Topic 7- Muscles + Respiration, and Exercise Flashcards
1
Q
What is skeletal muscle?
A
- the type of muscle you use to move
- work by contracting and relaxing to move bones around a joint
2
Q
What are tendons and ligaments?
A
- tendons attach bone to skeletal muscle
- ligaments attach bone to other bones (holding the together)
3
Q
What are antagonnistic pairs?
A
- muscles can only pull and not push so two muscles are needed creating opposite forces to move bone
4
Q
Describe the structure of muscle fibres
A
- sarcolemma= cell membrane and it folds inwards sticking into sarcoplasm (cytoplasm)
the folds are called T tubules which help to spread electerical charge throughout the sarcoplasm - sarcoplasmic reticulum= internal membranes running through sarcoplasm which stores and releases Ca2+ ions for muscle contraction
- lots of mitochondria to provide ATP for contraction
- multinucleate
- myofibrils= long cylindrical organnelles for contraction
5
Q
What is a flexor and extensor?
A
- flexor= a muscle that bends a joint when it contracts
- extensor= a muscle that straightens a joint when it contracts
6
Q
Describe the sliding filament theory
A
- action potential arrives at neuromuscular junction (synapse between motor neurone and fibre)
- Ca2+ released from SR which bind to tropin. Tropinin changes shape causing tropmyosin to change position on the actin filament
- myosin binding sites are exposed to globular myosin head can attach = cross bridge
- formation of cross-bridges causes myosin head to bend forward and pull actin towards centre of sarcomere (needs energy from ATP->ADP + Pi
- ATP binds to myosin heads changing their shape and they release from actin. ATPase hydrolyses ATP so myosin heads go back to og position recovery stroke
- myosin heads bind to another binding site and move again, further shortening sarcomere and muscle contracts
**continues as long as Ca2+ is provided so that troponin + tropomyosin aren’t blocking binding sites/ and ATP is supplies
7
Q
What happens when stimulation of the muscles stops?
A
- no more Ca2+ is released and is actively transported back to SR
- troponin changes back to og shape so that tropomyosin moves back to position = covering binding sites
- sarcomere lengthens as actin moves back to relaxed position
8
Q
Describe the struuctures of myosin and actin
A
- myosin= fibrous protein w/ globular head + many myosin molecules lie next to each other
- actin = globular protein molecules wich link in a chain/ 2 actin twist to form a thin filament
tropomyosin twists around the 2 chains + troponin is attached to actin at regular intervals
9
Q
Describe slow twitch muscle fibres
A
- contract slowly for endurance
- lots of mitochondria and blood vessels supply fibre with O2 for aerobic respiration
- reddish in colour as rich with myoglobin (protein that stores O2)
- fatigue more slowly due to less lactic acid formation
10
Q
Describe fast twitch muscle fibres
A
- contract quickly for short bursts of power
- energy released quickly through anaerobic respiration using glycogen (few mitochondria and blood vessels)
- fatigue quickly due to lactic acid formation during anaerobic respiration
- whitish in colour because they don’t have mych myoglobin (so can’t store much O)
11
Q
What are the similarities between slow and fast twitch fibres?
A
- both release energy
- help in movement and contraction
12
Q
Describe the mitochondrial structure
A
- outer membrane= smooth + permeable to several molecules
- inner memebrane= folded cristae + site of ETC + ATP synthase for oxidative phosphorylation
- intermembrane space= low pH due to high conc. of H+ ions/ occurs during ox. phos. for ATP production
- matrix= aqueous solution within the iner membrane containing ribosomes, enzymes and circular mitochondrial DNA
13
Q
A
14
Q
Why is glucose broken down in stages?
A
- so energy within chemical bonds is broken gradually
- a sudden release of energy = increase temperature of body and denature enzymes
15
Q
Describe lactate fermentation and how it is broken down
A
- NADH transfers a proton to pyruvate to form lactate
- NAD is then used in glycolysis
There are 2 ways lactate is broken down:
1. cells convert the lactic acid back to pyruvate which can the reenter aerobic respiration at the Krebs cycle
2. liver cells convert lactate to glucose to be respired or stored
16
Q
Describe the importance of 3 things maintained during homeostasis
A
- temperature= thermoregulation so there are optimal conditions for enzymes and cell activity
- blood glucose= cells need constant supply of energy (ATP)/ glucose respired to provide ATP and pancreatic cells monitor levels
- water= part of cytoplasm and metabolic reactions/ lost in sweat and urine + kidneys regulate
17
Q
Describe cooling mechanisms (3)
A
- sweating= sweat secreted by sweat glands so that it can evaporate and cool the skin
- less effective in humid environments as lower conc. gradient - vasodilation of blood vessels= muscles in atriole walls relax and dilate near skinso increased blood flow to skin capillaries
- increase heat loss to environment as capillaries have increased vol. blood - flattening of hairs= hair erector muscles RELAX and stops them forming insulating layer of trapped air/ heat can leave by RADIATION
18
Q
Describe warming mechanisms (4)
A
- vasoconstriction= muscles in arteriole walls contract so less blood flow to skin capillaries
- less heat loss to environment doesn’t increase temp. but reduces heat loss - erection of hairs= erector muscles contract so hairs stand upridght to trap air
- stops heat loss by radiation by forming insulating layer of air - shivering= reflex action to increase temperature
- muscles contract in a rapid + regular manner
- metabolic reactions to contract generate heat to warm blood - boost metabolism= increase thyroxine + adrenaline because most reactions are exothermic/ increase basal metabolic rate
19
Q
Define homeostasis
A
maintenance of a stable internal environment kept in a state of dynamic equilibrium
20
Q
How does the hypothalamus control body temperature?
A
- maintained at a constant level by hypothalamus in brain
- it receives information about temp. from thermoreceptors
- theremoreceptors send impulses along sensory neurones to hypothalamus
- hypothalamus sens impulses along motor neurones to effectors
- effectors restore body temp. back to normal
21
Q
Describe the general action of hormones and the difference between hormones inside and outside cells
A
- transcription factors control gene expression + alllows response to different factors in environment = a protein that binds to promoter region
- hormones inside cell= steroid hormones and cross cell membrane (lipid soluble) + enter nucleus/ bind to transcription factors present
- hormones outside cell= peptide hormones and can’t cross cell membrane/ bind to receptors on cell surface
22
Q
Describe the action of steroid hormones in cold temp.
A
- thyroxine hormone is released + binds to steroid hormone receptor/ transcription factor
- allows RNA polymerase to bind to start of gene + gene is switched on (this gene codes for proteins that increase metabolic rate)
- as rate of expression (transcription) increase, more protein is made, and increase in temperature
23
Q
Describe the action of streoid hormones in normal temperatures
A
- steroid hromone receptor binds to start of gene
- prevents RNA polymerase binding so gene switches off
- this gene codes for protein that increases metabolic rate but steroid hormone receptor blocks it
24
Q
Describe the action of peptide hormones
A
- bind to cell surface membrane receptors which activates 2nd messenger molecules in cytoplasm of cell
- 2nd messengers activate enzymes (protein kinases) and triggers cascade inside cell which changes activity of transcription factors
25
define positive feedback
- original stimulates a respones so that the factor deviates further from normal range
- enhances effect of OG stim
- not involved in homeostasis but good at quickly activating a process
26
define negative feedback
- receptor detects a stimulus and NS or HS transfers info to diff parts of body
- effector carries out response to counteract change
- factor gets closer to normal value and correction decreases
27
Describe Keyhole surgery
- less invasive than standard surgery because only a small incision
- insert a small video camera and specialised equipment
_:)_
- less blood loss and scarring
- less pain and quick recovery due to less damage
- shorter hospital stay
_e.g_
- damaged cruciate ligament (middle of knee connecting thigh to lower leg)
- can be removed or replaced by a graft from another tendon
28
Describe Prosthesis
- replace a whole limb or part of it
- some may have electronic devices that can read info from NS to operate body part
_e.g_
- replace damaged bone/cartilage and replace by metal device (smooth knee joint)
- more mobile
29
What are the 3 types of performance enhancing drugs?
1. stimulants= make you more alert + react faster/ greater endurance and less fatigue
2. anabolic steroids= increase muscle size (increased strength, speed and stamina) **increase aggression**
3. narcotic analgesics= reduce pain so injuries don't affect performance
30
What are the reasons FOR performance enhancing drugs? (3)
1. should be up to the individual whether worth the risk
2. drug-free isn't fair because athletes have access to different training facilities and coaches/ overcomes inequalities
3. athletes that want to compete at a higher level may need them
31
What are the reasons AGAINST performance enhancing drugs? (4)
1. some are illegal
2. competitions become unfair as people gain an advantage
3. serious health risks like increased blood pressure
4. athletes may not be fully informed of the risks
32
Describe the Control of Heart Rate
1. Cardiovascular Control Centre (CCC) in the medulla oblongata unonsciosly controls the HR by controlling rate at which SAN node generates impulses (fires)
2. this causes atria to contract and sets a rhythm
3. changes are detected by:
- BARORECEPTORS= stimulated by change in blood pressure
- CHEMORECEPTORS= detect changes in CO2 + pH
4. When stimulated they send impulses to medulla oblongata and CCC sends impulses to SA node along sympathetic/parasympathetic neurones
5. They then release different neurotransmitters:
- sympathetic = increase rate of SAN firing, preparing fight or flight and increase HR
- parasympathetic= decrease rate of SAN firing, calms body after exercise and decreases HR
33
Describe how Baroreceptors cause changes to heart rate
_increase in blood pressure_
1. detected by baroreceptor which sends impulse to CCC which sends impulses along parasympathetic neurone
2. parasympathetic neurone secretes acetylcholine to bind to SAN = fires less frequently and decreases HR
_decrease in blood pressure_
1. detected by baroreceptros and sends impulse to CCC which sends impulse along sympathetic neurone
2. sympathetic neurone secretes noradrenaline which binds to receptors on SAN = fires more frequently, increasing HR
34
Describe how chemoreceptors cause changes to HR
_increase in pH + increase in blood O2_
1. chemoreceptors detect change and send impulse to CCC which sends impulse along parasympathetic neurone
2. paraympathetic neurone secretes acetylcholine which binds to receptors on SAN= decrease rate of firing so that less O2 is pumped in blood
_decrease in pH, increase in CO2, decrease in O2_
1. chemoreceptors detect change and send impulses to CCC which sends impulse along sympathetic neurone
2. this secretes noradrenaline which binds to SAN = increase rate of firing + HR
35
Describe the regular beating of the heart
1. the SA node (sino atrial) in R-atrium sends regular waves of depolarisation
2. causes R atrium to contract w/ L atrium simultaneously
3. a band of non conducting collagen tissue prevents depolarisation being passed on directly to ventricles
4. wave of depolarisation is, instead, carried to AV node (atroventricular) which passes wave onto Bundle of His = group of muscle fibres in septum that divide into 2 conducting fibres (Purkyne fibres)
** there is a delay before AVN is stimulated so ventricles contract after**
5. Purkyne fibres carry wave of depolarisation into muscular walls of L + R ventricles and they contract from bottom up
36
What is the Bundle of His?
- group of muscle fibres running through the septum of the heart
- splits into 2 conducting fibres call Purkyne fibres
37
How do ECG's work?
- electrodes placed on chest + record depolarisation (contraction) and repolarisation
- electrocardiogram
38
Describe a normal ECG
- P wave= contraction and depolarisation of atria (atrial systole)
- QRS complex= contraction of ventricles (bigger wave because larger muscle)
- T wave= relaxation and repolarisation of ventricle
39
Describe fibrillation
- irregular heart beat
- atria/ventricles completely lose rhythm and stop contracting properly
**chest pain/fainting/lack of pulse/ death**
40
Describe Ectopic Heart beat
- early heart beat followed by a pause
- eaither early contraction of ventricals/atria
- commone + no treatment needed unless severe
41
Bradycardia
- bpm too slow (60bpm>)
- a lot of athletes have this and not usually dangerous
42
43
decribe Tachycardia
- heart beat too fast (100bpm<)
- this is tachycardia when resting
- common during exercise
44
Describe Cardiac Output
- the vol blood pumped by the heart (L+R ventricle) per unit of time
- fiiter means higher due to stronger + thicker ventricle muscles
- Cardiac output= bpm x stroke vol
- increases during exercise
45
What is stroke volume?
-the vol of blood pumped out of L ventricle during one cardiac cycle
46
What are the effects of too little exercise?
- higher incidence of coronary heart disease
- Type 2 diabetes is more prevailent
- BMI will increase but doesn't cause obesity
47
Describe what happens to breathing rate and heart rate during exercise
- muscles contract more frequently so increased O2 needed via aerobic respiration
1. increased breathing rate= more O2 and get rid of more CO2
2. increased heart rate= deliver more O2 + glucose to muscles faster while removing more CO2
48
What are the effects of too much exercise?
- increased wear and tear of joints (athletes have high risk of osteoarthritis)
- affects immine system as studies have shown more cases of respiritory illnesses
49
What is the inspiritory centre?
- controls the movement of air into lungs
50
Describe the control of breathing rate
1. Inspiritory centre in medulla oblongata sends nerve impulses to _intercostal + diaphragm muscles_ which causes them to contract
2. This increase the volume of lungs + decreases pressure in lungs
3. Air enters lungs due to pressure difference between lungs and air outside
4. Lungs inflate + lung's stretch receptors are stimulated = send impulses to medulla oblongata to inhibit inspiritory centre
5. _Expiritory centre_ is not inhibitted + sends impulse to diaphragm and intercostal muscles = relax
6. Lungs deflate + expel air= stretch receptors become inactive and _inspiritory centre no longer inhibited_
51
How is breathing rate increased during exercise?
1. CO2 conc. in blood increases, decreasing pH
2. _chemoreceptors_ in medulla oblongata, carotid bodies and aortic bodies are sensitive to changes in pH
3. they detect low pH and send nerve impulses to medulla oblongata so that MO sends more frequent nerve impulses to intercostal + diaphragm muscles
4. this increases rate + depth of breathing so gaseouys exchange speeds up = CO2 conc decrease and more O2 supplied to muscles
5. when pH is back to normal, breathing rate will decrease again
52
Define tidal volume
vol air in each breath (0.4dm3)
53
Define breathing rate
number of breaths per minute
54
Define O2 consumption
volume of O2 used by body (expressed as rate)
55
Define respiritory minute
vol gas breathed in or out in 1 minute
56
Describe how you would use spirometers
1. there is an O2 chamber with a moveable lid
2. person breathes in through tube connected + lid moves down and lid moves up when exhaled
3. these movements are recorded by a pen attached to the lid which writes on a rotating drum= makes spirometer trace
**the volume of gas in the chamber decreases over time due to CO2 being absorbed by soda lime and O2 being used up**
57
Describe the analysis of a spirometer trace
- breathing rate= no. peaks per minute
- tial volume= average difference in vl gas between each peak + trough
- O2 consumption= change in volume of gas in spirometer
- respiritory minute ventilation= tidal vol x breathing rate
58
How would you use a spirometer to investigate the effects of exercise on breathing?
1. first take a reading while person is at rest for 1 minute
2. person then exercises e.g runs on treadmilkl for 2 minutes/ while this happens spirometer chamber should be refilled w/ O2
3. immediately after 2 minutes of exercise, breathe into spirometer and recordings taken for another minute
4. compare trace before and after
