3B more exchange Flashcards
1
Q
why is food broken down into smaller molecules during digestion
A
as the large biological molecules are to big to cross cell membranes and be absorbed from the gut into the blood
2
Q
what are digestive enzymes produced by
A
specialised cells in the digestive system
3
Q
why do different enzymes needed to catalyse the breakdown of different food molecules
A
as enzymes only work with specific substrate
4
Q
what are carbohydrates broken down by
A
amylase and membrane bound disaccharide
5
Q
what does amylase catalyse starch conversion into
A
maltose
6
Q
where is amylase produced
A
salivary glands- into mouth
pancreas- into small intestine
7
Q
what are membrane bound disaccharide
A
enzymes which are attached to the cell membranes of epithelial cells lining the ileum
8
Q
what do membrane bound disaccharide do
A
help break down disaccharide into monosaccharides
involves hydrolysis
9
Q
what is the ileum
A
final part of small intestine
10
Q
how can monosaccharides be transported across cell membrane of the ileum epithelium cells
A
via transporter proteins
11
Q
what are lipids broken down by
A
lipase with the help of bile salts
12
Q
what does lipase catalyse the breakdown of lipids into
A
monoglycerides and fatty acids
13
Q
where is lipase made
A
made in pancreas
works in small intestine
14
Q
where are bile salts produced
A
liver
15
Q
what does bile slats do
A
emulsifies lipids into small droplets
16
Q
why are bile salts so important
A
as they emulsify lipid into small droplets which largely increases the surface area and therefore increases the rate of diffusion as there is more area for lipase to work on
17
Q
once lipids are broken down what do monoglycerides and fatty acids stick to bile salts to form
A
micelles
18
Q
what are proteins broken down by
A
endopeptidases and exopeptidase
19
Q
what are endopeptidases
A
they act to hydrolyse peptide bonds within a protein
20
Q
what are two examples of endopeptidases
and where are they found
A
chymotrypsin and trypsin
both synthesised in pancreases and secreted in small intestine
21
Q
details on pepsin (another endopeptidase)
A
released into stomach by cells in the stomach lining
only works in acidic conditions- what hydrochloric acid is for in the stomach
22
Q
what is exopeptidase
A
acts to hydrolyse peptide bonds at the end of protein molecules
removes single amino acid from proteins
23
Q
what are dipeptidases
A
exopeptidase that only work on dipeptides
24
Q
how do dipeptidases work
A
they separate the two amino acids which make up the dipeptide by hydrolysing the peptide bond between
25
where are dipeptidases located
found on cell surface membrane of epithelial cells in small intestine
26
what are the products of digestion absorbed across
the ileum epithelium into the blood stream
27
how is glucose and galactose absorbed
by active transport with sodium ions via co transporter proteins
28
how are monoglycerides and fatty acids absorbed
micelles help move them towards epithelium
| micelles release them allowing them to be absorbed
29
why can monoglycerides and fatty acids be absorbed across the epithelial cell membrane
as they are lipid soluble
30
how are amino acids absorbed
absorbed via co transport
sodium ions actively transported out of the ileum epithelial cells into the blood
creates sodium conc grad
Sodium ions diffused from lumen of ileum into epithelial cells through sodium dependent transporter proteins carrying amino acids with
31
How are proteins digested
Hydrolysis of peptide bonds
Endopeptidases breaks down polypeptides into smaller peptides
exopeptidases removes terminal Amino acid
Dipeptidase breaks down dipeptides into amino acids
32
Why is maltose only digested by Maltese
Maltase has specific active site shape
Only binds to maltose
To form an enzyme substrate complex
33
describe haemoglobin
large protein with quaternary structure
34
what does quaternary structure mean
made up of more than one polypeptide chain
35
in haemoglobin what is a haem group and what does it contain
each chain has haem group
| contains an iron ion giving the red colour
36
why is haemoglobin described as having a high affinity for oxygen
each molecule can carry four oxygen molecules
37
how and where is oxyhemoglobin formed
oxygen joins to haemoglobin in red blood cells forming oxyhemoglobin
this takes place in the lungs
38
what is the equation of the reversible reaction oxyhaemaglobin to haemoglobin
Hb + 4O2 Hb08
39
what is the partial pressure of oxygen
pO2
measure of oxygen concentration
higher conc of dissolved o2 in cells= higher partial pressure
40
what is the partial pressure of c02
pCO2 measure of concentration of carbon dioxide in cell
41
how does haemoglobin affinity for oxygen depend on the partial pressure of oxygen
oxygen loads onto haemoglobin to form oxyhemoglobin where there's a high po2
oxyhemoglobin unloads its oxygen when there is a low pO2
42
why does oxygen load onto haemoglobin in the alveoli
as The alveoli have a high p02
43
where does oxyhemoglobin unload its oxygen
in respiring cells as they have low pO2
44
how does pCO2 effect oxygen unloading
haemoglobin gives up its oxygen more readily at higher partial pressures of carbon dioxide
45
explain the bohr effect
1- when cells respire they produce co2 which increases pco2
2- this increases rate of oxygen unloading so dissacosiation curve moves to right
more oxygen released
46
what is the circulatory system
a mass transport system
47
what is the circualtory system made up of
heart and blood vessels
48
what does the heart do in the circulatory system
pumps bloood through blood vessels to reach different parts of body
49
what does the blood do in the circulatory system
transports respiratory gases, products of digestion,metabolic wastes, hormones around the body
50
what are the two circuits
1st- takes blood from heart to lungs
| 2nd- takes blood around the rest of the body
51
what is the hearts blood supply
left and right coronary arteries
52
what do arteries do
carry blood from heart to rest of body
53
describe arteries
thick muscular and have elastic tissue to stretch and recoil as heart beats
54
what is the inner lining of the artery called
endothelium
55
describe endothelium in the artery
folded allowing artery to stretch
| also helps maintain high pressure
56
what do pulmonary arteries carry
deoxygenated blood to the lungs
| all other arteries carry oxygenated blood
57
what do arteries divide into
aterioles
58
what do aterioles form and what do they do
forms network throughout body
blood is directed to areas of demand in body by muscles in aterioles
these muscles contract or relax to allow full blood flow
59
what do veins do
take blood back to heart under low pressure
60
describe veins
wider lumen , little elastic or muscle tissue
| have valves to prevent blood flowing backwards
61
how is bloodflow through veins helped
by surrounding body muscle
62
what does the pulmonary vein carry
oxgenated blood to heart from lungs
| all other veins carry deoxygenated
63
what do aterioles branch into
cappilleries
64
how are capilleries adapted for efficient diffusion
1) found near cells in exchange tissue so very short difffusion pathway
2) walls are one cell thick so short diffusion pathway
3) large number of cappileries so large SA
65
what is the network of capilleries in tissue called
capillary beds
66
what is tissue fluid
fluid which surrounds cells in tissues
67
what is tissues fluid made up from
made from small molecules that leave the blood plasma like oxygen water and nutrients
68
why cant tissue fluid contain red blood cells or big proteins
as too big to be pusshed through capillary wals
69
what do cells take in and release into tissue fluid
take in - oxygen and nutrients
| release- metabolic waste
70
process of pressure filtration
1) (artery)at start of capillary bed, hydrostatic pressure is higher in capilleries than in tissue fluid
2) this difference in pressure means an overall outward pressure forces fluid out of cap into spaces around the cells forming tissue fluid
3) as fluid leaves pressure in reduces in cap so pressure is lowest now at venule end of capillary bed( near vein)
4) due to fluid loss &increasing concentration of plasma proteins -water potential at venue end of cap bed is lower than water potential in tissue fluid
5) this means some water re-enters capillaries from the tissue fluid at venue and by osmosis
71
Where is excess tissue fluid drained
Lymphatic system which transports it from tissues and dumps it back into circulatory system
72
what is lymphatic system
network of tubes acting like drains
73
what does the right side of heart do
Pumps deoxygenated blood to the lungs
74
what does left side of heart do
Pumps oxygenated blood to the whole body
75
what are the for blood vessels in the heart and what do they pump
Vena cava and pulmonary veins carry blood to the heart
pulmonary artery and aorta carry blood away from her
76
quick heart summmary blood flow
Deoxygenated blood pumped through vena cava to right atrium to right ventricle then out of the pulmonary artery
oxygenated blood flows in through the pulmonary vein into the left atrium into right left ventricle out of aorta
77
describe difference between right and left ventricle
Left ventricle is thicker more muscular as it needs to contract powerfully to pump blood all around the body
right ventricle only need to get blood lungs
78
why do the ventricles have thicker walls than the atria
As they need to push blood out of the heart where as atria just need to push blood a short distance into ventricles
79
what do atrioventricular valves do
link atria to ventricles and stop blood flowing back into atria when the ventricles contract
80
what do semi lunar valves do
Link the ventricles to the pulmonary artery and aorta
| stop blood flowing backwards into heart after ventricles contract
81
what do cords in the heart do
attach atrioventricular valves to the ventricles to stop them being forced up into atria when ventricles contract
82
why can blood only flow in one direction in the heart
Valves only open one way
if there is pressure behind a valve it's forced open
but if there is pressure in front of the valve it's forced shut
83
first step of the cardiac cycle
atria contracts, ventricle relaxed
| causing higher pressure in the atria so blood moves down the pressure gradient into the ventricles
84
second step of the cardiac cycle
atria relax, ventricle contracts
increases pressure in ventricle , forcing AV valve shut( prevents back flow)
presure in ventricle higher than that in aorta and pulmonary artery so forces SL valve open so blood forced out
85
third step of the cardiac cycle
atri and ventricle relax
higher pressure in pulmonary artery and aorta now forcing semi lunar valves to close preventing back flow
blood returns and fills atria due to higher pressure in the pulmonary vein and vena cava this increases pressure of atria opening AV valve
86
What is a atheroma
Fibrous plaque
87
How is a atheroma formed
If damage occurs to endothelial lipids from the blood come together forming fatty streaks overtime this will harden to a atheroma
88
What is a aneurysm and has it formed
Atheroma plaques damage the arteries and narrows them
so when blood travels through narrowed artery at high-pressure it can push the inner layers of the artery through the outer elastic layer to form a lballoon like swelling
aneurysm can burst causing haemorrhage
89
What is thrombosis and how is it formed
Atheroma plaque can rupture the endothelial and this causes damage
platelets and fibre in accumulate at cited damage forming blood clot this can block an artery
90
What is a myocardial infarction
If coronary artery becomes completely blocked area of heart muscle will be cut off from blood supply is receiving no oxygen so can't respire causing heart attack
91
What are three risk factors of cardiovascular disease
High blood cholesterol and poor diet
cigarette smoking
a high blood pressure
92
How does high blood pressure and poor diet lead to cardiovascular disease
As cholesterol is one of the main constitutions of fatty deposits that from atheroma is leading to blood clots
93
How does cigarette smoking need to cardiovascular diseases
Nicotine increases risk of high blood pressure
carbon monoxide binds the haemoglobin reducing the amount of oxygen in the blood can lead to a heart attack
smoking decreases about antitoxin dents in the bloods
94
How can hide blood pressure need to cardio vascular diseases
Increases risk of damage to artery walls increasing risk of atheroma formation
95
what does xylem tissue transport
water and mineral ions
96
what does phloem tissue transport
sugars
97
describe xylem vessels
long tube like made up of dead cells
| no end walls making uninterrupted tube so water can pass through easier
98
how does water move up the plant
Water evaporates from the leaves at top of xylem
- creates tension pulling up more water
- as water is cohesive it pulls up even more water
- water enter stem from roots
99
whats transpiration
1- water evaporates from voice cells and accumulates in spaces between cells in the leaf
2-when stomato open water moves out of leaf down concentration gradient
100
how does light effect transpiration rate
more light means faster rate of transpirations as photosynthesis happens more in light
101
how does temperature effect transpiration rate
higher temp means faster rate of transpiration as molecules have more energy so can evaporate quicker
102
how does humidity effect transpiration rate
lower humidity the faster the transpiration rate as higher concentration gradient
103
how does wind effect the rate of transpiration
more windy means faster rate of transpiration as the wind can blow away more water molecules
104
what are seive tube cells and companion cells
seive tube elements are living cells which form the phloem tube but they have no nucleus so there is a companion cell for each of them to provide energy needed for active transport
105
what is translocation
the movement of solutes in a plant to where they are needed
106
does transloctaion require energy
yes
107
how do enzymes maintain the concentration gradient from source to sink
by changing (breaking down the solutes) the sloutes at the sink so there is always a lower concentration at the sink
108
what is the first step of mass flow hypothesis
1- active transport loads the solutes from companion cells into the sieve tube of p[phloem at the source
2- this lowers water potential inside the sieve tubes so water enters the tubes by osmosis from the companion cells and the xylem
3-this creates high pressure at the source end f the phloem and in the sieve tubes
109
what is the second step of the mass flow hypothesis
1- at the sink end solutes are removed from phloem to be used up
2- this increases water potential inside the sieve tubes so water leaves by osmosis
3-this loweres the pressure insed the sieve tubes
110
what is the third step of the mass flow hypothesis
1- this results in a pressure gradient from the sink to source end of the phloem
2- the gradient pushes the solutes from the source to sink end of the sieve tubes
3- when the solutes reach the sink they will be used or stored
111
what are two objections to the mass flow hypothesis
1- sugar and solutes travel to many different sinks not just the one with the highest water potential
2- the sieve plates would create a barrier to mass flow , a lot of pressure would be needed for solutes to get through at a reasonable rate
112
what are 4 supporting evidences for the mass flow hypothesis
1-tree ringing
radioactive tracker
aphids
metabolic inhibitir
