Section 3 - Mass Transport Flashcards
Why is mass transport systems required?
- Most cells too far away from exchange surfaces for diffusion alone to maintain composition of tissue fluid
- Mass transport maintains final diffusion gradients bringing substances to and from cells
- Mass transport helps maintain relatively stable immediate environment of cells
What is the double circulatory system?
- Pulmonary circulation: Deoxygenated blood in right side of heart pumped to lungs - oxygenated blood returns to side of heart - left side
- Systemic circulation: Oxygenated blood in left side pumped to tissues/ deoxygenated blood returns on right side
Why is the double circulatory system important to animals?
- Prevents mixing of oxygenated and deoxygenated blood - so blood is saturated with oxygen - efficient delivery of oxygen and glucose for respiration
- Blood can be pumped at a higher pressure - substances taken to and removed from cells quicker and more efficient.
What are the coronary arteries?
- Deliver oxygenated blood to cardiac muscle (heart)
What are the names if the blood vessels entering and leaving the heart?
- Aorta - takes oxygenated blood from heart - respiring tissue
- Vena cava - takes deoxygenated blood from respiring tissue to heart
- Pulmonary artery - takes deoxygenated blood from heart to lungs
- Pulmonary vein - takes oxygenated blood from lungs to heart
What are the names of the blood vessels entering and leaving the lungs?
- Pulmonary artery
- Pulmonary vein
What are the names of the blood vessels entering and leaving the kidney?
- Renal artery - Takes oxygenated blood - kidneys
- Renal veins - take deoxygenated blood to the vena cava from the kidneys
What are the different valves?
- Atrioventricular valves - prevent backflow of blood to ventricles from atria
- Semi-lunar valves - prevent backflow of blood from arteries to ventricles
What is the adaptation of the left ventricle
- Has thicker muscular walls
- Generates high blood pressure
- For oxygenated blood has to travel greater distance around the body
What is the structure of arteries related to their function?
- Thick smooth muscle layer - Contract pushing blood along and control blood flow/pressure
- Elastic tissue layer - stretch as ventricles contract and recoil as ventricle relaxes. Even out blood pressure and maintain high pressure
- Thick wall - Withstands high pressure and prevents artery bursting
- Smooth endothelium - reduces friction
- Narrow lumen - Increases and maintains high blood pressure
What are arterioles and what is their structure related to their function?
- Division of arteries to smaller vessels directing blood to capillaries. Structure similar to arteries BUT…
- Thicker muscle layer - constricts to reduce blood flow and dilates to increase blood flow
- Thinner elastic layer as lower pressure
What is the structure of veins related to its function?
- Wider lumen than arteries
- Very little elastic and muscle tissue
- Valves - prevents the backflow of blood
Exam Question: The rise and fall in blood pressure in the aorta is greater than in the small arteries. Suggest why.(3)
- Aorta is close/directly linked to the heart/ventricle/ pressure is higher
- Aorta has elastic tissue
- Aorta has stretch and recoil
Structure of capillaries related to its function
- Capillary wall is a thin layer (1 cell thick) - short diffusion pathway - rapid diffusion
- Capillary bed is made of a large network of capillaries - large SA - rapid diffusion
- Narrow lumen - reduces flow rate so more time for diffusion
- Capillaries permeate tissues - short diffusion pathway
- Pores - allows substances to escape
What is tissue fluid?
- The fluid surrounding cells/tissues
- Provides respiring cells with water, oxygen, glucose, amino acids
- Enables waste substances to move back into blood e.g urea, lactic acid
What is the formation of tissue fluid?
- Higher blood/ hydrostatic pressure inside capillaries than tissue fluid
- Forces fluid/ water out of capillaries
- Large plasm proteins remain in capillary
What is the return of tissue fluid to the circulatory system?
- Hydrostatic pressure reduces as fluid leaves
- An increasing conc of proteins lowers the WP in the capillary below the tissue fluid
- Water re-enters the capillaries from the tissue fluid by osmosis - down WP gradient
- Excess water taken up by lymph system and returned to circulatory system
How does a low concentration of plasma proteins cause the accumulation of tissue fluid?
- Water potential in capillary not as low so WP potential gradient is reduced
- More tissue fluid formed at arteriole end
- Less/ no water absorbed into blood capillary by osmosis
How does high blood pressure lead to the accumulation of tissue fluid?
- High blood pressure = high hydrostatic pressure
- Increases outward pressure from arterial end
- So more tissue fluid formed/ less reabsorbed
- Lymph cant drain fast enough
What are the different stages of the cardiac cycle?
- Atrial systole
- Ventricular systole
- Diastole
What is atrial systole?
- Atria contract - decreasing volume and increasing pressure inside atria
- AV forced open, semi lunar closed
- Blood pushed into ventricles
What is ventricular systole?
- Ventricles contract from the bottom up - decreasing the volume and increasing pressure in ventricles
- Semi lunar valves are open
- AV valves shut
- Blood pushed out of heart through arteries