Topic 8: Exchange and Transport in Animals Flashcards
Why do large multicellular organisms require specialised exchange surface?
Small SA/V ratio, diffusion insufficient to provide all cells with the required oxygen and nutrients, and to remove all waste products and exchange surfaces increase rate of diffusion and shorten diffusion distance
Why do some multicellular organisms not require specialised exchange surfaces?
Terese have a large number of leaves which provide a large SA/V ration 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
What are some of the substances transported into and out of the human body?
Oxygen, carbon dioxide, water, dissolved food molecules and urea
How does oxygen enter and carbon dioxide leave cells?
They diffuse into and out of cells
How does water enter cells?
It diffuses into cells by osmosis
How do food molecules and mineral ions enter cells?
They are dissolved in water which diffuses into cells
Why must urea be excreted from the body?
It’s a waste product so must be excreted
How is urea excreted from the body?
Urea diffuses out of cells into the blood plasma, the kidney filters urea out of the blood and urea is excreted in urine
Why must the human body exchange oxygen and carbon dioxide with the environment?
Oxygen is required for respiration so diffuses into the body and carbon dioxide is toxic waste product of respiration so diffuses out the body
How does oxygen enter and carbon dioxide leave the bloodstream?
Oxygen diffuses from air in the alveoli into blood in the capillaries and carbon dioxide diffuses from blood in the capillaries into the air in the alveoli
How are alveoli adapted for gaseous exchange?
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 membrane enabling diffusion and moist lining which enables gases to dissolve
What factors affect the rate of diffusion?
Diffusion distance, concentration gradient and surface area
How does diffusion distance affect the rate of diffusion?
The greater the distance 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?
Surface area x concentration gradient / thickness of membrane
What is respiration?
A process that releases energy in the form of ATP from the breakdown of organic compounds
What is ATP?
Short term energy store in all cells and is universal energy carrier
Why must respiration occur continuously in living cells?
ATP is required for many essential processes in living cells
Why type of reaction is respiration?
It’s an exothermic reaction that releases energy in the form of heat
Where do plants get the glucose required for respiration?
They produce their own glucose during photosynthesis
Where do animals get the glucose required for respiration?
From the breakdown of carbohydrates that they have ingested
What are the two types of respiration?
Aerobic and Anaerobic respiration
What is aerobic respiration?
Respiration in the presence of oxygen that forms ATP from the breakdown of glucose
What is the word equation for aerobic respiration?
Glucose + oxygen -> carbon dioxide + water
What is the symbol equation for aerobic respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O
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
What is the word equation for anaerobic respiration in muscle cells?
Glucose -> lactic acid (+ATP)
Why may anaerobic respiration in muscle cells eventually stop?
Lactic acid build-up inhibits anaerobic respiration
What are the symptoms of lactic acid build-up?
Cramp and fatigue
What is the word equation for anaerobic respiration in plants and yeast cells?
Glucose -> ethanol + carbon dioxide (+ATP)
Why is aerobic or anaerobic respiration more efficient?
Aerobic respiration is more efficient as it produce more molecules of ATP than anaerobic respiration
What is the circulatory system?
Network of organs and vessels, enables the flow of blood and transport of oxygen, carbon dioxide, nutrients and other molecules around the body
What are the main components of blood?
Red blood cells, white blood cells, platelets and plasma
What are red blood cells also known as?
Erythrocytes
What is the function of red blood cells?
Transport O2 from lungs to tissues and transport CO2 from tissues to lungs
How do red blood cells transport oxygen to body cells?
Lung, haemoglobin in RBCs binds reversibly with oxygen to form oxyhemoglobin and tissues, oxyhemoglobin 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, small and flexible so they can squeeze through capillaries and thin giving a short diffusion distance
What is the function of white blood cells?
Provide immunological protection
What are two types of white blood cells?
Phagocytes and Lymphocytes
What are phagocytes?
Type of WBC and engulf pathogens and digest them in a process known as phagocytosis
What is lymphocytes?
Type of WBC, produce antibodies specific to a pathogen and 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 and contains proteins, nutrients, waste products, hormones and antibodies
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 and veins
What is the function of the arteries?
Carry blood away from the heart under high pressure
How are arteries adapted to their function?
Narrow lumen maintains high pressure, thick walk to withstand high pressure, thick layer of smooth muscle provide strength, thick layer of elastic fibres callow stretch and recoil, smooth inner lining to reduce friction and no values
What is the function of the veins?
Return blood to the heart under low pressure
How are veins adapted to their function?
Large lumen eases blood flow, thin wall as blood at low pressure, thin layer of smooth muscle and elastic fibres and valves prevent back flow of blood
What is the function of the capillaries?
Allow the exchange of materials at tissues
How are capillaries adapted to their function?
Form large network so greater surface area for diffusion, walls one cell thick giving a short diffusion distance, walls permeable allowing the exchange of substances and narrow lumen decreases diffusion distance
What are the double circulatory system in humans?
Blood flows through the heart twice in two circuits: pulmonary and systemic circuit
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 and 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 and deoxygenated blood returns to the right side of the heart
What are the four chambers of the heart?
Left and Right atrium, Left and Right ventricle
What is pathway of blood around the body, naming the structure of the heart?
Pulmonary vein -> left atrium -> left ventricle -> aorta -> body -> vena cava -> right atrium-> right ventricle-> pulmonary artery -> lungs
Why is the left ventricle thicker than the right ventricle?
It pumps blood a further distance and it must generate a greater force of concentration so blood can be pumped at a higher pressure
What is the function of valves in the heart?
Prevent the back flow 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
What is heart rate?
The number of times the heart contracts in one minute
How is cardiac output calculated?
Heart rate x stroke volume
