short term response to exercise Flashcards
why does heart rate change during exercise
working muscles demand more o2 in order to produce energy for contractions
co2 needs to be transported away
the changes in heart rate regulate cardiac output
what is the cardiac control system (CCC)
under involuntary control and forms part of the automatic nervous system
what 2 parts is the ANS made up of
sympathetic nervous system
parasympathetic nervous system
what does the sympathetic nervous system do
stimulate heart to beat faster
what does the parasympathetic nervous system do
slows heart rate down back to resting levels
what are the 3 control mechanisms heart rate is controlled by
neutral control
hormonal control
intrinsic control
how does the nuetral control control heart rate
various receptors feedback information to our medulla oblongata (in CCC) to regulate hr
what are the 4 receptors
chemoreceptor
baroreceptor
proprioceptors
thermoreceptors
what do chemoreceptors do
changes in CO2 and decrease in O2
how do chemoreceptors work
tiny structures in the cartoid arteries and the aortic arch that detect changes in th acidity of the blood
co2 and latci acid lower the ph of the blood making it more acidic
info is sent to the CCC and as co2 conc increases and ph decreases the CCC increase heart rate
what do barorecpetors do
changes in blood pressure
how do baroreceptors work
special stretch recpetors in the walls of the aorta, vena cava and cartoid arteries to detect changes in blood pressure
an increase in BP causes an increase in stretch of the baroreceptors and result in increase in hr
what do propriorecpetors do
changes in muscle movement
how do the proprioceptors work
sensory nerve endings that detect changes in movement and body posistion
at the start of exersice they detect an increase in muslce movement
send info to the brain that causes the sympathetic nervous system to increase firing of the SAN node to increase hr
what do thermoreceptors do
detect changes in temperature
how do thermoreceptors work
as body temp rises the thermorecptors send info to the CCC
a message is sent from CCC via the accelerator nerve to the heart
SAN is stimulated to increase HR
also an increase in nerve transmission tot the SAN due to increased body temperature
how do does hormonal control control heart rate during exercise
sympathetic nerve cause adrenaline and noradrenaline to be realeased by adrenal gland
message sent via the accelerator nerve to SAN
increase strength of ventricular contractions and hear rate
caridac output increases
hormones also control blood pressure to help with vascular shunting
how do does hormonal control control heart rate when exercise stops
acetylcholine is released
parasympathetic nervous system is stimulated
message sent to SAN via vagus nerve
HR decreases
what is the cardiac muscle contraction
intinsic (doesnt entirely depend on nervous system)
what are the intrinsic ways of controlling heart rate
venous return
starlings law
sodium potassium balance
how does venous return control heart rate during exercise
increased blood returning to the right atrium
increase pressure in thr right atrium which increases heart rate
how does starlings law help to control heart rate during exercise
explains that venous return increases during exercise so the heart fills with more blood and the cardiac muscle fibres are strtched so greater force of contraction and increased cardiac output
how does sodium and potassium balance control heart rate during exercise
an increase in the electrolyte balance of sodium and potassium in the cardiac muscle cells cause the SAN to increase heart rate
how does the body control breathing rate during exercise
the accumilation of co2 in the body acts as poision
during exercise co2 builds up and body reponds by increasing minute ventilation
RCC controls regulation of minute ventilation via the phrenic nerve
the lung stretch recpetors and chemoreceptors detect changes in co2 together they feed back to RCC and control breathing rate and depth
what is RCC
respiratory control centre
how does the body control blood flow during exercise
working muscles require an increase in blood flow and joint movement increases
VCC controls regulation of the blood pressure and distribution
barorecptors measure BP and propiroceptors joint movement so together they feed nack sensory info to VCC to redirect blood flow to working muscles
what is VCC
vasomotor control centre
where is the VCC CCC RCC found in the body
medulla oblongata
