T7 Mass Transport DONE Flashcards
What organs are involved in the digestive system?
Mouth, Oesophagus, Liver ,Stomach, Pancreas, Gallbladder, Small intestine, Large intestine, Ileum, Rectum ,Anus
What is the stomachs function?
-mechanical digestion as stomach muscles contracting
-muscular sac which produces enzymes
-pH for pepsin (protein enzyme)
What is the ileum structure for its role?
-has villi which gives it a large SA
-absorbs products of digestion into the bloodstream
-its lining produces membrane bound disaccharidedases
Whats the large intestines role?
-absorbs water
Whats is the role of the rectum?
-final section of intestine
-feces stored here before ejection
Whats the role of the pancreas?
-produces and secretes pancreatic juices
What is physical breakdown?
-breaking up large food to smaller peices to increase SA for chemical digestion
What is chemical digestion?
-hydrolyses large insoluble molecules to smaller soluble ones
-done by enzymes
what are the three important digestive enzymes?
-Carbohydrases :hydrolyse carbohydrates to monosaccharides
-Lipases: hydrolyse lipids to glycerol and fatty acids
-Proteases: hydrolyses proteins to amino acids
How does carbohydrates digestion take place?
-salivary amylase hydrolyse any starch in the food to maltose , also contains mineral salts which maintain a neutral pH
-food enters the stomach where amylase denature due to acidic condition
-food passes small intestine and mixes with pancreatic juices
-pancreatic amylase continues hydrolysing starch to maltose, alkaline salts produces by pancreas and intestine walls to maintain pH
-muscles in intestine push food to ileum where maltase hydrolyses maltose to alpha glucose . maltase(part of cell surface membranes epithelial cells so is membrane bound disaccharidase )
What are the membrane bound disaccharidase?
-maltase (alpha glucose )
-sucrase (glucose fructose)
-lactase (glucse galactose)
how does lipids digestion take place?
-lipases (produces in pancreas)
hydrolyse ester bonds found in triglycerides
-lipids are split into micelles by bile salts in emulsification to increase SA
how does proteins digestion take place?
-hydrolysed by a group called peptidases which hydrolyse peptide bonds
what are the types of peptidases?
-Endopeptidases which hydrolyse bonds between the central amino acids
-Exopeptidases which hydrolyse bonds between the terminal amino acids releasing dipeptides and amino acids
-dipeptidases which hydrolyse bonds between the two amino acids of a dipeptide , they’re also membrane bound (part of cell surface membrane of epithelial cells lining the ileum)
What are bile salts ?
-emulsify lipids for a larger SA for enzyme inhibition
-produced in the liver
How are amino acids transported into the epithelial cells?
Co-transporter proteins
How are monosaccharides transported into the epithelial cells in the ileum?
-transporter proteins
Why cant monosaccharides cross the membrane of the epithelial cells?
-hydrophillic
-transporter proteins are required to help them cross
-(Glucose and galactose co-transported)
-(Fructose is absorbed by facillitated diffusion)
What is haemoglobin (Hb) role?
-Human haemoglobin is found in red blood cells
-role is to carry oxygen around the body in form of oxyhaemoglobin
What is haemoglobin?
-a large protein with a quaternary structure
-made up of four polypeptide chains
-each chain has a haem group which contains an iron ion(red colour)
-Each molecule of haemoglobin can carry four oxygen molecules.
What is it called when an oxygen molecule binds / unbinds to haemoglobin?
-association and loading
-dissociation and unloading
What is affinity for oxygen?
- tendency that a molecule to bind with oxygen
what affects haemoglobin’s affinity for oxygen?
-partial pressure of oxygen (pO2) which is a measure of oxygen concentration.
-As pO2 increases, haemoglobin’s affinity for oxygen also increases
Why does oxygen load onto haemoglobin in the alveoli?
-Oxygen enters blood capillaries at the alveoli in the lungs
-Alveoli have a high pO2 so oxygen loads onto haemoglobin to form oxyhaemoglobin
What happens when cells respire?
-they use up oxygen- this lowers the pO2
-RBC’s deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen
How are erythrocytes (RBC) adapted to transport oxygen?
-biconcave shape for large SA:V allowing oxygen to diffuse rapidly
-alot of haemoglobin (oxygen carrying protein)
-no nucleus for more space for haemoglobin
What does the oxygen dissociation curve show?
-shows how saturated the haemoglobin is when oxygen at any given partial pressure.
-y-axsis (% saturation of Hb with oxygen) x-axsis (partial pressure of oxygen kPa)
Why does the “Dissociation Curve” have an s shape
-sigmoid curve
-at low pO2 Hb has a low affinity to oxygen
-once the first oxygen molecule is bound its easier for other molecules
-last oxygen molecule needs a high pO2 to bind as 3/4 haem groups have already binded
What happens when one molecule of oxygen binds to haemoglobin?
-quaternary structure of the Hb molecule changes increasing affinity
-this is called positive cooperativity
What is the Bohr effect?
-cells respire they produce carbon dioxide, raising the pCO2.
-blood with oxygen is lower for a high pCO2
-This increases the rate of oxygen unloading- so the dissociation curve ‘shifts’ right
How does low oxygen environment affect animals haemoglobin?
-they have haemoglobin with a higher affinity for oxygen
-isnt much oxygen so haemoglobin has to be very good at loading any oxygen
How does high activity levels affect animals haemoglobin?
-High activity levels
-haemoglobin with a lower affinity for oxygen
-to deliver oxygen to respiring cells
How does an animals size affect their haemoglobin?
-small animals lose more heat so they have a high metabolic rate to compensate
-small mammals haemoglobin with a lower affinity for oxygen
-Hb has to easily unload to meet the high oxygen demand
What is the heart?
-muscular organ that lies in the thoracic cavity
-pumps blood around your body, through your blood vessels.
Whats the structure of the left ventricle for its function?
-thicker muscular walls
-contract powerfully and pump (oxygenated) blood all the way around the body.
What are the functions of pocket valves?
-in veins
-ensure that when the veins are squeezed, blood flows back towards the heart rather than away from it
What side of the heart transports de/oxygenated blood?
-right side pumps deoxygenated blood to the lungs
-left side pumps oxygenated blood to the whole body
What do the atrioventricular (AV)and semi-lunar (SL) valves do?
-AV links the atria to the ventricles
-SL links the ventricles to the pulmonary artery and aorta
- UNIDIRECTIONAL BLOOD FLOW
What do the cords/valve tendons do?
-attach the atrioventricular valves to the ventricles
-stops valves being forced up into the atria when the ventricles contract (backflow)
What does the vena cava do ?
-superior vena cava delivers blood from the head and chest area to the heart
-inferior vena cava returns blood from the lower body regions to the heart
What happens at ventricular systole stage of the cardiac cycle?
-ventricles contract
-volume decrease ,pressure increase
-semi-lunar valves open
-forces blood out through the pulmonary arteries and aorta
What happens at atrial systole stage of the cardiac cycle?
-atria contracts
-atroventricular valves open
-blood ejected into the ventricles
Whats the Circulatory system?
- mass transport system
-carries raw materials, waste products around the body
Why do multicellular organisms, like mammals need a circulatory system?
-low surface area to volume ratio
- specialised mass transport system to carry raw materials from specialised exchange organs to their body cells
What is the circulatory system is made up of?
-heart
-Blood vessels:
-arteries
-arterioles
-veins
-capillaries
What carries blood from heart to the lungs?
-Pulmonary artery
What carries blood from the lungs to the heart?
-Pulmonary vein
What carries blood from the heart to the body?
-Aorta
What carries blood from the body to the heart?
-Vena cava
What carries blood from the body to the Kidneys?
-Renal artery
What carries blood from the Kidneys to the Vena Cava?
-Renal vein
What do Arteries do ?
-carry blood away from the heart and to the rest of the body
-carry oxygenated blood except for the pulmonary arteries (deoxygenated blood to the lungs)
What are Arteries structure?
-thick and muscular walls
-elastic tissue (helps them recoil as the heart beats, and maintain the high pressure)
-endothelium /inner lining is folded (allows artery to stretch which maintain high pressure)
What are Arterioles and what do they do?
-arteries divide into smaller vessels
-form a network throughout the body
-muscles inside the arterioles contract to restrict the blood flow or relax to allow full blood flow.(to meet demands of blood)
What do Veins do ?
- take blood back to the heart under low pressure
-carry deoxygenated blood apart from pulmonary veins (oxygenated blood from lungs to heart)
What are the structures of veins?
-wider lumen
-very little elastic or muscle tissue (due to low pressure)
-pocket valves (prevent backflow of blood)
-Blood flow is helped by the contraction of the body muscles surrounding them
What do Capillaries do?
-Arterioles branch into capillaries
-smallest of the blood vessels
-adapted for efficient diffusion.
-form networks (capillary beds)
What are Capillary structure?
-found close to cells in exchange tissues (e.g. alveoli), so there’s a short diffusion pathway
-walls are only one cell thick, short diffusion pathway
-large number of capillaries, increase surface area
Whats in the blood?
Cells:
-Red blood cells
-White blood cells
-Platelets
Plasma:
-Glucose
-Amino acids
-Mineral ions
-Oxygen
-Plasma proteins (albumin)
What is tissue fluid?
-fluid that passes out of blood and bathes the tissue cells
How does tissue fluid move in and out of the capillaries?
-forced out of the blood at the arterial end of the capillaries
- transfers molecules like oxygen and glucose to tissue cells
-waste is transferred to the fluid
-returns back to the blood at the venous end of the capillaries
What are the competing factors for movement of tissue fluid?
-hydrostatic pressure
-oncotic pressure
How do substances move in and out of the capillaries, into the tissue fluid?
-pressure filtration
-tissue doesn’t contain RBCs or big proteins, too large to be pushed out the capillary walls
-Cells take in oxygen and nutrients from the tissue fluid, and release metabolic waste into it.
What pressure is high and why at the arterial end?
-hydrostatic pressure
-blood has just passed through an artery to an arteriole so still under high pressure
-pushes fluid out of blood to tissue
How can water move back into the blood by osmosis?
-Plasma proteins = hydrophillic
-they lower water potential in the blood plasma
-so water can move back into the blood by osmosis
What pressure is high and why at the venous end?
-Oncotic pressure is high
-plasma proteins in the blood plasma
What is ultrafiltration?
-tissue fluid being forced out of the capillary through the gaps in the endothelial cells
What happens to the remaining 10% of water not absorbed in tissue fluid?
-drains into a series of blind-ended vessels called lymph capillaries
Why is the water potential at the venule end of the capillary bed lower than the water potential in the tissue fluid?
-the fluid loss
-increasing concentration of plasma proteins(don’t leave the capillaries)
-SO some water re-enters the capillaries from the tissue fluid at the venule end by osmosis.
What is a Cardiovascular disease?
-describe diseases associated with the heart and blood vessels
-Most start with atheroma formation
What is Coronary heart disease and when does it occur?
-cardiovascular disease
-coronary arteries have lots of atheromas which restricts blood flow to the heart muscle
-lead to myocardial infarction
How do Atheromas form?
-damage occurs in endothelium (inner lining) by e.g, high BP
-WBCs and lipids from blood, clump together under the lining forming fatty streaks
-more WBC and lipids build up and harden forming fibrous plaque (atheroma)
-causes blockages in lumen of artery increasing BP
What is an Aneurysm and how does it form?
-balloon-like swelling of the artery
-starts with formation of atheromas which damage and weaken arteries
What is Thrombosis?
-formation of a blood clot
-clot can cause complete blockage of the artery
What is Myocardial infarction?
-coronary artery becomes completely blocked and an area of the heart receives no oxygen
How is smoking a risk factor for Cardiovascular disease?
-carbon monoxide and nicotine
-Carbon monoxide binds haemoglobin and reduces the amount of oxygen transported to tissues in blood
-decreases the amount of antioxidants so damage in the coronary artery walls is more likely
What happens at diastole stage of the cardiac cycle?
-relaxation of the heart
-atria begin to fill with blood
What does xylem tissue transport?
-water and mineral ions in solution
-from the roots to the leaves
What is the structure of the xylem?
-long, tube-like structures formed from dead cells
-no cytoplasm to for empty tube
-no end walls cells, making an uninterrupted tube
- rigid because of lignin in their thick side wall (withstand high water pressure)
What is the cohesion-tension theory?
-water is polar therefore cohesive
-Water evaporates from leaves at the ‘top’ of the xylem (transpiration)
- creates tension (suction) pulling more water up
-others water molecules follow forming column of water in the xylem due to cohesion
-water enters stem through the roots (transpiration pull) forming a continuous water column.
What is the evidence for cohesion-tension theory?
-Change in the diameter of tree trunks according to the rate of transpiration
-xylem vessel is broken and air enters it
-xylem vessel is broken, water does not leak out
What is the transpiration stream?
-passive process
-stomata are open, plants lose water vapour
-Water evaporates from the moist cell walls and accumulates in the spaces between cells in the leaf
-exits the leaf through the stomata down the water potential gradient
- loss of water is transpiration
Factors affecting transpiration rate:
-Light intensity
-Wind
-Humidity
-Temperature
What does a Potometer do?
-estimates transpiration rate
What does the Phloem transport?
-dissolved substances/assimilates (mainly sugars like sucrose) from source to sink
What is the structure of the phloem?
-cells arranged in tubes(like phloem)
-Sieve tube elements are living cells that form the tube for transporting solutes (no nucleus ,few organelles )
-companion cell for each sieve tube element (provide energy to seive tube )
-porous to allow liquids and
sucrose to flow through
What is Translocation?
-energy requiring process that takes place in the phloem.
-movement of solutes (e.g. amino acids and sugars like sucrose) to where they’re required in the plant
-Enzymes maintain a concentration gradient from the source to the sink by changing the solutes at the sink
What is the Mass flow theory?
1)transfer of sucrose into the sieve tube elements from the palisade cells (photosynthesising tissue via active transport to load the solutes and facilitated diffusion from the palisade cells into companion cells
2)Mass flow of sucrose through the sieve tube elements as water potential in sieve tubes is low soo water enters via osmosis from xylem and companion cells ccreating high hydrostatic pressure
3)Sucrose moves into the sink cells by facilitated diffusion down conc. gradient forming low water potential inside the sink cells so water to move into the respiring cells from the sieve cells via osmosis
What is evidence for mass flow theory?
-Ringing experiments (ring of bark including phloem not xylem is removed from a woody stem, a bulge forms above the ring in high conc of sucrose)
-Radioactive tracer(carbon (C14) can be used to track the movement of organic substances)
-Aphid experiments (evidence that there’s a pressure gradient)
