Topic 7: Run for your life Flashcards
what is antagonistic muscle action
muscles can only pull in one direction and so they act in antagonistic muscle pairs
a muscle pulls in one direction at a joint whilst the other pulls in the opposite direction
the flexor bends a joint when it contracts
the extensor straightens out a joint when it contracts
define tendon
non-elastic tissue connecting muscle to bone
define ligament
elastic tissue joining bones together, determines amount of movement possible at a joint
define joint
the site where 2 bones are attached for the purpose of allowing body parts to move, made of fibrous connective tissue and cartilage
outline the structure of a muscle
sarcomeres are made up of thick myosin and thin actin filaments
myofibrils are composed of repeated sarcomeres
a muscle fibre is made up of many myofibrils
muscles are made from muscle fibre bundles
outline the arrangement of muscle filaments during extension and contraction (sliding filament theory)
sarcomeres within myofibrils shorten bc Z discs are pulled closer together
the myofilaments, myosin and actin molecules remain the same length
Myosin and actin filaments slide over one another
explain the sliding filament theory of muscle contraction
- nerve impulse arrives at a neuromuscular junction
- Ca2+ are released from the sarcoplasmic reticulum into the sarcoplasm and bind to troponin
- troponin and the attached tropomyosin shift, exposing myosin binding sites on actin filaments
- ATP binds to myosin head and causes it to unbind from actin
- ATPase helps ATP split to release energy so that the myosin head can move and bind to actin
ATP binds again; etc. - the actin slides over the myosin which shortens the muscle fibre
- when a muscle relaxes, it isn’t being stimulated by nerve impulses and Ca2+ are actively pumped out of the muscle sarcoplasm using ATP. the troponin and tropomyosin move back, and again block the myosin binding site on the chain
what is actin
thin filament, made of 2 strands twisted around each other
what is myosin
thick filament, bulbous heads and rod shaped tail
what are troponin and tropomyosin
tropomyosin is wound around the actin, forming a fibrous strand
troponin is attached to the tropomyosin
define homeostasis
the maintenance of a steady internal environment
define negative feedback
when a deviation from the set level results in a change in the opposite direction, returning the change to the set level
define positive feedback
when a deviation from the set level results in the control centre moving the condition further away from the set level
define dynamic equilibrium
a state of balance between continuing processes
outline slow twitch skeletal muscles
- muscle fibres that contract slowly and so are good for endurance activities (maintaining good posture (high proportion in back) and long distance running)
- more effectively at aerobic respiration because more mitochondria and lots of capillaries for good O2 supply
- reddish in colour as theyre rich in myoglobin that can store oxygen and so probs won’t build up lactate
outline fast twitch skeletal muscles
- muscle fibres that contract very quickly and are so used for fast movement (eye movement and sprinting), so high proportion in eyes and legs
- get tired very quickly as energy is released quickly via anaerobic respiration using glycogen and there are few mitochondria/blood vessels
- whitish in colour bc they don’t have much myoglobin and so can’t store much oxygen
what is BMR and how is it measured
Basal Metabolic Rate is the minimum energy required to carry out basic metabolic processes required for life
BMR is dependent on age and gender due to impact of body fat % (as more body fat = more insulation = less heat loss = less energy needed to maintain bdy temp)
it is calculated during a fasting period in a temperature controlled room
what coenzymes are involved in respiration
NAD
FAD
coenzyme A
define respiration
a series of chemical reactions which bring about the release of energy which is used to make ATP
define aerobic respiration
respiration involving oxygen, where the substrate is oxidised completely into CO2 and H2O
define anaerobic respiration
respiration in the absence of oxygen, resulting in lactic acid formation in animals
what are the 4 stages of aerobic respiration and where do they occur
- glycolysis: cell cytoplasm
- link reaction: mitochondrial matrix
- kreb’s cycle: mitochondrial matrix
- oxidative phosphorylation: inner membrane of mitochondria
explain the 1st stage of aerobic respiration; glycolysis
occurs in cytoplasm (or sarcoplasm of muscle cells)
- phosphorylation of glucose:
2ATP hydrolysed –> 2ADP + 2Pi
glucose + 2Pi –> 2triose phosphate - oxidation of triose phosphate
enzyme oxidises triose phosphate, removing a H from each
NAD takes the H: 2NAD + 2H –> 2NADH
the Pi from each triose phosphate forms 2ATP; so 4ATP
this turns 2triose phosphate –> 2pyruvate
products: 2ATP, 2NADH, 2pyruvate
outline and explain the link reaction; the 2nd stage of aerobic respiration
if O2 available, pyruvate moves across mitochondria’s double membrane into matrix via active transport
- pyruvate is dehydrogenated and decarboxylated via pyruvate dehydrogenase to form acetate
removed carboxyl forms CO2
removed H accepted by NAD –> NADH
- acetate combines with Coenzyme A to form acetyl coenzyme A
products: CO2, NADH, acetyl CoA
this occurs 2x bc there are 2 pyruvate
outline and explain the Kreb’s cycle; 3rd stage of respiration
occurs twice per glucose, happens in mitochondrial matrix
- acteyl CoA (from Link reaction) –> CoA(reused in link) + actetate
2C acetate + 4C oxaloacetate –> 6C citrate - citrate is dehydrogenated and decarboxylated –> CO2 + 5C compound + NADH
- the 5C is decarboxylated and dehydrogenated –> 4Coxaloacetate + FADH2 + 2NADH + CO2 + ATP
ADP + Pi –> ATP (substrate level phosphorylation)
total products per cycle: 3NADH + FADH2 + 2CO2 + ATP
oxaloacetate is then reused!
outline and explain oxidative phosphorylation; the last stage of aerobic respiration
involves a combination of the electron transport chain (ETC) and chemiosmosis
1. NADH + FADH2 are oxidised to NAD + FAD, releasing H atoms
H –> e-+ H+
2. e- move down ETC and lose energy at each carrier in the chain
3. carriers use the energy to pump H+ from matrix to inter membrane space, forming an electrochemical gradient
4. chemiosmosis: H+ move down gradient back into matrix via ATP synthase, drives ADP + Pi —> ATP
5. in the matrix at the end of the ETC, H+, e- and O2(from blood) combine to H2O; O2 said to be final e- acceptor
3ATP made from each NADH
2ATP made from each FADH2
outline the process of anaerobic respiration
glucose —> lactic acid + energy
lactate fermentation:
NADH (from glycolysis) transfers H to pyruvate(from glycosisis)–> lactate + NAD
this oxidation needs extra oxygen (known as oxygen debt and is why u breathe hard and deep after excercise)
the NAD is then reused in glycolysis
how is lactic acid build up dealt with
- cells: lactic acid —> pyruvate, which can re-enter aerobic respiration at the krebs cycle
- liver cells: lactic acid —> glucose, which can be respired/stored
outline the experiment looking at respiration rate
method:
- set up the respirometer and run the experiment with both tubes for 30 minutes
- CO2 produced during respiration is absorbed by soda lime or KOH, reducing volume of gas
- This reduces the pressure in the capillary tube and manometer fluid will move towards the test tube containing the seeds
- Measure the distance moved by the liquid in a given time
- Use this measurement to calculate the change in gas volume within a given time, x cm3 min-1
- Allow air to re-enter the tubes via the screw cap and reset the manometer fluid using the syringe
- Repeat experiment several times and calculate the average volume of oxygen consumed
define myogenic
the ability to contract without any external stimulus because the impulse and depolarisation originates in the heart muscle
what is the SA node
a group cells in the wall of the right atrium aka pacemaker
what is the AV node
a region of conducting tissue between the atria and ventricles
what are the Purkyne fibres
large, specialised muscle fibres found around each ventricle that rapidly conduct impulses to the apex of ventricles
what is the bundle of His
the collective name for both the right and left Purkyne fibres
outline electrical activity in the heart during the cardiac cycle
- SA node sends out a wave of excitation/change in depolarisation
- atria contract simultaneously
- a band of non-conducting collagen tissue prevents the waves of activity from being directly passed from the atria to the ventricles
- the wave of electrical activity is instead transferred from the SA to the AV node
- the AV node passes these waves of activity onto the bundle of His with a slight delay to ensure that the atria have emptied before the ventricles contract
- the purkyne fibres carry the waves of excitation into the muscular walls of each ventricle and cause simultaneous contraction from the bottom up
how is cardiac output calculated
heart rate x stroke volume
label and explain this healthy heart ECG
milivolts
P wave: atrial depolarisation (atrial systole)
QRS complex: ventricular depolarisation (ventricular systole); largest bc most muscle mass
T wave: ventricular repolarisation (diastole)
higher wave = higher electrical charge = stronger contraction
what condition is shown by this ECG
tachycardia; when an individual has a resting heart rate of over 100bpm
what condition is shown by this ECG
bradycardia: when the resting heart rate is below 60bpm
what condition is shown by this ECG
ectopic heartbeat: caused by an earlier contraction of the atria followed by a pause
can be found occasionally in a healthy person without problem
what condition is shown by this ECG
atrial fibrillation: irregular heartbeat disrupting the heart rhythm, the atria/ventricles stop contracting properly
in severe cases it can be fatal
how is heart rate controlled
the cardiovascular control centre in the medulla oblongata receives electrical impulses from baroreceptors (pressure change) and chemoreceptors (O2, CO2, pH) in the aortic and carotid bodies
the cardiovascular control centre processes the info and send impulses to the SAN along sympathetic and parasympathetic neurones of the autonomic nervous system
what hormone controls heart rate and how
adrenaline
it causes increased heart rate and directly acts on the SA node
causes dilation of arterioles supplying skeletal muscles and contraction of those supplying the digestive system
what is tidal volume
the volume of air that we breathe in and out in each breath
what is vital capacity and what factors can impact it
the maximum amount of air we can inhale and exhale
factors:
size of person
age
gender
fitness
what is minute ventilation
the volume of air taken into the lungs in one minute
what is oxygen consumption
the volume of oxygen consumed by the body
how do we measure lung volume
with a spirometer
label this spirometer trace
residual, vital, tidal, total
what is residual volume
the volume of air remaining in the lungs even after forced expiration; this air remains in the airways and alveoli and is approx 1.5dm^3
how does a spirometer work
add pic
- during inspiration, air is drawn from the chamber, moving down the lid
- during expiration, the air returns to the chamber, raising the lid
- the movements are recorded by a pen attached to the chamber lid which writes on a rotating drum, creating a spirometer trace
the total volume of gas in the chamber decreases because the exhale is O2 and CO2, but CO2 is absorbed by soda lime and there’s only O2 in the chamber which is inhaled and used up in respiration
how can a spirometer be used to measure breathing with excercise
- A person at rest will breathe into the spirometer for one minute
Record the results - The person will then exercise for two minutes while the spirometer chamber is refilled with oxygen
- After they stop exercising, they will immediately breathe into the spirometer for one minute
Record the results - Compare the recordings taken before and after exercising
how is breathing rate controlled
- the respiratory centre in the medulla oblongata send impulses to the intercostal muscles of the ribs and diaphragm muscles
- the muscles contract, causing chest volume to increase, lowering lung pressure and air flows into the lungs
- stretch receptors in the lungs are stimulated, sending nerve impulses back to the medulla oblongata, which inhibits the inspiratory centre
- expiratory centre is no longer inhibited and now does the same but causes muscles to relax and decrease chest volume
how is breathing rate changed during excercise
- blood CO2 level increases with exercise, and lactic acid is produced, decreasing blood pH
- chemoreceptors in the medulla are sensitive to changes in blood pH
- except use initiates impulses from stretch receptors in muscles which go to medulla
- medulla then sends more frequent nerve impulses to the intercostal muscles and diaphragm, to increase rate and depth of breathing
- CO2 is removed, returning pH to normal and decreasing ventilation rate
what can be the effects on health of too much excercise
- joints can be damaged from increased wear and tear
- excessive exercise may suppress the immune system, making you more susceptible to disease
outline keyhole surgery, when it could be used, and its benefits
a less invasive procedure where small incision are made into the skin
a small video camera, light and specialised medical instruments are then inserted to perform the surgery
eg. fixing a damaged cruciate ligament by replacing it with a graft from a tendon in the patients leg or from a donor
+ less blood loss and scarring
- less pain and quicker recovery
when does heart muscle contract
when it’s depolarised
when does heart muscle relax
when it repolarises
outline the effect of hormones inside cells
hormones that can cross the cell surface membrane bc theyre lipid soluble (eg. steroid and thyroid hormones) can enter the nucleus and bind to hormone receptors (transcription factors) and also act as transcription factors themselves
eg. hormonal regulation of body temperature
1. at normal body temp: a transcription factor aka the thyroid hormone receptor binds to a section of DNA at the start of a gene
2. this gene codes for a protein that increases metabolic rate and generates more heat
3. as long as this is bound to the region of DNA at the start of the gene, the gene won’t be expressed
4. BUT in cold, thyroxine (hormone) is released which binds to the thyroid hormone receptor
5. this allows RNA polymerase to bind and transcription rate increases
how do hormones work when they can’t enter the cell membrane
cells that can’t cross the cell membrane bind to receptors in the cell surface membrane
1. the hormone binds to receptors in the cell membrane, activating messenger molecules in the cell cytoplasm
2. the activate protein kinase enzymes which trigger a cascade of reaction in the cell
3. during this, transcription factors can be activated
what are similarities between slow and fast twitch muscle fibres
they both produce energy and help in movement
they both generate force by contraction
they are both present in relatively equal amounts in the human body
what positive impacts can prostheses have
- reduce weight gain
- reducing sedentary lifestyle –> heart disease
- less pain
- less mental health issues
how many ATP formed from one glucose molecule in respiration
38
how do you calculate tidal volume
difference between peak and trough
how do you calculate oxygen consumption
give it as a rate
how much the peaks decrease by over a given time frame
how do you calculate the respiratory minute ventilation
multiply tidal volume by no. breaths in a minute
how do you calculate breathing rate
the number of peaks in a minute
what types of hormones work inside cells
steroid and thyroid hormones
what types of hormones work outside cells
protein
how is the concentration of calcium ions around myofibrils controlled
Ca2+ are released from the sarcoplasmic reticulum in response to a nerve impulse
Calcium ion channels open to take calcium ions back into the sarcoplasmic reticulum via active transport
what is needed in a respirometer
soda lime to remove KOH
measurement of air volumes entering and leaving the chamber
measure the decrease in volume to find the O2 used
control temperature
divide the volume used in a unit of time by body mass to get metabolic rate
how is body temperature controlled
thermoreceptors detect temperature change
this stimulates the thermoregulatory centre in the hypothalamus
hypothalamus sends impulses to sweat glands
vasodilation/vasoconstriction
what is bradycardia
resting heart beat below 60 bpm
evaluate the use of performance enhancing drugs
+ athletes should have the freedom to choose if they want to take the risk
+ they may help overcome training if inequalities
+ competing at a higher level may only be possible for some athletes if they can use performance enhancing drugs
— many are illegal
— they can give an unfair advantage whilst performance should only be the result of training and hard work
— health risks: insomnia, anxiety, higher heart rate and bp, stroke etc.
— athletes aren’t always fully informed of the health risks involved
what is tachycardia
a heart beat over 100 bpm
what is an ectopic heartbeat
a type of arrhythmia where the atria contract early followed by a break
can be completely fine
what is atrial fibrillation
an arrhythmia involving the rapid contraction of the atria
how do you measure tidal volume on a spirometer
draw a line above and below
measure 3/4 volumes between the lines
take the mean
where do Ca2+ come from and to for muscle contraction
from sarcoplasmic reticulum into the sarcoplasm
