects this

3. The brain sends a signal to your heart so it beats faster and more forcefully.

4. More blood is sent out from the heart (stroke volume) in each heart beat the blood arrives at the lungs and muscles quickeR

5. More oxygen arrives at the muscles and more CO2 is removed

6. Therefore, the muscles contract more.

How does the heart rate change under the influence of adrenaline?

• adrenaline is released from the adrenal glands

• It increases the heart rate (more oxygen and glucose arrive at the muscles)

• The muscles can therefore contract more

Risk factors for coronary heart disease:

• Smoking - nicotine + CO put strain on heart, making it work harder. Other chemicals damage the lining of your coronary arteries, causing arterial furring.

• Lack of exercise - fatty deposits more likely to build up in your arteries.

• High blood pressure - puts high strain on your heart

• Bad diet - high amounts saturate fats in diet can cause high cholesterol

What are the three types of blood vessels?

Arteries, veins and capillaries

Arteries

• carry blood away from the heart to the organs

• The blood is under high pressure so the walls must be able to stretch and recoil

• Generally carry oxygenated blood

Veins

• carry blood from the organs back towards the heart

• Under low pressure

• Must allow blood to pass through easily and prevent it flowing backwards

• Veins generally carry deoxygenated blood

• They have ‘watch-pocket’ valves to prevent back flow

Capillaries

• carry blood through organs, bringing the blood close to the cells in the organ

• They are permeable so that substances are transferred between the blood and the cells

• Their walls are only one cell thick

What does 1 represent?

Pulmonary artery

What does 2 represent?

Hepatic vein

What does 3 represent?

Mesentric vein

What does 4 represent?

Infenar vena cava

What does 5 represent?

Mesentric artery

What does 6 represent?

Hepatic artery

What does 7 represent?

Aorta

What does 8 represent?

Pulmonary veins

What do the lungs excrete?

Carbon dioxide and water

What does the skin excrete?

Water and salt by sweating

What do the kidneys excrete?

Urea, water and ions from the blood. This is called urine.

Label this diagram

1. Vena cava

2. Left kidney

3. Left ureter

4. Urethra

5. Bladder

6. Right ureter

7. Right kidney

8. Aorta

   renal vein + vena cava = blue

   renal artery + aorta = red

How does the kidney carry our its role of excretion?

The kidneys filter the blood to get rid of harmful substances, particularly urea, which is produced in the liver from the breakdown of amino acids

Label this diagram

1. Glomerulus

2. Bowman’s capsule

3. Proximal convoluted tubule

4. Loop of Henle

5. Distal convoluted tubule

6. Collecting duct

Ultrafiltration

• The blood arriving at each glomerulus is under high pressure.

• Small molecules cross over into the kidney nephron whereas large molecules stay in the blood.

• The fluid moves along the nephron, it is known as the glomerular filtrate

Selective reabsorption

• glucose (and other useful small molecules) mustn’t stay in the nephron and leave in the urine (it’s needed for respiration)

• It is reabsorpted into the bloodstream from the proximal convoluted tubule

• This happens via active transport - there are lots of mitochondria in the cells lining this part of the nephron.

osmoregulation (reabsorption of water in the loop of henle)

• the wall of the nephron is permeable to water

• The surrounding area has low water potential and therefore the some water will leave via osmosis.

Osmoregulation (hormonal control of water)

• the body can control the water content of the blood using the kidney.

• Special cells in the hypothalamus of the brain can detect the amount of water in the blood.

• If you are dehydrated, the cells in the hypothalamus can cause the pituitary gland to release a hormone called the anti-diuretic hormone (ADH)

• This then travels through the blood to the kidney where it make the walls of the nephron more permeable to water and therefore more water is reabsorpted into the blood.

• This make the urine more concentrated (less water excreted.)

• Opposite happen when there is a normal amount of water in the blood.

Myelin sheath

An insulating layer, or sheath, that forms around nerves, including those in the brain and spinal cord.

Cell body

The spherical part of the neurone that contains the nucleus

Axon

The long, thin extension of a neurone that carries electrical impulses away from the cell body toward other neurones, muscles, or glands.

Dendrite

The receiving or input portions of a neuron

Motor neurone

Cells in the brain and spinal cord that allow us to move, speak, swallow and breath by sending commands from the brain to the effectors (muscles) that carry out these functions.

Sensory neurone

A nerve cell that detects and transmits sensory information from the environment to the brain

Relay neurone

A cell in the CNS that acts as a messenger between sensory and motor neurones

1

Cornea

2

Aqueous humour

3

Pupil

4

Iris

5

Tear duct

6

Suspensory ligaments

7

Lens

8

Ciliary muscle

9

Sclera

10

Choroid

11

Retina

12

Fovea

13

Optic nerve

14

Vitreous humour

15

Blind spot

Cornea

It refracts light and protects the eye

Iris

Controls how much light enters the pupil

Lens

Focuses light onto the retina

Optic nerve

Bundle of sensory neurones that carry impulse to the brain

Retina

Layer of tissue at the back of the eye that contains light receptor cells (rods + cones)

Fovea

Area of the retina with the highest concentration of cone cells that provide sharp vision

Aqueous humour

Maintains pressure in the eye and nourishes the cornea

Vitreous humour

• Maintains eye shape - ensures correct focusing of light

• Supports retina - keeps photoreceptors in position

• Transparent medium - allows clear passage of light

• Shock absorption - protects delicate internal structures

Sclera

Strong outer layer of tissue of the eye that wraps around your eyeball.

Pupil

Hole in the center of the eye that lets light in

What happens to the eye in bright light?

• circular muscle contracts

• Radial muscles relax

• Pupils constrict

What happens to the eye in dim light?

• Circular muscles relax

• Radial muscles contract

• Pupil dilates (gets bigger)

What happens to the eye when it’s focusing on a distant object?

• ciliary muscles relax

• Suspensory ligaments pulled tight (stretched)

• Lens flatten

What happens to the eye when its focusing on a nearby object?

• ciliary muscles contract

• Suspensory ligaments slacken

• Lens more rounded (convex)

• Light refracts MORE

Homeostasis

The maintenance of a constant internal environment e.g. temperature

features of nervous control system

• nerve impulses

• Travel fast

• Short-lived effect

• Localised effect

features of hormonal control systems

• hormone in blood

• Travel more slowly

• Long-lived effect

• Widespread effect

What happens to the body when we are too hot?

• lots of sweat - when it evaporates it transfers energy from your skin to the environment cooling you down

• blood vessels close to the surface of the skin widen - this is called vasodilation. it allows more blood to flow near the surface, so it can transfer more energy into the surroundings, which cools you down.

• hairs lie flat

What happens when we are too cold?

• hair - stands on end to trap an insulating layer of air, which helps you keep warm

• vasoconstrictions - blood vessels near the surface of the skin contract so less blood is flowing to near the surface, so less energy is transferred to the surroundings.

• shiver - increases rate of respiration, which transfers more energy to warm the body. exercise does the same.

• very little sweat produced

1

Hair

2

Nerve

3

Epidermis

4

Dermis

5

Fatty tissue