3.3 Organisms exchange substances with their environment Flashcards
3.3.1
how do you calculate surface area to volume ratio?
- calculate surface area
- calculate volume
- surface area divided by volume
- put into a ratio of x:1
3.3.1
what does Fick’s law state?
as the surface area of the membrane increases, the rate of diffusion also increases
3.3.1
what is the equation for Fick’s law?
diffusion ∝ (surface area x difference in concentration) / length of diffusion pathway
3.3.1
how does surface area to volume ratio effect metabolism?
The larger the SA:Vol ratio the greater the metabolic rate per unit volume.
This is due to the greater loss of heat from a larger SA:Vol ratio.
Therefore energy is required more quickly to ensure that the adequate body temperature is maintained.
3.3.1
how have larger organisms adapted to having a small surface area to volume ratio?
developed mass transport systems
(to gain the nutrients needed)
3.3.2
what is gas exchange?
the biological process through which gases are transferred across cell membranes to either enter or leave the organism
3.3.2
what organ is used for human gas exchange?
lungs
3.3.2
what are the structure in the lungs and breathing pathways?
(twelve)
deoxygenated blood
trachea
pulmonary vein
capillaries
bronchus
lungs
pulmonary artery
alveoli
bronchiole
nasal cavity
oxygenated blood
muscle
3.3.2
what is the structure of the lungs?
a pair of lobed structures made up of a series of highly branched tubules, called bronchioles, which end in tiny air sacs called alveoli.
3.3.2
what is the structure of the trachea?
a flexible airway that is supported by rings of cartilage.
The cartilage prevents the trachea collapsing as the air pressure inside falls when breathing in.
The tracheal walls are made up of muscle, lined with ciliated epithelium and goblet cells.
3.3.2
what is the structure of the bronchi?
two divisions of the trachea, each leading to one lung.
They are similar in structure to the trachea and, like the trachea, they also produce mucus to trap dirt particles and have cilia that move the dirt-laden mucus towards the throat.
The larger bronchi are supported by cartilage, although the amount of cartilage is reduced as the bronchi get smaller.
3.3.2
what is the structure of the bronchioles?
a series of branching subdivisions of the bronchi.
Their walls are made of muscle lined with epithelial cells.
This muscle allows them to constrict so that they can control the flow of air in and out of the alveoli.
3.3.2
what is the structure of the alveoli?
minute air sacks, with a diameter of between 100µm and 300µm micrometres, at the end of the bronchioles.
Between the alveoli there are some collagen and elastic fibres. The alveoli are lined with epithelium.
3.3.2
what do goblet cells do?
excrete mucus
3.3.2
what is inspiration?
inhaling
When the air pressure of the atmosphere is greater than the air pressure in the lungs, air is forced into the lungs
3.3.2
what is expiration?
exhaling
When the air pressure of the atmosphere is less than that of the inside of the lungs, air is forced out of the lungs
3.3.2
what happens when you inhale?
(five)
diaphragm contracts
external intercostal muscles contract which raises the ribs
chest cavity volume increases
the chest cavity pressure falls below the atmospheric pressure
air moves into the lungs
3.3.2
what happens when you exhale?
(five)
diaphragm relaxes
external intercostal muscles relax which causes the ribs to fall
chest cavity volume decreases
the chest cavity pressure rises above the atmospheric pressure
air moves out of the lungs
3.3.2
what is ventilation?
The constant moving in and out of air from the lungs
3.3.2
what is the function of the lungs?
Main site of gas exchange.
To take in oxygen and excrete carbon dioxide
3.3.2
what is the function of the trachea?
To allow air to move into and out of the bronchi/lungs.
Muscle allows the trachea to contract and move air.
Cartilage supports the trachea keeping it open.
3.3.2
what is the function of the bronchi?
Allow air to move into and out of each lung.
Goblet cells produce mucus that traps dirt/pathogens preventing them from entering the lungs.
3.3.2
what is the function of the bronchioles?
Allow air to pass to and from the alveoli.
Muscle allows for contraction (constriction) to move gases
3.3.2
what is the function of the alveoli?
The site of gaseous exchange.
Oxygen diffuses into the blood and carbon dioxide from the blood.
Stretch and recoil during ventilation.
3.3.2
what are the structures in an insects gas exchange system?
tracheae
tracheoles
spiricles
3.3.2
what are tracheoles in insects?
they extend through all the body of the insect
(allowing a short diffusion distance with atmospheric air)
3.3.2
what is the structure of the trachea in insects?
supported by strengthened rings to prevent collapse
3.3.2
describe the gas exchange diffusion gradient in insects?
Oxygen is used up during respiration whilst carbon dioxide is produced.
These changing concentration levels cause diffusion of these gases between the tracheoles and the air surrounding the insect.
Oxygen: atmosphere → tracheoles
Carbon dioxide: tracheoles → atmosphere
3.3.2
what is the mass transport system in insects?
muscular contractions (abdominal pumping) squeeze the tracheoles enabling the mass transport of gases, speeding up gas exchange
3.3.2
why is there water in the end of tracheoles in insects?
some of the respiration is anaerobic, producing lactate, which lowers the water potential of the muscle cells.
Water therefore enters the cells from the tracheoles by osmosis.
The decrease in volume of water in the tracheoles causes air to be drawn in and provides a gaseous exchange (rather than a fluid and so rate of diffusion increases)
Rate of diffusion increases, though evaporation increases.
3.3.3
name the components of the human digestion system
(ten)
mouth
oesophagus
stomach
ileum
large intestine
rectum
anus
pancreas
gallbladder
salivary glands
3.3.3
what does the mouth do?
increases the surface area of food by chewing
3.3.3
what does the oesophagus do?
carries food from the mouth to the stomach
3.3.3
what does the stomach do?
a muscular sack with the inner layer that produces enzymes
its role is to store and digest food, especially proteins
it has glands that produce enzymes which digest protein
3.3.3
what does the ileum do?
food is further digested by enzymes that are produced by its walls and by glands that pour their secretion into it
the inner walls of the ileum are folded into villi, which gives it a large surface area.
absorbing the products of digestion into the blood stream
3.3.3
what does the large intestine do?
absorbs water
most of the water that is absorbed is water from the secretions of many digestive glands
3.3.3
what does the rectum do?
the final section of the intestines
the faeces are stored here before periodically being removed by the anus in a process called egestion
3.3.3
what do the salivary glands do?
they pass their secretions via a duct into the mouth.
these secretions contain the enzyme salivary amylase, which hydrolyses starch into maltose
3.3.3
what does the pancreas do?
a large gland situated below the stomach
it produces a secretion called pancreatic juice
this secretion contains proteases, lipase and pancreatic amylase
3.3.3
what does the anus do?
sphincter muscle that controls egestion
3.3.3
what doe the gallbladder do?
stores and concentrates bile from the liver
3.3.3
what enzyme is present in the mouth?
salivary amylase
3.3.3
what enzymes are present in the stomach?
lipase
endopeptidases
3.3.3
what enzymes are present in the ileum?
maltase
lactase
sucrase
lipase
exopeptidases
dipeptidases
amylase
3.3.3
describe amylase?
substrate = starch
bonds hydrolysed = glycosidic
product = maltose
3.3.3
describe maltase?
substrate = maltose
bonds hydrolysed = glycosidic
product = glucose
3.3.3
describe maltase?
substrate = maltose
bonds hydrolysed = glycosidic
product = glucose
3.3.3
describe lactase?
substrate = lactose
bonds hydrolysed = glycosidic
products = glucose + galactose
3.3.3
describe sucrase?
substrate = sucrose
bonds hydrolysed = glycosidic
products = glucose + fructose
3.3.3
describe lipase?
substrate = triglycerides
bonds hydrolysed = ester
products = monoglycerides + fatty acids
3.3.3
describe endopeptidases?
substrate = proteins
bonds hydrolysed = peptide
product = polypeptides
3.3.3
describe exopeptidases?
substrate = polypeptides
bonds hydrolysed = peptide
product = dipeptides
3.3.3
describe dipeptides?
substrate = dipeptides
bonds hydrolysed = peptide
product = amino acids
3.3.3
describe the role of the villi?
Increases surface area for diffusion of substances
Increases number of epithelial cells with membrane enzymes
3.3.3
describe the role of the thin walls in the ileum?
Shorter diffusion pathway for faster absorption of substances
3.3.3
describe the roles of the muscles in the ileum?
Allows movement of substances and mixes the contents of the ileum
maintains concentration gradients and ensures the products of digestion are close to the epithelial cells/villi
3.3.3
describe the roles of the rich blood supply in the ileum?
Carry absorbed molecules away
maintains diffusion gradient
3.3.3
describe the roles of the microvilli?
Increases surface area for diffusion of substances
3.3.3
describe the absorption of triglycerides in the ileum?
Lipids are emulsified by bile salts and broken down by lipase into monoglycerides and fatty acids
These products combine with the bile salts to form micelles which move to the epithelial membrane.
The micelles break down (releasing the bile salts) and the non-polar monoglycerides and fatty acids diffuse across the epithelial membrane.
They move through the SER and golgi reforming as triglycerides and combining with cholesterol and lipoproteins to form chylomicrons
Chylomicrons move out of the epithelial cells by exocytosis into lymphatic capillaries (lacteals) and then into blood vessels.
3.3.4.1
FILL IN THE GAPS
when oxygen molecules join a haemoglobin it is called _____________ or _____________
association
loading
3.3.4.1
FILL IN THE GAPS
when oxygen molecules leave an oxyhaemoglobin it is called _____________ or _____________
dissociation
unloading
3.3.4.1
what does affinity mean?
the tendency for oxygen to bind or unbind
3.3.4.1
what does it mean if there is high affinity for haemoglobin?
oxygen will readily associate
3.3.4.1
what does it mean if there is low affinity for haemoglobin?
oxygen will not be able to bind and any bound oxygen will dissociate
3.3.4.1
what will the affinity to oxygen be in gas exchange surfaces and what will oxygen do?
high
associate
3.3.4.1
what will the affinity to oxygen be in a respiring tube and what will oxygen do?
low
dissociate
3.3.4.1
what type of protein is haemoglobin?
globular
quaternary
3.3.4.1
how many polypeptide chains does haemoglobin have?
four
3.3.4.1
describe the tertiary structure of haemoglobin?
final folding
incorporated with ONE haem group iron molecule
3.3.4.1
describe the quaternary structure of haemoglobin?
two alpha and two beta
four haem group irons
four polypeptide strands
3.3.4.1
how many oxygen molecules can one haemoglobin hold at once?
four
3.3.4.1
where are the tertiary and quaternary structure processed?
golgi apparatus
3.3.4.1
how is oxygen concentration measured?
partial pressure (pO2)
3.3.4.1
The greater the concentration of oxygen, the _____ the partial pressure
higher
3.3.4.1
where there is a high pO2, haemoglobin has a ______ affinity to oxygen
high
3.3.4.1
Where there is a high pO2, oxygen _________ with (loads onto) haemoglobin forming __________
associates
oxyhaemoglobin
3.3.4.1
Where there is a low pO2, oxygen _______ (unloads from) from haemoglobin, here haemoglobin has a ______ affinity with oxygen
dissociates
low
3.3.4.1
when haemoglobin is 100% saturated, how many oxygen molecules are attached?
four
3.3.4.1
when there are zero oxygen molecules attached to haemoglobin, what percent is it saturated?
0%
3.3.4.1
what is needed for the first oxygen molecule to associate?
large increase in partial pressure is needed to increase the % saturation
3.3.4.1
what does the first O2 molecule do to the haemoglobin for other molecules to associate?
it alters the conformation of haemoglobin
causes a change to the quaternary structure of the haemoglobin molecule making 2nd and 3rd binding easier
3.3.4.1
when the second and third O2 associate, what happens to the partial pressure and therefore the % saturation?
> small increase in partial pressure
results in a large increase in % saturation
3.3.4.1
why is it hard for the fourth o2 to associate?
less binding sites available
3.3.4.1
what happens to the partial pressure when the fourth O2 is trying to associate with the haemoglobin?
large increase in partial pressure
3.3.4.1
high pO2 = ____ affinity = ____ % saturation
high
high
3.3.4.1
low pO2 = ____ affinity = ___ % saturation
low
low
3.3.4.1
when is O2 affinity high?
in oxygen-rich areas (lungs)
3.3.4.1
when is O2 affinity low?
in oxygen-starved areas (muscles)
3.3.4.1
when pCO2 is high, which way does the graph shift?
right
3.3.4.1
when pCO2 is high, what is this effect called?
Bohr effect
3.3.4.1
what causes the Bohr effect?
high pCO2
high temperature
low pH
3.3.4.1
what are features of transport systems in animals?
(three)
> suitable medium
closed system of vessels that contain and distribute the medium
mechanism for moving the medium through the vessels in one direction
> animals use muscular contractions and have valves to maintain flow
3.3.4.1
what is a closed system?
blood is confined to and circulates in closed tubular vessels
3.3.4.1
what is a double circulatory system?
blood passes through the heart twice for each complete circuit of the body
3.3.4.1
give an example of a species with a single and a double circulatory system?
single - fish
double - humans (all mammals)
3.3.4.1
name all the structures of a mammalian heart
(twelve)
superior vena cava
inferior vena cava
pulmonary artery
pulmonary vein
right atrium
right ventricle
left atrium
left ventricle
aorta
coronary artery
semilunar valve
atrioventricular valve
3.3.4.1
what are the three simplified stages of the cardiac cycle?
arterial and ventricular diastole
atrial systole and ventricular diastole
ventricular systole and arterial diastole
3.3.4.1
describe cardiac diastole
all chambers are relaxed and blood flows into the heart
3.3.4.1
describe what happens when arterial systole and ventricular diastole occurs
atria contract pushing blood into the ventricles
3.3.4.1
describe what happens when atrial diastole and ventricular systole occur
after the atria relax, the ventricles contract, pushing blood out of the heart
3.3.4.1
what is diastole?
heart muscle relaxes which allows the chamber to fill with blood
3.3.4.1
what is systole?
heart muscles contract, which pushes the blood out of the chamber
