Topic 3 - Exchange, Absorption, Digestion + Mass Transport Flashcards
1
Q
What sized organisms have a large surface area to volume ratio?
A
Small.
2
Q
What does a larger surface area to volume ratio create?
A
A short diffusion pathway to all parts of the cell.
3
Q
What happens to the surface area to volume ratio as the size of the organism increases?
A
Decreases.
4
Q
Name 2 examples of specialised exchange structures in organisms to overcome a small surface area to volume ratio
A
Lungs and gills.
5
Q
Why do elephants have large ears?
A
To increase its surface area to volume ratio to allow greater rate of heat loss from metabolic processes such as respiration.
6
Q
Why do mice have to respire at a high rate?
A
To maintain a constant body temperature due its large surface area to volume ratio.
7
Q
What surrounds the trachea?
A
Incomplete rings of cartiliage which prevent it collapsing during the pressure changes.
8
Q
What does the trachea divide into?
A
Bronchi.
9
Q
What does the bronchi divide into?
A
Bronchioles.
10
Q
What is at the end of the bronchioles?
A
Alveoli.
11
Q
What do the alveoli provide?
A
A large surface area where gaseous exchange occurs.
12
Q
Why are the alveoli flat and in large numbers?
A
To produce a large surface area.
13
Q
What present in the alveoli allows for gases to dissolve and difuse across?
A
Moist fluid.
14
Q
How many cell layers seperate the blood and the air?
A
2.
15
Q
Name the 2 different cells types in the layer between the blood and the air
A
Flattened epithelial cells
Endothelial cells
16
Q
Where are the flattened epithelial cells found?
A
Alveolar wall.
17
Q
Where are the endothelial cells found?
A
Capillary wall.
18
Q
What surrounds the alveolus?
A
Blood capillary so oxygen can be absorbed and carbon dioxide can be released.
19
Q
What does the circulatory system maintain in terms of gas exchange?
A
High diffusion gradient.
20
Q
What type of blood is transported to the lungs?
A
Deoxygenated blood.
21
Q
What type of blood is transported from the lungs?
A
Oxygenated blood.
22
Q
What does the ventilation mechanism maintain in terms of gas exchange?
A
A high diffusion gradient.
23
Q
What is the total surface area of alveoli in the body?
A
80 squared-metres.
24
Q
Where does oxygen diffuse?
A
Across flattened epithelial cells of the alveolus and the endothelial cells of the capillary wall.
25
What does oxygen combine with in red blood cells?
Haemoglobin.
26
What forms in red blood cells when oxygen is taken onboard?
Oxyhaemoglobin.
27
Where does carbon dioxide diffuse?
From the blood into the alveolar space across endothelial cells and the epithelial cells of the alveolus.
28
What concentration is maintained in the alveolar space?
High oxygen and low carbon dioxide concentration.
29
What concentration is maintained in the blood next to the alveoli?
High carbon dioxide and low oxygen concentration.
30
How manyoxygen binding sites does haemoglobin have?
4.
31
What does ventilation refer to?
The method by which air is passed over the respiratory surface to ensure a high diffusion gradient is maintained.
32
What do the external intercostal muscles do during inspiration?
Contract which pulls the ribs upwards and outwards.
33
What do the internal intercostal muscles do during inspiration?
Relax.
34
What does the diaphragm do during inspiration?
Contracts and moves down to flatten.
35
Where does volume increase in inspiration?
Thoracic cavity.
36
What happens to the pressure in the lungs during inspiration?
Decreases below atmospheric pressure and air enters the lungs along a pressure gradient.
37
Define tidal volume
Volume of air breathed in during 1 breath.
38
What is the tidal volume of an average human?
0.5dm cubed.
39
What happens to the external intercostal muscles during expiration?
Relax.
40
What happens to the internal intercostal muscles during expiration?
Contract which pulls the ribcage downwards and inwards.
41
What happens to the diaphragm during expiration?
Relaxes and moves upwards into a dome shape.
42
Where does the pressure decrease in expiration?
Thoracic cavity.
43
What happens to the pressure in the thorax during expiration?
Increases above atmospheric pressure and air is forced out of the lungs.
44
What does elastic recoil of the lung tissue also help with during expiration?
To force air out of the lungs.
45
Define pulmonary ventilation
The total volume of air that is normally moved into the lungs during one minute.
46
Give the equation for pulmonary ventilation
Tidal volume x Ventilation rate
47
What is ventilation rate?
The number of breaths per minute (12-20).
48
What does FEV stand for?
Force expiratory volume.
49
What does FVC stand for?
Forced vital capacity (deep breath out).
50
What is a risk factor?
Anything that increases the chance of getting a disease.
51
Name 3 risk factors associated lung disease
Smoking
Air pollution
Infections
52
What is relative risk?
Compares the likelihood of harm occuring to those exposed to a hazard,with those who are not exposed to it.
53
Do insects have blood?
No.
54
What part of the body of an insect prevents diffusion directly through the skin?
Exoskeleton.
55
What is the name of the system found in insects for gas exchange?
Tracheal system.
56
What is the name of the tiny holes on the insect's surface?
Spiracles.
57
What do spiracles contain?
Valves so that they can close to reduce water loss via evaporation.
58
What does each spiracle lead into?
Tracheae tubes.
59
What do the tracheae contain?
Hairs to filter anything not needed.
60
What branches of tracheae?
Tracheoles.
61
Why are tracheoles thin?
Provide a short diffusion distance.
62
Why are there many tracheoles?
To provide a large surface area.
63
What happens to the oxygen in insects?
Diffuses through the cell membrane of the tracheole into the cells.
64
What happens to the carbon dioxide in insects?
Diffuses from the cell and into the tracheoles across its cell membrane.
65
What does the opening of spiracles depend on?
Levels of carbon dioxide in the insect's body.
66
When do carbon dioxide levels rise in insects?
Respiration which causes the spiracles to open wider which increases the rate of diffusion of gases.
67
What happens in abdominal pumping?
Large/active insect's body muscles contract to compress the trachea which forces air out. When the muscles relax, the trachea springs back into shape and fresh, oxygen rich air is drawn into them.
68
What does abdominal pumping increase?
Rate of diffusion.
69
What happens during anaerobic respiration in insects?
Lactic acid is produced in the cells which lowers their water potential and some of the water in the end of the tracheoles moves into cells via osmosis.
70
Where does gas exchange occur in fish?
Gills.
71
How many gill arches are there in the gills?
4.
72
What is the name of part which protects the gill filaments?
Operculum.
73
What increases the surface area in the gills?
A large amount of gill filaments which possess lamellae, increasing the surface area even further.
74
Why is there a short diffusion path in the gills?
A two cell layer seperating the blood and water:
Epithelial layer of the lamellae
Endothelial layer of the capillaries
75
What does the circulatory system provide in fish?
Continual flow of blood through the respiratory surface to absorb oxygen and remove carbon dioxide, maintaing a high diffusion gradient for gas exchange.
76
What does the ventilation mechanism provide in fish?
A continual flow of water flowing over the gills which maintains a high diffusion gradient for gas exchange.
77
What does the countercurrent system provide in fish?
Ensures that blood continually meets water with a higher oxygen concentration so that a high diffusion gradient is maintained along the whole length of the lamellae.
78
How much water can be oxygen saturated?
100%.
79
How much blood can be oxygen saturated?
95%.
80
Which component of the plant allows very little gas exchange?
Waxy cuticle covering the leaves.
81
Name the 3 main structures involved in gas exchange in plants
Stomata
Mesophyll cells
Air spaces between the mesophyll cells
82
What is the name of the pores in the epidermis?
Stomata.
83
What surrounds the stomata?
2 guard cells.
84
How do gasses diffuse in/out of the leaves?
Stomata.
85
What is the formula for photosynthesis?
Carbon dioxide + Water --> Glucose + Oxygen
86
What is the chemical formula for photosynthesis?
6CO2 + 6H20 --> C6H12O6 + 6O2
87
Name the order of structrures in leaves from top to bottom
Waxy cuticle
Upper epidermis
Palisade Mesophyll
Spongy mesophyll (+ air spaces)
Lower epidermis
Stomata
88
When does respiration occur in plants?
At night so oxygen enters the leaf and carbon dioxide leaves the leaf.
89
What happens during the day in plants?
Photosynthesis and respiration
Rate of photosynthesis is greater than the rate of respiration
90
What part of the plant provides a large surface area for gas exchange?
Mesophyll cells lining the intercellular air spaces.
91
Where does physical digestion occur in humans?
Mouth and stomach.
92
Where does chemical digestion occur in humans?
Mouth, stomach and the small intestine.
93
Which part of the digestive system doesn't have any food passing through?
Pancreas.
94
What enzyme released in the mouth hydrolyses starch?
Salivary amylase.
95
What does salivary amylase do?
Hydrolyses starch in maltose.
96
Why does chewing help with the hydrolysis?
Breaks down particles to increase the surface area for enzymes to hydrolyse on.
97
Which organ releases enzymes into the small intestine?
Pancreas.
98
What does pancreatic amylase do?
Hydrolyses the remaining starch into maltose.
99
Where does the complete digestion of starch occur?
In the ileum.
100
Where is the ileum located?
At the final part of the small intestine's wall.
101
Where is maltase located in the human body?
In the cell-surface membrane of the epithelial cells lining the ileum.
102
What is maltase in the ileum plasma membrane also referred to as?
Membrane-bound disaccharidase.
103
What is the cell-surface membrane of the epithelial cells folding into?
Microvilli which increases the surface area of the ileum for absorption.
104
What does lactase hydrolyse?
Lactose into glucose and galactose.
105
What does sucrase hydrolyse?
Sucrose into glucose and fructose.
106
What are lipids hydrolysed into?
Glycerol, fatty acids and monoglycerides.
107
What composes monoglycerides?
Glycerol and 1 fatty acid.
108
Which enyzyme digests lipids?
Lipase.
109
Which organ secretes lipase?
Pancreas
110
Where is lipase secreted into?
Small intestine.
111
What do bile salts do?
Emulsify lipids causing them to form into small droplets in the small intestine, increasing the surface area to lipase to hydrolyse.
112
What are proteins hydrolyses by?
Endopeptidases
Exopeptidases
Dipeptidases
113
Where are amino acids absorbed into?
The ileum.
114
Where does hydrolyses of proteins begin?
Stomach.
115
Which enzyme begins the hydrolysis of proteins in the stomach?
Endopeptidases.
116
Name an example of endopeptidase
Pepsin.
117
What do endopeptidases do?
Hydrolyse interal peptide bonds between the amino acids to form smaller polypeptides and peptides (shorter amino acids chains).
118
What does the pancreas also secrete in terms of protein digestion?
Exopeptidases.
119
What do exopeptidases do?
Hydrolyse the terminal peptide bonds at the ends of the polypeptide so that indivdual amino acids are removed one at time.
120
What do exopeptidases form?
Dipeptides and amino acids.
121
Where and by what is the final stage of protein digestion?
Dipeptidases found in the cell-surface membrane of the epithelial cells in the ileum.
122
What do dipeptidases form?
Amino acids.
123
What does the presence of villi and microvilli in the ileum create?
A large surface area.
124
What does the villi contain in the ileum?
Blood capillaries that absorb monosaccharides and amino acids which maintains a high diffusion gradient for further absorption.
125
How many cells thick is the wall of each villus in the ileum?
One layer of epithelial cells (short diffusion pathway).
126
What forms when bile salts associate themselves with monoglycerides and fatty acids?
Micelles.
127
What do micelles do?
Transport poorly soluble monoglycerides and fatty acids to the surface membreanr of the epithelial cell. The micelles then break down and release the fatty acids and monoglycerides.
128
How does the characteristic of non-polar affect the diffusion of monoglycerides and fatty acids?
They can diffuse through the phospholipid bilayer of the folded cell-surface membrane.
129
What happens when monogylcerides and fatty acidsa re inside the cell?
They reform into triglycerides in the smooth endoplasmic reticulum.
130
What forms when protein is added to the triglyceride?
Chylomicrons.
131
Where are chylomicrons formed?
Golgi apparatus.
132
What happens to chylomicrons?
Absorbed into the lacteals (lymphatic vessels) in the villi which eventually drain into the blood.
133
What is exocytosis?
When chylomicrons are secreted into lacteals.
134
What happens in stage 1 in the co-transport of monosaccharides?
A sodium-potassium pump actively transports sodium out of the epithelial cells and into the blood capillary. (needs ATP)
135
What happens in stage 2 in the co-transport of monosaccharides?
A concentration gradient is set up, a higher concentration of sodium is present in the lumen of ileum, and a lower concentration is present inside the epithelial cells.
136
What happens in stage 3 in the co-transport of monosaccharides?
Sodium diffuses down the concentration gradient from the ileum lumen into the epithelial cells and take glucose with them against its concentration gradient.
137
What happens in stage 4 in the co-transport of monosaccharides?
Glucose moves by facilitated diffusion through a carrier protein from a high concentration in the epithelial cell to a low concentration in the blood.
138
Name the 4 scenarios when valves open
1. When the pressure behind the valve is greater than the pressure in front of the valve.
2. When the ventricular pressure exceeds the aortic pressure (semi-lunar valve opens).
3. Due to an increase in volume of blood.
4. Contraction of the atria.
139
When will valves close?
1. When the pressure in front of the valve exceeds the presuure behind the valve. (pressure in ventricle > pressure in atria).
2. Pressure in pulmonary artery > pressure in ventricles
140
Which ventricle has thicker muscular wall?
Left ventricle.
141
What do tendinous cords do?
Prevent atrio-ventricular valves from turning inside out as ventricular pressure exceeds atria pressure.
