Exchange and Transport in Animals

Where is oxygen exchanged in the body and why?

• Alveoli in lungs

• Needed for respiration

Where is carbon dioxide exchanged in the body and why?

• Alveoli in lungs

• Waste product of metabolism

Where is water exchanged in the body and why?

• Nephrons in kidney

• Needed for cells to function properly

Where are dissolved food molecules exchanged in the body and why?

• Small intestine

• Needed for respiration

Where are mineral ions exchanged in the body and why?

• Small intestine

• Needed for cells to function properly

Where is urea exchanged in the body and why?

• Nephrons in kidney

• Waste product of metabolism

Why do more complex organisms not rely solely on diffusion?

• As an organism gets bigger, their surface area to volume ratio gets smaller

• They need to have specialised exchange surfaces and transport systems

What happens in the lungs when you breathe?

• Oxygen diffuses out of the air and into the blood

• Carbon dioxide diffuses out of the blood and into the air

How is the lung adapted for efficient gas exhange?

It contains millions of tiny alveoli (air sacks), creating a large surface area for diffusion of gases

How are alveoli adapted for efficient gas exchange?

• One-cell thick- minimises diffusion distance

• Good blood supply- this maintains a high concentration gradient

• Large surface area

• Moist lining- allows gasses to dissolve then diffuse

• Good ventilation- good supply of air

What factors effect the rate of diffusion?

• Increase in surface area

• A shorter distance for diffusion

• Maintenance of a high concentration gradient

What is Fick’s Law?

An equation used to calculate the rate of diffusion:

Rate of diffusion ∝ (Surface area x conc difference)/Membrane thickness

• For the rate of diffusion to be as high as possible, the surface area and concentration difference need to be as big as possible and the thickness of the membrane has to be as low as possible

What is blood made of mainly?

Plasma, red blood cells, white blood cells and platelets

What is plasma and what does it do?

• The liquid part of the blood

• It carries blood cells through the blood vessels

• It contains many dissolved substances, such as carbon dioxide and glucose

What are white blood cells like and what do they do?

• Larger than red blood cells

• They have a nucleus

• They are part of the immune system and attack pathogens in the body

• Some white blood cells (phagocytes) will ingest pathogens to destroy them

• Other white blood cells (lymphocytes) produce chemical antibodies that attack pathogens and destroy them

What are platelets and what do they do?

• Fragments of larger cells

• They have no nucleus

• They cause blood to clot when a blood vessel has been damaged

• The clot blocks the wound and prevents pathogens getting into the blood

How are red blood cells adapted for their fuction?

• They contain haemoglobin which can carry 4 oxygen molecules

• Has a biconcave shape increasing surface area so more oxygen can be carried

• Has no nucleus- more space to carry oxygen

What are the three types of blood vessels?

• Arteries, veins and capillaries

How are veins structured and what is their function?

• Carries blood to the heart

• Thin, smooth muscle walls

• Large lumen

• They contain valves

• This stops blood flowing backwards, so that it is returned to the heart

• Large space to allow blood to flow easily back to the heart at low pressures

• Blood is squeezed back to the heart by action of skeletal muscle

How are capillaries structured and what is their function?

• Connects arteries and veins through cells

• Substances are exchanged between the body cells and blood in capillaries

• They are one blood cell wide

• Walls are only one cell thick- short diffusion distance

• Tiny vessel with narrow lumen

• Waste products like carbon dioxide and other cells products like hormones move out of the body cells and into the blood

• Substances need by cells such as oxygen and glucose move from the blood in the capillary into the body cells

What makes up the circulatory system?

The heart and blood vessels

What does the heart do?

Pumps blood around the body

How does the heart function on the right side?

Note that the right side will be on the left in a diagram

• The right side contains deoxygenated blood

• The vena cava brings oxygenated blood from the body to the heart

• The blood flows through the right atrium and down into the right ventricle

• The tricuspid valve stops blood flowing backwards

• the right ventricle contracts, forcefully pumping blood out of the pulmonary artery which carries deoxygenated blood from the heart to the lungs

How does the heart function on left side?

Note that the left side will be on the right in a diagram

• The left side contains oxygenated blood

• The pulmonary vein brings oxygenated blood from the lungs to the heart

• The blood flows through the left atrium and down into the left ventricle

• The bicuspid valve stops blood flowing backwards

• the left ventricle contracts, forcefully pumping blood out of the heart through the aorta which carries oxygenated blood from the heart to the body

What do arteries do?

They take blood away from the heart

What is the part of the heart called that separates the right and left side?

The septum

How does blood circulate around the body?

• Blood enters the atria

• The atria contract forcing blood into the ventricles

• The ventricles contract, forcing blood into the arteries

• Blood flows through the arteries to the organs and returns to the heart through veins

What is cellular respiration?

A process that releases energy from glucose for use in cellular activities

What is aerobic respiration?

• Takes place mostly in mitochondria

• Exothermic because it releases energy

• Main source of energy for cells

• Requires oxygen

What is the word equation for aerobic respiration?

Glucose + Oxygen → Carbon dioxide + water

What is energy from respiration used for in animals?

• Metabolic processes to build larger molecules from smaller ones such as proteins from amino acids

• To enable muscle contraction

• To maintain steady body temperature in cold surroundings

What is energy from respiration used for in plants?

Used to build larger molecules from smaller ones e.g sugars, nitrates and other nutrients into amino acids, which are then used to make proteins

When does anaerobic respiration take place?

When there is not enough oxygen or aerobic respiration is not possible

What is the word equation for anaerobic respiration?

Glucose → Lactic acid

How does anaerobic respiration work?

• It is the incomplete breakdown of glucose to release energy

• Does not use oxygen

• Can supply energy to muscles when there is not enough oxygen for aerobic respiration

• In muscle cells it produces lactic acid

• Blood flowing through muscles then removes lactic acid

• 19 times less energy is released than aerobic respiration

What does lactic acid do to muscles?

It causes pain and muscle fatigue, and inhibits the ability for muscles to contract

What is anaerobic respiration like in plant and fungal cells?

• It produces ethanol

• Involves the breakdown of glucose

• No oxygen is used

• Less energy is released per glucose molecule than anaerobic respiration in animals

What are the advantages of anaerobic respiration?

• It can release energy for the muscles to contract when then heart and lungs cannot deliver oxygen fast enough for aerobic respiration

• Respiration can continue in organisms that have no, or very limited, oxygen supply

What are the disadvantages of anaerobic respiration?

• Releases less energy than aerobic respiration

• Lactic acid is not removed from the body, it builds up in muscles and must be removed after exercise

• Lactic acid can build up in muscle cells, causing cramps and soreness

How to calculate rate of respiration?

rate = change/time

What is the equation for cardiac output?

Cardiac output= stroke volume x heart rate

What is pulse measured as?

Beats per minute (bpm)

What does a faster heart rate cause?

• Blood being pumped around the body faster

• Blood takes oxygen and glucose to the cells faster and removes carbon dioxide faster

What is the structure of the arteries and what is their function?

• Carries blood away from the heart

• Has small lumen

• Thick walls

• Thick layer of muscle and elastic fibers

• Arteries stretch as high pressure blood is pumped through it before returning to it’s original shape- this is felt as a pulse