Transport Flashcards
Why can amoeba rely on diffusion for movement of substances into and out of the cell?
- Large surface area to volume ratio
- Short diffusion distance
Why do animals need circulatory systems?
- Surface area to volume ratio is too small
- Diffusion is too slow
- Circulatory system needed to transport oxygen
What is the role of the xylem?
Transports mineral ions and water from roots to flowers
Describe the structure of xylem
- Hollow forming a continuous column - no cytoplasm
- Lignin gives the xylem strength and support
What is the role of the phloem?
Transports sugars from leaves to growing regions/roots for storage
Describe the structure of phloem
- Sieve tubes with sieve plates in between
- Companion cells contains lots of mitochondria for release of energy
List the components of the blood
- Plasma
- White blood cells (phagocytes and lymphocytes)
- Red blood cells
- Platelets
What does the blood transport?
- Oxygen from the lungs to other parts of the body
- Carbon dioxide from other parts of the body to the lungs
- Nutrients from the gut to all parts of the body
- Urea from liver to kidneys
List substances transported in the plasma
- Carbon dioxide
- Urea
- Glucose
- Amino acids
- Hormones
How are red blood cells adapted for their function?
- Biconcave disc shape - large surface area for transport of oxygen
- Haemoglobin binds to oxygen forming oxyhemoglobin
- No nucleus - more space for haemoglobin
How does the body prevent pathogen entry?
- Skin acts as a barrier
- HCl in stomach destroys pathogens
- Hairs prevent entry
- Platelets clot the blood at the site of a wound
How do white blood cells attack invading pathogens?
- Phagocytes engulf pathogens
- Lymphocytes recognise antigens and produce antibodies which destroy pathogens
- Antitoxins made
How do lymphocytes destroy pathogens?
- Recognise antigens
- Make antibodies which destroy pathogens
How does a vaccine work?
- Dead or weakened pathogen injected
- Lymphocytes recognise antigens and produce antibodies
- Memory cells made
- Produce antibodies much faster next time
Provide some examples of vaccines and their mode of action
- Dead pathogens e.g. whooping cough
- Weakened pathogens e.g. TB, measles
- Antigens e.g. influenza
What is the role of platelets?
- Platelets clot the blood at the site of a wound
- Soluble fibrinogen is connected to insoluble fibrin
Describe the movement of the blood around the body starting at the right atrium
- Deoxygenated blood enters the right atrium via the vena cava
- Right atrium contracts forcing blood through tricuspid valve into right ventricle
- Blood enters the right ventricle and leaves via the pulmonary artery
- Blood flows to the lungs and becomes oxygenated
- Blood returns to the heart and enters the left atrium via the pulmonary vein
- Left atrium contracts forcing blood through bicuspid valve into the left ventricle
- Left ventricles contracts forcing blood into the aorta
- Oxygenated flows around the body and is used in respiration
How is our heart rate increased?
- Adrenaline increases heart rate
- When we exercise, muscles produce carbon dioxide
- Receptors in aorta and carotid artery detect this increase in carbon dioxide
- Electrical impulses sent to medulla
- Accelerator nerve raises heart rate
What does single circulation mean?
Blood is pumped from the heart to the lungs and then to rest of the body
What does double circulation mean?
Blood flows twice into the heart for every once around the body
What does the circulatory system consist of?
- Heart
- Arteries, veins and capillaries
- Blood
Why is the wall of the ventricles thicker than that of the atria?
The ventricles have to pump the blood further
Why are the artery walls so thick?
To withstand the high pressure of the blood flowing inside
Why is the wall of the left ventricle thicker than that of the right ventricle?
- Blood from the right ventricle is only pumped to the lungs
- Blood from the left ventricle is pumped much further - around the whole body
What is the coronary artery?
Blood vessel that supplies the heart with oxygen
Describe the structure of arteries
- Thick muscle and elastic fibre walls
- Narrow lumen
- High blood pressure
Describe the structure of the veins
- Thin muscle and elastic fibre walls
- Large lumen
- Lower blood pressure
- Semi-lunar valves prevent the back flow of blood
Describe the structure of the capillaries
- Thin walls - one cell thick
- Short diffusion distance
- Narrow lumen
What factors contribute to coronary heart disease?
- Heredity
- High blood pressure
- Diet - high levels of saturated fat and cholesterol
- Smoking
- Stress
- Lack of exercise
Explain why reducing the blood supply to the heart muscles cells can cause a heart attack
- Less oxygen
- Less aerobic respiration
- Anaerobic respiration
- Lactic acid
- Low pH
