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Biology > Organisms Exchange Subtances With Their Environment > Flashcards

Organisms Exchange Subtances With Their Environment Flashcards

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1
Q

What affects substances diffusion between organism and surroundings

A

Size and metabolic rate

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2
Q

What types of exchange are there, and which exchange does not use these

A

Passive by diffusion, osmosis
Active by active transport
Except heat

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3
Q

How is exchange effective regarding surface area and volume

A

Large surface area to volume ratio

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4
Q

How do you find the area of a cell

A

Pi x r^2

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5
Q

How do you find he volume of a sphere

A

4/3 Pi x r^3

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6
Q

What happens to surface area volume ratio as volume increases

A

Decreases

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7
Q

What features have large active organisms got as they cannot rely on simple diffusion (would take too long)

A

Flattened shape so no cell ever far from surface

Specialised exchange surfaces, large areas increase surface area:volume ratio

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8
Q

What is around cells of multicellular organisms

A

Tissue fluid, mass transport system distributes materials to tissue fluid, return waste product to exchange surface, removed

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9
Q

What is Ficks law

A

Rate diffusion (dependent on) SA x concentration difference/distance

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10
Q

What are the specialised exchange surface features

A

Large SA:Volume
Very thin (short diffusion pathway)
Selectively permeable
Movement of environmental medium (maintain steep concentration gradient)
Movement of internal medium using transport systems (maintain steep concentration gradient)

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11
Q

Why are thin, specialised exchange surfaces inside the organism

A

Easily damaged, dehydrated

Need to move external medium over surface e.g ventilating lungs

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12
Q

What SA:V would could slow heat loss

A

Small SA:V

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13
Q

What practical was used to test the rate of penetration / diffusion

A

Cresol red gelatine cubes
Different block sizes, timing how long lol dilute hydrochloric acid to penetrate and dissolve the cubes
Smaller cube, faster rate of penetration - acid penetrating cube by diffusion

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14
Q

What is the benefit of single-celled organisms

A

Large SA:V, quick gas exchange through cell

Oxygen absorbed by diffusion across their body surfaces, only covered by cell surface membrane

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15
Q

What does terrestrial mean

A

Lives on land

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16
Q

How is water loss reduced

A

Waterproof covering over whole body surface

Small SA:V minimise water loss

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17
Q

How do insects control gas exchange

A

Spiracles, openings in tracheae, can close to reduce water loss, need oxygen so usually closed when at rest

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18
Q

What prevents the insects internal network of tubes (tracheae) from collapsing

A

Supported by rings of chitin

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18
Q

How does atmospheric air get water to respiring tissues

A

Tracheae divide into tracheoles, extend through all body tissues of insect. Air with oxygen brought directly to respiring issue

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19
Q

How do gases leave/enter insect

A

Through spiracles

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20
Q

How do gases move in/out of the tracheal system

A

Along diffusion gradient
Mass transport
Ends of tracheoles filled with water

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21
Q

How do gases move along the diffusion gradient in the tracheal system

A

Respiring cells cause oxygen concentration in spiracle ends fall, diffusion gradient for oxygen to diffuse all,b tracheae, tracheoles to cells
Respiring cells make CO2, concentration gradient in opposite direction
Air direction more rapid than water, respiratory gases exchanged quickly

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22
Q

How do gases move my mass transport in the tracheal system

A

Contraction of muscles in insects can squeeze trachea enabling mass movement of air in/out (ventilation) further speeds respiratory gas exchange

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23
Q

What happens to water when an insect is resting

A

Water diffuses out of cells into tracheole ends, oxygen ,use diffuse through water to reach cells, slow process

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24
Q

What happens during vigorous exercise

A

Muscles anaerobically respire, make lactate. Is soluble so lowers water potential of muscle cells, water drawn into muscle cells from tracheae - osmosis
Tracheae water volume decrease reducing cells diffusion pathway
Air gas exchange quicker, more efficient

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25
Q

What is the limitation of the tracheal system

A

For effective diffusion, pathway. Just be short, limits insect size

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26
Q

What is the covering like on fish and the SA:V

A

Waterproof, gas tight covering

Small SA:V

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27
Q

What are the specialised internal gas exchange surfaces in fish

A

Gills

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28
Q

What are fills made of, how does it effect gas exchange and where are they

A

Thousands of filaments, covered in feathery lamellae each only few cells thick containing capillaries
Ensures large surface area and short diffusion pathway
Behind head

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29
Q

What are the gulls covered by

A

Muscular flaps - operculum

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30
Q

How does water go through fish and how does it effect concentration of oxygen and carbon dioxide

A

Water in through mouth, forced over gills, out through opening on both sides of body
Flow through filaments, lamellae, oxygen can diffuse down concentration gradient between blood and water
Carbon dioxide diffuses in opposite direction, down concentration

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31
Q

How does the placing of lamellar on filaments effect surface area

A

At right angles to filaments, increase fills surface area

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32
Q

How does the epithelium effect diffusion

A

Is thin, reduce diffusion distance between blood and water

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33
Q

What is the countercurrent exchange principle

A

Blood flows towards front of fish in gill lamellae, water flows towards back
Always higher oxygen concentration in water than blood
Oxygen diffuses across whole lamellae length, steep diffusion gradient kept across whole
80% dissolved oxygen extracted
Equilibrium between oxygen concentration of water and blood never reached

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34
Q

How is the gas exchange system useful in leafs

A

Many plants photosynthesis (and respire), gases made in one process can be used for the other

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35
Q

How does the volume and types of gases exchanged vary

A

Depends on balance between rates of photosynthesis and respiration

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36
Q

What process occurs all the time

A

Respiration

Photosynthesis can’t at night as no light

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37
Q

How is a plant leaf adapted to function

A

Many stomata on lower epidermis, allow gas diffusion in/out, no cells far from stomata, short diffusion pathway
Mesophyll cells have large SA for rapid diffusion
Main gas exchange surface - spongy mesophyll cells in leaf, loosely packed many interconnecting air spaces throughout do gases readily come into contact with them

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38
Q

How are plant cells in the leaf adapted to function

A

Spongy mesophyll layer crate large surface area for diffusion
Upper epidermis - transparent, sun,Igbo reach chloroplasts
Chloroplasts in palisade mesophyll can move near surface, maximise light absorption
Palisade cells packed tightly together for mass light absorption
Waxy cuticle, guard cell reduce water loss

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39
Q

What is the photosynthesis equation

A

Carbon dioxide + water -> glucose + oxygen

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40
Q

What is the respiration equation

A

Glucose + oxygen -> carbon dioxide + water

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41
Q

What and where are stomata and what do they do

A

Minute pores, occur on leaves, especially underside
Each surrounded by pair of guard cells
Open/ lis control rate gas exchange and water loss

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42
Q

What causes stomata to open

A

When potassium ions actively transported into guard cells, lower water potential of surrounding cells
Water moves in - osmosis
Guard cells become turgid, stomata open

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43
Q

What causes stomata to close

A

When potassium ions actively transported out guard cells, lower water potential of surrounding cells
Water moves out by osmosis (down concentration gradient)
Cells become flaccid, stomata closes

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44
Q

What is the human gas exchange system structure like

A

All aerobic organisms require constant oxygen supply release energy - ATP during respiration, CO2 made in process needs to be removed as built up could be harmful to body
Oxygen volume that needs to be absorbed, volume CO2 must be removed in large mammals

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45
Q

Why must CO2 be removed in large mammals

A

Relatively large organisms wi h large volume of living cells

Maintain high body temperature, related to them having high metabolic and respiratory rates

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46
Q

Why are lungs inside

A

Air not dense enough support, protect delicate structures

Body would lose lots water, dry out

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47
Q

How are the lungs supported/protected

A

Bony box - rib cage

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48
Q

What protected the alveolus from da,axe as mucus made by goblet cells

A

Cells lining trachea and bronchus

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49
Q

How is the mucus moved to be swallowed

A

Ciliated epithelium cells have tiny hairs that waft mucus, swallowed

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50
Q

What are the bronchi, how are they supported

A

Two divisions of trachea, lead to one lung structure to trachea
Larger bronchi supported by cartilage but amount reduces as get smaller
Have ciliated epithelium and goblet cells

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51
Q

Where are the external intercostal muscles

A

Outside rob age

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52
Q

Where are the internal intercostal muscles

A

Inside ribcage

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53
Q

What are trachea, how are they supported and what are they made of

A

Flexible airways supported by cartilage rings, stop it collapsing
Tracheal walls ,are of muscle lined with ciliated epithelium and goblet cells

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54
Q

What are bronchioles and what are they made of

A

Series of branching subdivisions of bronchi
Walls are muscle lined with epithelial cells
Allows them to contract controlling air flow in/out alveoli

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55
Q

What do goblet cells produced and why is this useful

A

Make mucus to trap dirt particles and bacteria, cilia move mucus up throat passes down oesophagus to stomach, swallowed

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56
Q

What are alveoli, what is their function and how is this useful

A

Minute air sacs found at ends of bronchioles
Contain collagen and elastic fibres lined with epithelium elastic fibres, can stretch when filled with air, spring back (recoil) to empty
Gas exchange occurs at alveoli surface

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57
Q

What is the rib cages function and how does it move

A

Protect lungs, moved by intercostal muscles between them

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58
Q

What is the diaphragm

A

Muscle sheet, separates thorax and abdomen

Relaxes and contracts

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59
Q

What are the lungs

A

Loved structures specialised for gas exchange

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60
Q

What is the pulmonary ventilation equation

A

Pulmonary ventilation=tidal volumexbreathing rate

dm^3min^-1 dm^3 min^-1

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61
Q

What occurs in inspiration

A

External intercostal muscles and diaphragm muscles contract
Rib cage moves upwards and outwards, diaphragm flattens
Volume of thorax increase
Lung pressure decrease (below atmospheric pressure) air flows into lungs
Active process - needs energy

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62
Q

What occurs in expiration

A

Internal intercostal muscles contract only up during strenuous activity and external intercostal muscles and diaphragm muscles relax
Rib cage moves downwards and inwards, diaphragm becomes curved again (pushed up by abdomen contents)
Volume of thorax decrease
Lung pressure increase (above atmospheric pressure) air forced out lungs
Passive process

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63
Q

Why is residual air needed

A

Remains in lungs to stop alveolus sticking together

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64
Q

What is pulmonary ventilation

A

Total volume air loved into lungs in one minute

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65
Q

What is tidal volume

A

Volume of air moved into lungs in one breath (changes in strenuous activity)

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66
Q

What is ventilation

A

Breathing rate - number breathes taken in one minute

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67
Q

How does oxygen get to blood

A

Passes through sing,e layer alveoli epithelium, the. Single layer of endothelical cells of blood capillaries

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68
Q

What is diffusion

A

Particles in fluid move from high concentration to low, till evenly distributed

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69
Q

How is material efficiently transferred by diffusion/active transport

A

Large SA:V speed rate of exchange
Partially permeable allow selected materials easily diffuse
Movement of internal medium
Movement of environmental medium
Thin for short diffusion pathways, cross rapidly

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70
Q

What is the role of alveoli in gas exchange

A

Each alveolus has network of capillaries, so narrow red blood cells flattened against thin capillary wall to fit through
Walls of capillary single cell thick

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71
Q

How are body cells adapted for short diffusion pathway

A

Distance between alveolar air and red blood cells reduced as red blood cells flattened
Walls of both alveoli and capillaries very thin, short diffusion distance

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72
Q

How are body cells adapted for steel concentration gradient

A

Breathing movements always ventilate lungs, action of heart always circulates blood round alveoli ensure steep concentration gradient from gas exchange
Blood flow through pulmonary capillaries maintains concentration gradient

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73
Q

How are body cells adapted for large SA:V

A

Alveoli and pulmonary capillaries have very large total surface area

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74
Q

How is diffusion time increases

A

Red blood cells slowed as pass through pulmonary capillaries

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75
Q

What are correlations and casual relationships

A

Sometimes cannot know fro, data if the thing is a cause, ,au suggest but with no real evidence. Needs clear casual connection, as could be a different factor causing it. So experimental evidence to show distinct correlation

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76
Q

What are the risk factors offer lung disease, the chromic obstructive pulmonary disease

A

Smoking, 90% people suffering COPD are/were heavy smokers
Air pollution, pollutant particles, gases e.g So2, especially in heavy industry areas
Genetic makeup, some genetically more likely to, why non smokers get lung disease
Infections, frequently get chest infections, build up scar tissue, higher COPD
Occupation, harmful chemicals, gases, dusts inhaled increase risk

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77
Q

What lung diseases are there

A

Pulmonary fibrosis
Asthma
Emphysema

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78
Q

Why does pulmonary fibrosis arise

A

When scars on epithelium form, so irreversibly thickened, reduce lungs elasticity

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79
Q

What are the symptoms of pulmonary fibrosis

A

Shortness of breath, especially when exercising, due to considerable air space in lungs occupied by fibrous tissue - less air in lungs in each breath (affects concentration gradient)
Chronic dry cough, pain/discomfort to chest, weakness/fatigued to reduce respiration

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80
Q

How does pulmonary fibrosis effects rate of diffusion

A

Scar tissue increases diffusion pathway

Less air in lungs in each breath affects concentration gradient

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81
Q

How is asthma caused

A

By one/more allergens, white blood cells of bronchi/bronchioles release chemical - histomine
Lining of airways inflamed epithelial cells of airway make mucus
Muscles round bronchioles contract, constrict airway

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82
Q

What are the symptoms of asthma

A

Difficulty breathing, wheezing, tight feeling in chest, coughing

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83
Q

How does asthma effect rate of diffusion

A

Narrow airways reduce efficient ventilation, reduces concentration gradient
Mucus reduces bronchioles surface area, less oxygen diffusing into cell

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84
Q

How is emphysema caused

A

By smoking, 1 in 5 smokers
Disease develops over 20 years is irreversible
Alveoli contain lots elastic tissue containing protein - elastin
Tissue stretches alveoli when breathe in, recoils when breathe out, permanently stretched can’t recoil

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85
Q

What are the symptoms of emphysema

A

Shortness of breath (reduces surface area and decreases ventilation)
Chronic cough
Bluish skin colouration - oxygen lack

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86
Q

How does emphysema affect rate of diffusion

A

Reduced expel CO2, affects concentration gradient, less air in/out
Alveoli walls destroyed, surface area reduced

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87
Q

Where are the salivary glands and what do they do

A

Near mouth, pass secretion via duct into mouth

Secretions contain amylase to hydrolyse starch to maltose

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88
Q

How does the oesophagus carry food from the mouth to stomach

A

Peristalsis

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89
Q

What is the pancreas and what does it do

A

Large gland below stomach

Produces secretion - pancreatic juice

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90
Q

What does the pancreatic juice contain

A

Proteases to hydrolyse proteins
Lipases to hydrolyse lipids
Amylase to hydrolyse starch

91
Q

What else other than pancreatic juice does the pancreas make

A

Insulin

92
Q

What is the stomach and what does it do

A

Muscular sac with inner layer that makes enzymes
Stores and digests food especially protein
Glands make protease to digest protein

93
Q

What does the large intestine do

A

Absorb water

Most secretions of many digestive glands

94
Q

What does the small intestine (ileum) and what does it do

A

Long muscular tube

Further food digested by enzymes made in its walls and glands

95
Q

How is the ileum adapted for absorption and digestion into the bloodstream

A

Inner ileum walls folded into villi, large surface area, increased by microvilli, on epithelial cells of each villus

96
Q

What does the rectum do

A

Final section of intestines

Faeces stored and removed via anus - egestion

97
Q

What is physical digestion and how is it beneficial

A

Large food broken to small pieces by structures e.g teeth

Provides large surface area for chemical digestion, helps ingest food, also churned by muscles in stomach wall

98
Q

What is chemical digestion

A

Hydrolysis large insoluble molecules into small soluble ones, carried out by enzymes
All digestive enzymes function by hydrolysis

99
Q

What is carbohydrases for

A

Hydrolyse carbohydrates ultimately to monosaccharides

100
Q

What are lipases for

A

Hydrolyse lipids into glycerol and fatty acids

101
Q

What are proteases for

A

Hydrolyse proteins ultimately into amino acids

102
Q

How are carbohydrates digested

A
  1. Physical digestion, salivary amylase hydrolysis starch to maltose, mineral salts for neutral pH - amylase optimum
  2. Swallowed, acidic stomach denatures amylase stop hydrolysing
  3. Small intestine - pancreatic juice has pancreatic amylase hydrolysis remaining starch, alkaline salts maintain neutral pH
  4. Ileum wall muscles push food along. Epithelial lining makes maltase, hydrolysis maltose into alpha glucose
103
Q

What produces alkaline salts in the carbohydrate digestion system and why

A

Saliva in mouth has mineral salts and pancreas intestinal wall make alkaline salts to maintain neutral pH for amylase to function

104
Q

What happens in lactase hydrolysis and what’s made

A

Hydrolyses single glycosidic bond in lactose

Makes alpha glucose and galactose

105
Q

What happens in sucrase hydrolysis and what’s made

A

Hydrolyses single glycosidic bond in sucrose

Makes alpha glucose and fructose

106
Q

Where are sucrose and lactose found

A

Wall of small intestine

107
Q

What digests proteins

A

Peptidases

108
Q

What do endopeptidases do

A

Hydrolyse bonds between amino acids in central region of protein, form series peptide molecules

109
Q

What do exopeptidase do

A

Hydrolyse peptide bonds on ends of smaller polypeptide chains made by endopeptidases
Progressively release dipeptides, single amino acids

110
Q

What do dipeptidases do

A

Hydrolyses bond between two amino acids in central region of protein, make series of peptide molecules

111
Q

How are lipids digested and what is formed

A

Lipids hydrolysed by lipases (made in pancreas) hydrolyses ester bond in triglycerides to make fatty acids and monoglycerides

112
Q

What is a monoglyceride

A

Glycerol with single fatty acid

113
Q

How are lipids first spilt into tiny droplets (what are these called) and how does this affect lipases speed

A

Tiny droplets - micelles by bile salts made in liver

Is an emulsification, increases lipids surface area so action of lipases speed up

114
Q

How are lipids digested in small intestine

A
  1. Bile salts in liver released into small intestine from gall bladder, break lipids to small droplets - emulsification (increases SA for enzymes)
  2. Lipases digest lipids to fatty acids and monoglycerides, these remain stuck with bile salts - micelles
  3. Micelles contact with epithelial cells of small intestine, break down release fatty acid and monoglycerides (non polar) fat soluble, diffuse through phosoplipid bilayer of epithelial cells, travel to endoplasmic reticulum
  4. Go to Golgi body, triglycerides join with cholesterol and lipoproteins - chylomicrons, released from epithelial cells by exocytosis, pass into capillaries of lymphatic system - lacteals into blood
  5. Here triglycerides in chylomicrons hydrolysed by enzyme in endothelial cells of blood capillaries
  6. Release fatty acids and monoglycerides, diffuse out capillaries into cells, used
115
Q

Where are bile salts made and where are the release into and from

A

Made in liver

Released into small intestine from gall bladder

116
Q

What do bile salts do to lipids

A

Break lipids up into small droplets - emulsification

Increases surface area for enzymes

117
Q

What are micelles

A

Monoglycerides and fatty acids stuck to bile salts

118
Q

Why can monoglycerides and fatty acids diffuse through phosoplipid membrane

A

They’re non polar, fat soluble

119
Q

What are chylomicrons and how are they release from epithelial cells

A

Triglycerides combined with cholesterol and lipoproteins

Released from epithelial cells by exocytosis

120
Q

What happens to chylomicrons when they pass through lymphatic system

A

Triglycerides in chylomicrons hydrolysed by enzyme on endothelial cells of blood capillaries
Fatty acids and monoglycerides diffuse into cells

121
Q

How is the ileum adapted for absorption

A

Small intestine wall folded, has finger-like projections - villi
Epithelial cells have microvilli on other side blood capillary network
Villi increase surface area, accelerate absorption

122
Q

Where are the villi

A

Interface between lumen of intestines

123
Q

How is a concentration gradient created for blood diffusion

A

Usually make products of digestion in small intestine than blood
Blood always circulated so product of digestion removed
Villi contain muscles, contract and relax, mixing contents of small intestine

124
Q

Where is active transport in absorption

A

Co-transport, facilitated diffusion,

125
Q

How do the villi affect ficks law

A

Thin walled - thin diffusion pathway
Regularly contract, relax mix contents of small intestine - concentration gradient
Wall covered in folded villi and microvilli - large surface area
Good blood supply - concentration gradient

126
Q

Why are there usually more products of digestion in the small intestine than blood

A

Proteins and carbohydrates always digested, usually more products of digestion in small intestine

127
Q

How does the amount of products being higher in the small intestine than blood affect where the products of digestion diffuse

A

Creates a concentration gradient for products of digestion to diffuse into the blood

128
Q

How is the concentration gradient between blood and small intestine kept

A

Blood always circulated so products of digestion removed

129
Q

How is the contents of the villi mixed, what effect does this have

A

Villi contain muscles, contract, relax so mix contents of small intestine so maintain concentration gradient

130
Q

Why is not all available glucose absorbed

A

May pass out of body

131
Q

Why do glucose and amino acids need to be transported

A

Or concentrations either side of the intestinal epithelium equal

132
Q

How are sodium and glucose molecules moved into cell

A

Sodium - down concentration gradient
Glucose - against concentration gradient
Sodium powers glucose movement into cells rather than ATP
Indirect active transport (co-transport)

133
Q

How is sodium removed from the cell

A

Through sodium potassium pump - active transport
Low concentration in cell, moves jerk blood capillary
Potassium ions move into cell

134
Q

How is glucose moved out of the cell

A

Moved into a blood capillary by facilitated diffusion

135
Q

How are villi adapted to Ficks law

A

Thin walled - short diffusion distance
Micro-villi - increase SA
Regularly contract mixing contents- concentration gradient
Well supplied blood vessels - concentration gradient

136
Q

How do transport systems affect diffusion

A

Create larger organisms smaller surface area:volume

Longer distance for diffusion, not as rapid

137
Q

What does blood transport

A

Oxygen, carbon dioxide, hormones, idea, glucose, amino acids

138
Q

What is blood made up of

A

55% plasma

45% red blood cells, platelets and white blood cells

139
Q

What is plasma

A

Straw coloured liquid, carries hormones, nutrients, urea, (heat)

140
Q

What do red blood cells art

A

Carry oxygen and carbon dioxide

141
Q

What is another word for red blood cells

A

Erythrocytes

142
Q

What do platelets do and carry

A

Form scabs

Carry carbon dioxide

143
Q

What are white blood cells for

A

Immunity

144
Q

How are RBC SA:V adapted for function

A

Large SA:V lots of oxygen can diffuse at fast rate through outer surface to cell centre

145
Q

How is RBC size adapted for function

A

Small in diameter and relatively thick, can fit through capillaries one at a timme

146
Q

How does RBS shape adapted for function

A

Biconcave discs increases surface compared to inside volume even more

147
Q

How is the adaption of RBC having no nucleus benefit

A

Before RBC leaves bone marrow (where made) and enters blood, nucleus breaks down so more room for haemoglobin

148
Q

How is oxyhaemoglobin formed and where

A

In lungs 0: oxygen + haemoglobin -> oxyhaemoglobin

149
Q

How does oxyhaemoglobin break down and where

A

Tissues: oxyhaemoglobin -> oxygen + haemoglobin

150
Q

What structure do haemoglobin have and how does effect (un)/loading of oxygen

A

Quaternary structure, evolved to make loading and unloading of oxygen efficient

151
Q

What is the quaternary structure of haemoglobin

A

All 4 polypeptides are linked to form almost spherical molecule polypeptide is associated with haeme group containing Fe^2+ ion

152
Q

What are the subunits in haemoglobin

A

2 alpha and 2 beta

153
Q

What does each subunit contain

A

A haeme group (inorganic prosthetic iron group)

154
Q

How does oxygen combine with a haemoglobin molecule

A

Binds to the iron in subunit

Can carry 4 oxygen molecules

155
Q

What must haemoglobin be to be efficient at transporting oxygen

A

Readily associate with oxygen where loading occurs - lungs

Readily dissociate where unloading occurs - tissues

156
Q

Why is the pO2 low at the start of the oxygen dissociation curve

A

Low pO2 of Hb saturation is low

pO2 increase there is an in increase in in oxygen saturation, slow at first

157
Q

When does oxygen associate with Hb easier

A

When oxygen concentration high, higher saturation percentage

158
Q

When does oxygen dissociate from Hb

A

When Hb low concentration so lower percentage saturation

159
Q

Why does oxygen unload in tissues

A

Lower pO2 so Hb gives up some oxygen- unloads

160
Q

Why is it difficult to load oxygen at start of oxygen dissociation curve

A

At very low oxygen concentration, 4 polypeptide chains of Hb molecule closely united so difficult to absorb first oxygen molecule

161
Q

Why does the oxygen dissociation curve increase rapidly after one oxygen molecule has combined to the Hb

A

Causes polypeptides to load remaining 3 oxygen molecules easily as first one changes quaternary structure to make it easier for oxygen to bind. Smaller increase in pO2 needed to bind second oxygen molecule - positive co-operativity, so steeper gradient

162
Q

Why does the oxygen dissociation curve plateau at the end

A

High pO2 as Hb saturated with oxygen. After binding third oxygen molecule, while easier to bind to fourth, most binding sites occupied so less likely to get empty space

163
Q

What is partial pressure of oxygen (pO2)

A

Amount of gas present in mixture measured by pressure it contributes to total pressure of gas mixture
Measured in kilopascal (kPa)

164
Q

How does the environment affect haemoglobin in different organisms

A

In low oxygen areas, oxygen dissociation curve shifted to left
Hb can become fully saturated even at low pO2 of oxygen
Only effective if organism has low metabolic rate

165
Q

How does the size effect haemoglobin in different organisms

A

Small organisms have large SA:V, lose heat rapidly, keep constant body temperature, high respiration rate, need lots oxygen so readily unloaded at higher pO2, shifts right

166
Q

How does activity affect haemoglobin in different organisms

A

Active organisms have high respiration rates, oxygen unloaded readily in respiring tissues. Curve shifts right

167
Q

How does carbon dioxide affect haemoglobin in different organisms

A

Higher concentrations, Hb bind more loosely so Hb releases oxygen, CO2 acidic and low pH causes Hb to change shape

168
Q

What is the Bohr effect

A

Carbon dioxide and water form carbonic acid which dissociates to give hydrogen ions. Decrease pH (more acidic) hydrogen ions bind with Hb, causes a decrease in oxygen affinity.

169
Q

Why does Hb have a reduced affinity for oxygen when carbon dioxide is present

A

Greater the carbon dioxide the more readily oxygen dissociates

170
Q

Why is oxygen affinity high at gas exchange surface, why does this cause the oxygen-dissociation curve shifted to the left.

A

At gas exchange surface (lungs) CO2 is low, diffuses across exchange surface, expelled. Oxygen affinity of Hb is high, coupled with high concentration of oxygen in lungs, oxygen readily loaded by Hb.

171
Q

Why is oxygen readily unloaded in respiring tissues, and why does this cause the oxygen-dissociation curve to shift to the right

A

In rapidly respiring tissue (muscles) level of CO2 is high, affinity of Hb for oxygen is less, low concentration of oxygen in muscles, readily unload

172
Q

How is a high pH achieved at the lungs and why is this good

A

CO2 constantly removed, pH raised due to low amount. Higher pH changes Hb shape so oxygen is more readily loaded, increases affinity of Hb for oxygen

173
Q

Why does CO2 lower the pH

A

Is acidic in solution, so pH of blood in tissues lowered, changes Hb shape to one with lower oxygen affinity, unloads

174
Q

How do single celled organisms exchange materials between them and environment

A

Over body surface

175
Q

WHy can’t larger organisms exchange materials between them and the environment over their body surface

A

Increase of size, surface area:volume decreases, need of organism can’t be met by only body surface

176
Q

What are specialist exchange surfaces needed for

A

to absorb nutrients and respiration gases, removes excretory products

177
Q

What makes the transport system more essential for larger organisms

A

As organisms evolved to larger, more complex structures, tissues and organs that they’re made of become more specialised and dependent of each other

178
Q

What causes organisms transport systems to need a pump

A

Lower SA:V, and more active organism is, greater need for specialised transport

179
Q

What medium is used to carry materials

A

Normally liquid based on water, as readily dissolves substances, easily moved, can be a gas

180
Q

How does transport medium reach all parts of organism

A

Closed system of tubular vessels that contain the transport medium and form branched network to distribute to all part of organism

181
Q

What mechanism causes medium in vessels to be moved

A

Pressure difference between one part of the system and another.
Muscular contraction for animals/specialised pumping of organ (heartPlants rely on passive physical process - evaporation of water

182
Q

What mechanism maintains mass flow movement in one direction

A

Valves

183
Q

What is the double circulatory system in mammals

A

closed, double circulatory system

184
Q

What is the double sirculatory system

A

blood confined to vessels, pass through heart, when blood passed through lungs, pressure reduced. If past to rest of body straight away, low pressure would make circulation slow
blood returns to heart to boost pressure before circulated to rest of tissues

185
Q

Why must blood be pumped round to rest of the heart quickly in mammals

A

High body temperature, so high heart rate of metabolism

186
Q

What are the vessels that make up the circulatory system of a mammal

A

Arteries
Veins
Capillaries

187
Q

What system is used to transport substances longer distances. What is the final part of the journey into the cell

A

Transport system

Final part of he journey into the cells is by diffusion

188
Q

Why is the exchange from blood vessels to cells rapid

A

Takes place over a large surface area, across short distances and there is a steep diffusion gradient

189
Q

What is the function of the arteries

A

Transport blood rapidly under high pressure away from heart, into arterioles

190
Q

What is the function of the arterioles

A

Smaller arteries that control blood flow (through their muscle layer) from arteries to capillaries

191
Q

What is the function of the capillaries

A

Tiny blood vessels that link arterioles and veins, exchange metabolic materials e.g oxygen

192
Q

What is the function of veins

A

Carry blood slowly from capillaries to heart under low blood pressure

193
Q

What are the layers (from outside inwards) of arteries, arterioles and veins

A 
Tough outer layer 
Muscle layer 
Elastic layer 
Thin inner lining (endothelium)
Lumen
194
Q

What is the tough outer layer for

A

Resists pressure changes from in and out

195
Q

What is the muscle layer for

A

Can contract, control blood flow (especially important for arterioles)

196
Q

What is the elastic layer for

A

Helps maintain blood pressure by stretching/springing back (recoiling)

197
Q

What is the lumen for

A

Central cavity through which blood flows

198
Q

What causes valves to close, preventing blood backflow

A

Blood flowing away from heart pushes valves closed, so blood is prevented from flowing further in direction

199
Q

Which blood vessel has the thickest muscular layer

A

Arterioles

200
Q

Which blood vessel has the thickest elastic layer

A

Arteries

201
Q

Why do the arteries have relatively thick muscular layer (compared to veins)

A

Means smaller arteries can be constricted and dilated in order to control volume blood passing through

202
Q

Why do arteries have a thick elastic layer (compared to veins)

A

Important for blood pressure in arteries kept high if to reach extremities of body
Elastic wall is stretched at each beat of the heart

203
Q

Why is the overall thickness large in arteries

A

Resists vessel bursting under pressure

204
Q

Why do arteries have no valves (except leaving the heart)

A

Blood under constant high pressure due to heart pumping blood into the arteries, doesn’t flow backwards

205
Q

Why is the arterioles muscle layer relatively thicker than arteries

A

Contraction of muscle layer allows constriction of lumen of arterioles. Restricts blood flow, controls movement into capillaries into capillaries that supply tissues with blood

206
Q

Why do arteries have relatively thinner elastic layer

A

Lower blood pressure

207
Q

Why do veins have a thin muscle layer (compared to arteries)

A

Veins carry blood away from tissues, constriction and dilation can’t control flow into tissues

208
Q

Why do veins have a thin elastic layer

A

Low blood pressure in veins, won’t cause them to burst, pressure too low to create recoil

209
Q

Why is the overall thickness of veins small

A

Don’t need to be thick as pressure in veins too low to create risk of bursting. Can be flattened easily,aiding blood flow

210
Q

Why do veins have valves throughout

A

Ensure blood doesn’t flow back, which could otherwise as low pressure when body muscles contract, veins compressed, pressure blood in.
Ensure pressure directs blood only to heart

211
Q

Why is there a slow blood flow in capillaries

A

Gives time for materials to diffuse

212
Q

What is the final journey of metabolic substances

A

Metabolic substances made in liquid solution that bathes tissues - tissue fluid

213
Q

What is the important exchange surface in capillaries

A

Capillary bed

214
Q

How are capillary walls adapted to short diffusion distance

A

Is endothelium lining (one cell thick) so extremely thin, short diffusion distance, rapid diffusion between blood and cells

215
Q

How do capillaries provide large surface area

A

Highly branched

216
Q

Why is no cell far from capillaries

A

Narrow diameter so can permeate tissues

217
Q

What causes red blood cells to be squeezed flat

A

Narrow lumen so red blood cells are squeezed flat against capillary side, closer to cells to which they supply oxygen, reduces distances, slows flow

218
Q

What does the reduces diffusion distances and slow blood flow cause

A

Increases diffusion time

219
Q

How do white blood cells escape from capillaries and why

A

Through spaces in endothelial lining cells

Deal with infections in tissues

220
Q

What substances does tissue fluid carry

A

Watery liquid containing glucose, amino acids, fatty acids, salts, oxygen

221
Q

What substances does tissue fluid recieve

A

Carbon dioxide, waste materials from tissues

222
Q

What does the tissue fluid do

A

Bathes cells of body, exchanges materials between blood and cells

223
Q

What is tissue fluid formed by

A

Blood plasma, controlled by homeostatic mechanisms, providing a constant environment to cells near

224
Q

What is the formation of tissue fluid

A

Blood gradually moves, narrowing vessels to capillaries, pressure forms - hydrostatic pressure

225
Q

How is tissue fluid removed from blood plasma

A

Pressure found at arterial end of capillaries, forces tissue fluid out of blood plasma into tissues

226
Q

What is ultrafiltration

A

Capillaries hydrostatic pressure is only enough to force small molecules out (cells and proteins remain in blood)
Filtration under pressure

Biology (4 decks)

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