Short Term Responses To Exercise Flashcards
How do you calculate cardiac output
SV x HR
How do you calculate max HR?
220-age
What happens to stroke volume as exercise intensity increases?
Increases but only up to 40-60%
After this it plateaus
Why would a big increase in cardiac output benefit a trained athlete?
⬆️ oxygen supply to muscles = ⬆️ exercise capacity
⬆️ CO2 removal from muscles = ⬇️ DOMS + muscle cramps
What happens during gaseous exchange?
O2 diff from alveoli across alveolar + capillary membranes into RBC.
CO2 diff from RBC + blood plasma into alveoli.
Define partial pressure
Pressure exerted by an individual gas when exists within a mixture of gases.
What aids pulmonary diffusion?
Large:SA ratio
Gases dissolve in surfactant moisture lining the alveoli = MOIST
Walls are made of squamous epithelium - 1 cell thick = short diff pathway
Extensive capillary network to maintain diff gradients
Why will oxygen combine to haemoglobin
Because they have a higher affinity to each other.
What are the 2 ways in which oxygen is transported in the blood?
97% combines w/ haemoglobin to form oxyhemoglobin
3% dissolves into plasma
What are the 3 ways in which CO2 is transported?
5% in solution in the plasma
85% as H carbonate ion - HCO3-
10% bound to Hb as carbaminoHb
Explain the transport/diffusion of CO2 into the blood
Diffuses into RBC down conc. grad.
Carbonic anhydrase catalyses CO2 + H2O to carbonic acid/bicarbonate
Carbonic acid dissociates into H + H carbonate ions
The H carbonate ions diff out of RBC into plasma
To balance outflow of -ive ions + maintain electrochemical neutrality, chloride ions diff INTO RBC from plasma. == CHLORIDE SHIFT
H+ attach to Hb to form Haemoglobinic acid + displace the O2
O2 diffuses out of RBC into tissues.
List the 4 types of receptors
Chemo (pH)
Thermo
Proprio (Detects changes in body movement + position)
Baro (Detects changes in bp)
How does the sympathetic nervous system increase heart rate?
By releasing adrenaline and noradrenaline from the adrenal medulla.
Define adrenaline
Stress hormone that stimulates the SAN to ⬆️ speed and force of contraction.
Define noradrenaline
Neurotransmitter that aids the spread of the impulse throughout the heart.
What does the parasympathetic nervous system release?
Acetylcholine (a neurotransmitter) that slows the spread of impulses throughout the heart = back down to resting levels.
What happens to the CO2 levels in the blood when exercise begins and how does it stimulate the sympathetic nervous system?
CO2 ⬆️ = ⬇️ blood pH = detected by chemoreceptors = send message to CCC in medulla oblongata.
CCC sends impulse to SAN via accelerator nerves.
Adrenaline and noradrenaline released = heart rate + strength ⬆️
END of exercise = parasympathetic takes over. Vagus nerve is stimulated and acetylcholine is released = slowing HR.
What does it mean that the hearts contraction is intrinsic?
It doesn’t depend on the nervous system.
What are the 3 different ways in which the heart is controlled intrinsically?
Venous return
Na+ + K+ ion balance
Heart muscle temp
Intrinsic control of the heart
Explain the sodium and potassium ion balance
Changes in this balance in the cardiac muscle cells cause the SAN to generate an electrical impulse = changes in heart rate.
Describe the mechanics of breathing when you inhale
External intercostal muscles + diaphragm contract
Ribs up + out
Thorax volume ⬆️ = pressure ⬇️
Atmospheric air pressure is greater than in lungs so air moves in.
Describe the mechanics of breathing when you exhale
External intercostal muscles + diaphragm relax
Ribs down + in
Thorax volume ⬇️ = pressure ⬆️
Atmospheric air pressure is less than in lungs so air moves out.
Describe the mechanics of breathing when you inhale during exercise
All as normal + greater volumes of air filling in lungs due to sternocleidomastoid + pectorals minor helping to move ribs + ⬆️ chest cavity further.
Describe the mechanics of breathing when you exhale during exercise / Forced expiration
Internal intercostal muscles contract
Ribs down + in
Abdominal muscles contact to push diaphragm upwards
Thorax volume ⬇️ = pressure ⬆️
Atmospheric air pressure is less than in lungs so air moves out.
