Mass transport

Frage	Antworten
What is mass transport?	An efficient system that carries substances to and from individual cells
Why is mass transport necessary?	Can't use straightforward diffusion to absorb and excrete substances so need an efficient system to carry substances to and from individual cells
Describe the structure of the a mammalian circulatory system	Made up of the heart and blood vessels (arteries, arterioles, veins and capillaries)
Which vessels carry blood from and to the lungs?	From: Pulmonary vein To: Pulmonary artery
What vessels carry blood to and from the body (from and to the heart)?	To: Aorta From: Vena cava
What vessel carries blood from the body to the liver?	Hepatic artery
What vessel carries blood from the liver to the vena cava?	Hepatic vein
What vessel carries blood from the gut to the liver?	Hepatic portal vein
What blood vessel carries blood from and to the kidneys (to the vena cava and from the body)?	From: Renal vein To: Renal artery
Which blood vessel has the lowest pressure?	Vena Cava
What does the blood transport?	Respiratory gases, products of digestion, metabolic wastes and hormones
What vessels supply the heart with blood?	Right and left coronary arteries
Describe the structure of the arteries and how it relates to their function	Thick muscle layer - can constrict and dilate to control flow of blood Thick elastic layer - can stretch and recoil to help maintain high bp and smooth pressure surges created by the heart beating Smooth endothelium - reduces friction Large overall thickness of the wall - Resists the pressure so that the vessel doesn't burst
Describe the structure of arterioles and how it relates to their function	Muscle layer thicker than arteries - contraction of this muscle allows constriction of lumen which restricts the flow of blood and so controls its movement into the capillaries that supply the tissues with blood
Describe the structure of the veins and how it's related to its function	Muscle layer thinner - lower pressure Elastic layer thinner - too low a pressure to create recoil Thickness of wall is lower - Pressure low so low risk of bursting Valves - To prevent backflow of blood due to low pressure
Describe the structure of the capillaries and how this makes them adapted for their function	The endothelium is single cell thick and flattened - reduces diffusion pathway Narrow lumen - RBCs flattened and in contact with wall so short diffusion pathway and more time for diffusion due to slow passage of cells through capillary Small diameter - large SA:vol/short diffusion distance
What is tissue fluid?	Fluid that surrounds cells in tissue - made from subs that leave the blood e.g. water, nutrients
Explain what causes the decrease in water potential at the arterial end of the capillary	Loss of water due to hydrostatic pressure
Explain what causes the increase in water potential towards the venous end of the capillary	Watter enters due to osmosis/ more -ve WP (in capillary)
How is tissue fluid formed and how may it be returned to the circulatory system?	1) Hydrostatic pressure of blood high at arterial end 2) Fluid/water pass out 3) while proteins remain 4)This lowers the WP 5) Water moves back into venous end of capilary 6) by osmosis/ diffusion 7) Lymph system collects any excess tissue fluid 8) and returns it to blood/cirulatory system
What's one difference in the composition of blood plasma and tissue fluid? What causes this difference?	1) Blood plama contains proteins (tissue fluid doesn't) 2) Proteins too large to pass through capillary walls
What's the role of proteins in blood plasma in returning fluid to the capillary?	1)Too large to pass through wall of capillary and 2)lower WP 3)causing water to move into capillary by osmosis
What's the function of the lymphatic vessels? (in relation to tissue fluid)	1) Drains excess tissue fluid (because not all reenters capillaries) and 2) transports it back into blood/circ system
Explain how the active transport of mineral ions into xylem vessels in the roots results in water entering these vessels and then being moved up the xylem tissue	1)WP in xylem reduced (by entry of ions); 2) Water potential gradient established between xylem and surrounding cells; 3) Plasma membranes of surrounding cells are partially permeable; 4) Water enters xylem by osmosis; 5) Volume of water in xylem increases; 6) Cannot move back due to gradient; Pressure in xylem increases (and 7) forces water upwards)
Why does the presence of an air bubble in the xylem block the movement of water?	1) Evaporation from leaves/ transpiration 2)Water in xylem under tension/negative pressure 3) Water molecules cohere/stick together/form hydrogen bonds 4) Water forms a single column 5) Air bubble breaks column / prevents cohesion
Explain how water enters a plant root from the soil and travels through to the endodermis	1) water enters root hair cells; 2) by osmosis; 3) because active uptake of mineral ions has created a WP gradient; 4) water moves through the cortex; 5) (by osmosis) down a WP gradient; 6) through cell vacuoles and cytoplasms / symplastic pathway; 7) through cell walls / apoplastic pathway;
How is water used by a plant?	1) (water is used in) the light-dependent reactions of photosynthesis; 2) electrons from water enable ATP production/ produces O2 ; 3) (water can be used in) hydrolysis reactions within the plant; 4) to create turgor; 5) as a solvent for transport; 6) as a medium for chemical reactions; 7) component of cells / cytoplasm
How does water move via the apoplastic and symplastic pathways from the soil to the xylem in a root?	Apoplastic – 1)Via cell walls / spaces external to cell membrane/ external to cytoplasm / between cells; 2) As far as endodermis / Casparian strip / layer of wax; 3) Caused by transpiration pull; 4) Cohesion / hydrogen-bonding between water molecules; Symplastic – 1) Through cell surface membrane (of epidermis /root hair cell) / ref. vacuoles membrane; 2) High to low WP; 3) Diffusion / osmosis; 4) Cell-to-cell via plasmodesmata / via strands of cytoplasm; 5) Secretion / active transport of ions into xylem by endodermis; OR Active uptake of ions from soil at epidermis; Lowers WP in xylem / increases osmosis into xylem
Draw a labelled diagram of a dicot	Image: image014 (image/jpg)

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