Topic 8 - Exchange And Transport Flashcards
What is respiration
A process that released enrergy in the form of atp from the breakdown of organic compounds (e,g glucose)
Why must respiration occur all the time in living cells?
ATP is required for many essential processes in living cells e,g movement homeostatsis and active transport
What type of reaction is respiration
It is an exothermic reaction that released energy in the form of heat
Where do plants get glucose from?
Produce their own during photosynthesis.
Where do animals get glucose requires for respiration?
From the breakdown of carbohydrates that they have ingested
What are the two types of respiration?
Aerobic respiration
Anaerobic respiration
What is aerobic respiration?
Respiration in the presence of oxygen that forms ATP from the breakdown of glucose
Write the word equation for aerobic respiration
Glucose + oxygen —> carbon dioxide + water (+atp)
Write the symbol equation for aerobic respiration
C6H12O6 + 6O2 —> 6CO2 + 6H2O (+ATP)
What is anaerobic respiration?
Respiration that takes place without oxygen and forms ATP from the breakdown of glucose
When may anaerobic respiration take place in human cells?
During vigorous exercise
When may anaerobic respiration take place in plant cells?
If the soil becomes waterlogged
Write word equation for anaerobic respiration in muscle cells
Glucose —> lactic acid (atp)
Symtoms of lactic acid build-up
Cramp and fatigue
Anaerobic respiration in yeast and plant cells:
Glucose —> ethanol + carbon dioxide
Is aerobic or anaerobic respiration more efficient? Explain why
Aerobic respiration is more efficient as it produces more molecules of ATP than anaerobic respiration
What are the main components of blood?
Red blood cells
White blood cells
Platelets
Plasma
What are red blood cells also know as?
Erythrocytes
Function of red blood cells?
Transport O2 from lungs to tissues
Transport CO2 from tissues to lungs
How do red blood cells transport oxygen to body cells?
Lungs: Heamoglobin in RBCs bind reversibly to form oxyhaemogblin
Tissues: oxyhaemoglobin breaks down to form haemoglobin and oxygen which diffuses into cells
How are red blood cells adapted to their function?
Biconcave disk gives large SA/V ratio, increasing diffusion rate
Lack nucleus, allowing more space for haemoglobin molecules (increasing oxygen carrying capacity of the cell)
Small and flexible so they can squeeze through capillaries
Thin giving a short diffusion distance
What is the function of white blood cells?
Provide immunological protection
Name two types of white blood cell
Phagocytes
Lymphocytes
What are phagocytes?
Type of WBC
Engulf pathogens and digest them in a process known as phagocytosis
What are lymphocytes?
Type of WBC
Produce antibodies specific to a pathogen
Produce antitoxins to neutralise toxins
What is the function of platelets?
Role in blood clotting
What is plasma?
Pale-yellow liquid portion of the blood
Contains proteins, nutrients, waste products, hormones, antibodies etc
How is plasma adapted to its function?
Plasma consists mainly of water. This acts as a solvent, enabling the transport of materials around the body.
What are the three main types of blood vessel?
Arteries
Capillaries
Veins
What is the function of the arteries?
Carry blood away from heart under high pressure
Describe how the arteries are adapted to their function? (6)
Narrow lumen maintains high pressure
Thick wall to withstand high pressure
Thick layer of smooth muscle provides strength
Thick layer of elastic fibres allow stretch and recoil
Smooth inner lining to reduce friction
What is the function of the veins?
Return blood to the heart under low pressure
Describe how the veins are adapted to their function (4)
Large lumen eases blood flow
Thin wall as blood at low pressure
Thin layer of smooth muscle and elastic fibres
Valves prevent backflow of blood
What is the function of the capillaries?
Allow the exchange of materials at tissues
How are red blood cells adapted to their function?
Biconcave disk gives large SA/V ratio, increasing diffusion rate
Lack nucleus, allowing more space for haemoglobin molecules (increasing oxyen carrying capacity of the cell)
Small and flexible so they can squeeze through capiliaries
Thin giving a short diffusion distance
How capiliaries are adapted to their function? (3)
Form large network: greater surface area of diffusion
Walls one cell thick giving a short diffusion distance
Walls permeable allowing the exchange of substances
Describe the double circulatory system in humans?
Blood flows through the heart twice in two circuits:
Pulmonary circuit
Systemic circuit
Describe pathway of blood around the body, naming the structures of the heart.
Pulmonary vein — left atrium — left ventricle — aorta — body — vena cava —> right atrium —> right ventricles —> pulmonary artery —> lungs
Why is the left ventricle thicker than the right ventricle?
It pumps blood a further distance
It must generate a greater force of contraction so blood can be pumped at a higher pressure
What is the function of valves in the heart?
Prevent the backflow of blood
What is cardiac output?
The volume of blood pumped out of a ventricle in one minute.
What is stroke volume?
The volume of blood pumped out of a ventricle in one contraction
Cardiac output formula
Q = hr x SV
Why do large multicellular organisms require specialised exchange surfaces?
Small SA/V ratio
● Diffusion insufficient to provide all cells with the required oxygen and nutrients, and to remove all waste products
● Exchange surfaces increase rate of diffusion and shorten diffusion distance
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Why do some multicellular organisms (e.g. trees) not require specialised exchange surfaces?
Trees have a large number of leaves which provide a large SA/V ratio for diffusion.
How does the size of an organism affect its surface area to volume ratio?
The larger the organism, the smaller the SA/V ratio.
Name some of the substances transported into and out of the human body
● Oxygen ● Carbon dioxide ● Water ● Dissolved food molecules ● Urea
Why must the human body exchange oxygen and carbon dioxide with the environment?
● Oxygen is required for respiration so diffuses into the body
● Carbon dioxide is a toxic waste product of respiration so diffuses out of the body
How does oxygen enter and carbon dioxide leave the bloodstream?
● Oxygen diffuses from air in the alveoli (high O2 conc) into blood in the capillaries (low O2 conc)
● Carbon dioxide diffuses from blood in the capillaries (high CO2 conc) into air in the alveoli (low CO2 conc)
How are alveoli adapted for gaseous exchange? (6)
● Large surface area
● Network of capillaries provide a good blood supply
● Rapid blood flow maintains a steep concentration gradient
● Thin walls give a short diffusion distance
● Cell walls have partially permeable membranes enabling diffusion
● Moist lining, enables gases to dissolve
What factors affect the rate of diffusion
● Diffusion distance
● Concentration gradient
● Surface area
How does diffusion distance affect the rate of diffusion?
The greater the diffusion distance, the further the molecules must travel and the slower the rate of diffusion.
How does concentration gradient affect the rate of diffusion?
The steeper the concentration gradient, the faster the rate of diffusion.
How does surface area affect the rate of diffusion?
The larger the surface area, the greater the number of molecules that can diffuse across in a given time, so the faster the rate of diffusion.
How can the rate of diffusion be calculated?
What is the pulmonary circuit?
● Part of the circulatory system involving the right side of the heart
● Deoxygenated blood is transported to the lungs
● Gaseous exchange occurs between the alveoli and capillaries in the lungs
● Oxygenated blood is returned to the left side of the heart
What is the systemic circuit?
Part of the circulatory system involving the left side of the heart
● Oxygenated blood is pumped to tissues and organs around the body
● Exchange of materials occurs at tissues
● Deoxygenated blood returns to the right side of the hear
Name the four chambers of the heart
Left atrium
● Left ventricle ● Right atrium
● Right ventricle
What is stroke volume?
The volume of blood pumped out of a ventricle in one contraction
Cardiac output unit
Cm3 min-1
