topic 8 Flashcards
why is transport of substances into and out of organisms important?
to take in valuable nutrients, minerals, food molecules and water
to remove waste product and prevent them accumulating, eg. urea and excess ions
adaptations of alveoli
- small and in clusters, creating a large surface area for diffusion
- capillaries provide a large blood supply, maintaining the concentration gradient
- the walls of the alveoli are v thin, so there’s a short diffusion pathway
factors affecting diffusion rate
- concentration gradient - more particles randomly moving down the gradient than against it so faster diffusion
- temperature - higher temperature means greater particle movement + more collision, so faster diffusion
- surface area of membrane - greater surface area, more space for particles to move through, results in a faster rate of diffusion
what is ficks law
rate of diffusion (=) surface area x concentration difference/ thickness of membrane
plasma
- straw-coloured liquid
- carries components of the blood: red blood cells, white blood cells, platelets, glucose, amino acids, CO2, urea, hormones, proteins, antibodies, antitoxins
red blood cells
- aka erythrocytes
- biconcave disc shape gives a large surface area to absorb more oxygen
- no nucleus, so more room to carry oxygen
- red pigment, haemoglobin contains iron
- binds with oxygen to get oxyhaemoglobin in lungs, splits into haemoglobin and oxygen in body tissues to release oxygen into cells
white blood cells
- phagocytes - engulf unwanted micro organism (phagocytosis)
- lymphocytes - produce antibodies against microorganisms, some also produce antitoxins to neutralise toxins
- your white blood cells multiply to fight off infections when you’re ill
platelets
- small fragments of cells without a nucleus
* help blood to clot at the wound; allows skin to grow, prevents blood loss and prevents microorganisms from getting in
arteries
carry blood away from the heart
thick layers of muscle and strong elastic fibres
thick walls compared to lumen size
capillaries
one cell thick, permeable wall to allow diffusion
very small lumen
veins
- take blood into the heart
- valves because of the low pressure of blood
- bigger lumen than arteries to help blood flow even though it’s low pressure
- thinner elastic fibres and smooth muscle
what is a double circulatory system
- the system that mammals have
- blood is pumped around the body in two circuits
- deoxygenated blood is pumped to the lungs to take in oxygen then goes back to the heart
- the newly oxygenated blood is pumped around the body and returns to the heart deoxygenated
blood flow through the mammalian heart
- vena cava carried deoxygenated blood to the right atrium
- the blood moves through the tricuspid valve to the right ventricle, where the pulmonary artery takes it to the lungs
- pulmonary vein carries oxygenated blood from lungs to the left atrium
- blood moves through the bicuspid valve to the left ventricle, where the aorta pumps it around the body
what is respiration
an exothermic reaction which occurs continuously in living cells to release energy for metabolic processes
cardiac output equation
cardiac output = stroke volume x heart rate
