Topic 3 Flashcards

1
Q

Surface area to volume ratio

A

The surface area of an organism divided by its volume
the larger the organism, the smaller the ratio

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2
Q

Factors affecting gas exchange

A

diffusion distance
surface area
concentration gradient
temperature

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3
Q

Ventilation

A

Inhaling and exhaling in humans
controlled by diaphragm and antagonistic interaction of internal and external intercostal muscles

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4
Q

Inspiration

A

External intercostal muscles contract and internal relax
Pushing ribs up and out
Diaphragm contracts and flattens
Air pressure in lungs drops below atmospheric pressure as lung volume increases
Air moves in down pressure gradient

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5
Q

Expiration

A

External intercostal muscles relax and internal contract
Pulling ribs down and in
Diaphragm relaxes and domes
Air pressure in lungs increases above atmospheric pressure as lung volume decreases
Air forced out down pressure gradient

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6
Q

Passage of gas exchange

A

Mouth / nose -> trachea -> bronchi -> bronchioles -> alveoli
crosses alveolar epithelium into capillary endothelium

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7
Q

Alveoli structure

A

Tiny air sacs
highly abundant in each lung - 300 million
surrounded by the capillary network
epithelium 1 cell thick

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8
Q

Why large organisms need specialised exchange surface

A

They have a small surface area to volume ratio
higher metabolic rate - demands efficient gas exchange
specialised organs e.g. lungs / gills designed for exchange

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9
Q

Fish gill anatomy

A

Fish gills are stacks of gill filaments
Each filament is covered with gill lamellae at right angles

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10
Q

How fish gas exchange surface provides large surface area

A

Many gill filaments covered in many gill lamellae are positioned at right angles creates a large surface area for efficient diffusion

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11
Q

Countercurrent flow

A

When water flows over gills in opposite direction to flow of blood in capillaries
equilibrium not reached
diffusion gradient maintained across entire length of gill lamellae

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12
Q

Name three structures in tracheal system

A

Involves trachea, tracheoles, spiracles

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13
Q

How tracheal system provides large surface area

A

Highly branched tracheoles
large number of tracheoles
filled in ends of tracheoles moves into tissues during high metabolic activity
so larger surface area for gas exchange

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14
Q

Fluid-filled tracheole ends

A

Adaptation to increase movement of gases
When insect flies and muscles respire anaerobically - lactate produced
Water potential of cells lowered, so water moves from tracheoles to cells by osmosis
Gases diffuse faster in air

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15
Q

How do insects limit water loss(4)

A

Small surface area to volume ratio
Waterproof exoskeleton
Spiracles can open and close to reduce water loss
Thick waxy cuticle - increases diffusion distance so less evaporation

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16
Q

Dicotyledonous plants leaf tissues

A

Key structures involved are
mesophyll layers with many interconnecting air spaces
Palisade and spongy mesophyll - lots of air spaces and chlorophyll.
Stomata created by guard cells

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17
Q

Gas exchange in plants

A

Palisade mesophyll is site of photosynthesis
Oxygen produced and carbon dioxide used creates a concentration gradient
Oxygen diffuses through air space in spongy mesophyll and diffuse out stomata

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18
Q

Role of guard cells

A

Swell - open stomata
Shrink - closed stomata
At night they shrink, reducing water loss by evaporation

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19
Q

Xerophytic plants

A

Plants adapted to survive in dry environments with limited water (e.g. marram grass/cacti)
Structural features for efficient gas exchange but limiting water loss like:
Stomata in sunken pits and small hairs reduce conc extraction gradient as water vapour is trapped
Thick waxy cuticle
Leaves modified to spines which reduces surface area
Roots seep deep down to reach water
Rolling up of leaves as majority of stomata in lower epidermis this traps layer of still air reducing concentration gradient

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20
Q

Adaptations of xerophyte

A

Adaptations to trap moisture to increase humidity -> lowers water potential inside plant so less water lost via osmosis
-sunken stomata
-curled leaves
-hairs
Thick cuticle reduces loss by evaporation
longer root network

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21
Q

Digestion

A

Process where large insoluble biological molecules are hydrolysed into smaller soluble molecules
So they can be absorbed across cell membranes

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22
Q

Locations of carbohydrate
digestion

A

Mouth -> duodenum -> ileum

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23
Q

Locations of protein digestion

A

Stomach -> duodenum -> ileum

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24
Q

Endopeptidases

A

Break peptide bonds between amino acids in the middle of the chain
Creates more ends for exopeptidases for efficient hydrolysis

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25
Exopeptidases
Break peptide bonds between amino acids at the ends of polymer chain
26
Membrane- bound dipeptidases
Break peptide bond between two amino acids
27
Digestion of lipids
Bile salts combine with lipids which causes them two split and form tiny droplets called micelles and this increases the S.A for the action of lipase - this is called emulsification Lipase hydrolyses the ester bonds and forms monoglycerides and fatty acids (non polar and lipid soluble) Lipase produced in pancreas Bile salts produced in liver and stored in gall bladder
28
Lipase
Produced in pancreas Breaks ester bonds in triglycerides to form : monoglycerides glycerol fatty acids
29
Role of bile salts
Emulsify lipids to form tiny droplets called micelles Increases surface area for lipase action - faster hydrolysis
30
Micelles
Water soluble vesicles formed from fatty acids, glycerol, monoglycerides and bile salts
31
Lipid absorption
Micelles after emulsification and digestion delivers fatty acids, glycerol and monoglycerides to epithelial cells of ileum for absorption Cross via simple diffusion as these are lipid-soluble and non-polar
32
Lipid modification
Smooth ER reforms monoglycerides / fatty acids into tryglycerides Golgi apparatus combines tryglycerides with proteins to form vesicles called chylomicrons
33
How lipids enter blood after modification
Chylomicrons move out of cell via exocytosis and enter lacteal lymphatic vessels carry chylomicrons and deposit them in bloodstream
34
How are glucose and amino acids absorbed
Via co-transport in the ileum 1-Na+ actively transported out of epithelial cells by sodium potassium pump. Takes place in a different type of carrier protein. 2-Thus maintains concentration gradient between lumen and epithelial cells as there is high concentration of Na+ in the ileum compared to epithelial cells 3-So Na+ moves down the concentration gradient into epithelial cells using co transport protein as it carries either amino acids or glucose into the epithelial cells. 4- the glucose or amino acid moves into blood plasma by facilitated diffusion using different type of carrier protein 5-Na+ is down the concentration gradient while glucose/amino acid is against. It’s the movement of Na+ down the concentration gradient rather than ATP which drives this process
35
Haemoglobin (Hb)
Quaternary structure protein - globular protein 2 alpha chains 2 beta chains 4 associated haem groups in each chain containing Fe2+ transports oxygen Primary structure, secondary structure and tertiary structure decides the further folding which is an important factor in its ability to carry oxygen
36
Affinity of haemoglobin
The ability of haemoglobin to attract / bind to oxygen
37
Saturation of haemoglobin
When haemoglobin is holding the maximum amount of oxygen it can hold
38
Loading / unloading of haemoglobin
Binding/detachment of oxygen to haemoglobin also known as association and disassociation
39
Oxyhaemoglobin dissociation curve
Oxygen is loaded in regions with high partial pressures (alveoli) Unloaded in regions of low partial pressure (respiring tissue) S shaped
40
Oxyhaemoglobin dissociation curve shifting left
Hb would have a higher affinity for oxygen Load more at the same partial pressure Becomes more saturated Adaptation in low-oxygen environments e.g. llamas/ in foetuses
41
Cooperative binding
Hb's affinity for oxygen increases as more oxygen molecules are associated with it When one binds, Hb’s quaternary structure changes meaning others bind more easily explaining S shape of curve Positive cooperativity
42
How carbon dioxide affects haemoglobin
When carbon dioxide dissolves in liquid, carbonic acid forms decreases pH causing Hb to change shape into one that has lower affinity for O2 at respiring tissues more oxygen is unloaded Bohr shift
43
Bohr effect
High carbon dioxide partial pressure- respiring tissues -pH decreases causes oxyhaemoglobin curve to shift to the right Low CO2 partial pressure - pH is high eg lungs-alveoli Causes oxyhemoglobin curve to shift to the left
44
Oxyhaemoglobin dissociation curve shifting right
Hb has lower affinity for oxygen unloads more at the same partial pressures less saturated present in animals with faster metabolisms that need more oxygen for respiration e.g. birds/rodents
45
Closed circulatory system
Blood remains within blood vessels
46
Name different types of blood vessels
Arteries, arterioles, capillaries, venules and veins
47
Structure of arteries
Thick muscular layer compared to veins- smaller arteries control the flow of blood by constricting and dilating thick elastic layer compared to veins - important to maintain high pressure of blood by stretching and recoiling thick outer layer - resists the vessel bursting under pressure small lumen no valves except in the ones leaving the heart, due to constant high pressure
48
Capillary endothelium
Extremely thin one cell thick contains small gaps for small molecules to pass through (e.g. glucose, oxygen) Numerous as they’re highly branched providing larger SA for exchange Very narrow diameter and can permeate tissues and therefore no cell which is far from capillary
49
Capillaries
Form capillary beds narrow diameter (1 cell thick) to slow blood flow red blood cells squashed against walls shortens diffusion pathway small gaps for liquid / small molecules to be forced out
50
Arterioles
Branch off arteries Relatively thicker muscle layer(smooth endothelium) compared to arteries - contraction of this layer constricts the lumen and this restricts blood flow Helps control movement of blood into capillaries Thinner elastic layer and outer layer than arteries as pressure lower
51
Tissue fluid
Liquid bathing all cells contains water, glucose, amino acids, fatty acids, ions and oxygen enables delivery of useful molecules to cells and removal of waste
52
Tissue fluid formation
-At arterial end of capillary, high hydrostatic pressure due to pumping of heart and also the smaller diameter -Hydrostatic pressure is high inside capillaries than outside which causes small molecules forced out (ultrafiltration) through the small gaps in the capillary endothelium, red blood cells / large proteins too big to fit through capillary gaps so remain inside. -However the osmotic pressure or the water potential is lower inside capillary than outside causing fluid to move back in -But HP is stronger than osmotic pressure which means the combined effect causes the fluid to move out of capillary
53
Reabsorption of tissue fluid
Large molecules remaining in capillary lower its water potential towards venule end of capillary bed there is lower hydrostatic pressure due to loss of liquid water reabsorbed back into capillaries by osmosis down the water potential gradient Not all tissue fluid is reabsorbed by capillaries, the remaining unabsorbed ones are carried back via the lymphatic system which drains their contents back into bloodstream via ducts that joins veins to the heart.
54
Role of the lymph in tissue fluid reabsorption
Not all liquid will be reabsorbed by osmosis as equilibrium will be reached Excess tissue fluid (lymph) is absorbed into lymphatic system and drains back into bloodstream and deposited near heart
55
Cardiac muscle
Walls of heart having thick muscular layer unique because it is: myogenic - can contract and relax without nervous or hormonal stimulation never fatigues so long as adequate oxygen supply Coronary arteries present all through the cardiac muscle which provides oxygenated blood
56
Coronary arteries
Blood vessels supplying cardiac muscle with oxygenated blood branch off from aorta if blocked, cardiac muscle will not be able to respire, leading to myocardial infarction (heart attack)
57
Structure of heart
Labels: Aorta Right atrium and ventricle Left atrium and ventricle Superior vena cava Pulmonary artery and vein Tricuspid valve and mitral or bicuspid Aortic valve Inferior vena cava Pericardium Semilunar valve
58
Adaptation of left ventricle
Has a thick muscular wall in comparison to right ventricle enables larger contractions of muscle to create higher pressure ensures blood reaches all body cells
59
Veins connected to the heart(2)
Vena cava - carries deoxygenated blood from body to right atrium Pulmonary vein - carries oxygenated blood from lungs to left atrium
60
Arteries connected to the heart
Pulmonary artery - carries deoxygenated blood from right ventricle to lungs Aorta - carries oxygenated blood from left ventricle to rest of the body
61
Valves within the heart
Ensure unidirectional blood flow Semilunar valves are located in aorta and pulmonary artery near the ventricles Atrioventricular valves between atria and ventricles
62
Opening and closing of valves
Flaps made of fibrous, elastic but strong fibre which forms a cusp like shape If blood builds in the convex side it is allowed to pass across If blood collects in the concave side it’s collected and not let through and it passes in one direction Valves open if the pressure is higher behind them compared to in front of them. AV valves open when pressure in atria > pressure in ventricles SL valves open when pressure in ventricles > pressure in arteries
63
The Septum
Muscle that runs down the middle of the heart Separates oxygenated and deoxygenated blood Maintains high concentration of oxygen in oxygenated blood Maintaining concentration gradient to enable diffusion to respiring cells
64
Cardiac output
Volume of blood which leaves one ventricle in one minute. Cardiac output = heart rate * stroke volume heart rate = beats per minute Stroke volume - amount of blood in one contraction that is pumped from left ventricle of the heart
65
Stroke volume
Volume of blood that leaves the heart each beat measured in dm^3
66
Cardiac cycle
Consists of diastole, atrial systole and ventricular systole
67
Diastole
Atria and ventricular muscles are relaxed When blood enters atria via vena cava and pulmonary vein Increasing pressure in atria Atrioventricular valves open Blood flows into the ventricles and this is aided by gravity, relaxation of the ventricle walls causes them to recoil which reduces the pressure of ventricles below that of aorta and pulmonary artery causing semilunar valves to close This is accompanied by the characteristic dub sound of heart beat
68
Atrial systole
Contraction of the atrial walls along with the recoiling of the relaxed ventricle’s walls forces the remaining blood into ventricles from atria Throughout this stage ventricle relaxed.
69
Ventricular systole
After a short delay (so ventricles fill), ventricle walls contract simultaneously which increases the pressure in ventricle Pressure ventricle > atria causes atrioventricular valve to shut This increases the pressure further in ventricles When pressure in ventricles > pressure in pulmonary artery and aorta semilunar valves open and blood moves to those Left ventricle more thicker than right as left has to pump blood to the whole body including extremities so contraction of LV has higher pressure Right ventricle pumps blood to lungs
70
Transpiration
Loss of water vapour from stomata by evaporation affected by: light intensity temperature humidity wind can be measured in a lab using a potometer
71
How light intensity affects transpiration
As light intensity increases, rate of transpiration increases more light means more stomata open larger surface area for evaporation
72
How temperature affects transpiration
As temperature increases, rate of transpiration increases the more heat there is, the more kinetic energy molecules have faster moving molecules increases evaporation
73
How humidity affects transpiration
As humidity increases, transpiration decreases the more water vapour in the air, the greater the water potential outside the leaf reduces water potential gradient and evaporation
74
How wind affects transpiration
As wind increases, rate of transpiration increases the more air movement, the more humid areas are blown away maintains water potential gradient, increasing evaporation
75
Cohesion in plant transport
Because of the dipolar nature of water, hydrogen bonds can form - cohesion water can travel up xylem as a continuous column
76
Adhesion in plant transport
Water can stick to other molecules (xylem walls) by forming H-bonds helps hold water column up against gravity
77
Root pressure in plant transport
As water moves into roots by osmosis, the volume of liquid inside the root increases therefore the pressure inside the root increases this forces water upwards down the water potential gradient
78
Cohesion- tension theory
Water forms continuous, unbroken column across the mesophyll cells and xylem As water evaporates out the stomata or mesophyll cells due to heat from sun, this lowers water potential Causes water molecules to be pulled from behind i.e xylem due to this cohesion. Column of water is therefore pulled up xylem due to transpiration- transpirational pull Along with cohesion, water molecules also adhere to walls of xylem The transpirational pull creates tension in xylem pulling xylem inwards Negative pressure in xylem
79
Translocation
Occurs in phloem explained by mass flow hypothesis transport of organic substances through plant
80
Sieve tube elements
Living cells contain no nucleus few organelles this makes cell hollow allowing reduced resistance to flow of sugars
81
Companion cell
Provide ATP required for active transport of organic substances contains many mitochondria
82
Mass flow hypothesis
Organic substances, sucrose, move in solution from leaves (after photosynthesis) to respiring cells source -> sink direction
83
How is pressure generated for translocation
Photosynthesising cells produce glucose which diffuses into companion cell by facilitated diffusion Companion cells actively transports H+ ions into spaces within cell wall of companion cells The H+ ions move down the concentration gradient via co transport protein into seive tube elements as it also transports sucrose molecules along with it. This lowers water potential of phloem so water moves in from xylem via osmosis as xylem has higher water potential Hydrostatic pressure gradient generated
84
What happens to sucrose after translocation?
Used in respiration at the sink stored as insoluble starch
85
Investigating translocation
Can be investigated using tracer and ringing experiments proves phloem transports sugars not xylem
86
Tracing
Involves radioactively labelling carbon - used in photosynthesis create sugars with this carbon thin slices from stems are cut and placed on X-ray film which turns black when exposed to radioactive material stems will turn black as that is where phloem are
87
Ringing experiments
Ring of bark (and phloem) is peeled and removed off a trunk consequently, the trunk swells above the removed section analysis will show it contains sugar when phloem removed, sugar cannot be transported
88
How do small organisms exchange gases
Simple diffusion across their surface
89
Why don't small organisms need breathing systems
They have a large surface area to volume ratio no cells far from the surface
90
How alveoli structure relates to its function
Round shape & large number in - large surface area for gas exchange (diffusion) Lined with epithelium and epithelial cells are flat and very thin to minimise diffusion distance Capillary network maintains concentration gradient Contains collagen and elastic fibres between alveoli allows it to stretch and recoil during inspiration and exhalation
91
How fish gas exchange surface provides a short diffusion distance
Thin lamellae epithelium means short distance between water and blood capillary network in every lamella
92
How fish gas exchange surface maintains diffusion gradient
Counter-current flow mechanism - water and blood flows in opposite direction which means equilibrium is never reached Circulation replaces blood saturated with oxygen Ventilation replaces water with oxygen removed
93
Name of gas exchange system in terrestrial insects
Tracheal system
94
Describe structure of spiracles
Round, valve-like openings running along the length of the abdomen
95
Describe trachea & tracheoles structure
Network of internal tubes Have rings of cartilage adding strength and keeping them open Trachea branch into smaller tubes - tracheoles Tracheoles extend through all tissues delivering oxygen to insects
96
How tracheal system provides short diffusion distance
Tracheoles have thin walls so short diffusion distance to cells
97
How tracheal system maintains concentration gradient
Mass transport - muscle contraction squeezes trachea which enables mass movement of air in and out and this speeds up exchange. Use of oxygen in respiration and production of CO2 sets up steep concentration gradients
98
Amylase
Produced in pancreas & salivary gland hydrolyses starch into maltose
99
Membrane-bound disaccharidases
Maltase / sucrase / lactase hydrolyse disaccharides into monosaccharides
100
Enzymes involved in protein digestion
endopeptidases exopeptidases membrane-bound dipeptidases
101
Products of protein digestion
Large polymer proteins are hydrolysed to amino acids
102
Double circulatory system
Blood passes through heart twice pulmonary circuit delivers blood to/from lungs systemic circuit delivers blood to the rest of the body
103
Coronary arteries
Supply cardiac muscle with oxygenated blood for continued respiration and energy production for contraction
104
Blood vessels entering / exiting the kidney
Renal artery carries oxygenated blood to kidney Renal vein carries deoxygenated blood to heart
105
Blood vessels entering / exiting the lung
Pulmonary artery carries deoxygenated blood to lung pulmonary vein carries oxygenated blood to heart
106
Blood vessels entering / exiting the heart
Vena cava carries deoxygenated blood to heart (right atrium) aorta carries oxygenated blood to body pulmonary artery - carries blood from the heart to the lungs pulmonary vein - carries blood from the lungs into the heart
107
Describe then structure of veins
Thin muscular layer compared to arteries as they carry blood away from the body so constriction and dilation cannot control the flow of blood thin elastic layer - as low pressure it’s too low to create a recoil action thin walls- very low pressure so no risk of bursting valves - due to low pressure makes sure blood flows in one direction, prevents back flow.
108
Explain role of elastic layer in arteries
Thick elastic layer to help maintain blood pressure by stretching and recoiling
109
Describe the elastic layer in veins
Thin elastic layer as pressure lower cannot control the flow of blood
110
Explain the role of valves in veins
Due to low pressure in veins skeletal muscle usually used to flatten walls of veins for blood flow valves prevent the backflow of blood unidirectional flow
111
What causes the AV valves to open
Higher pressure in the atria than in the ventricles
112
What causes the semi-lunar valves to open
Higher pressure in the ventricles than in the arteries
113
Tell me about the lymphatic system
System of vessels that begin in the tissues Carry lymph which are the excess fluid which wasn’t reabsorbed by capillaries as equilibrium reached Initially they resemble capillaries except they have a dead ends Gradually merges into lager vessels that forms a network around the body These vessels drain their content back into the bloodstream via ducts that joins veins to the heart