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Biology > Organisms Exchange Subtsances With Their Environment (3.3) > Flashcards

Organisms Exchange Subtsances With Their Environment (3.3) Flashcards

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1
Q

What materials need to be exchanged?

A
  • Respiratory gasses (oxygen, carbon dioxide)
  • Nutrients (glucose, fatty acids, amino acids, minerals)
  • Excretory products (urea and carbon dioxide)
  • Heat
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2
Q

How can exchange take place?

A

Passively (diffusion or osmosis)
Actively (active transport)

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3
Q

Simple diffusion of materials across the surface can only meet the needs of a relatively __________ organism. Even if the surface area could supply enough material it would still take too______ for it to reach the middle of the organism.

A

Inactive
Long

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4
Q

What are the features of a specialised exchange surface?

A
  • large surface area
  • thin
  • partially permeable
  • movement
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5
Q

Why is a large surface area to volume ratio a feature of a specialised exchange surface?

A

Increases the rate of exchange

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6
Q

Why is being thin a feature of a specialised exchange surface?

A

Provides a short diffusion pathway meaning materials can cross the exchange surface rapidly.

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7
Q

Why is being partially permeable a feature of a specialised exchange surface?

A

It allows selected materials to cross without obstruction.

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8
Q

Why is movement a feature of a specialised exchange surface?

A

Movement of an environmental medium maintains a concentration gradient e.g blood moves to maintain the concentration gradient.

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9
Q

How can you calculate diffusion?

A

Diffusion = surface area X difference in concentration
—————————————————————
Length of diffusion pathway

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10
Q

Why are exchange surfaces often located in an organism?

A

Because they are easily damaged.

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11
Q

Diffusion is sufficient if….

A

The distances are short (less than 0.5mm)
The surface area is relatively large

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12
Q

Why do large, active organisms need exchange surfaces?

A

The distances are too great for the materials to reach the centre of the organism.

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13
Q

How do you find the volume of a cube/rectangle?

A

Base x height x width

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14
Q

How do you find the area of a sphere?

A

4/3 pi r 3

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15
Q

How do you find the surface area of a sphere?

A

4 pi r 3

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16
Q

How do you find the surface area of a sphere?

A

4 pi r 2

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17
Q

If size increases, surface area increases ___________ compared to volume.

A

Disproportionally

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18
Q

Large organisms have a ______ surface area to volume ratio.

A

Small

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19
Q

Small organisms have a ________ surface area to volume ratio.

A

Large

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20
Q

Insects have no blood so they need……?

A

Tubules

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21
Q

Why do insects have tubules?

A

To take oxygen to muscle cells

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22
Q

What makes an insect’s tubule system?

A

Trachea and tracheoles

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23
Q

How does oxygen reach an insets trachea?

A

Spiracles on their surface

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24
Q

What are trachea and tracheoles supported by to prevent their collapse?

A

Strengthened rings

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25
Q

Why do spiracles close their valves?

A

To minimise water loss

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26
Q

What are the two ways spiracles minimise water loss?

A
  • close spiracles using valves
  • there are hairs around the spiracles to trap humid air
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27
Q

What are the three ways respiratory gasses move in an insect?

A
  • along the concentration gradient
  • contraction of muscles
  • movement of water into muscle cells which increases the volume of gasses that can fit into the end of a tracheole.
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28
Q

Describe how insects prevent water loss.

A
  • the ends of tracheoles are filled with water.
  • during active periods, muscle cells around tracheoles carry out anaerobic respiration.
  • this produces a soluble lactate.
  • water (containing the dissolved lactate) move into cell from the tracheoles by osmosis, lowering the water potential of the muscle cells.
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29
Q

What is the limitation of gas exchange in insects?

A

It heavily relies on diffusion which requires a short diffusion pathway, meaning the insect has to be relatively small.

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30
Q

What protects the gills in a fish?

A

Operculum/ gill cover

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31
Q

How does water get into the fish for gas exchange?

A

The mouth

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32
Q

Describe the movement of water in a fish.

A

Water enters the mouth and passes over the gills.

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33
Q

Describe 3 features of gills in a fish?

A

-large surface area provided by *gill lamellae**
- rich blood supply
- counter current flow

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34
Q

Why can fish not survive out of water?

A

In water their gills are feathery, increasing their surface area for exchange. When a fish is out of the water their gills collapse down, decreasing their surface area- this reduced ur face area does not allow sufficient gas exchange.

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35
Q

What two features of a gill increase the surface area?

A

Gill filaments
Lamellae

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36
Q

What is counter current?

A

When blood flow passes in the opposite direction to water flow

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37
Q

Describe how the blood and water supply interact in counter current ,when they flow in opposite directions.

A
  • oxygen rich blood encounters oxygen rich water
  • oxygen poor blood encounters oxygen poor water
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38
Q

What would happen if parallel flow occurred in the gills of a fish?

A

Exchange would reach equilibrium (no longer occur).

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39
Q

Why do highly active fish swim with their mouths open?

A
  • they maintain a high rate of water flow across gills to provide sufficient oxygen for a high rate of respiration
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40
Q

Why is countercurrent flow import?

A

It maintains a favourable concentration gradient. (A concentration gradient is maintained across the entire distance of the gill lamella)

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41
Q

what makes up the mesophyll layer in a leaf?

A

Palisade mesophyll
Spongy mesophyll
Air space

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42
Q

What makes up the vascular bundle in a leaf cell?

A

Xylem
Phloem

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43
Q

What surrounds the stomata in a leaf?

A

Guard cells

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44
Q

What is the role of the waxy cuticle in a leaf?

A

Waterproofing and protection

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45
Q

what is the role of the palisade mesophyll in a leaf?

A
  • rich in chloroplasts = photosynthesis
  • ‘crammed’ = maximum amount of light can be absorbed
  • vertical - increasing likelihood of light striking chlorophyll molecules
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46
Q

What is the role of the spongy mesophyll in a leaf cell?

A

It has air spaces to allow gasses to circulate when diffusion to and from the environment

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47
Q

What is the role of the vascular bundle in a leaf?

A

Transport vessels

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48
Q

Plant cells respire ___ hours a day.

A

24

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49
Q

Photosynthesis only occurs in________.

A

Daylight

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50
Q

In plants, waste gasses from __________ respiration can be sued for ____________ visa Vera’s.

A

Respiration
Photosynthesis

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51
Q

How is the leaf a specialised exchange surface?

A
  • flat shape provides a large surface area
  • stomata allow many routes into/out of the leaf
  • spongy mesophyll offers interconnected air spaces
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52
Q

What is the singular word for stomata?

A

Stoma

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53
Q

What are stomata?

A

Tiny pores, surrounded by guard cells, that allow control of gas exchange and water loss by evaporation.

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54
Q

How do guard cells open and close stomatal pores?

A

They manipulate the water potential.

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55
Q

How do guard cells open a stomatal pore?

A
  • ions move into the guard cells, making the water potential more negative
  • water follows by osmosis
  • cells become more turgid and the pore opens
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56
Q

How do guard cells close to stomata?

A
  • ions move out of the guard cells making the water potential less negative
  • water follows by osmosis
  • cells become flaccid and the pore closes
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57
Q

what is a xerophyte?

A

A plants which is adapted to live in very dry conditions.

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58
Q

What is an example of a xerophyte?

A

Cacti
Marram grass

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59
Q

What are some structural adaptations of a xerophyte?

A

Waxy cuticle - reduce evaporation from epidermis

Long, shallow spread out root system - reaches water supplies on the surface of the ground

Swollen succulent system - store moisture

Leaves reduces to spikes and round shape - reduces surface area:volume which means water isn’t lost

Hairs on surface to reflect light - reduces photosynthesis, reduces demand for water

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60
Q

Where is marram grass found?

A

Sand dunes

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61
Q

Name two adaptations of marram grass.

A

Rolled leaf
Fewer stomata sunken into pits with hairs

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62
Q

Why does marram grass have a rolled leaf?

A

Less surface area which means there are less stomata.
The stomata are internal, trapping humid air.

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63
Q

Why does marram grass have stomata with hairs?

A

The hairs trap humid air, reducing the concentration gradient.

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64
Q

What do hinge cells do?

A

Allow a leaf to roll up when short of water so that stomata aren’t exposed to wind or dry air.

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65
Q

Where in the body are the lungs found?

A

The thorax

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66
Q

What two parts connect the lungs to the mouth?

A

Trachea and bronchi

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67
Q

There are __ bronchi in the lungs.

A

2

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68
Q

What provides support and flexibility to the bronchi and trachea?

A

Many C shaped rings of cartilage.

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69
Q

What lines the lumen of the bronchi and trachea?

A

Ciliated epithelial cells

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70
Q

How do the ciliated epithelial cells and goblet cells work together in the bronchi and trachea?

A

Goblet cells lie in between the epithelial cells. They produce mucus to trap dirt and pathogens. Cilia waft mucus out of the airways.

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71
Q

What does the smooth muscle do in the bronchi and trachea?

A

Controls their diameters
This can reduce air flow e.g when pollen is inhaled.

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72
Q

What do bronchioles not have?

A

Cartilage

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73
Q

How many alveoli are in the lungs?

A

Millions

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74
Q

What do alveoli consist of?

A

Squamous epithelial tissue and elastic fibres.

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75
Q

Where does gas exchange occur in the lungs?

A

Alveoli

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76
Q

Where does gas exchange occur in the lungs?

A

Alveoli

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77
Q

Alveoli have a large _______ _____ and a good _______ supply, this maximised gas exchange.

A

Surface area
Blood

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78
Q

Alveoli have a short diffusion pathway that is 2 cells thick. What are these cells?

A

Squamous epithelia of the alveoli. The endothelia of the walls of the blood vessels.

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79
Q

What is pulmonary fibrosis caused by?

A

Damaged alveoli cause lungs to become stiff and thick scar tissue on alveoli, increasing the diffusion pathway making it difficult for 02 to get into the blood.

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80
Q

what are the risk factors that can cause pulmonary fibrosis?

A

Smoking
Acid reflux
Viral infections
Family history
Exposure to certain types of dust e.g metal and wood dust

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81
Q

what are the symptoms of pulmonary fibrosis?

A

Shortness of breath
Tiredness
Persistent dry cough
Loss of appetite and weight loss
Swollen fingertips

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82
Q

What are the symptoms of emphysema?

A

Shortness of breath

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83
Q

What is emphysema caused by?

A

Damaged alveoli causes the inner walls of the air sacs to weaken and rupture. This created large air spaces, reducing the surface area which reduces the rate of gas exchange.

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84
Q

What are the risk factors that can cause emphysema?

A

Smoking
Age
Exposure to 2nd hand smoke
Exposure to pollution

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85
Q

Summarise what the trachea is.

A
  • has c shaped rings of cartilage to keep it open. Has ciliated epithelial tissue to waft pathogens and mucus out of the airways. Leads to bronchi.
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86
Q

Summarise what the bronchi are.

A

1 per lung, has c shaped cartilage rings to keep them open.

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87
Q

Summarise what the bronchioles are.

A
  • branch off bronchi, supplied 02 to alveoli.
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88
Q

Summarise what the alveoli are.

A
  • sacs with a large surface area in which 02 moves into the capillaries surrounding them. Site of gas exchange.
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89
Q

Summarise what the diaphragm is.

A

A large sheet of muscle that separates the lungs from the abdominal cavity. Contracts to help you inhale and exhale.

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90
Q

Summarise what the intercostal muscle is.

A

Located in the rib cage to provide support. Expands and shrinks the size of the chest cavity.

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91
Q

What is inspiration?

A

Breathing in

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92
Q

Describe the process of inspiration.

A
  • the external intercostal muscles contract, while the internal intercostal muscles relax.
  • the ribs are pulled upwards and outwards, increasing the volume of the thorax.
  • the diaphragm muscles contract, causing it to flatten, which also increases the volume of the thorax.
  • the volume of the thorax results in reduction of pressure in the lungs.
  • atmospheric pressure is now greater than pulmonary pressure, and so air is forced into the lungs.
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93
Q

What is expiration?

A

Breathing out

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94
Q

Describe the process of expiration.

A
  • the internal intercostal muscles contract, while the external intercostal muscles relax.
  • the ribs move downwards and inwards, decreasinf the volume of the thorax.
  • the diaphragm muscles relax, making it return to its upwardly domed position, again decreasing the volume of the thorax.
  • the decreases volume of the thorax increases the pressure in the lungs.
  • the pulmonary pressure us now greater than that of the atmosphere, and so air is forced out of the lungs.
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95
Q

Why do the external intercostal muscles contract, while the internal intercostal muscles relax during inspiration?

A

The intercostal muscles are antagonistic

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96
Q

What is the tidal volume?

A

Volume of air breathed in and out of the lungs during each breath

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97
Q

How do you calculate pulmonary ventilation?

A

Tidal volume x ventilation rate

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98
Q

Define digestion.

A

Large biological molecules are hydrolysed to smaller ones that can be absorbed across cell membranes.

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99
Q

What is mechanical digestion?

A

Large chunks of food get broken down into smaller ones

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100
Q

What is chemical digestion?

A

The action of enzymes break don the food into energy

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101
Q

What food needs to be broken down?

A

Large molecules or macromolecules such as carbohydrates, proteins, lipids.
Small molecules or micro molecules like minerals, vitamins and water

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102
Q

What are macromolecules broken down by?

A

Hydrolysed by enzymes called hydrolases. E.g amylase, lipase, protease

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103
Q

Carbohydrates require more than one ________ to hydrolyse them into monosaccharides.

A

Enzyme

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104
Q

What do carbohydrates require to be broken down?

A

Amylases
Membrane bound disaccharides

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105
Q

Where is amylase produced?

A

The Pancreas and salivary glands

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106
Q

What does amylase do to carbohydrates?

A

Hydrolysed polysaccharides into the disaccharide maltose by hydrolysing the glycosidic bonds.

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107
Q

During digestion of carbohydrates, where do amylase act?

A

In the mouth

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108
Q

Which membrane bound enzymes act in the 2nd part of carbohydrate digestion?

A

Sucrase and lactase.

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109
Q

In the ______________ and _______, sucrase and lactase hydrolyse sucrose and lactose into monosaccharides.

A

Duodenum
Ileum

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110
Q

What does sucrase digest sucrose to?

A

Glucose and fructose

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111
Q

What does lactase digest lactose into?

A

Glucose and galactose

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112
Q

MOUTH (?). (?)
Starch glycogen ————————-> maltose——————-> glucose

A

1.Amylase
2. Maltase

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113
Q

ILEUM (?)
Sucrose ———————-> glucose + fructose

                  (?)	 Lactose ———————> glucose + galactose
A
  1. Sucrase
  2. Lactase
114
Q

Amylase is produced by the _______ and ___________ _______. It hydrolyses polysaccharides into the disaccharide ___________ by hydrolysing the ____________ bonds.

A

Pancreas
Salivary glands
Maltose
Glycosidic

115
Q

Which 3 enzymes can hydrolyse proteins?

A

Endopeptides
Exopeptides
Membrane bond dipeptidases

116
Q

What do endopeptidases do?

A

Hydrolyse peptide bonds between amino acids in the middle of a polymer chain

117
Q

What do exopeptidases do?

A

Hydrolyse peptide bonds between amino acids at the end of a polymer chain

118
Q

What do membrane-bound dipeptidases do?

A

Hydrolyse peptide bonds between two amino acids e.g when there are only 2 amino acids together left in a protein chain.

119
Q

Protein digestion starts in the ________, continues in the ____________ and is fully digested in the _____.

A

Stomach
Duodenum
Ileum

120
Q

Lipids are digested by _______ and the action of _______ _______.

A

Lipase
Bile salts

121
Q

Where is lipase produced?

A

The pancreas

122
Q

What does lipase hydrolyse?

A

The ester bond in triglycerides

123
Q

Lipase is produced in the ______ and it can hydrolyse the ______ bond in ________________to form the monoglycerides and fatty acids.

A

Pancreas
Ester
Triglycerides

124
Q

Where are bile salts produced?

A

The liver

125
Q

what do bile salts do?

A

Emulsify fats to form Micelles.
Micelles increase the surface area for lipase to act on.
This occurs before lipase action.

126
Q

Describe how micelles assist lipid digestion.

A

Fatty acids and monoglycerides (from fat digestion) leave micelles and enter epithelial cell as they are non polar.

Monoglycerides and fatty acids are transported to the Endoplasmic reticulum where they form triglycerides.

This process starts in the ER and continues in the Golgi apparatus.

Chylomicrons are formed. (Triglycerides associate with cholesterol and lipoproteins to form these). Chylomicrons are adapted for the transport of lipids.

Chylomicrons move out of the epithelial cells by exocytosis.

They then enter the lymphatic capillaries and lacteals (found in the centre of each villus).

127
Q

What happens in lacteals?

A

Chylomicrons pass via lymphatic vessels, into the blood system. The tri-glycerides in the chylomicrons are hydrolysed by an enzyme in the endothelial cells of blood capillaries from where they diffuse into cells.

128
Q

How long is the small intestine?

A

7 metres

129
Q

The small intestine has an upper tube called the ____________ into which opens the bile duct and the pancreatic duct.

A

Duodenum

130
Q

What is the upper tube of the small intestine called?

A

The duodenum

131
Q

The duodenum leads via the _________ to a lower tube called the ileum.

A

Jejunum

132
Q

What are the 2 major functions of the small intestine?

A

Digestion
Absorption

133
Q

What is the lining of the small intestine called?

A

Ileum

134
Q

Where are villi found?

A

On the ileum

135
Q

What do villi do?

A

Increase the surface area for enzyme action and the absorption of food.

136
Q

Where is the Bruner glands found?

A

The duodenum

137
Q

What do the burners glands in the duodenum secrete?

A

Alkaline secretions which neutralise acidic chyme from the stomach.

138
Q

What is the optimum PH for duodenal enzymes?

A

Ph8

139
Q

What does the epithelial layer release which prevents the duodenum from acid damage?

A

Mucus

140
Q

What are the small projections on villi called?

A

Microvilli

141
Q

How much do microvilli increase the surface area of the small intestine?

A

15-40 x

142
Q

What are the deep folds between villi?

A

Lieberkuhn

143
Q

What is made in the lieberkuhn?

A

New columnar cells along with enzymes e.g peptidases and lipases

144
Q

What are the villli and sub mucosa surrounded by and why?

A

Lymph vessels
So digested food gets around the body

145
Q

How thick is the epithelium and why?

A

One cell thick
Reducing the diffusion distance

146
Q

What enables movement of the small intestine?

A

Muscularis externica (consists of 2 layers)

147
Q

The ______ is the main sight of absorption.

A

Ileum

148
Q

Bile from the ____ _________ is released into the ileum. This contains sodium ____________________ which helps to neutralise stomach acid.

A

Gall bladder
Hydrogencarbonate

149
Q

Bile acts to __________ lipids into __________.

A

Emulsify
Micelles

150
Q

To absorb glucose and amino acids from the lumen to the gut there must a higher concentration gradient in the __________ compared to the __________ ______ (for ____________ diffusion).

A

Lumen
Epithelial cell
Facilitated

151
Q

Haemoglobin + 02 ————-> ?

A

Oxyhaemoglobin

152
Q

Haemoglobin is a ______ protein.

A

Globular

153
Q

What are the 4 polypeptide chains that make up Haemoglobin?

A

2 alpha globins
3 beta globins

154
Q

How many polypeptide chains are there in Haemoglobin?

A

4

155
Q

Each polypeptide chain in Haemoglobin contains _ haem group. Each haem group can combine with _ oxygen molecule.

A

1

1

156
Q

How many oxygen molecules can Haemoglobin bind to?

A

4

157
Q

Describe the tertiary structure of Haemoglobin.

A

Each polypeptide chain is folded into a precise shape - an important factor in its ability to carry oxygen.

158
Q

Describe the quaternary structure of Haemoglobin.

A

4 polypeptide chains are linked together to form an almost spherical molecule. Each polypeptide chain is associated with a haem group - containing ferrous iron (Fe2+). Each ion can combine with a single oxygen.

159
Q

What is oxygen saturation?

A

The amount of oxygen bound to the haemoglobin in our blood.

160
Q

What are the units for oxygen saturation?

A

SaO2%

161
Q

Describe how oxygen associates and disassociated from Haemoglobin

A

At a gas exchange surface C02 is being removed. C02 is acidic so the PH is raised, due to the low level of C02.

Change in PH (increase) changes the shape of haemoglobin to one that loads readily and increases the affinity of Haemoglobin for 02. (Tertiary structure changes).

In tissues C02 is produced by respiring cells. PH of blood is lowered.

A lower PH changes the shape of Haemoglobin into one with a lower affinity for oxygen - releasing the oxygen.

162
Q

The effect of carbon dioxide is to shift the whole oxygen dissociation curve to the……

A

Right

163
Q

Carbon dioxide causes the oxygen affinity of haemoglobin to ________.

A

Decrease

164
Q

The partial pressure of carbon dioxide will be high in _________ tissue undergoing _________ ___________.

A

Active
Aerobic respiration.

165
Q

When does haemoglobin have a higher affinity for oxygen?

A

Where the partial pressure of carbon dioxide is low e.g in the lungs

166
Q

Why does haemoglobin unload bound oxygen in respiring tissues?

A

The Haemoglobin has a lower oxygen affinity because the partial pressure of carbo dioxide is high.

167
Q

What can carbon dioxide form in the blood?

A

Carbonic acid

168
Q

What does carbonic acid release?

A

Hydrogen ion (H+)

169
Q

What does H+ do to haemoglobin?

A

It combines with haemoglobin and causes the quaternary structure of the haemoglobin to change. As a result of the change in the quaternary structure, the haemoglobin has a lower affinity for oxygen. This causes the haemoglobin to unload its oxygen more readily.

170
Q

What 5 factors can cause a right shift on an oxygen dissociation curve?

A
  • affinity for oxygen decreases
  • high concentration of carbon dioxide
  • PH lowered
  • increase in temperature
  • high metabolic rate
171
Q

What causes a left shift on the oxygen dissociation curve?

A
  • increased affinity for oxygen
  • low concentration of carbon dioxide
  • PH increase
  • decrease in temperature
  • low metabolic rate
172
Q

What is a right shift in the oxygen dissociation curve called?

A

The Bohr effect

173
Q

What type of curve is the oxygen dissociation curve?

A

Sigmoid curve (s shape)

174
Q

At low partial pressures of oxygen, haemoglobin has a _____ affinity for oxygen.

A

Low

175
Q

What happens once one oxygen molecule is bound to a haem group?

A

The affinity of haemoglobin for oxygen increases. It becomes much easier to bind further oxygen molecules.

When one molecule of oxygen binds, the quaternary structure of the haemoglobin molecule changes - this now increases the affinity of the haem groups for oxygen. So, binding molecules only requires a relatively small increase in the oxygen partial pressure.

176
Q

What is positive cooperativity?

A

When one oxygen molecule binds to haemoglobin, changing the quaternary structure. This means that binding molecules only require a relatively small increase in the oxygen partial pressure.

177
Q

Where is the partial pressure of oxygen high?

A

Alveoli

178
Q

What happens to red blood cells as they move into body tissues?

A

There is a lower partial pressure of oxygen as the tissues are carrying out aerobic reparation. So, at a certain point one oxygen molecule will dissociate from the haemoglobin molecule. This unloading changes the quaternary structure of the haemoglobin molecule. The effect of this is to decrease the oxygen affinity of the remaining haem groups.

179
Q

It is _______ that all oxygen molecules will unload from a haemoglobin molecule under normal conditions. But, it could take place in very ______ tissue. E.g muscle tissue during intensive _______.

A

Unlikely
Active
Exercise

180
Q

Name the 4 chambers of the heart?

A

Right atrium Left atrium

Ventricle Left ventricle

181
Q

What do large organisms have to ensure that they obtain the oxygen and glucose they require?

A

A double circulatory system

182
Q

Why do large organisms have a double circulatory system?

A

They have a small surface area: volume ratio so they cannot obtain the oxygen and glucose they require by diffusion

183
Q

What are the features of a transport system?

A
  • a watery liquid (blood) that readily dissolves substances
  • a closed system of branching vessels to distribute the transport medium to all the parts of the organism
  • a mechanism for moving the transport medium e.g heart and other muscles (arteries) - or the transpiration stream in plants
  • a mechanism to ensure the flow is in one direction and a way of controlling the flow to meet the demand e.g valves to prevent back flow of blood
184
Q

What arteries is a closed system made up of?

A

Arteries, capillaries, veins

185
Q

What takes oxygenated blood to the heart?

A

Pulmonary vein

186
Q

What takes deoxygenated blood to the lungs?

A

Pulmonary artery

187
Q

What transports oxygenated blood to the body?

A

Aorta

188
Q

What takes oxygenated blood to the liver?

A

Hepatic artery

189
Q

What takes deoxygenated blood from the liver?

A

Hepatic vein

190
Q

What takes oxygenated blood to the kidneys?

A

Renal artery

191
Q

What takes deoxygenated blood from the kidneys?

A

Renal vein

192
Q

What takes oxygenated blood to the lower limbs?

A

Iliac artery

193
Q

What takes deoxygenated blood from the lower limbs?

A

Iliac vein

194
Q

what makes a closed blood system?

A

If the blood is confined to vessels

195
Q

What is the function of an artery?

A

Transports blood from the heart rapidly under high pressure

196
Q

Describe the structure of an artery.

A

❑ Thicker muscle layer (compared to vein): Can be constricted and dilated to control blood flow
❑Thicker elastic layer: blood pressure needs to be kept high in arteries in order to reach extremities of body. They are stretched at each beat of the heart. It then springs back(recoils) when it relaxes.
❑ Overall thickness large: stops the vessel bursting under pressure
❑ No valves (except in those leaving heart): Blood is under constant high pressure and doesn’t flow backwards

197
Q

What is the function of an arteriole?

A

Carry blood under lower pressure than arteries, from arteries to capillaries & regulate blood flow between the two.

198
Q

Describe the structure of an arteriole.

A

❑ Muscle layer thicker than arteries: allows constriction of the lumen in order to control blood flow into capillaries
❑ Elastic layer thinner than arteries: blood pressure lower

199
Q

What is the function of a vein?

A

Carry blood slowly, under low pressure from tissues to heart.

200
Q

Describe the stature of a vein.

A

❑ Muscle layer relatively thin: does not control flow to the tissues
❑ Elastic layer relatively thin: Low pressure will not cause them to burst
❑ Overall thickness small: no need for thick wall as pressure is low. Allows them to be easily flattened aiding flow of blood
❑ Valves: ensure blood does not flow backwards, when body muscles contract, veins are compressed, pressurising the blood within them, forcing & pushing blood along the vein

201
Q

What is the function of a capillary?

A

Exchange of Oxygen, Carbon dioxide and glucose between blood and cells. Slow blood flow allows more time for exchange of materials.

202
Q

Describe the structure of a capillary.

A

❑ Walls extremely thin, so short diffusion pathway between blood and cells
❑ Numerous and highly branched- creating a large surface area
❑ Narrow: Permeate tissue so that no cell is far away from a capillary
❑ Narrow lumen: RBC’s squeeze flat against the side to bring them closer to the cells
❑ Pores in the endothelium: allow WBC’s to escape

203
Q

where does coronary heart disease occur?

A

Coronary arteries

204
Q

What is coronary heart disease caused by?

A

An atheroma specific to the coronary artery

205
Q

What is an atheroma?

A

Fatty deposits form within the wall of an artery.
•These are accumulations of white blood cells that have taken up Low-density lipoproteins (LDL’s)

•Bulge into lumen taking up room narrowing of arteries and blood flow is reduced.

206
Q

What is a myocardial infaraction?

A

Heart attack- reduced supply of oxygen to the muscle of the heart. Blockage in the coronary arteries.
•If occurs close to junction of coronary artery and aorta, the heart will stop beating.

207
Q

What are the risk factors for heart disease?

A

Smoking

2-6 times more likely to suffer from heart disease
Smoking
•
haemoglobin to form carboxyhaemoglobin which reduces the oxygen-carrying capacity of blood. The heart has to work harder to deliver the same amount of oxygen.
•High blood pressure which increases risk of CHD and strokes
Carbon monoxide
combines irreversibly with

Nicotine:
•Stimulates adrenaline production which increases heart rate and raises blood pressure
- makes red blood cells and more ‘sticky’ and leads to higher risk of thrombosis

Diet

High levels of salt:
raises blood pressure
High levels saturated fat: density lipoproteins
increases low

Blood cholesterol

High - density lipoproteins remove
cholesterol from tissues and transport to liver for excretion. Help protect against heart disease

Low density lipoproteins transport
cholesterol from liver to tissues, including artery walls, which they infiltrate, leading to development of atheroma.
density lipoproteins (HDL’s): remove

208
Q

Why is smoking a risk factor for heat disease?

A

2-6 times more likely to suffer from heart disease
Carbon monoxide combines irreversibly with haemoglobin to form carboxyhaemoglobin which reduces the oxygen-carrying capacity of blood. The heart has to work harder to deliver the same amount of oxygen.
High blood pressure which increases risk of CHD and strokes

Nicotine:
Stimulates adrenaline production which increases heart rate and raises blood pressure
Makes red blood cells more ‘sticky’ and leads to higher risk of thrombosis

209
Q

why is diet a risk factor for heart disease?

A

High levels of salt: raises blood pressure
High levels saturated fat: increases low density lipoproteins

210
Q

How is blood cholesterol a risk factor for heart disease?

A

High-density lipoproteins (HDL’s): remove cholesterol from tissues and transport to liver for excretion. Help protect against heart disease

Low-density lipoproteins (LDL’s) transport cholesterol from liver to tissues, including artery walls, which they infiltrate, leading to development of atheroma.

211
Q

What are the 2 types of blood cholesterol?

A

High-density lipoproteins (HDL’s)

Low-density lipoproteins (LDL’s)

212
Q

What are the 2 components that make up the bloood?

A

Cells
Blood plasma

213
Q

what makes up the cells in the blood?

A

Red blood cells
White blood cells
Platelets

214
Q

What makes up blood plasma?

A

Glucose
Amino acids
Mineral ions
Oxygen
Plasma proteins

215
Q

Where does tissue fluid leave the blood?

A

The parts of the capillary which are near the artery

216
Q

Tissue fluid transfers molecules such as ________ and __________ to the tissue cells

A

Oxygen
Glucose

217
Q

Tissue fluid returns back to the blood at the _______ end of a capillary

A

Venous

218
Q

Blood at the arterial end of the capillary is under relatively ______ pressure.

A

High

219
Q

___________________ _________ tends to force fluid out of the blood and into the tissue.

A

Hydrostatic pressure

220
Q

What lowers the water potential of blood plasma and why?

A

Plasma proteins
They are hydrophilic

221
Q

Plasma proteins are hydrophilic so they lower the water potential of the blood plasma. So there is a tendency for water to to move back _______ the blood by _______.

A

Into
Osmosis

222
Q

What is ultrafiltration?

A

Tissue fluid is forced out of the capillary through gaps between endothelial cells because in the ar arterial end of the capillary, the hydrostatic pressure is greater than the onctic pressure.

223
Q

What molecules are too large to leave the capillary so remain in the blood plasma?

A

Blood cells and plasma proteins

224
Q

At the venous end of the capillary, the hydrostatic pressure is much ________.

A

Lower

225
Q

why is the hydrostatic pressure at the venous end of the capillary much lower?

A

A large amount of water has left the blood

226
Q

What causes water to move into the blood by osmosis at the venous end of a capillary?

A

The hydrostatic pressure is less than the oncotic pressure

227
Q

What happens to the tissue fluid that isn’t re absorbed?

A

It is drained into lymph capillaries

228
Q

What do lymph capillaries connect to?

A

Larger lymph vessels, forming the lymphatic system

229
Q

How does lymph fluid move along lymph vessels?

A

The lymph vessels are squeezed by nearby skeletal muscles

230
Q

What helps lymph fluid to move forward in the lymph vessels?

A

Valves

231
Q

what happens to lymph fluid?

A

It eventually returns to the bloodstream via blood vessels

232
Q

What is the cardiac cycle?

A

The sequence of events during one heartbeat

233
Q

How long is the cardiac cycle?

A

0.8 seconds

234
Q

Describe an atrial systole?

A
  • cardiac muscles of atria contracts
  • volume of atria decreases
  • blood pressure in atria increases
235
Q

What is this the process of?

cardiac muscles of atria contracts
- volume of atria decreases
- blood pressure in atria increases

A

Atrial systole

236
Q

A systole is a _________.

A

Contraction

237
Q

A diastole is a ________.

A

Relaxation

238
Q

Describe the process of a ventricular systole?

A
  • cardiac muscles of ventricles contract
    -volume of ventricles starts to decrease
  • blood pressure in ventricles starts to rise
  • when blood pressure increases above that of the atrial the atrioventricular valves slam shut (“lubb”)
  • blood pressure continues to rise as ventricular cardiac muscles continues to contract
  • blood pressure now becomes greater in ventricles compares with arteries
  • semi-lunar valves which have been shut until now open
  • blood flows out of the heart into the aorta and pulmonary arteries
239
Q

what is this process?

cardiac muscles of ventricles contract
-volume of ventricles starts to decrease
- blood pressure in ventricles starts to rise
- when blood pressure increases above that of the atrial the atrioventricular valves slam shut (“lubb”)
- blood pressure continues to rise as ventricular cardiac muscles continues to contract
- blood pressure now becomes greater in ventricles compares with arteries
- semi-lunar valves which have been shut until now open
- blood flows out of the heart into the aorta and pulmonary arteries

A

Ventricular systole

240
Q

cardiac muscles of ventricles________
-volume of________ starts to decrease
- blood pressure in ventricles starts to rise
- when blood pressure increases above that of the atrial the______________ valves slam shut (“lubb”)
- blood pressure continues to rise as ventricular cardiac muscles continues to contract
- blood pressure now becomes greater in ventricles compares with__________
- semi-lunar valves which have been shut until now______
- blood flows out of the heart into the aorta and pulmonary arteries

A

Contract
Ventricles
Atrioventricular
Arteries
Open

241
Q

Describe the process of an atrial diastole

A
  • atrial cardiac muscle relaxes
  • pressure decreases and blood flows into atria from veins so volume increases
242
Q

What is this the process of?

  • atrial cardiac muscle relaxes
  • pressure decreases and blood flows into atria from veins so volume increases
A

Atrial diastole

243
Q

Describe the process of a ventricular diastole.

A
  • cardiac muscles of ventricles relaxes
  • pressure in ventricles starts to decrease and volume increases
  • when the blood pressure drops below that in the arteries, the semi-lunar valves slam shut (“dub” sound)
  • on further relaxation, continued increase in volume and drop in pressure brings the blood pressure of the ventricles below that in the atria
  • atrioventricular valves now open and blood starts to flow into the ventricles from the relaxed but filling atria
244
Q

What is this the process of?

  • cardiac muscles of ventricles relaxes
  • pressure in ventricles starts to decrease and volume increases
  • when the blood pressure drops below that in the arteries, the semi-lunar valves slam shut (“dub” sound)
  • on further relaxation, continued increase in volume and drop in pressure brings the blood pressure of the ventricles below that in the atria
  • atrioventricular valves now open and blood starts to flow into the ventricles from the relaxed but filling atria
A

Ventricular diastole

245
Q

Define heart rate.

A

Number of heart beats per minute

246
Q

Define stroke volume

A

Volume of blood (cm3) pumped by heart in 1 beat

247
Q

Define cardiac output

A

Stroke volume multiplied by the heart rate gives the amount of blood (cm3) pumped by heart in 1 minute

248
Q

How do you calculate heart rate?

A

Heart rate = #beats
————-
Minute

249
Q

how do you calculate stroke volume?

A

Stroke volume = bloom cm3
—————
Beat

250
Q

How do you calculate cardiac output?

A

Cardiac output = blood cm3 X #beats = blood
————- ———- ——
Beat. Min. Min.

251
Q

What factors can change cardiac output?

A

Cardiovascular centre in brain
Hormones e.g. adrenaline
Stretching of cardiac muscle

252
Q

Narrower vessels=…….?

A

Vasoconstriction

253
Q

Wider vessels= ………….?

A

Vasodilation

254
Q

What factors affect blood pressure?

A

Cardiovascular centre
Smoking
Diet
Adrenaline
Increase in blood viscosity

255
Q

How does the cardiovascular centre affect blood pressure?

A

Diameter of blood vessels controlled by stimulation of sympathetic and parasympathetic nerves

256
Q

How does smoking affect blood pressure?

A

Nicotine causes vasoconstriction
Build up of fatty deposits in vessels

257
Q

How does diet affect blood pressure?

A

High fat diet leads to build up of fatty deposits in blood vessels

258
Q

How does adrenaline affect blood pressure ?

A

Causes selective vasoconstriction & vasodilation

259
Q

How does increase in blood viscosity affect blood pressure?

A

Excess water loss (sweating/excessive urination)

260
Q

What is the SA node also known as?

A

Pacemaker

261
Q

Describe the cardiac cycle (electrical activity)

A
  • SA mode starts initial stimulus
  • a wave of excitation is started
  • the wave spreads across both atria
  • atrial systole - blood is pushed into the ventricles
  • the atria relax
  • there is a short delay
  • excitation reaches the AV node
  • the excitation reaches the bottom of the bundle of His
  • excitation passes along the Purkyne fibres
  • the excitation moves up the sides of the ventricles
  • the ventricles contract in a wringing movement
  • blood is forced into the arteries
  • the heart is relaxed
  • the atria refill with blood
  • the next cycle starts
262
Q

The cardiac cycle

  • __ node starts initial stimulus
  • a wave of _________ is started
  • the wave spreads across both____
  • atrial systole - blood is pushed into the_________
  • the atria ______
  • there is a short ______
  • excitation reaches the __ node
  • the excitation reaches the bottom of the______ of His
  • excitation passes along the Purkyne ______
  • the excitation moves up the sides of the_________
  • the ventricles ____________ in a wringing movement
  • blood is forced into the ________
  • the_______ is relaxed
  • the atria refill with blood
  • the next cycle starts
A
  • SA
  • excitation
  • atria
  • ventricles
  • relax
  • delay
  • AV
  • bundle
  • fibres
  • ventricles
  • contract
    -arteries
    -heart
263
Q

What forms the vascular bundle?

A

Xylem and phloem

264
Q

What are the elements of the xylem vessel?

A

Dead cells (walls made of lignin, impermeable to water)

The end of the walls break down to form an uninterrupted pathway for the water (xylem vessels)

Gaps in the walls called pits to allow movements between vessels and/or living tissues nearby

265
Q

What is transpiration the movement of?

A

Water

266
Q

What ‘dilemma’ do plants have to balance water uptake with water loss?

A

Stomata open =more gas exchange but also more water loss
Stomata closed =less water loss but also less gas exchange

267
Q

How does temperature increase evaporation in a plant?

A

Temperature increase ———> water molecules gain kinetic energy——-> increased evaporation

268
Q

What happens to the rate of evaporation when you decrease humidity?

A

Increases

269
Q

Describe cohesion-tension theory.

A

Water in the xylem vessels is pulled (therefore under tension) towards the leaves because of the transpiration (transpiration pull).
Water molecules attract each other, because they are dipoles. This provides cohesion (stickiness) of the molecules, hence the uninterrupted column of water.

270
Q

Describe the root pressure theory.

A

In the roots, endodermis cells (around the xylem vessels) actively transport mineral ions into the xylem, reducing its water potential
water is drawn in hydrostatic pressure increases water is pushed upwards
(mainly herbaceous plants)

271
Q

Describe capillarity.

A

Water molecules ‘climb up’ in narrow tubes (μm) because they are attracted (adhesion) to polar molecules of the tube.
The narrower the tube the higher the water goes

272
Q

What are the 3 water movement theories?

A

Cohesion-tension theory
Root pressure
Capillarity

273
Q

Describe how plants uptake mineral ions.

A

• Plants obtain the mineral from the soil (except carnivorous plants and legumes)
• Nitrogen usually enters the plant as nitrates/ammonium ions
• Ions move into the roots by diffusion (down the concentration gradient) or active transport
• Ions move across the roots.
• At the endodermis these ions are actively transported to by-pass the Casparian bands. Plants can so be selective of the ion taken in

274
Q

What is translocation?

A

Where the phloem tissue transports substances made in the leaves to all other parts of the plant.

275
Q

What does the phloem transport?

A

Sucrose (soluble carbohydrate)
Amino acids
Minerals
Hormones

276
Q

Describe the process of translocation.

A
  1. Sucroseismanufacturedinleavesfromglucosemadeinphotosynthesis
  2. Sucrose is transported by facilitated diffusion into the companion cells
  3. Hydrogen ions are actively transported from companion cells into phloem along with sucrose.
  4. This means the contents of the phloem now has a lower water potential than the Xylem.
  5. Water from the xylem moves by osmosis into the phloem creating a hydrostatic pressure.
  6. Respiring cells are using up sucrose which lowers their water potential.
  7. Water then moves from the phloem into the xylem by osmosis.
    8 The pressure is lowered in respiring cells
    Sucrose moves from source to sink using the hydrostatic pressure gradient.
277
Q

TRANSLOCATION

  1. Sucrose is manufactured in leaves from _______made in photosynthesis
  2. Sucrose is transported by _________ diffusion into the companion cells
  3. Hydrogen ions are_____ transported from companion cells into phloem along with sucrose.
  4. This means the contents of the phloem now has a______ water potential than the Xylem.
  5. Water from the xylem moves by _______ into the phloem creating a hydrostatic pressure.
  6. Respiring cells are using up _______ which lowers their water potential.
  7. Water then moves from the phloem into the _____ by osmosis.
    8 The pressure is lowered in __________cells
    Sucrose moves from source to sink using the hydrostatic pressure gradient.
A
  1. Glucose
  2. Facilitated
  3. Actively
  4. Lower
  5. Osmosis
  6. Sucrose
  7. Xylem
  8. Respiring
278
Q

Describe the experiment using aphids to show phloem transport of food substances.

A
  • aphid penetrates the stem into the phloem using its mouthpart called stylet and sucks the plant sap
  • a feeding aphid can be anaesthetised and the stylet cut off
  • the phloem sap flows out through the stylet and can be analysed. It is found to contain sugars and other organic substances
279
Q

Describe how ringing experiments show phloem transport of food substances.

A

In the ringing experiment, a ring of bark is scraped away that also removes the phloem, exposing the xylem. Sugar then attempts to move down the stem but is stopped by the ring. This is demonstrated by a bulge of sugar forms above the ring, suggesting that sugar moves down the stem in the phloem and is transported by the xylem.

280
Q

Describe how radioactive tracers show phloem transport of food substances.

A

These show the direction of flow of sucrose, This method uses radioactive carbon dioxide (14C). This radioactive carbon dioxide is put in a bag over a leaf and sealed. The carbon dioxide gets converted into glucose and an x-ray can
be taken that will show the radioactive C in the phloem.

281
Q

What are the 3 experiments that can show phloem transport of food substances?

A
  • using aphids
  • ringing experiments
  • radioactive tracers
282
Q

What are the two ways in which water goes through a plant?

A
  • cell wall pathway
  • cytoplasmic pathway

Biology (8 decks)

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