Exchange Flashcards
How do Microorganisms Obtain Nutrients & Remove Waste?
by exchange via their surface
nutrients (e.g. glucose, oxygen) move in by diffusion via their surface
waste (e.g. carbon dioxide) move out by diffusion via their surface
Why are Microorganisms able to perform exchange via their surface?
have a large surface area to volume ratio
have a short diffusion distance
have low demand
Why can’t Animals/Plants perform exchange via their surface?
have a small surface area to volume ratio
multicellular (large diffusion distance and high demand)
impermeable surface (prevent pathogens entering and reduce water loss)
therefore, require specialised Exchange & 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 a small surface area to volume ratio, large diffusion distance, high demand & body surface impermeable
therefore, cannot perform gas exchange (O2 in/CO2 out) via their surface, they require a specialised gas exchange system called Gills
Structure of Gills in Fish?
many gill filaments and gill lamellae = large surface area
gill lamellae have a thin wall (short diffusion distance) and are permeable
ventilation brings in pure water (high oxygen, low carbon dioxide) and circulation brings in deoxygenated blood (low oxygen, high carbon dioxide), the water and blood pass over in opposite directions (countercurrent flow), which maintains concentration gradient all the way along the 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 & body surface made of exoskeleton (impermeable barrier to reduce water loss)
therefore, cannot perform gas exchange (O2 in/CO2 out) via their surface, they require a specialised gas exchange system called Tracheal System
Structure of Tracheal System in Insects?
starts with openings on body surface called Spiracles
spiracles contain valves, open = gas exchange, closed = prevent water loss
spiracles connect to Trachea
trachea connect to Tracheoles
tracheoles connect directly to Respiring Cells (delivering oxygen, removing carbon dioxide)
How does Gas Exchange occur in Tracheal System of Insects?
at rest = down a concentration gradient, oxygen moves in & carbon dioxide moves out by simple diffusion
when active = by ventilation, air inhaled for mass flow of O2 in & air exhaled for mass flow of CO2 out
Function of Lungs?
site of gas exchange in mammals (oxygen into blood – used in cells for respiration, carbon dioxide out of the blood – toxic waste product of respiration)
What is Lungs made up of?
Trachea, Bronchi, Bronchioles, Alveoli (+ capillaries)
Function of trachea, bronchi, bronchioles?
transport of air and filter air, (bronchioles also controls amount of air reaching alveoli)
Structure of trachea/bronchi?
wall made of c-shaped cartilage
cartilage is strong so trachea/bronchi do not collapse
cartilage is c-shaped to give flexibility
lining made of goblet cells and ciliated epithelial cells
goblet cells make mucus, which traps pathogens/particles
ciliated epithelial cells have cilia, which pushes mucus up and out of lungs
Structure of bronchioles?
wall made of smooth muscle
smooth muscle contracts, lumen narrows, bronchiole constricts
(occurs when surrounded by noxious gases – reduces amount reaching alveoli)
lining made of goblet cells and ciliated epithelial cells
Adaptation of alveoli?
millions of tiny alveoli that are folded (large surface area)
thin wall/one cell thick/squamous epithelial cells (short diffusion distance)
elastic tissue in wall (stretches when breathing in to increase surface area, recoils when breathing out to push the air out)
ventilation maintains concentration gradient (high oxygen, low carbon dioxide)
Adaptation of capillaries?
millions of tiny capillaries (large surface area)
thin wall/one cell thick/squamous epithelial cells (short diffusion distance)
narrow lumen (increases diffusion time, decreases diffusion distance)
circulation maintains concentration gradient (low oxygen, high carbon dioxide)
How O2 moves from the alveoli to the capillaries?
by simple diffusion passing thru the alveolar epithelium and capillary epithelium
How CO2 moves from capillaries to the alveoli?
by simple diffusion passing thru the capillary epithelium and alveoli epithelium
Inhalation?
- external intercostal muscles contract
- internal muscles relax
- ribcage pulled up and out
- increased volume in the thorax
- diaphragm muscles contract and it will move down
- increased volume in thorax and decreased pressure inside
- atmospheric pressure is now greater than pulmonary pressure
- air is forced into lungs
Expiration?
- internal intercostal muscles contract
- external muscles relax
- rib cage moves down and in
- volume in the thorax decreases
- diaphragm muscles relax and it is pushed up
- decreased volume in thorax increased pressure inside
- pulmonary pressure is now greater than atmospheric pressure
- air is forced out of the lungs
Formula for Pulmonary Ventilation?
PV = tidal volume x ventilation rate
tidal volume = volume of air breathed in/out in one breath
ventilation rate = number of breaths per minute
Pulmonary Ventilation = volume of air breathed in/out per minute
Function of Intestines?
site of exchange of digested nutrients in mammals
What is Digestion?
Breakdown of Large Insoluble Molecules into Small Soluble Molecules (so they can move into the blood and then into the body cells)
Starch/Glycogen (Carbohydrates) into Glucose by Amylase (Salivary in mouth, Pancreatic in small intestine) and Maltase/Lactase/Sucrase (on lining of small intestine)
Proteins into Amino Acids by Endopeptidase/Exopeptidase/Dipeptidase (Endopeptidase in stomach, Exopeptidase in small intestine, Dipeptidase on lining of small intestine)
Lipids into Monoglyceride and 2 Fatty Acids by Lipase (in small intestine)
What do Intestine Absorb?
Small Intestine absorbs small soluble nutrients (glucose, amino acids, monoglyceride and fatty acid, vitamins and minerals)
Large Intestine absorbs water
Why do Humans/Mammals require a Specialised Transport System?
multicellular organisms therefore have large diffusion distances and high demand
need a transport system to deliver nutrients and remove waste from all cells
transport system in humans/mammals called Circulatory System
Circulatory System made of heart, blood vessels, blood
(heart pumps blood, blood vessels carry blood, blood carries nutrients/waste)
Why is the transport system in mammals called a double circulatory system?
the heart pumps twice, the blood goes through the heart twice – generates enough pressure to supply all body cells
Why is the transport system in mammals called a closed circulatory system?
blood is transported in blood vessels – helps to maintain pressure and redirect blood flow
Lipid digestion?
- hydrolysed by lipases produced in the pancreas
- hydrolyse ester bonds to form fatty acids and monoglycerides
- lipids are first broken down into micelles by bile salts produced by the liver
- this process in called emulsification
- it creates a larger surface area for the enzyme to be able to work more rapidly
Bile salts?
- one end is soluble fat (lipophilic) but not in water
- other side is insoluble in fat (lipophobic) but soluble in water (hydrophilic)
- fat is prevented from sticking back together
Protein digestion?
-peptidases hydrolyse peptide bonds in protein
- endopeptidases - hydrolyse in the central region forming smaller polypeptide. Increases SA for exopeptidases
- exopeptidases - hydrolyse at terminal amino acids of the peptide molecules formed by endopeptidases
- dipeptidases - hydrolyse the bonds between the two amino acids of a dipeptide. Membrane bound- part of the cell surface membranes of the epithelial cells lining the ileum.
Absorption of triglycerides?
- lipid mixed with bile salts
- this forms micelles
- monoglycerides and fatty acids are released
- monoglyceride and fatty acids are absorbed through the membrane of the ileum
- monoglycerides and fatty acids are converted back to triglycerides in the endoplasmic reticulum
- triglycerides are packaged back into chylomicrons
- chylomicrons released by exocytosis
- chylomicrons go into lymphatic vessels and then into the bloodstream
Chylomicrons?
- a small fat globule composed of protein and lipids
- they transport fat from the intestine to the liver and to dispose tissue
- the chylomicrons are synthesised in the lining of the intestine
how are dicotyledonous plants adapted for gas exchange?
- guard cells open and close to allow o2 in and co2 out
- stomata allows gasses in
- air spaces- create a diffusion pathway
how is water loss limited in insects?
- small SA : vol ratio- minimises the area over which water is lost
- rigid exoskeleton- waterproof cuticle - made of chitin
- spiracles- open and close to reduce water loss
how do gasses move in and out of the tracheal system?
- diffusion gradient
- muscle contractions
- water filled tracheoles
how does a diffusion gradient allow gasses to move in and out of the tracheal system?
- oxygen is used during respiration
- concentration of oxygen at tracheae end falls which creates a diffusion gradient
- oxygen diffuses from atmosphere
- co2 is produced by respiring cells
- diffusion gradient in opposite direction
- co2 diffuses into the atmosphere
how does muscle contractions allow gasses to move in and out of the tracheal system?
- abdominal pumping
- tracheae squeezed, which reduces their volume
- some air is expelled from tracheae
- uses energy
how does water filled tracheoles allow gasses to move in and out of the tracheal system?
- anaerobic respiration produces lactate
- lactate is water soluble
- water potential of the muscles becomes more negative
- water moves into muscle cells from tracheoles
- volume in the tracheoles decreases, drawing air in from the atmosphere
