Topic 7 Muscles Flashcards
1
Q
What are the components involved in movement?
A
Skeletal muscles, tendons, ligaments, and joints
2
Q
How are skeletal muscles attached to bones?
A
By tendons
3
Q
What type of muscle is used for movement?
A
Skeletal muscle
4
Q
What is the role of ligaments?
A
Attach bones to other bones
5
Q
What happens when skeletal muscles contract?
A
They move bones at a joint
6
Q
What are the two muscles involved in moving the lower arm?
A
Biceps and triceps
7
Q
What is the term for a muscle that bends a joint when it contracts?
A
Flexor
8
Q
What is the term for a muscle that straightens a joint when it contracts?
A
Extensor
9
Q
What are muscles that work together to move a bone called?
A
Antagonistic pairs
10
Q
Why do muscles work in pairs?
A
Because they can only pull and not push
11
Q
What are skeletal muscle fibers made up of?
A
Large bundles of long cells called muscle fibers
12
Q
What is the cell membrane of muscle fiber cells called?
A
Sarcolemma
13
Q
What are transverse (T) tubules?
A
Folds of the sarcolemma that spread electrical impulses
14
Q
What does the sarcoplasmic reticulum do?
A
Stores and releases calcium ions needed for muscle contraction
15
Q
What is the function of mitochondria in muscle fibers?
A
Provide ATP needed for muscle contraction
16
Q
What does it mean that muscle fibers are multinucleate?
A
They contain many nuclei
17
Q
What are myofibrils?
A
Long, cylindrical organelles made up of proteins highly specialized for contraction
18
Q
What is the structural unit of a myofibril?
A
Sarcomere
19
Q
What are the dark bands in myofibrils called?
A
A bands
20
Q
What are the light bands in myofibrils called?
A
I bands
21
Q
What is the M-line?
A
The middle of the sarcomere
22
Q
What is the H-zone?
A
The region around the M-line that only contains thick filaments
23
Q
What are the two main proteins involved in muscle contraction?
A
Myosin and actin
24
Q
True or False: Sarcomeres contract simultaneously to shorten the muscle.
A
True
25
Fill in the blank: Skeletal muscle fibers have lots of _______ to provide ATP.
Mitochondria
26
What are the components involved in movement?
Skeletal muscles, tendons, ligaments, and joints
27
How are skeletal muscles attached to bones?
By tendons
28
What type of muscle is used for movement?
Skeletal muscle
29
What is the role of ligaments?
Attach bones to other bones
30
What happens when skeletal muscles contract?
They move bones at a joint
31
What are the two muscles involved in moving the lower arm?
Biceps and triceps
32
What is the term for a muscle that bends a joint when it contracts?
Flexor
33
What is the term for a muscle that straightens a joint when it contracts?
Extensor
34
What are muscles that work together to move a bone called?
Antagonistic pairs
35
Why do muscles work in pairs?
Because they can only pull and not push
36
What are skeletal muscle fibers made up of?
Large bundles of long cells called muscle fibers
37
What is the cell membrane of muscle fiber cells called?
Sarcolemma
38
What are transverse (T) tubules?
Folds of the sarcolemma that spread electrical impulses
39
What does the sarcoplasmic reticulum do?
Stores and releases calcium ions needed for muscle contraction
40
What is the function of mitochondria in muscle fibers?
Provide ATP needed for muscle contraction
41
What does it mean that muscle fibers are multinucleate?
They contain many nuclei
42
What are myofibrils?
Long, cylindrical organelles made up of proteins highly specialized for contraction
43
What is the structural unit of a myofibril?
Sarcomere
44
What are the dark bands in myofibrils called?
A bands
45
What are the light bands in myofibrils called?
I bands
46
What is the M-line?
The middle of the sarcomere
47
What is the H-zone?
The region around the M-line that only contains thick filaments
48
What are the two main proteins involved in muscle contraction?
Myosin and actin
49
True or False: Sarcomeres contract simultaneously to shorten the muscle.
True
50
Fill in the blank: Skeletal muscle fibers have lots of _______ to provide ATP.
Mitochondria
51
What are the two main types of filaments in muscle contraction?
Thick myofilaments (myosin) and thin myofilaments (actin)
## Footnote
Myosin and actin are the proteins that make up the muscle fibers and are essential for muscle contraction.
52
What are A-bands and I-bands in muscle fibers?
A-bands contain thick myosin filaments and overlapping thin actin filaments; I-bands contain only thin actin filaments
## Footnote
A-bands appear dark, while I-bands appear light under a microscope.
53
What marks the ends of each sarcomere?
Z-line
## Footnote
The Z-line is crucial for the structural integrity of the sarcomere.
54
What is the M-line in a sarcomere?
The middle of the myosin filaments
## Footnote
The M-line serves as an anchoring point for myosin filaments.
55
What does the H-zone contain?
Only myosin filaments
## Footnote
The H-zone is the area in a sarcomere where there are no overlapping actin filaments.
56
What theory explains muscle contraction?
Sliding Filament Theory
## Footnote
This theory states that myosin and actin filaments slide over each other to contract the sarcomeres.
57
What happens to the length of sarcomeres during contraction?
Sarcomeres get shorter
## Footnote
The A-bands remain the same length, while the I-band and H-zone get shorter.
58
Fill in the blank: The __________ are the functional units of muscle fibers.
sarcomeres
59
What is the relationship between myofilaments, muscle fibers, myofibrils, and muscles?
Myofilaments form myofibrils, which make up muscle fibers, which together form muscles
## Footnote
This hierarchical structure is essential for muscle function.
60
True or False: When a muscle contracts, the myofilaments themselves change length.
False
## Footnote
The myofilaments do not change length; rather, they slide past each other.
61
What are antagonistic pairs in muscle movement?
Muscles that work together to move a bone by one contracting while the other relaxes
## Footnote
This mechanism allows for controlled movement, such as bending and straightening limbs.
62
What is the role of transverse (T) tubules in muscle fibers?
They help transmit electrical signals deep into the muscle fiber
## Footnote
This process is crucial for initiating muscle contraction.
63
What do myosin filaments have that allows them to move back and forth?
Globular heads and binding sites
## Footnote
Myosin filaments have globular heads that are hinged.
64
What proteins are found between actin filaments that help myofilaments move past each other?
Tropomyosin and troponin
## Footnote
These proteins are essential for the muscle contraction process.
65
What blocks the actin-myosin binding site in resting muscles?
Tropomyosin
## Footnote
Tropomyosin is held in place by troponin.
66
What triggers muscle contraction?
An action potential
## Footnote
The action potential comes from a motor neurone.
67
What happens to the sarcolemma during depolarisation?
The difference in charge across the sarcolemma is reduced
## Footnote
This is a crucial step in triggering muscle contraction.
68
What is released from the sarcoplasmic reticulum when it is stimulated?
Calcium ions (Ca²⁺)
## Footnote
These ions play a key role in muscle contraction.
69
What does calcium bind to, causing a change in shape?
Troponin
## Footnote
This binding pulls tropomyosin out of the actin-myosin binding site.
70
What is formed when a myosin head binds to an actin filament?
An actin-myosin cross bridge
## Footnote
This bond is essential for muscle contraction.
71
What enzyme is activated by calcium ions to provide energy for muscle contraction?
ATPase
## Footnote
ATPase breaks down ATP into ADP + Pᵢ.
72
What happens to the actin filament when the myosin head moves?
It is pulled along in a rowing action
## Footnote
This movement leads to muscle contraction.
73
What provides the energy needed to detach the myosin head from the actin filament?
ATP
## Footnote
ATP is crucial for both movement and detachment processes.
74
What occurs after the myosin head detaches from the actin filament?
It reattaches to a different binding site
## Footnote
This process repeats, forming many cross bridges quickly.
75
What happens to the sarcomere during muscle contraction?
It shortens
## Footnote
This shortening results from the sliding of actin filaments.
76
What is required for the cycle of muscle contraction to continue?
Calcium ions must be present and bound to troponin
## Footnote
This ensures that the binding sites remain exposed.
77
Fill in the blank: In skeletal muscles, the muscle fibers that are good for endurance are known as _______.
Slow twitch
## Footnote
Slow twitch fibers are characterized by high mitochondrial content and reddish color.
78
What type of muscles are good for posture and long-distance activities?
Skeletal muscles
## Footnote
These muscles can work for a long duration due to their energy efficiency.
79
What happens to calcium ions when muscle excitation stops?
Calcium ions leave their binding sites in the sarcoplasmic reticulum and are transported back into the sarcoplasmic reticulum, which requires ATP.
80
What is the role of troponin in muscle contraction?
Troponin changes shape when calcium ions bind to it, allowing myosin heads to attach to actin filaments.
81
What is the effect of tropomyosin when muscle contraction stops?
Tropomyosin blocks the actin-myosin binding sites, preventing myosin heads from attaching to actin filaments.
82
What occurs to the actin filaments when muscle relaxation happens?
The actin filaments slide back to their relaxed position, lengthening the sarcomere.
83
What are the two types of skeletal muscle fibres?
Slow twitch and fast twitch muscle fibres.
84
List three properties of slow twitch muscle fibres.
* Contract slowly
* Good for endurance activities
* Rich in mitochondria and myoglobin
85
List three properties of fast twitch muscle fibres.
* Contract very quickly
* Good for short bursts of speed and power
* Rich in glycogen
86
What is the primary energy source for slow twitch muscle fibres?
Aerobic respiration.
87
What is the primary energy source for fast twitch muscle fibres?
Anaerobic respiration using glycogen.
88
What color are slow twitch muscle fibres and why?
Reddish in color due to high myoglobin content.
89
What color are fast twitch muscle fibres and why?
Whitish in color due to low myoglobin content.
90
Which molecule blocks the actin-myosin binding site in resting muscles?
Tropomyosin.
91
What is the name of the bond formed when a myosin head binds to an actin filament?
Actin-myosin cross bridge.
92
Fill in the blank: Rigor mortis is the stiffening of muscles in the body after death. It happens when _______ reserves are exhausted.
ATP
93
Describe the effect of Bepridil on muscle contraction.
Bepridil blocks calcium ion channels, preventing calcium ions from entering the muscle cells, which inhibits muscle contraction.
94
What is the overall equation for aerobic respiration?
C6H12O6 (glucose) + 6O2 = 6CO2 + 6H2O + Energy
## Footnote
This equation summarizes the process of aerobic respiration, highlighting the reactants and products involved.
95
What is the primary purpose of the energy released during aerobic respiration?
To phosphorylate ADP to ATP
## Footnote
ATP is then used to provide energy for all biological processes inside a cell.
96
What are the four stages of aerobic respiration?
* Glycolysis
* Link reaction
* Krebs cycle
* Oxidative phosphorylation
## Footnote
The first three stages involve a series of reactions that produce products used in the final stage to produce ATP.
97
Where does glycolysis occur in the cell?
In the cytoplasm
## Footnote
The other three stages of aerobic respiration take place in the mitochondria.
98
What is a rate-limiting enzyme?
The enzyme with the slowest activity that determines the overall rate of respiration
## Footnote
Each reaction in respiration is controlled and catalyzed by specific intracellular enzymes.
99
What role do coenzymes play in respiration?
They transfer hydrogen from one molecule to another
## Footnote
Examples include NAD and FAD, which can reduce or oxidize a molecule.
100
What is a respiratory substrate?
A molecule that can be respired, such as glucose
## Footnote
All cells use glucose to respire, but other complex organic molecules can also be broken down.
101
What happens during glycolysis?
Glucose is split into two molecules of pyruvate
## Footnote
This process occurs in the cytoplasm and does not require oxygen.
102
What are the two stages of glycolysis?
* Phosphorylation
* Oxidation
## Footnote
During phosphorylation, ATP is used to phosphorylate glucose; in oxidation, triose phosphate is oxidized to form pyruvate.
103
What is the net gain of ATP from glycolysis?
2 ATP
## Footnote
Four ATP are produced, but 2 are used up in the phosphorylation stage.
104
What type of process is glycolysis?
Anaerobic process
## Footnote
Glycolysis does not require oxygen.
105
What happens to the two pyruvate molecules after glycolysis?
They go into the matrix of the mitochondria for the link reaction
## Footnote
This is the next step in aerobic respiration.
106
How many molecules of reduced NAD are formed during glycolysis?
2 molecules
## Footnote
These are used in the last stage of respiration (oxidative phosphorylation).
107
Fill in the blank: Glycolysis involves the partial oxidation of glucose via _______.
triose phosphate
## Footnote
To completely oxidize glucose, oxygen and the other steps in aerobic respiration are needed.
108
What is the first stage of aerobic respiration?
Glycolysis
## Footnote
Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate.
109
What is produced during the link reaction?
Acetyl coenzyme A (acetyl CoA)
## Footnote
The link reaction decarboxylates pyruvate, releasing CO2 and forming acetyl CoA.
110
How many times does the link reaction occur for each glucose molecule?
Twice
## Footnote
This is because two pyruvate molecules are produced from one glucose molecule.
111
What does NAD do during the link reaction?
NAD is reduced
## Footnote
NAD collects hydrogen from pyruvate, forming reduced NAD.
112
What is released as a waste product during the link reaction?
CO2
## Footnote
One carbon atom is removed from pyruvate, forming CO2.
113
What is the overall net gain of ATP from glycolysis?
2
## Footnote
Glycolysis uses 2 ATP but produces 4 ATP, leading to a net gain of 2 ATP.
114
Where in the cell does glycolysis occur?
Cytoplasm
## Footnote
Glycolysis takes place in the cytoplasm of the cell.
115
Is glycolysis an anaerobic or aerobic process?
Anaerobic
## Footnote
Glycolysis does not require oxygen.
116
What is the product of the link reaction?
Acetyl coenzyme A (acetyl CoA)
## Footnote
Acetyl CoA is formed from acetate and coenzyme A.
117
Name one coenzyme involved in respiration.
Coenzyme A (CoA)
## Footnote
CoA plays a crucial role in the link reaction and Krebs cycle.
118
How many ATP molecules are used up in glycolysis?
2
## Footnote
Glycolysis requires an investment of 2 ATP for the process to begin.
119
True or False: ATP is phosphorylated to form ADP during glycolysis.
False
## Footnote
ATP is generated from ADP during glycolysis, not the other way around.
120
What happens to pyruvate once produced by glycolysis?
It enters the link reaction
## Footnote
Pyruvate is converted to acetyl CoA in the link reaction.
121
What is the net gain of glycolysis?
2 ATP
## Footnote
Glycolysis is the first stage of aerobic respiration and produces a net gain of 2 ATP molecules.
122
What are the main stages of aerobic respiration?
1. Glycolysis
2. Link Reaction
3. Krebs Cycle
4. Oxidative Phosphorylation
## Footnote
These stages are essential for the complete breakdown of glucose to produce ATP.
123
How many times does the Krebs Cycle occur for each glucose molecule?
Twice
## Footnote
The Krebs Cycle occurs once for each pyruvate molecule, and since one glucose produces two pyruvate, the cycle runs twice.
124
What compound does Acetyl CoA combine with in the Krebs Cycle?
Oxaloacetate
## Footnote
Acetyl CoA combines with oxaloacetate to form citrate, initiating the Krebs Cycle.
125
What is produced during the decarboxylation process in the Krebs Cycle?
CO₂
## Footnote
Decarboxylation involves the removal of carbon dioxide from organic compounds.
126
What are the products of one turn of the Krebs Cycle?
* 1 Coenzyme A
* 2 CO₂
* 1 ATP
* 3 reduced NAD
* 1 reduced FAD
## Footnote
These products are generated from one molecule of Acetyl CoA in the Krebs Cycle.
127
What is substrate-level phosphorylation?
Direct transfer of a phosphate group from one molecule to another
## Footnote
This process is how ATP is produced during certain steps in the Krebs Cycle.
128
What are the two processes involved in oxidative phosphorylation?
* Electron transport chain
* Chemiosmosis
## Footnote
These processes work together to produce ATP using the energy from reduced coenzymes.
129
How is ATP generated during chemiosmosis?
By the movement of protons across the mitochondrial membrane
## Footnote
The flow of protons through ATP synthase generates ATP.
130
What is the final electron acceptor in the electron transport chain?
Oxygen
## Footnote
Oxygen is critical for the process as it combines with electrons and protons to form water.
131
True or False: Reduced NAD and FAD are produced in the Krebs Cycle.
True
## Footnote
Both reduced NAD and reduced FAD are generated as byproducts of the Krebs Cycle.
132
Fill in the blank: Oxidative phosphorylation produces lots of _______.
ATP
## Footnote
The main purpose of oxidative phosphorylation is to generate a large amount of ATP.
133
What is the total maximum ATP yield from aerobic respiration?
38 ATP
## Footnote
This total includes ATP produced from glycolysis, Krebs Cycle, and oxidative phosphorylation.
134
What is the main function of the Krebs cycle?
The Krebs cycle generates reduced coenzymes NADH and FADH2 for oxidative phosphorylation.
135
Where does the Krebs cycle take place?
In the mitochondrial matrix.
136
What is chemiosmosis?
The movement of H+ ions across a membrane that generates ATP.
137
What are the final products of the electron transport chain?
Water (H2O) is formed from protons, electrons, and oxygen.
138
What is the role of oxygen in cellular respiration?
Oxygen is the final electron acceptor in the electron transport chain.
139
How many ATP are produced from one reduced NAD?
3 ATP.
140
How many ATP are produced from one reduced FAD?
2 ATP.
141
Complete the sentence: The electrochemical gradient created during oxidative phosphorylation is due to the _______ of protons.
concentration difference.
142
What metabolic process is inhibited by some poisons targeting electron carriers?
Oxidative phosphorylation.
143
What happens to reduced NAD and reduced FAD when electron transport chain activity is halted?
They are not oxidized, preventing regeneration for the Krebs cycle.
144
True or False: The Krebs cycle occurs only once for each molecule of glucose.
False.
145
How many ATP are produced during glycolysis?
2 ATP.
146
How many carbon dioxide molecules are produced during one turn of the Krebs cycle?
2 carbon dioxide molecules.
147
What is the total ATP yield from one molecule of glucose in aerobic respiration?
38 ATP.
148
List the stages of respiration where ATP is produced.
* Glycolysis
* Link Reaction
* Krebs cycle
* Oxidative phosphorylation
149
What is the consequence of insufficient ATP synthesis for cellular processes?
Failure to fuel ATP-requiring processes, which can be fatal.
150
What role does ATP synthase play in ATP production?
It synthesizes ATP from ADP and inorganic phosphate using the energy from H+ ion movement.
151
Complete the sentence: The concentration of protons is higher in the _______ than in the mitochondrial matrix.
intermembrane space.
152
What does a respirometer measure?
The volume of oxygen being taken up in a given time
## Footnote
The more oxygen taken up, the faster the rate of respiration.
153
How can the rate of respiration be determined?
By measuring the volume of oxygen taken up or the volume of carbon dioxide produced in a given time
154
What is the purpose of potassium hydroxide solution in a respirometer?
To absorb carbon dioxide produced during respiration
155
What is the role of the control tube in a respirometer experiment?
To ensure results are only due to the woodlice respiring, using beads with the same mass instead of woodlice
156
What should be done before starting a respirometer experiment?
Set the fluid in the manometer to a known level using a syringe
157
What happens to the volume of air in the test tube during respiration?
There will be a decrease in the volume of air due to oxygen consumption by the woodlice
158
What causes the colored liquid in the manometer to move towards the test tube?
The decrease in volume of air that reduces the pressure in the tube
159
What must be controlled to ensure accurate respirometer results?
Temperature and volume of potassium hydroxide solution in each test tube
160
How is the volume of oxygen taken in by the woodlice calculated?
By measuring the distance moved by the liquid in the manometer over a given time
161
What is lactate fermentation?
A process that occurs during anaerobic respiration, producing lactic acid
162
Fill in the blank: The apparatus is left for a set period of time (e.g. _______ minutes).
[20]
163
True or False: Other small invertebrates, such as aphids, can be used in respirometer experiments.
True
164
What should be ensured when working with living organisms in experiments?
They are treated with respect and not harmed or distressed unnecessarily
165
What is the purpose of repeating the experiment in respirometry?
To produce more precise results and calculate a mean volume of oxygen
166
What does a respirometer measure?
The rate of respiration
## Footnote
A respirometer is an instrument used to measure the amount of oxygen consumed or carbon dioxide produced by an organism.
167
Lactate fermentation is an example of what type of respiration?
Anaerobic respiration
## Footnote
Anaerobic respiration occurs in the absence of oxygen and includes processes like lactate fermentation.
168
Give one way that animals can break down lactate.
Cells can convert the lactic acid back to pyruvate
## Footnote
Pyruvate can then re-enter aerobic respiration at the Krebs cycle.
169
What is the first step of lactate fermentation?
Glycolysis
## Footnote
Glycolysis converts glucose to pyruvate, producing reduced NAD which is essential for lactate formation.
170
What does reduced NAD do in lactate fermentation?
Transfers hydrogen to pyruvate to form lactate
## Footnote
This process regenerates NAD, allowing glycolysis to continue under anaerobic conditions.
171
Fill in the blank: Anaerobic respiration doesn't use _______.
oxygen
172
What happens to lactic acid after a period of anaerobic respiration?
It builds up in the body
## Footnote
Lactic acid accumulation can lead to muscle fatigue and discomfort.
173
How can liver cells break down lactic acid?
Convert the lactic acid back to glucose
## Footnote
This glucose can then be respired or stored in the liver.
174
What is the role of potassium hydroxide in a respirometer?
Absorbs carbon dioxide
## Footnote
This allows for the measurement of oxygen consumption without interference from CO2 production.
175
True or False: Anaerobic respiration can produce a small amount of ATP.
True
## Footnote
Even in low oxygen conditions, anaerobic respiration allows for some ATP production, which is crucial for survival.
176
What is the end product of lactate fermentation in animals?
Lactate (lactic acid)
## Footnote
This product is formed when pyruvate is reduced by NADH during anaerobic conditions.
177
What is the function of the control tube in a respirometer experiment?
To serve as a baseline measurement
## Footnote
The control tube helps account for any changes not related to respiration, ensuring accurate results.
178
Which process allows glycolysis to continue in anaerobic conditions?
Lactate fermentation
## Footnote
This process regenerates NAD from reduced NAD, facilitating ongoing ATP production.
179
Fill in the blank: The Krebs cycle occurs during _______ respiration.
aerobic
180
What inhibits the electron transport chain in aerobic respiration?
Antimycin C
## Footnote
This substance prevents electron transfer, affecting ATP production but not lactate formation.
181
What is produced from the breakdown of glucose during glycolysis?
Pyruvate
## Footnote
Pyruvate is a key intermediate that can enter either aerobic respiration or anaerobic fermentation.
182
What is the role of the sino-atrial node (SAN) in the heart?
The SAN sets the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls.
## Footnote
The SAN is often referred to as the heart's pacemaker.
183
What happens when the SAN sends out electrical activity?
It causes the right and left atria to contract at the same time.
184
What type of tissue prevents electrical activity from passing directly from the atria to the ventricles?
A band of non-conducting collagen tissue.
185
What is the function of the atrioventricular node (AVN)?
The AVN passes the waves of electrical activity on to the bundle of His after a slight delay.
186
What is the bundle of His responsible for?
Conducting the waves of electrical activity to the Purkyne fibres in the ventricles.
187
What are Purkyne fibres?
Finer muscle fibres in the right and left ventricle walls that carry the waves of electrical activity.
188
How do the ventricles contract?
They contract simultaneously from the bottom up.
189
What is an electrocardiograph?
A machine that records the electrical activity of the heart.
190
What does the heart muscle do when it contracts and relaxes?
It depolarises (loses electrical charge) when it contracts and repolarises (regains charge) when it relaxes.
191
What is the trace produced by an electrocardiograph called?
Electrocardiogram (ECG).
192
What does the P wave in an ECG represent?
Contraction (depolarisation) of the atria.
193
What is the QRS complex in an ECG?
The main peak of the heartbeat, caused by contraction (depolarisation) of the ventricles.
194
What does the T wave in an ECG indicate?
Relaxation (repolarisation) of the ventricles.
195
Fill in the blank: A bigger wave in the P and R waves of an ECG indicates a _______.
stronger contraction.
196
True or False: Doctors use ECGs to compare the heart's rhythm with healthy conditions.
True.
197
What might an ectopic heartbeat indicate?
It suggests that there is an additional contraction that occurs earlier than expected.
198
Describe the purpose of an electrocardiograph in cardiac health assessment.
To record the electrical activity of the heart and assess heart function.
199
What is tachycardia?
A heartbeat that is too fast, around 120 beats per minute.
## Footnote
It may be normal during exercise but indicates inefficient blood pumping at rest.
200
What is bradycardia?
A heartbeat that is too slow, below 60 beats per minute at rest.
## Footnote
This condition can indicate potential heart issues.
201
What is an ectopic heartbeat?
An 'extra' heartbeat caused by earlier contraction of the atria or ventricles.
## Footnote
Occasional ectopic heartbeats in healthy individuals typically do not cause problems.
202
What does fibrillation indicate?
A really irregular heartbeat where the atria or ventricles lose rhythm and stop contracting properly.
## Footnote
It can lead to symptoms ranging from chest pain to fainting and even death.
203
What prevents impulses from the atria travelling straight into the ventricles?
The atrioventricular node (AVN).
204
What structure picks up impulses from the atria and passes them on to the ventricles?
The bundle of His.
205
What is the function of the Purkyne fibres?
To conduct electrical impulses to the ventricles, causing them to contract.
206
What causes the P wave of an ECG trace?
The depolarization of the atria.
207
True or False: Occasional ectopic heartbeats are always a cause for concern.
False.
208
Fill in the blank: A heartbeat that is too fast is called _______.
[tachycardia]
209
Fill in the blank: A heartbeat that is too slow is called _______.
[bradycardia]
210
What are the potential outcomes of fibrillation?
* Chest pain
* Fainting
* Lack of pulse
* Death
211
Describe the function of the sinoatrial node.
It acts as the natural pacemaker of the heart, initiating the heartbeat.
212
Give one possible cause of an ECG which has a QRS complex that is not as high as normal.
Muscle damage or poor electrical conduction.
213
What happens to breathing rate and heart rate when you exercise?
They increase to supply more oxygen and remove carbon dioxide
## Footnote
This increase is due to the muscles contracting more frequently and using more energy.
214
What are the two main functions of increased breathing during exercise?
* Obtain more oxygen
* Remove more carbon dioxide
215
What is the role of the heart rate during exercise?
To deliver oxygen and glucose to muscles faster and remove extra carbon dioxide
216
Which part of the brain controls breathing rate?
The medulla oblongata
217
What are the two ventilation centres in the medulla oblongata?
* Inspiratory centre
* Expiratory centre
218
What does the inspiratory centre do?
Sends nerve impulses to intercostal and diaphragm muscles to contract
219
What is the effect of the inspiratory centre on lung volume and pressure?
Increases lung volume, which lowers pressure in the lungs
220
How does air enter the lungs?
Due to the pressure difference between the lungs and the air outside
221
What stimulates the stretch receptors in the lungs?
Inflation of the lungs
222
What happens when the stretch receptors are stimulated?
They send nerve impulses back to the medulla oblongata, inhibiting the inspiratory centre
223
What does the expiratory centre do when it is no longer inhibited?
Sends nerve impulses to the diaphragm and intercostal muscles to relax
224
What is the result of the diaphragm and intercostal muscles relaxing?
Lungs deflate, expelling air
225
Fill in the blank: The ventilation centre can also be called the _______.
[respiratory centre]
226
True or False: The inspiratory centre inhibits the expiratory centre.
True
227
What happens to the cycle of breathing after the lungs deflate?
The stretch receptors become inactive, allowing the inspiratory centre to function again
228
What happens to the level of carbon dioxide (CO2) in the blood during exercise?
The level of carbon dioxide (CO2) in the blood increases
## Footnote
This increase decreases the pH of the blood.
229
What are chemoreceptors?
Chemoreceptors are receptors that sense chemicals
## Footnote
They are located in the medulla oblongata and in the aortic and carotid bodies.
230
What effect do chemoreceptors have when they detect a decrease in blood pH?
They send nerve impulses to the medulla oblongata
## Footnote
This results in more frequent nerve impulses to the intercostal muscles and diaphragm.
231
What is the primary function of the ventilation centre?
The ventilation centre controls the rate of breathing
## Footnote
It is also known as the respiratory centre.
232
What is the definition of ventilation rate?
Ventilation rate is the volume of air breathed in or out in a period of time, e.g., a minute.
233
How does exercise affect ventilation rate?
Ventilation rate increases during exercise
## Footnote
This is due to an increase in both breathing rate and depth.
234
Fill in the blank: The carotid arteries carry blood to the _______.
brain
235
What happens to the CO2 level during increased breathing rate and depth?
The CO2 level drops
## Footnote
This occurs as extra O2 is supplied for the muscles.
236
What triggers exhalation following inhalation?
Stretch receptors in the lungs
## Footnote
They respond to lung expansion and signal for exhalation.
237
True or False: The intercostal muscles contract during inhalation.
True
238
What is the expected effect of adding dilute carbonic acid to the blood in the coronary artery of an anaesthetised animal?
The animal's breathing rate would increase
## Footnote
This is due to the increased CO2 levels in the blood.
239
List the components of the ventilation rate that increase during exercise.
* Breathing rate
* Depth of breathing
240
What happens to the breathing rate after the pH of the blood returns to normal?
Breathing rate decreases
241
What part of the brain controls the heart rate?
The medulla oblongata
## Footnote
The cardiovascular control centre in the medulla oblongata manages heart rate unconsciously.
242
What is the role of the sinoatrial node (SAN) in heart function?
The SAN generates electrical impulses that cause the atria to contract, setting the rhythm of the heartbeat.
243
What types of receptors detect stimuli in the blood related to heart rate?
Pressure receptors (baroreceptors) and chemical receptors (chemoreceptors)
## Footnote
Baroreceptors are located in the aortic and carotid bodies, while chemoreceptors monitor oxygen, carbon dioxide, and pH levels.
244
True or False: The sympathetic nervous system decreases heart rate.
False
## Footnote
The sympathetic nervous system prepares the body for action and increases heart rate during exercise.
245
What neurotransmitter is secreted by parasympathetic neurones to decrease heart rate?
Acetylcholine
246
Fill in the blank: Baroreceptors detect ______ blood pressure.
high or low
247
What is the response of the SAN when high blood pressure is detected?
The SAN fires impulses less frequently to slow heart rate and reduce blood pressure back to normal.
248
What happens when chemoreceptors detect low blood oxygen levels?
The SAN fires impulses more frequently to increase heart rate and return oxygen levels back to normal.
249
How does the cardiovascular control centre respond to low blood pressure?
It sends impulses along sympathetic neurones, secreting noradrenaline to increase heart rate.
250
List the factors that chemoreceptors monitor in the blood.
* Oxygen level
* Carbon dioxide level
* pH
251
What is the primary function of the cardiovascular control centre?
To process information from receptors and regulate heart rate through sympathetic and parasympathetic impulses.
252
Fill in the blank: The parasympathetic nervous system is known as the '______ and digest' system.
rest
253
What effect does exercise have on heart rate?
Increases heart rate
254
What is the function of baroreceptors in relation to blood pressure?
They detect high and low blood pressure.
255
True or False: The medulla oblongata is responsible for conscious control of heart rate.
False
## Footnote
Heart rate is controlled unconsciously by the cardiovascular control centre in the medulla oblongata.
256
What is the equation for calculating cardiac output?
Cardiac output (cm³ min⁻¹) = heart rate (beats per minute) x stroke volume (cm³)
## Footnote
Cardiac output increases with exercise due to increased heart rate and stroke volume.
257
Define stroke volume.
The volume of blood pumped by one ventricle each time it contracts
## Footnote
Stroke volume is measured in cm³.
258
What happens to cardiac output during exercise?
Cardiac output increases due to increased heart rate and stroke volume
## Footnote
This change supports the body's increased demand for oxygen.
259
Fill in the blank: Stroke volume (cm³) = _______.
cardiac output (cm³ min⁻¹) / heart rate (beats per minute)
260
What is the heart rate of a swimmer before swimming 50 m?
65 bpm
## Footnote
This is the heart rate at rest.
261
Calculate the cardiac output before swimming for a swimmer with a heart rate of 65 bpm and a stroke volume of 70 cm³.
4550 cm³ min⁻¹
## Footnote
Calculation: 65 bpm x 70 cm³ = 4550 cm³ min⁻¹.
262
What is the heart rate of the swimmer after swimming 50 m?
120 bpm
## Footnote
This represents the increased demand after exercise.
263
What is the difference in cardiac output for the swimmer before and after the swim?
6250 cm³ min⁻¹
## Footnote
Calculation: 10,800 cm³ min⁻¹ (after) - 4550 cm³ min⁻¹ (before) = 6250 cm³ min⁻¹.
264
What is the stroke volume of the swimmer after swimming?
90 cm³
## Footnote
Calculation: 10,800 cm³ min⁻¹ / 120 bpm = 90 cm³.
265
Which type of receptors detect changes in blood pressure?
Baroreceptors
## Footnote
These receptors play a crucial role in regulating blood pressure.
266
What effect do neurotransmitters released from parasympathetic neurones have on heart rate?
They decrease heart rate
## Footnote
This is part of the body's response to rest.
267
What neurotransmitter do sympathetic neurones release onto the SAN?
Norepinephrine
## Footnote
This neurotransmitter increases heart rate.
268
True or False: Cardiac output decreases during exercise.
False
## Footnote
Cardiac output increases to meet the body's higher oxygen demand.
269
Before a race, a runner has a stroke volume of 72 cm³ and a cardiac output of 5420 cm³ min⁻¹. What is the runner's heart rate before the race?
75 bpm
## Footnote
Calculation: 5420 cm³ min⁻¹ / 72 cm³ = 75 bpm.
270
Explain how information about chemical changes in the blood are relayed to the brain during exercise.
Chemoreceptors detect changes and send signals to the brain, influencing heart rate and breathing
## Footnote
This involves a feedback loop that helps regulate physiological responses.
271
Explain how increased activity of sympathetic neurones affects the runner's heart rate when running.
It increases heart rate to supply more oxygen to muscles
## Footnote
This response is critical during physical exertion.
272
What is tidal volume?
The volume of air in each breath, usually about 0.4 dm³
## Footnote
1 dm³ is equivalent to 1 litre.
273
What does breathing rate refer to?
How many breaths are taken, usually measured per minute.
274
What is oxygen consumption?
The volume of oxygen used by the body, often expressed as a rate.
275
How is respiratory minute ventilation calculated?
Respiratory minute ventilation = tidal volume x breathing rate (breaths per minute).
276
What is another term for respiratory minute ventilation?
Ventilation rate (per minute).
277
What is a spirometer?
A machine that can give readings of tidal volume and measure breathing rate, oxygen consumption, and respiratory minute ventilation.
278
How does a spirometer work?
A person breathes through a tube into an oxygen-filled chamber with a movable lid; movements are recorded by a pen on a rotating drum.
279
What happens to the total volume of gas in a spirometer chamber over time?
It decreases because the exhaled air is a mixture of oxygen and carbon dioxide, with carbon dioxide absorbed by soda lime.
280
How does exercise affect breathing parameters?
Exercise increases breathing rate, tidal volume, oxygen consumption, and respiratory minute ventilation.
281
What is the procedure to investigate the effects of exercise using a spirometer?
1) Measure breathing at rest for one minute. 2) Exercise for two minutes. 3) Measure breathing again for one minute after exercise and compare recordings.
282
Fill in the blank: The volume of gas breathed in or out in a minute is called _______.
respiratory minute ventilation.
283
True or False: A spirometer can be used to measure only tidal volume.
False.
284
What is tidal volume?
The volume of air in each breath, usually about 0.4 dm³.
## Footnote
Tidal volume is equivalent to 0.4 liters.
285
How is breathing rate defined?
The number of breaths taken, usually measured in a minute.
286
What does oxygen consumption refer to?
The volume of oxygen used by the body, often expressed as a rate.
287
What is the formula for calculating respiratory minute ventilation?
Respiratory minute ventilation = tidal volume x breathing rate (breaths per minute).
288
What is another term for respiratory minute ventilation?
Ventilation rate (per minute).
289
What is residual air?
Air that cannot be expelled from the lungs.
290
What is a spirometer?
A machine that measures tidal volume, breathing rate, oxygen consumption, and respiratory minute ventilation.
291
How does a spirometer record breathing?
A pen attached to the lid of the chamber writes on a rotating drum, creating a spirometer trace.
292
What happens to the total volume of gas in the spirometer chamber over time?
The total volume decreases as exhaled air is a mixture of oxygen and carbon dioxide, with carbon dioxide absorbed by soda lime.
293
How does exercise affect breathing parameters?
Exercise increases breathing rate, tidal volume, oxygen consumption, and respiratory minute ventilation.
294
What is the first step in using a spirometer to investigate the effects of exercise?
A person breathes into a spirometer for one minute at rest, and recordings are taken.
295
What happens during the exercise phase of spirometer testing?
The person exercises, e.g. runs on a treadmill, for two minutes while the spirometer chamber is refilled with oxygen.
296
What is compared after exercise in spirometer testing?
Recordings taken before and after exercise.
297
Fill in the blank: Tidal volume is usually about ______ dm³.
0.4
298
True or False: A spirometer can only measure tidal volume.
False
299
What is the formula to calculate breathing rate from a spirometer trace?
Count the number of peaks in the trace in a minute.
300
How is tidal volume determined from a spirometer trace?
Find the average difference in the volume of gas between each peak and trough on the trace.
301
What does oxygen consumption represent in a spirometer trace?
Find the change in volume of gas in the spirometer (read values from the troughs).
302
What is the tidal volume of a person at rest with a body mass of 60 kg?
0.4 dm³.
303
What is the breathing rate of a person at rest?
12 breaths per minute.
304
What is the rate of oxygen consumption at rest for a person with a body mass of 60 kg?
0.6 dm³ per minute.
305
How do you calculate the rate of oxygen consumption per kg of body mass?
Divide the total oxygen consumption by body mass (60 kg).
306
What is the formula for respiratory minute ventilation?
Tidal volume x Breathing rate.
307
What is the respiratory minute ventilation for a person at rest with a tidal volume of 0.4 dm³ and a breathing rate of 12?
4.8 dm³ min⁻¹.
308
True or False: During exercise, the body needs more oxygen and must remove more carbon dioxide.
True.
309
What changes occur in breathing rate, tidal volume, and oxygen consumption during exercise?
All increase.
310
What happens to breathing rate and tidal volume during recovery after exercise?
They return to rest levels.
311
How does fitness training affect breathing rate at rest and during recovery?
Training decreases breathing rate both at rest and during recovery.
312
What effect does fitness training have on tidal volume?
Training increases tidal volume.
313
Fill in the blank: Training allows for _______ air to be taken in with each breath.
[more]
314
How does fitness training impact the recovery rate of breathing rate and tidal volume?
They decrease faster due to training.
315
What is the formula to calculate breathing rate from a spirometer trace?
Count the number of peaks in the trace in a minute.
316
How is tidal volume determined from a spirometer trace?
Find the average difference in the volume of gas between each peak and trough on the trace.
317
What does oxygen consumption represent in a spirometer trace?
Find the change in volume of gas in the spirometer (read values from the troughs).
318
What is the tidal volume of a person at rest with a body mass of 60 kg?
0.4 dm³.
319
What is the breathing rate of a person at rest?
12 breaths per minute.
320
What is the rate of oxygen consumption at rest for a person with a body mass of 60 kg?
0.6 dm³ per minute.
321
How do you calculate the rate of oxygen consumption per kg of body mass?
Divide the total oxygen consumption by body mass (60 kg).
322
What is the formula for respiratory minute ventilation?
Tidal volume x Breathing rate.
323
What is the respiratory minute ventilation for a person at rest with a tidal volume of 0.4 dm³ and a breathing rate of 12?
4.8 dm³ min⁻¹.
324
True or False: During exercise, the body needs more oxygen and must remove more carbon dioxide.
True.
325
What changes occur in breathing rate, tidal volume, and oxygen consumption during exercise?
All increase.
326
What happens to breathing rate and tidal volume during recovery after exercise?
They return to rest levels.
327
How does fitness training affect breathing rate at rest and during recovery?
Training decreases breathing rate both at rest and during recovery.
328
What effect does fitness training have on tidal volume?
Training increases tidal volume.
329
Fill in the blank: Training allows for _______ air to be taken in with each breath.
[more]
330
How does fitness training impact the recovery rate of breathing rate and tidal volume?
They decrease faster due to training.
331
What is homeostasis?
The maintenance of a constant internal environment in the body.
332
What mechanisms are used to reduce body temperature?
* Sweating
* Vasodilation
* Hairs lie flat
333
What is the function of sweating in temperature regulation?
More sweat is secreted when the body's too hot, and its evaporation cools the skin.
334
What occurs during shivering?
Muscles contract in spasms, producing more heat from increased respiration.
335
How do hairs contribute to temperature regulation?
Hairs stand up to trap air for insulation when cold and lie flat to reduce insulation when hot.
336
What is vasodilation?
The dilation of arterioles near the skin surface, increasing blood flow and heat loss.
337
What role do hormones play in temperature regulation?
Hormones like adrenaline and thyroxine increase metabolism, producing more heat.
338
What is vasoconstriction?
The constriction of arterioles near the skin surface, reducing blood flow and heat loss.
339
Which part of the brain controls body temperature?
The hypothalamus.
340
How do thermoreceptors contribute to thermoregulation?
They send impulses to the hypothalamus regarding temperature changes.
341
What is thermoregulation?
The control of body temperature.
342
Fill in the blank: The normal body temperature for mammals is ______.
37 °C
343
What happens when body temperature rises?
* Vasodilation
* Sweating
* Hairs lie flat
* No shivering
* No adrenaline or thyroxine released
344
What happens when body temperature falls?
* Vasoconstriction
* Much less sweating
* Hairs stand upright
* Shivering
* Adrenaline and thyroxine released
345
True or False: Exercise decreases body temperature.
False
346
How do steroid hormones affect transcription factors?
They bind to DNA to alter gene transcription.
347
What is the role of the thyroid hormone receptor?
It binds to DNA to decrease transcription of a gene coding for a protein that increases metabolic rate.
348
What happens when thyroxine is released at cold temperatures?
It binds to the thyroid hormone receptor, increasing transcription and metabolic rate.
349
How do protein hormones affect transcription factors?
They bind to cell membrane receptors, activating messenger molecules that influence transcription factors.
350
What triggers a cascade of reactions inside the cell when a protein hormone binds to a receptor?
Activation of messenger molecules and protein kinases.
351
Describe what is meant by a positive feedback mechanism.
A process that amplifies change, moving away from a set point.
352
Give two mechanisms that can reduce body temperature.
* Sweating
* Vasodilation
353
What effect does a very high body temperature have on metabolic reactions?
It can lead to denaturation of enzymes and disrupt normal metabolic processes.
354
How does homeostasis work like a teacher?
It corrects deviations from a set point to maintain balance.
355
What is negative feedback in homeostasis?
A response mechanism that counteracts changes in the internal environment.
356
What is the relationship between physical activity and BMI according to the data?
The percentage of people who do very little physical activity increases as BMI increases, while the percentage of people who do ≥ 5 days of physical activity per week decreases as BMI increases.
## Footnote
BMI is used as an index of obesity, with a BMI of ≥ 30 kg/m² classed as obese.
357
What correlation is observed between physical activity and obesity?
There's a correlation between doing less physical activity and being obese, but causation cannot be established.
## Footnote
Other factors may influence this correlation.
358
What was the age range of the men involved in the CHD study?
The men were aged 71-93 years at the start of the follow-up period.
359
What trend was observed in the incidence of CHD based on distance walked daily?
Men who walked less each day had a higher incidence of CHD than those who walked more.
## Footnote
The study only involved elderly men and only looked at walking.
360
How does physical activity relate to the prevalence of Type 2 diabetes according to the survey?
Diabetes is more prevalent in inactive than active people, regardless of BMI.
## Footnote
There is also a correlation between increasing BMI and increasing prevalence of diabetes.
361
What is the effect of too much exercise on joint health?
The percentage of male former elite athletes admitted to hospital for osteoarthritis is more than twice that of healthy men (5.9% compared to 2.6%).
## Footnote
Endurance athletes had the highest admission rates.
362
What conclusion can be drawn about elite athletes and respiratory illnesses?
There's a correlation between being an elite athlete and a higher number of respiratory illnesses compared to recreational athletes and sedentary controls.
## Footnote
Elite athletes may be exposed to more infections during competitions.
363
Define correlation in the context of exercise and health.
A correlation indicates a relationship between two variables, but it does not imply causation.
364
Fill in the blank: A BMI of ≥ _______ kg/m² is classed as obese.
30
365
True or False: The study on CHD can conclude that increased physical activity directly reduces the risk of CHD.
False
366
What key factor should be considered when interpreting data on exercise and health?
Correlation does not imply causation.
367
What is keyhole surgery?
A way of doing surgery without making a large incision in the skin.
## Footnote
Surgeons make a much smaller incision and insert a tiny video camera and specialized medical instruments.
368
What are the advantages of keyhole surgery over regular surgery?
* Less blood loss
* Less scarring of the skin
* Less pain post-operation
* Quicker recovery
* Shorter hospital stay
## Footnote
Keyhole surgery involves less damage to the body.
369
What is a common sports injury related to the cruciate ligaments?
Damage to the cruciate ligaments in the knee.
## Footnote
Cruciate ligaments connect the thigh bone to the lower leg bone.
370
What is a prosthesis?
An artificial device used to replace missing or damaged body parts.
## Footnote
Prostheses can replace whole limbs or parts of limbs.
371
How can prostheses assist athletes?
They allow people with disabilities or injuries to participate in sports.
## Footnote
For example, prosthetic legs (blades) allow individuals without legs to run.
372
What is the role of electronic devices in some prostheses?
They operate the prosthesis by picking up information from the nervous system.
## Footnote
This allows users to move their prosthetic fingers, for example.
373
What are performance-enhancing drugs?
Drugs that improve a person's athletic performance.
## Footnote
Examples include anabolic steroids, stimulants, and narcotic analgesics.
374
What are anabolic steroids used for?
To increase strength, speed, and stamina by increasing muscle size.
## Footnote
They also increase aggression.
375
What are the arguments against using performance-enhancing drugs?
* Some drugs are illegal
* Competitions become unfair
* Serious health risks
* Athletes may be uninformed about risks
## Footnote
Side effects include high blood pressure and heart problems.
376
What are the arguments in favor of using performance-enhancing drugs?
* Individual choice
* Drug-free sport isn't fair due to inequalities
* Higher competition levels may require drug use
## Footnote
Different athletes have varying access to resources.
377
Fill in the blank: Keyhole surgery involves making a _______ incision.
smaller
378
True or False: Performance-enhancing drugs are allowed in most sports.
False
379
What is the purpose of a knee joint replacement?
To replace damaged cartilage and bone in the knee.
## Footnote
It helps individuals with serious knee issues participate in low-impact sports.
380
What is the typical procedure for fixing damaged cruciate ligaments?
Removal of the damaged ligament and replacement with a graft.
## Footnote
The graft may come from the patient's own tendon or a donor.
381
List three types of performance-enhancing drugs.
* Anabolic steroids
* Stimulants
* Narcotic analgesics
382
How does a prosthetic joint help individuals with knee problems?
It allows movement and participation in low-impact sports.
## Footnote
Cushioning in the joint reduces impact on the knee.
383
What is a stimulus?
Any change in the internal or external environment.
384
How do animals increase their chances of survival?
By responding to changes in their external and internal environment.
385
What are receptors?
Cells or proteins on cell surface membranes that detect stimuli.
386
What are effectors?
Cells that bring about a response to a stimulus, producing an effect.
387
Name two types of effectors.
* Muscle cells
* Gland cells (e.g., pancreas)
388
What is the nervous system made up of?
A complex network of cells called neurones.
389
What are the three main types of neurones?
* Sensory neurones
* Motor neurones
* Relay neurones
390
What do sensory neurones do?
Transmit electrical impulses from receptors to the central nervous system (CNS).
391
What do motor neurones do?
Transmit electrical impulses from the CNS to effectors.
392
What do relay neurones do?
Transmit electrical impulses between sensory neurones and motor neurones.
393
What happens when an electrical impulse reaches the end of a neurone?
Neurotransmitters carry the information across to the next neurone.
394
What is the CNS responsible for?
Processing information and sending impulses along motor neurones to effectors.
395
What is the response of the eyes to dim light?
Radial muscles in the iris contract to dilate pupils.
396
What is the response of the eyes to bright light?
Circular muscles in the iris contract to constrict pupils.
397
What is the hormonal system made up of?
Glands and hormones.
398
What is a gland?
A group of cells that are specialised to secrete a useful substance, such as a hormone.
399
What are hormones?
Chemical messengers that are often proteins or peptides.
400
How are hormones secreted?
When a gland is stimulated by a change in concentration of a specific substance or by electrical impulses.
401
How do hormones travel in the body?
They diffuse directly into the blood and are taken around the body by the circulatory system.
402
What are target cells?
Cells that have specific receptors for a hormone, allowing them to respond to that hormone.
403
What is the effect of glucagon released by the pancreas?
Target cells in the liver convert glycogen into glucose, increasing blood glucose concentration.
404
True or False: Nervous communication uses electrical impulses.
True.
405
True or False: Hormonal communication has a faster response than nervous communication.
False.
406
List three differences between nervous and hormonal communication.
* Nervous communication uses electrical impulses, hormonal communication uses chemicals
* Nervous communication has a faster response, hormonal communication is slower
* Nervous communication is localized, hormonal communication is widespread
407
What are receptors specific to?
One kind of stimulus
## Footnote
Receptors detect specific stimuli such as light, pressure, or glucose concentration.
408
What are photoreceptors?
Light receptors in the eye
## Footnote
Photoreceptors include rods and cones that detect light.
409
What happens to the cell membrane when a receptor is in resting state?
It is polarized
## Footnote
A difference in charge exists between the inside and outside of the cell.
410
What is the voltage across the membrane called?
Potential difference
## Footnote
It is generated by ion pumps and ion channels.
411
What triggers an action potential?
A sufficient change in potential difference
## Footnote
The action potential is an electrical impulse along a neurone.
412
What are the two types of photoreceptors in the human eye?
Rods and cones
## Footnote
Rods are for black and white vision, while cones are for color vision.
413
Where are rods mainly found?
In the peripheral parts of the retina
## Footnote
Cones are packed in the fovea.
414
What type of vision do rods provide?
Monochromatic vision
## Footnote
Rods give information only in black and white.
415
What do cones provide?
Trichromatic vision
## Footnote
Cones enable color vision and are sensitive to red, green, and blue light.
416
What is the blind spot?
Where the optic nerve leaves the eye
## Footnote
It lacks photoreceptor cells, making it not sensitive to light.
417
Fill in the blank: Light-sensitive pigments are found in _______.
Photoreceptors
## Footnote
These pigments are crucial for detecting light.
418
What happens to rhodopsin when it is stimulated by light?
It breaks apart into retinal and opsin
## Footnote
This process is known as bleaching.
419
What is hyperpolarization in rod cells?
When the inside of the cell becomes more negative than the outside
## Footnote
This occurs when sodium channels close after light stimulation.
420
What effect does hyperpolarization have on neurotransmitter release?
Stops neurotransmitter release
## Footnote
This prevents inhibition of the bipolar neurone.
421
True or False: Bipolar neurones are inhibited when it is dark.
True
## Footnote
In darkness, bipolar neurones are inhibited due to neurotransmitter release.
422
What connects photoreceptors to the optic nerve?
Bipolar neurones
## Footnote
These neurones carry nerve impulses from photoreceptors to the brain.
423
What is the role of sodium ion channels in rod cells?
They control the movement of sodium ions in and out of rod cells
## Footnote
Sodium channels are crucial for the depolarization and hyperpolarization processes.
424
What is the basic structure of all neurones?
All neurones have a cell body with a nucleus and cytoplasm.
425
What are the three different types of neurones?
* Motor Neurones
* Sensory Neurones
* Relay Neurones
426
What is the function of motor neurones?
Carry nerve impulses from the central nervous system (CNS) to effector cells.
427
What is unique about sensory neurones?
One long dendron carries nerve impulses from receptor cells to the cell body.
428
What is the role of relay neurones?
Carry nerve impulses from sensory neurones to motor neurones.
429
What does it mean for a neurone's cell membrane to be polarised at rest?
The outside of the membrane is positively charged compared to the inside.
430
What is the resting potential of a neurone?
About -70 mV.
431
How is the resting potential created and maintained?
By sodium-potassium pumps and potassium ion channels in a neurone's membrane.
432
What is the function of sodium-potassium pumps?
Move three sodium ions out and two potassium ions in using active transport.
433
What happens during depolarisation of a neurone?
Sodium ions diffuse into the neurone, causing the membrane potential to become less negative.
434
What is the peak membrane potential during action potential?
Around +30 mV.
435
What occurs after depolarisation?
Potassium ion channels open, allowing potassium ions to diffuse out.
436
What is hyperpolarisation?
When the membrane potential becomes more negative than the resting potential.
437
What resets the ion channels after an action potential?
The sodium-potassium pump returns the membrane to resting potential.
438
Fill in the blank: The change in potential across a neurone membrane during an action potential is called _______.
depolarisation
439
True or False: The neurone cell membrane can be excited again immediately after an action potential.
False
440
What is the refractory period in neurones?
The time during which the neurone cannot be excited again.
441
What happens during repolarisation?
The neurone returns to its resting potential after depolarisation.
442
What is the role of potassium ion channels during an action potential?
Allow potassium ions to diffuse out of the neurone.
443
What is an action potential?
A rapid change in membrane potential that propagates along the neurone.
444
What is the effect of the sodium ion electrochemical gradient?
Creates a difference in charge across the neurone's membrane.
445
What happens when an action potential occurs in a neurone?
Some sodium ions enter the neurone and diffuse sideways, causing sodium ion channels in the next region to open.
446
How does the action potential move along the neurone?
As a wave of depolarisation.
447
What is the refractory period?
A time during which ion channels are recovering and cannot be opened, preventing overlap of action potentials.
448
What effect does the refractory period have on action potentials?
It ensures action potentials are discrete and unidirectional.
449
What happens when a bigger stimulus is applied to a neurone?
It causes action potentials to fire more frequently, but does not increase the size of the action potential.
450
What is the role of local anaesthetics in nerve conduction?
They bind to sodium ion channels, preventing sodium ions from entering the neurones and stopping action potentials.
451
What is a myelinated neurone?
A neurone that has a myelin sheath, which is an electrical insulator made of Schwann cells.
452
What are the nodes of Ranvier?
Bare membrane regions between Schwann cells where sodium ion channels are concentrated.
453
What is saltatory conduction?
The process where depolarisation occurs only at the nodes of Ranvier, allowing the impulse to 'jump' from node to node.
454
How does conduction velocity differ between myelinated and non-myelinated neurones?
Impulses travel faster in myelinated neurones than in non-myelinated neurones.
455
Fill in the blank: The speed at which an impulse moves along a neurone is known as the _______.
[conduction velocity]
456
True or False: Action potentials can overlap due to the refractory period.
False.
457
What is the function of Schwann cells on a neurone?
To form the myelin sheath, which insulates the neurone.
458
What is the primary effect of multiple sclerosis on action potential transmission?
It damages the myelin sheaths of neurones, affecting the speed and efficiency of action potentials.
459
What is a synapse?
A synapse is the junction between a neurone and another neurone, or between a neurone and an effector cell, e.g. a muscle or gland cell.
460
What is the tiny gap between the cells at a synapse called?
The synaptic cleft.
461
What does the presynaptic neurone contain that is crucial for neurotransmitter release?
Synaptic vesicles filled with neurotransmitters.
462
How do neurotransmitters affect the postsynaptic membrane?
They bind to specific receptors, which may trigger an action potential, cause muscle contraction, or stimulate hormone secretion.
463
True or False: Synapses allow impulses to travel in both directions.
False.
464
What happens to neurotransmitters after they have triggered a response?
They are removed from the cleft, either taken back into the presynaptic neurone or broken down by enzymes.
465
Name two examples of neurotransmitters.
* Acetylcholine
* Dopamine
466
What triggers the influx of calcium ions into the synaptic knob?
An action potential arriving at the synaptic knob.
467
What is the process called when synaptic vesicles release neurotransmitters into the synaptic cleft?
Exocytosis.
468
What effect does the influx of sodium ions into the postsynaptic membrane have?
It causes depolarisation, which can generate an action potential if the threshold is reached.
469
What is synaptic divergence?
When one neurone connects to many neurones, allowing information to be dispersed to different parts of the body.
470
What is synaptic convergence?
When many neurones connect to one neurone, allowing information to be amplified.
471
Fill in the blank: Summation is where the effect of neurotransmitter released from many neurones, or one neurone that's stimulated a lot in a short period of time, is ______.
[added together]
472
What role do synaptic knobs play in neurotransmitter release?
They contain lots of mitochondria that produce ATP, needed for active transport and the movement of vesicles.
473
What is the primary way plants respond to stimuli?
By regulating their growth towards or away from stimuli.
474
What is a tropism?
The response of a plant to a directional stimulus.
475
What is a positive tropism?
Growth towards the stimulus.
476
What is a negative tropism?
Growth away from the stimulus.
477
What is phototropism?
The growth of a plant in response to light.
478
In phototropism, which part of the plant is positively phototropic?
Shoots.
479
In phototropism, which part of the plant is negatively phototropic?
Roots.
480
What is geotropism?
The growth of a plant in response to gravity.
481
In geotropism, which part of the plant is negatively geotropic?
Shoots.
482
In geotropism, which part of the plant is positively geotropic?
Roots.
483
How do plants respond to stimuli without a nervous or circulatory system?
Using growth factors.
484
What are growth factors?
Chemicals that speed up or slow down plant growth.
485
Where are growth factors produced in a plant?
In the growing regions such as shoot tips and leaves.
486
What is the role of auxins in plants?
Stimulate the growth of shoots by cell elongation.
487
What effect do high concentrations of auxins have on roots?
Inhibit growth.
488
Name two other plant growth factors besides auxins.
* Gibberellins
* Cytokinins.
489
What is the function of gibberellins?
Stimulate flowering and seed germination.
490
What is the function of cytokinins?
Stimulate cell division and cell differentiation.
491
What does ethene do for plants?
Stimulates fruit ripening and flowering.
492
What is the role of abscisic acid (ABA) in plants?
Involved in leaf fall.
493
What is Indoleactic Acid (IAA)?
An important auxin that affects plant growth.
494
How does IAA move within the plant?
By diffusion, active transport over short distances, and via the phloem over longer distances.
495
What happens to IAA during phototropism?
Moves to the shaded parts of the shoots, causing uneven growth.
496
What are phytochromes?
Photoreceptors that detect light in plants.
497
What states do phytochromes exist in?
* P_r (absorbs red light)
* P_fr (absorbs far-red light).
498
What effect does red light have on phytochromes?
Converts P_r to P_fr.
499
What effect does far-red light have on phytochromes?
Converts P_fr to P_r.
500
How do phytochromes influence flowering in plants?
High levels of P_fr stimulate flowering.
501
Fill in the blank: _______ is a growth response of a plant to gravity.
Geotropism
502
True or False: Roots grow upwards in response to gravity.
False.
503
What do plants use to detect the amount of daylight?
Phytochromes.
504
During which season do some plants flower when there are long days?
Summer.
