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Biology > Unit 1: Exchange and Transport > Flashcards

Unit 1: Exchange and Transport Flashcards

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1
Q

How to increase rates of diffusion?

A

Thin cell wall=short diffusion distance
Large Surface area= increased rate of diffusion
Good blood supply= substances quickly removed, maintains steep diffusion gradient

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2
Q

Roles of cartilage?

A

Cartilage=supports trachea, prevents airway from collapsing in low pressure+doesn’t go all the way round to allow flexibility

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3
Q

What is Ventilation rate?

A

volume of air breathed per minute

Calculated as tidal volume x breathing rate

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4
Q

Define Tidal volume?

A

Volume of air you breathe in or out during one breath

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5
Q

Define breathing rate?

A

number of breaths per minute

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6
Q

Define vital capacity?

A

total volume of air that can be expired (exhaled) after a max. inhilation

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7
Q

How does a Spirometer work?

A

Spirometer= a chamber filled with medical grade oxygen that floats on a tank of water

Attached is a disposable mouthpiece connected to the chamber which the person breathes in/out of.

Inhilation removes Oxygen from chamber so chamber sinks down

Exhilation pushes air into chamber so chamber floats up

Movement of chamber recorded by datalogger which plots trace on a graph

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8
Q

Define Inspiritory and Expiritory reserve volume?

A

Inspiritory= the extra air breathed in on top of the tidal volume

Expiritory= the extra air breathed out after a normal breath

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9
Q

What is the Pleural membrane?

A

Membranes surrounding the lungs and lining the thoracic cavity-contain a fluid that reduces friction

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10
Q

Define squamous epithelium cells?

A

The type of epithelium making up the walls of the alveolus

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11
Q

What happens in the diastole phase of the cardiac cycle?

A

=Filling phase

  • relaxed atria and ventricles
  • Semi-lunar valves closed
  • Atrio-ventricular valves open so blood from vena cava and pulmonary vein fill atria and ventricles
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12
Q

What happens in the atrial systole phase of the cardiac cycle?

A

=Atria contracting (starts heartbeat)

  • Atria volume decreases so pressure increases and blood is pushed into Ventricles
  • As blood enters ventricles, Ventricles contract and blood fills atrio-ventricular valves. This forces AV valve flaps shut preventing backflow of blood
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13
Q

What happens in the ventricular systole phase of the cardiac cycle?

A

=All 4 valves start off shut

  • Contraction starts at base of ventricle and pushes blood towards arteries and out of heart
  • Semi-lunar valves prevent backflow into ventricle as they relax
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14
Q

The cardiac cycle is myogenic. Define myogenic?

A

Myogenic means the cardiac cyle initiates its own cycle and will beat even if the nerves attached to it stopped working

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15
Q

Describe how the heart coordinates itself?

A

Sinoatrial node (SAN) initiates a wave of excitation (electrical impulse) which spreads over atria via membranes of muscle tissue=contractions

Wave can only travel through Atrio-ventricular node (AVN). At the base of the atria there are discs of non-conducting tissue which can’t conduct the impulse, creating a delay between Atria and ventricles contracting (prevents them contracting at once)

Wave travels through specialized conducting tissue (Purkyne tissue) to Apex and up walls so blood is forced upwards.

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16
Q

Myocardial infarction?

A

=HEART ATTACK
heart muscles respire w/ fatty acids instead of glucose. If there’s a blood clot in coronary artery this deprives heart of oxygen and those cells die.

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17
Q

What products are taken in/removed by our transport system?

A

Constant supply of Oxygen, Nutrients, Amino acids and fatty acids
Rapid removal of Carbon dioxide

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18
Q

What kind of circulatory system do mammels have?

A

Closed systems-blood is always contained within a vessel

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19
Q

Insects have an open circulatory system. How do they ensure blood circulation?

A

Muscular pumping organ similar to heart. Long muscular tube under dorsal surface of the insect.
Blood enters the heart through pored (ostia) which gets pumped towards the head by Peristalsis where the blood simply pours into the blood cavity.

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20
Q

Circulatory system of a fish?

A

Closed system- Blood always in vessels

Heart can pump it at high pressure so blood flows quickly. Nutrients delivered and carbon dioxide removed quicker.

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21
Q

Formation of tissue fluid

A

When the arterial end of the capillary contracts, HYDROSTATIC PRESSURE causes the blood fluid plasma (containing dissolved nutrients and oxygen) to be pushed out of the capillaries through tiny gaps in capillary wall.
RBC,WBC, platelets and plasma proteins too big to fit through.
Tissue fluid is formed and surrounds the body cells so gas and nutrient exchange can occur.

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22
Q

Return of fluid back to circulatory system

A

Tissue fluid mostly returns to capillary through osmatic pressure (some goes into lymphatic system)

Tissue fluid and blood contain solutes giving them a -ve water potential
-Water potential of fluid is less negative so can diffuse down a concentration gradient via diffusion.

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23
Q

Functions of Lymphatic system

A

Absorption of excess fluid and its return to the blood in the chest cavity

Absorption of fat from the small intestine.

Immune system function-fluid contains immune cells which help fight infection.

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24
Q

What are Lymph nodes and what do they do?

A

Lymph nodes=places where WBC develop and lymphocytes are produced
Lymph nodes filter bacteria from blood

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25
Properties of airways?
``` Large enough to supply sufficient air without obstruction Divide into smaller airways Strong Flexible Stretch and recoil ```
26
Role of cartilage?
Supports trachea and bronchi under low pressure (during inhalation) Doesn't go all round so allowing flexibility+allows oesophagus to expand when swallowing
27
Role of smooth muscle?
Contract to constrict airways and narrow lumen -controls the flow of air Isn't voluntary, can be triggered by allergic reaction to substances in airways
28
Role of elastic fibres?
Counteract constriction of smooth muscle-deform then reform into original shape during constriction =allows airways to DILATE
29
Role of goblet cells and glandular tissue?
Produce mucus which helps trap tiny particles from the air e.g. Pollen and bacteria =reduces risk of infection
30
Role of ciliated epithelium?
Have tiny, hair-like structures projecting from membrane called CILLIA Cillia move in synchronised pattern to waft mucus up the airway, to the back of the throat. The mucus then gets swallowed and broken down in stomach killing any bacteria
31
Role of phagocytic WBC?
Engulf and destroy pathogens the find at the surface of the airways
32
Which sides of the heart carry oxygenated and deoxygenated blood?
Left= oxygenated | Right=deoxygenated
33
Starting at the vena cava, briefly describe the route that blood takes through the heart and around the body
Body-> Vena cava-> Pulmonary artery-> lungs Lungs-> pulmonary vein-> aorta-> body
34
What are the roles of the semi-lunar, tricuspid and bicuspid valves? Where are they found?
The valves prevent the backflow of blood ``` Semi-lunar= in pulmonary artery and aorta Tricuspid= between R atrium and R ventricle Bicuspid= between L atrium and L ventricle ``` (Tricuspid and bicuspid=atrioventricuar valves)
35
What is the name for the type of muscle found in the heart?
Cardiac muscle
36
Why does the left side of the heart have thicker muscle?
Because the left side pumps blood round to the rest of the body so requires greater force
37
Role of valve tendons?
Prevent valves from inverting under pressure of blood
38
Where does the heart get nourishment? How?
Coronary artery - Feeds the heart with glucose and oxygen - Comes off aorta and feeds on vena cava with deoxygenated blood
39
What is the function of a circulatory system?
Pumps oxygen filled blood around the body so body can respire and produce energy
40
On an ECG (electrocardiogram), what do the different letters represent?
``` P= atrial systole QRS= ventricular systole T= diastole ```
41
Describe the position of different blood vessels in the circulatory system
Starting from the aorta | -> arteries -> arterioles -> capillaries -> venuoles -> veins -> vena cava
42
Function of an artery?
To carry blood away from the heart
43
Structure of an artery?
Small lumen to maintain high pressure Thick wall with collagen = strength Elastic tissue and smooth muscle=allows airway to stretch and recoil Endothelium can fold and unfold when atrey streches
44
Function of a vein?
To carry blood back to the heart
45
Structure of a vein?
Large lumen to ease flow of blood Thinner layers of collagen, elastic tissue and smooth muscle= less need for vein to stretch Often contain valves
46
Function of a capillary?
To allow exchange of materials between blood and tissues cells via tissue fluid
47
Structure of capillary?
Vr thin walls (often 1 cell thick) to allow efficient gas exchange Vr narrow lumen, roughly 7 micrometers (size of a RBC)-squeezes RBC to release oxygen
48
What is another name for RBC? What is the function of an RBC?
Erythrocyte Carrying and transporting substances around the body
49
Structure of Erythrocytes? Where are they produced?
Bioconcave disc-large SA, no ER or mitochondria or nucleus, contains haemoglobin proteins Produced in liver of a foetus Once born, produced in bone marrow
50
What is the role of haemoglobin?
Combine with oxygen (form oxyhaemoglobin)
51
Structure of haemoglobin?
4 subunits made up of protein chain and prosthetic group (non-protein)=haem group made up of iron ion, Fe 2+
52
What is partial pressure?
Amount of oxygen measured by calculating the pressure it contributes to a mixture of gases Measured in oxygen tension/kPa
53
Relate the shape of the oxygen dissociation curve to oxygen tension
Low oxygen pressure= haemoglobin doesn't absorb readily (1st O2 molecule difficult to attract as haem groups found in centre) High oxygen pressure= oxygen absorbed more readily (2nd and 3rd O2 molecules easier to absorb as RBC changes shape allowing more oxygen to diffuse in) Vr high oxygen pressure= more difficult to absorb final oxygen molecule (4th O2 molecule), saturation rarely reaches 100%
54
How does the foetal haemoglobin dissociation curve differ from that of an ordinary person?
Curve shifted to left Due to increased affinity for oxygen as foetus gains oxygen from mothers blood (Foetal and maternal blood don't mix but flow side-by-side allowing O2 to diffuse into foetal blood)
55
How is carbon dioxide transported?
``` 85%= carried in form of HCO3- ions 10%= combines with haemoglobin forming haemoglobonic acid 5%= solution in plasma ```
56
How does carbon dioxide form haemoglobinic acid in RBC?
1) CO2 diffuses into RBC 2) CO2 combines with water (with enzyme, carbonic anhydrase as catalyst) to form CARBONIC ACID 3) carbonic acid dissociates and HCO3- ions diffuse out of RBC (Cl- ions move in to maintain overall charge) leaving H+ ions 4) Meanwhile oxyhaemoglobin dissociates, releasing oxygen into blood 5) haemoglobinic acid formed between H+ ions and haem group which maintains constant pH in RBC
57
Whta is the bohr effect?
The change in affinity in RBC for oxygen
58
Where is there an increased affinity for oxygen? | Where is there a decreased affinity for oxygen?
Increased affinity= alveoli, pick up O2 from lungs Decreased affinity= cells/tissues, more CO2 so more H+ to knock off O2 from haemoglobin
59
Describe the distribution of vascular bundles in the roots of a plant
Bundles found in centre Central x-shaped, core of xylem Phloem found between arms of xylem
60
Describe the distribution of vascular bundles in the stem
Found in a ring outside outer edge of the stem Xylem found on inside Phloem found on outside Between xylem and phloem is cambium (layer of meristem cells-can divide as an adult to produce new X and P)
61
What is the job of the xylem?
Carry water and dissolved minerals to parenchyma cells
62
What are parenchyma cells?
Regular living plant cells
63
Structure of the xylem? (4)
Long, thick walled cells Cells are dead so water is not needed by cells Lignin in walls waterproof cells and cause end walls to decay Lignin strengthens wall and keeps vessel from collapsing under low pressure
64
What different patterns can lignin by laid in in the xylem?
Spiral, annular, reticulate
65
How is the flow of water not impeded in the xylem?
No end walls No cell contents No nucleus or cytoplasm Lignin prevents walls from collapsing
66
What is the function of bordered pits in the xylem?
Allows water to leave one vessel and pass into adjacent vessels or other parts of plant
67
Function of the phloem?
To transport sugars from one part of the plant to another
68
Structure of sieve tube element in phloem? (4)
No nucleus and very little cytoplasm=not true cells Line up end to end to make a tube to transport plant sap (sugars and water) Contain pores to allow sap to flow=called sieve plates Tubes very thin and normally 5/6 sided
69
Structure of companion cells in phloem? (3)
Small with large nucleus and dense cytoplasm Many mitochondria (ATP production)=Carry out metabolic processes for sieve tube elements including loading sucrose into dive tubes using ATP Cytoplasm linked by plasmodesmata-allows communication and flow of materials between cells
70
Describe the distribution of vascular bundles in the leaf
Bundles form central midrib and veins of leaf Xylem found on top of phloem
71
What is the difference between monocotyledons and dicotyledons?
``` D= 2 first leaves M= 1 first leaf ```
72
What routes can water take between cells?
Apoplast- through water spaces in cell walls and spaces between cells Symplast- through cytoplasm via plasmodesmata Vacuolar- similar to Symplast but can also travel through vacuoles
73
How can dissolved ions in water be moved between cells?
They cannot pass through cell membranes due to charge Use Apoplast pathway (spaces between cells)
74
How is water taken up into root hairs?
Root hairs using ATP to actively transport minerals in soil=lower water potential in root Water can move out so soil into root via osmosis as WP outside root higher than inside
75
How is water transported across the root?
Endodermis move minerals bis active transport from cortex into xylem Water follows via osmosis, driven through symplast route by casparian strip
76
What is the role of the casparian strip?
Blocks Apoplast pathway Ensures nitrate ions transported actively through transporter proteins lowering WP in xylem, allows for water movement via osmosis
77
Describe how water moves up the stem via root pressure
Process of water moving into xylem via osmosis pushes water up xylem Root pressure can push water up stem only a few metres but can't guarantee water reaches very tops of plants
79
Describe how water moves up the stem via transpiration pull
According to cohesion tension theory, water molecules have high cohesion with another (strongly attracted) by ionic bonding This cohesion force is strong enough to pull water up plant in a long column called a transpiration stream Lignin supports xylem vessels under this high pressure
80
Describe how water moves up the stem via adhesion (capillary action)
Water molecules use cohesion to grip and climb xylem vessel walls, attracted by adhesion
81
What is water potential?
A measure of the tendency of water molecules to diffuse from one place to another
82
What is transpiration? How does this occur?
Transpiration=The loss of water from upper parts of the plant Water enters leaves, passes through spongy mesophyll cells by osmosis and a water vapour forms Vapour diffuses out of large air spaces in mesophyll=increased water vapour potential When WVP inside is higher than outside water molecules diffuse out of leaf via the stomata (pores in epidermis), a small amount diffuse through the waxy cuticle
83
What is a transpiration stream?
The movement of water form the roots to replace water lost through upper parts of the plant
84
Why is a transpiration stream vital to a plant?
``` Transports water nought plant-needed for photosynthesis Needed for cells to elongate and grow Keeps cells turgid Carry useful minerals up plant Evaporation from leaf keeps plant cool ```
85
Name 3 factors that can affect the rate of water loss in a plant and how
Number of leaves-more leaves=bigger SA=greater water loss Number, size, position of stomata-many, large stomata on upper surface= greater water loss Waxy cuticle-if present=decreased evaporation from leaf Light-stomata open in light for gaseous exchange=greater water vapour loss Temperature-higher temp=more evaporation=higher rate of diffusion=lower WVP outside leaf (allows diffusion) Humidity-more water vapour molecules in air=lower water vapour loss Air movement-carries away water vapour molecules=maintains high WVP gradient Water availability-little water in soil=less water vapour loss
86
What happens if a plant loses too much water?
Plant cells lose turgidity | Non-woody plants eventually wilt and die
87
Why is a potometer not 100% accurate?
Not all water taken up by plant lost in transpiration stream, some water used in photosynthesis
88
Why is water loss unavoidable?
Stomata open all day to remove products of photosynthesis
89
How can plants control water loss?
Waxy cuticle reduces water loss due to evaporation through epidermis Stomata found on underside of leaves Most stomata close at night when there's no light Most plants lose leaves in winter when ground is frozen/temp too low for photosynthesis
90
What is a xerophyte?
A plant adapted to live in dry/arid conditions
91
How are xerophytes adapted to their environment? Give 3 specific example (Remember to expand on the brackets in answers)
Smaller leaves (reduced SA) Densely packed spongy mesophyll (less exposed cell surface area) Thicker waxy cuticle (less evaporation) Stomata close at low water availability (less water vapour loss) Hairs on leaf surface (layer of saturated moisture) Pits with stomata at base (trapped air with saturated water vapour) Rolling leaves (lower epidermis not exposed) High salt concentration in cells (low water vapour potential inside cells)
92
What is translocation?
The movement of assimilates (sugars and other chemicals made by the plant) from a source to a sink
93
What is a source?
Any part of the plant where sucrose is released into the phloem
94
What is a sink?
Any part of a plant that removes sucrose from the phloem
95
Describe the process of translocation at a source
@source: 1) companion cells actively pump H+ ions out 2) H+ ions diffuse back in via cotransporter protein with sucrose attached 3) sucrose transported into companion cells until diffusion gradient allows diffusion through plasmodesmata into sieve tube element 4) sucrose in sieve tube powers WP allowing water to follow via osmosis 5) water moving into sieve tube creates high hydrostatic pressure forcing assimilates to move
96
Describe the process of translocation at a sink
@sink: 1) sucrose diffuses into companion cells= greater WP in sieve tube 2) water enters companion cells via osmosis 3) water moving out creates low hydrostatic pressure in sieve tube-> maintains translocation process
97
Give an example of translocation including when it occurs and why
Source: leaf -> sink: flowers =late spring, summer, early autumn = sucrose needed to do photosynthesis Source: stores in plants -> sink: leaf =early spring =leaves need sugars to grow Source: roots -> sink: other parts of plant =spring = in summer and autumn roots become sink to store sugars
98
How do we know ATP is used for translocation?
Companion cells have ATP If ATP is inhibited process stops Rate of flow of sugars is so high it must require energy
99
How do we know the mass flow mechanism is used?
pH of companion higher than that of surrounding cells (due to movement of H+ ions) Concentration of sucrose is higher at source than in the sink
100
What evidence is there against mass flow?
Not all solutes in phloem sap are made at the same rate Role of sieve plates in unclear Sucrose is moved to all plants at same rate,rather than going more quickly to areas of lower concentration
101
How can an aphid be used to show sugars travel in phloem?
When an aphid punctures stem, stylet enters phloem vessels | Aphid can be removed to show sugary sap drips from cut end of stylet
102
Role of smooth muscle?
Smooth muscle= Can contract+constrict airways to narrow lumen =contraction isn't voluntary, triggered in allergic reactions
103
Role of elastic fibres?
Elastic fibres= counteract constriction of airways-deform then reform to allow airways to dilate
104
Role of goblet cells and ciliated epithelium?
Goblet cells+glandular tissue=produce mucus to help trap tiny particles from air eg pollen and bacteria to reduce risk of infection Ciliated epithelium= tiny, hair like structures and move in sychronized pattern to waft mucus up airway to back of throat. MUcus then swallowed and digested, breaking down any bacteria in stomach
105
Role of phagocytic WBC in airways?
Phagocytic white blood cells= engulf and destroy pathogens they find on the surface of the airways

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