7B- Exercise Flashcards
(28 cards)
In an ECG, what are the:
P waves
QRS Complex
T wave
P wave is the atria depolarising/atrial systole
QRS complex is the contraction/depolarisation of the ventricles
T wave is the ventricles relaxing/diastole
The atrial systoles electrical activity occurs at the same time when ventricular systole occurs, so the electrical activity isnt detected by the ECG as the ventricular diastole overpowers it.
What are the following conditions called:
When the heart beat is too fast (around 120bpm resting)
The heart rate is too slow (below 60bpm resting)
The atria contracting too early (p wave will occur earlier compared to the typical ECG)
The P QRS and T are very disregulated
Tachycardia
Bradycardia
Ectopic beat
Fibrillation
What are the ways the body compensate in response to an increase in exercise?
Increasing breathing rate and depth- This is to get more oxygen into the blood via alveolar diffusion in the lungs, as well as more carbon dioxide out of the blood via exhalation.
Increasing heart rate- This is to circulate oxygen around the body at an increased rate, so that aerobic respiration can occur at an increased rate. It is also so that carbon dioxide can be transported to the lungs and removed quicker.
What part of the brain controls breathing rate?
The medulla oblongata
How does the medulla oblongata control the breathing rate?
The ventilatory control centres are responsible for breathing regulation. When an individual needs to inhale, the ventilatory control centre sends action potentials to the external intercostal muscles as well as the diaphragm to contract. This causes them to contract, which allows for more room within the lungs for air. The volume of space wihin the lungs increases, so the pressure decreases, and this difference in concentration of air causes air to diffuse into the lungs from the air by diffusion. When a person is inhaling, stretch receptors detect muscular stretching, and send impulses back to the medulla oblongata. These impulses inhibit the ventilatory control centre in the medulla oblongata from sending impulses to the external intercostals and diaphragm. This means they are no longer stimulated, and they no longer contract, and begin to relax. This causes the space available to the lungs to decrease, so the volume decreases and the pressure builds up, so the pressure difference causes the air to be forced out of the lungs into the air- the person exhales.
How does exerice trigger an increase in breathing rate by decreasing blood pH?
During exerice, the level of carbon dioxide in the blood increases. This leads to the concentration of bicarbonate and hydrogen ions in the blood to increase, so the pH decreases. Chemoreceptors in the medulla oblongata, the aorta, and the carotid artery detect this change in pH, and they send action potentials to the ventilatory control centres in the medulla oblongata, which more frequent impulses to the external intercostal muscles and the diaphragm. This increases breathing rate and depth, and therefore the rate of gaseous exchange. CO2 levels drop and O2 levels increase, increasing the pH back to the optimum of 7.4.
What controls the rate at which the SAN sends impulses?
Why is this important?
The cadriovascular control centre
Animals must respond to their environment (i.e. if they are going to faint due to low blood pressure etc.)
What receptors detect Blood pressure?
What receptors detect blood pH, Oxygen levels, and Carbon Dioxide levels?
Baroreceptors
Chemoreceptors
What is the parasympathetic nerous system?
The nervous system which calms the body down- ‘rest and digest’ system. It therefore helps to decrease the heart rate after exercise.
What is the sympathetic nervous system?
It is the nervous system which gets the body ready for action and is onvolved in the fight or flight response. It therefore is involved in increasing the heart rate during exercise.
Describe how blood pressure detection by baroreceptors leads to changes in blood pressure:
Low blood pressure
High blood pressure
The baroreceptors in the carotid and coronary artery detect a low blood pressure. They send action potentials along the sympathetic nervous pathway which instruct the cardiovascular control centre to send action potentials to the SAN, where neurotransmitter (noradrenaline) to bind to the SAN and increase the heart rate, which increases the blood pressure.
The baroreceptors in the carotid and coronary artery detect the increased blood pressure, and they send impulses along the parasympathetic nervous pathway, which sends action potentials to the SAN which leads to the release of neurotransmitters (acetyl choline) which bind to the SAN, instructing the SAN to fire impulses less quickly. This means that the heart rate decreases, and the blood pressure also does subsequently.
What is the cardiac output?
How is it calculated?
The total volume pumped out of the ventrical every minute.
Cardiac output = heart rate (beats per minute) x stroke volume (cm3)
What is the tidal volume?
The amount of air in each breath.
What is the breathing rate?
The number of breaths taken in within a minute.
What is oxygen consumption?
The amount of oxygen used by the body is a given time (usually expressed as a rate).
What is respiratory minute ventilation?
How is it calculated?
The volume of oxygen breather in or out in a minute.
Respiratory minute ventilation= Breathing rate x tidal volume. RMV=TB
How would you use a spirometer to measure ventilation?
Set up a spirometer. Fill it with a known volume of O2 so that the trace becomes calibrated. Breath into the spirometer like normal and do this a few times. The lid of the spirometer will rise and fall, and the pen attached to it will trace on a rotating drum of paper the changes in air in the lungs. The volume of air within the spirometer will decrease over time as the sodium hydroxide in the spirometer will absorb the CO2 exhaled, so the only gas being inhaled is oxygen. Attach a medicinal grade oxygen tank so that the person does not sufficate.
How can spirometers be used to investigate the effect of exercise on breathing rate etc.
You can have someone at rest breath into the spirometer for a fixed time period, like a minute. You could have them do exercise for, 2 mins for example, and you could have the person breath back into the spirometer for the same time period.
What can be calculated from the trace of a spirometer?
Breathing rate- this is the number of peaks on the trace in a minute. Peaks represent breaths, so this will be the number of breaths within a minute.
Oxygen consumption- This is the starting volume of oxygen in the spirometer - the final volume of oxygen in the spirometer.
Tidal volume- This is the change in volume between the peaks and the troughs. So this is the volume of air in each breath, averaged over a specific time.
What is negative feedback?
It is a response to a change in the internal conditions of the body, where the change is reverted back to normal.
However, if the change is too drastic, it may be impossible to counter act. For example, if the bodys internal temperature has fallen too low, it will not be able to come back to its original temperature, so people may die (hypothermia).
What is positive feedback?
Why isnt this involved in homeostasis?
It is amplifying a change from the normal level. For example, if the body has a cut, platelets become increasingly activated to form bloot clots.
It is not involved in homeostasis because it is not keeping the bodys internal environment stable.
What is homeostasis?
The process by which changes to the bodies internal environment trigger a reponse which counteracts the change, to revert the change so that the internal environment is back to a stable condition.
What are the mechanisms to:
Increase body temperature?
Decrease body temperature?
Shivering- muscles spasm, so increased respiration, so more heat is produced.
Secrete less sweat- less heat escapes the body through water.
hairs stand up to create an air layer which offers some extra insulation, erector pili muscles contract.
vasoconstriction- Arterioles nearest the capillaries near the skin constrict so that less blood can flow to the capillaries. This means that less heat is lost when heat is transferred to the sweat glands.
hormones- adrenaline and thyroxine are released to increase metabolic reactions, so that more heat is produced
Sweating- Heat is transferred to the sweat on the epidermis. This is secreted out of the sweat glands, and the water evaporates off of the surface of the skin. This takes the heat with it, and the skin is cooled.
Hairs lie flat- The pili erector muscles relax, and the hairs lie flat. This means that the hairs no longer trap a layer of air on the skin, so the body loses this layer of insulation, so heat can be lost more easily.
Vasodilation- The arterioles near the capillaries dilate, so that more blood can get to the capillaries near the surface of the epidermis. The heat in the blood can therefore be transferred to the sweat, and the sweat is secreted. The body loses the heat when the sweat evaporates.
How can hormones act as transcription factors?
A hormone receptor may bind to the start of a gene, decreasing the transcription of the gene which codes for a protein associated with increased metabolic rates, so the rates decrease. If the temperature changes so that the hormone receptor doesnt bind to the operator, then the gene will be transcribed and the metabolic rate protein is produced, so the metabolic rate increases.
