Module 3:Exchange and Transport Flashcards
How do microorganisms obtain nutrients and remove waste
Exchange via their surface
Nutrients move in via diffusion
Waste moves out via diffusion
Why are microorganisms able to perform exchange via their surface
Large surface area to volume ratio
Short diffusion distance
Low demand
Why can’t animals/plants perform exchange via their surface
Small surface area to volume ratio
Multicellular (large diffusion distance and high demand)
Impermeable surface (prevent pathogens entering and reduce water loss)
Require exchange and transport systems
Exchange system
Increases rate of diffusion of nutrients in and wastes out
Transport system
Deliver nutrients and remove waste from all cells
Why do fish have specialised gas exchange systems
Multicellular organism so has small surface area to volume ratio, large diffusion distance, high demand and body surface is impermeable
Can’t perform gas exchange via surface
Need transport system
Structure of gills in fish
Many Gill filaments and Gill lamellae=large surface area
Gill lamella have a thin wall (shirt diffusion distance) and are permeable
Ventilation brings in pure water with high oxygen and low carbon dioxide
Circulation brings deoxygenated blood low oxygen and high carbon dioxide
Water and blood have countercurrent flow to maintain favorable concentration gradient all the way along Gill lamellae
Why do insects have specialised gas exchange systems
Multicellular organism so has a small surface area to volume ratio, large diffusion distance, high demand and body surface made of exoskeleton (impermeable barrier to reduce water loss)
Can’t perform gas exchange via their surface so require tracheal system
Structure of tracheal system in insects
Starts with openings on the body called spiracles
Spiracles contain valves which open for gas exchange and close to prevent water loss
Spiracles connected to trachea
Trachea connected to tracheoles
Tracheoles connect directly to respiring cells delivering oxygen and removing carbon dioxide
How does gas exchange occur in the tracheal system of insectx
At rest: down a concentration gradient oxygen moves in and carbon dioxide moves out by simple diffusion
When active: by ventilation, air inhaled for mass flow of oxygen in and air exhaled for mass flow of carbon dioxide out
Function of the lungs
Site of gas exchange in mammals
Oxygen in blood used in cells for respiration
Carbon dioxide out of the blood toxic waste product of respiration
What are the lungs made up of
Trachea Bronchi Bronchioles Alveoli Capillaries
Function of trachea, bronchi, bronchioles
Transport of air and filter air
Bronchioles also control the amount of air reaching the alveoli
Structure of the trachea and bronchi
Wall made of c shaped cartilage
Cartilage is so strong so trachea and bronchi don’t collapse
C shaped to give flexibility
Lining made of goblet cells and ciliates epithelial cells
Goblet cells make mucus which traps pathogens
Ciliated epithelial cells have cilia which pushes mucus up and out of the lungs
Structure of the bronchioles
Walls made of smooth muscle
Smooth muscle contracts, lumen narrows and bronchioles constricts
This occurs when surrounded by noxious gases to reduce the amount that reaches the alveoli
Lining made of goblet cells and epithelial cells
Adaptations of the alveoli
Millions of alveoli that are folded to increase the surface area
One cell thick/squamous epithelial cells for a short diffusion distance
Elastic tissue in wall (stretches with breathing in to increase surface area,recoils when breathing out to push air out)
Ventilation maintains concentration gradient of high oxygen and low carbon dioxide
Adaptation of capillaries
Millions of tiny capillaries for large surface area
One cell thick so short diffusion distance
Narrow lumen to increase diffusion time but decrease diffusion distance
Circulation maintains concentration gradient of low oxygen and high carbon dioxide
How does oxygen move from the alveoli to the capillaries
Simple diffusion
Passing through alveolar epithelium and capillary epithelium
How does carbon dioxide move from the capillaries to the alveoli
Simple diffusion
Capillary epithelium and alveoli epithelium
Inhalation
External intercostal muscles contract, internal relax Rib cage moves up and out Diaphragm contacts and flattens Increase in thoracic volume Decreased thoracic pressure Increased atmospheric pressure Air drawn into lungs
Exhalation
External intercostal relax, internal contract
Rib cage moves down and in
Diaphragm relaxes, dome shape
Decrease thoracic volume
Increased thoracic pressure, decrease atmospheric pressure
Air forced out
Aided by elastic recoil in alveoli
Formula for pulmonary ventilation
Tidal volume x ventilation rate
Tidal volume definition
Volume of air breathed in/out in one breath
Ventilation rate definition
Number of breaths per minute
Pulmonary ventilation definition
Volume of air breathed in/out in one minute
Function of intestines
Site of exchange of digested nutrients in mammals
Digestion definition
Hydrolysis of large insoluble molecules into small soluble molecules so they can move into the blood and into the body cells
Digestion of starch/glycogen
Into glucose by Amylase (salivary in mouth,pancreatic in small intestine)
And maltase/lactase/sucrase (lining of small intestine)
Digestion of proteins
Amino acids by endopeptidases, exopeptidases,dipeptidases
In stomach, small intestine, lining of small intestine
(In that order relating to enzyme above)
Lipids digestion
Into monoglycerides and two fatty acids by lipase found in small intestine
What do intestines absorb
Small intestine absorbs small soluble nutrients (glucose, amino acids,monoglycerides and fatty acids, vitamins and minerals)
Large intestine absorbs water
Why do humans/mammals require a specialised transport system
Multicellular so have large diffusion distance and high demands
Needs transport system to deliver nutrients and remove waste
Circulatory system
What is the circulatory system made of
Heart
Blood vessels
Blood
Why double circulatory system?
Heart pumps twice
Blood goes through heart twice in one cycle
Two separate blood flows
Why is the transport system in mammals called a closed circulatory system
Blood is transported in blood vessels
Helps to maintain blood pressure and redirect blood flow
Layout of circulatory system
Heart Arteries Arterioles Capillaries Venues Veins Heart
Artery/aterioles
Blood away from heart
Arterioles are small arteries
Capillaries
Site of exchange
Nutrients out
Waste in
Veins/venules
Return blood back to the heart
Venules are small veins
Brief blood flow in heart
Vena cava Right atrium Right ventricles Pulmonary artery Lungs Pulmonary vein Left atrium Left ventricle Aorta Body
Which ventricle wall is thicker
Left
Pumps blood to rest of the body
At higher pressure
Stronger contractions
Valves in the heart
Tricuspid= right AV
Bicuspid= left AV
two semi lunar
When are AV valves open or closed
Open=pressure in atria is greater than pressure in the ventricles
Closed=pressure in ventricles greater than pressure in the atria
When are SL valves open or closed
Open= pressure in ventricles greater than pressure in arteries
Closed=pressure in arteries greater than pressure in ventricles
Describe the process of the cardiac cycle
Filling stage:atria relaxed, ventricles relaxed, AV valves open,SL valve closed
Atrial systole:SAN in right atrium initiates heart beat and sends impulse across both atria so they contract and pushes all remaining blood into the ventricles
Ventricular systole:AVN picks up impulse, delays it so ventricles can fill and sends impulse down non conductive septum down the bundle of His, at apex the impulse goes up both walls of ventricles in purkinje fibres so ventricles contract from base upwards, when ventricles contract the AV valve closes and SL valve opens and blood leaves the heart
Ventricular diastole: SL valve closes Then the AV valve opens and filling starts again
What causes the heart sounds
When the valves close
1st when AV closes
2nd when SL closes
Formula for cardiac output
Stroke volume x heart rate
Stroke volume definition
Volume of blood pumped out of the heart in one beat
Heart rate definition
Number of beats per minute
Cardiac output definition
Volume of blood pumped out of the heart in one minute