Group Project Flashcards
List all the different cardiac factors
(7)
Systolic pressure
Diastolic pressure
Mean systemic arterial pressure
Cardiac output
Heart rate
Stroke volume
Total peripheral resistance
What is systolic pressure
The amount of pressure experienced by the arteries while the heart is beating
What is diastolic pressure?
The amount of pressure in the arteries while the heart is resting in between heart beats
What is Mean systemic arterial pressure?
The average arterial pressure throughout one cardiac cycle, systole, and diastole
What is cardiac output?
Cardiac output is how many litres of blood your heart pumps in one minute
Stroke volume x heart rate
What is stroke volume?
The volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction.
What is total peripheral resistance?
The amount of resistance to blood flow present in the vascular system of the body
List the pulmonary factors
(4)
Minute ventilation
Respiratory rate
Tidal volume
Vital capacity
List the metabolic factors
(3)
Oxygen consumption (VO2)
Respiratory Exchange Ratio (RER)
Carbon dioxide production (VCO2)
List the thermal factors
(4)
Metabolic rate
Core body temperature
Pallor
Sweat
What is minute ventilation?
the amount of air a person breaths in a minute.
Tidal volume x respiratory rate
What is tidal volume?
The amount of air that moves in or out of the lungs with each respiratory cycle
What is vital capacity?
The greatest volume of air that can be expelled from the lungs after taking the deepest possible breath
What is the respiratory exchange ratio?
The ratio between the amount of carbon dioxide (CO 2) produced in metabolism and oxygen (O 2) used
What is metabolic rate
The rate of energy expenditure per unit time
What type of testing is this?
Cardiopulmonary exercise testing
What type of exercise is this?
Incremental exercise
Why are CPET exams carried out?
They can be used to assess patient’s with pulmonary or cardiac diseases
How effective are CPETs at identify heart abnormalities?
70% of heart abnormalities can be exposed
Who was our subject?
A healthy 19 year old with no comorbidities
How was the exercise carried out?
Using a bicycle ergometer
How was core temperature measured?
Using a tympanic thermometer (in ear canal)
How was respiratory rate of the patient measured?
By watching the rise and fall of the patient’s chest
How was systolic and diastolic blood pressure recorded?
Measured using the auscultatory method at rest
Measured using a sphygmomanometer during exercise
What is the auscultatory method?
(5)
Blood flow in the left brachial artery is occluded
Cuff is inflated to 160mmHg and then pressure is released gradually
Characteristic korotkoff sounds were listen to with a stethoscope
Systolic pressure = first korotkoff sounds
Diastolic pressure = no longer hear sounds
And the pressure readings were determined
How do you determine MSAP?
(Diastolic + diastolic + systolic)/3
How was heart rate measured?
By palpating the wrist
How was oxygen and carbon dioxide levels recorded?
(2)
The patient was asked to wear a Douglas bag which collected the expired gas
This collected gas was then transferreed to 2L gas analysis bags for analysis by a gas analysis meter
How was oxygen consumption and carbon dioxide production calculated?
Using a dry gas meter
Why did MSAP increase during exercise?
Systolic and diastolic were raised
Why did cardiac output increase during exercise?
Due to increase in heart rate and stroke volume
What happened to total peripheral resistance during exercise?
Total peripheral resistance decreased during exercise
Why did TPR go down?
Due to an increased MSAP and increased cardiac output
What happened to TPR after exercise?
It increased to above the resting level prior to exercise
What was the only cardiac value to decrease?
Total peripheral resistance
What division of the nervous system controls our cardiac responses to exercise?
The sympathetic nervous system
How does the cardiac system prepare for exercise?
The sympathetic nervous system responds to the anticipation of exercise by increasing heart rate
How does the sympathetic division increase heart rate?
Through neurotransmitters such as noradrenaline and hormones such as adrenaline
Why does heart rate increase in preparation of exercise?
To increase cardiac output and therefore prepare for the increased demand in oxygen and nutrients
What happens to stroke volume when exercise begins?
Stroke volume increases due to the increase in venous return
What increases venous reserve, blood flow back to the heart?
Venous reserves are accessed
Skeletal muscle activity and respiratory pump also increase venous return
What is a respiratory pump?
During inspiration, the diaphragm moves down, expanding the thoracic cavity, resulting in a decreased intra-thoracic pressure and a subsequent expansion of the lungs.
Part of this change in pressure is transmitted across the walls of the heart, lowering right atrial pressure and thus facilitating venous return.
How does an increase in venous return condition the heart?
Conditions the myocardium
Increases the degree of stretching prior to contraction
What is Starling’s law?
the strength of the heart’s systolic contraction is directly proportional to its diastolic expansion
What is responsible for increasing heart rate?
(3)
Sympathetic division of the ANS
Bainbridge reflex
Noradrenaline
What is the Bainbridge reflex?
Increase in central venous pressure causes increased blood volume to be detected by stretch receptors
Results in increased heart rate
What is central venous pressure?
Pressure in the right atrium
How exactly does the sympathetic division increase heart rate?
(3)
Increases release of noradrenaline at B1 receptors
This increases Na+ and Ca++ entry
This increases rate of depolarisation and shortens repolarisation (more stress and less refilling)
What is a change in heart rate called?
A chronotropic effect
What activates the Bainbridge reflex?
The stetching of the walls of the right atrium
How exactly does increased venous return activate the Bainbridge reflex?
Venous return fills up the right atrium - right atrium stretches - Bainbridge reflex activated
What hormones are released after ANS activation? (Cardiac)
Adrenaline
Noradrenaline
Thyrdoid hormone
How does adrenaline, noradrenaline and thyroid hormone affect the cardiac system?
They increase the rate o f depolarisation of the SA node and decrease repolarisation duration
How is blood pressure maintained and blood flow optimised throughout incremental exercise?
(3)
Vascular dilation and constriction in different areas of the body is controlled by the medulla oblongata
Active areas will undergo vasodilation to lower peripheral resistance and optimise blood flow
While not as active tissue will undergo vasoconstriction and blood will be shunted away to more active areas
Why does systolic blood pressure only increase slightly?
Due to the increase in cardiac output but the decrease in peripheral resistance
Why does diastolic pressure remain somewhat constant?
Due to peripheral vasodilation
What happened to minute ventilation during exercise?
It increased significantly and then returned to near normal
How do you calculate minute ventialation?
Respiratory rate x tidal volume
Why was there such a high increase in minute ventilation?
As both respiratory rate and tidal volume increased
How was Vt/Vc % calculated?
By dividing tidal volume by vital capacity and mumltiplying by 100%
What happened to Vt/Vc?
It increased during exercise
What happened to respiratory rate?
It increased during exercise and then returned to near normal
Which of the pulmonary responses was not considered normal and what was the explanation for this?
Respiratory rate was elevated
This is probably due to the anticipatory response to exercise
Why does minute ventilation increase?
(2)
Due to an increase in respiratory rate and tidal volume which increases to meet the demands of oxygen uptake and carbon dioxide production
This maintains the serum partial pressure of oxygen and carbon dioxide
Why do the pulmonary responses return to normal?
As the requirement for oxygen decreases and carbon dioxide production decreases
What causes ventilation to increase in response to anticipation of exercise?
(3)
Feedforward mechanism
Sympathetic output from neural activities in the motor cortex or the hypothalamus
These stimulate an involuntary increase in respiration
During exercise, why does ventilation increase?
(3)
Chemoreceptors detect changes in chemical balances of the blood
They send sensory input to the dorsal respiratory group (DRG) of the medulla
The DRG initiates inhalation and gives the ventral respiratory group output to modify breathing rhythm
What makes up the respiratory centre?
(2)
The dorsal respiratory group and the ventral respiratory group of the medulla
In the pons, the pontine respiratory group is made up of two areas – the pneumotaxic centre and the apneustic centre
What does the DRG control?
Initiation of inhalation
What does the VRG control?
Exhalation
Other than from chemoreceptors, where does the DRG get it’s input?
Input from proprioceptors which detect movement in skeletal muscle and joint capsules
The DRG modifies the efferent output to the breathing muscles
What happened to oxygen consumption, carbon dioxide production and respiratory exchange rate during exercise?
(3)
VO2 increased sharply but returned to normal
VCO2 increased sharply but returned to normal
RER increased during exercise and returned to normal
Why was there a drop in pulmonary results during exercise?
Due to operator error
Is the VCO2 normal during exercise?
(3)
When compared to other studies our VCO2 max is low
But this is more than likely due to a difference in the levels of intensity in our experiment
It is also known that VCO2 tends to be lower in cycle experiments than in treadmill experiments
Why does oxygen consumption rise during exercise?
Due to rising levels of catecholamine hormones e.g. adrenaline and noradrenaline produced by the adrenal glands
How do the adrenal glands increase oxygen consumption?
(3)
Adrenal glands are innervated by sympathetic neurons
When stimulates these bring on a fight or flight response
This increases the metabolic rate and increases blood flow to muscles
Why does VCO2 increase?
(4)
There is an increase need for energy -> more ATP is produced
Skeletal muscle rich in mitochondria
Cycles such as the TCA cycle are activated by strenuous exercise
CO2 is produced along with ATP
Explain what RER is?
The ratio of the amount of carbon dioxide produced by the body to the amount of oxygen taken in by the body
What does an RER of 1 mean?
The body is favouring the metabolism of carbohydrates
(Same amount of VCO2 and VO2)
According to RER, what type of metabolism takes place at minute 30?
Metabolism of carbohydrates
According to RER, what type of metabolism takes place before minute 30?
Metabolism of protein and fats
What does an RER of above 1 mean?
Body is producing more CO2 than O2
What happens to metabolic rate during exercise?
It increases linearly and then returns to a level below what it was at rest
Why does metabolic rate increase?
(2)
During exercise the skeletal muscle needs more ATP production to work harder
Increased need for nutrients and energy
What happens to body temperature during exercise?
Increases slightly and then returns to normal
Why does body temperature increase?
(3)
Heat energy is given of from the production of mechanical energy
The body uses heat dissipating mechanisms to cope with heat production e.g. evaporative heat loss
Any heat that cannot be dissipated results in an increase in body temperature
What happens to sweat production during exercise?
(3)
Sweat is not produced until minute 40 -> 18 mins of exercise needed
1g of sweat
Sweat production stops at 60 mins during recovery
Why is sweat produced?
(3)
Heat dissipation - thermoregulation
Produced by sweat glands - mostly eccrine glands
Sympathetic response to increased body temperature
Name the three types of glands?
Eccrine
Apocrine
Apoeccrine
What determines amount of sweat produced?
(2)
External temperature, type of exercise
Fitness level, body mass
How are sweat glands stimulated?
(3)
Muscle mechanoreceptors, osmoreceptors and baroreceptors are stimulated in muscle during exercise
Stimulus goes to hypothalamus
Sympathetic response activated -> noradrenaline at sweat gland - sweat produced
What happened to pallor during exercise?
(2)
At 45 minutes the individual got redder due to vasodilation
Red colour faded at 55 minutes and returned to normal by 65 minutes
Why did pallor change?
(2)
Increase in body temperature -> causes sympathetic response
Vasodilation
