Topic 7B Breathing And Heart Flashcards
What is the SA node
- Pacemaker that controls HB
2. Sends out regular waves of electrical activity
Define cardiac output
Total volume of blood pumped by a ventricle in a minute
How is heart rate controlled
- Unconsciously by cardiovascular centre in Medulla oblongata
- Controls the rate at which SNA generates electrical impulses (cause atria to contract)
What does the height of the wave indicate
Size of electrical charge/ strength of contraction
How does your body respond to exercise
- Muscles contract more frequently so more aerobic respiration
- Increase depth and rate of breathing for more o2 and less Co2
- Increase heart rate to deliver more o2 and glucose + remove Co2
What is tidal volume
Normally 0.4dm*3
State the function of collagen tissue in the heart
- Non-conducting
2. Prevents wave of electrical activity being passed directly from atria to ventricles
Why do animals need to be able to alter heart rate?
To be able to respond to internal stimuli
Where does the signal go after AV node
Delay to let atria fully empty
What is the stroke volume
Volume of blood pumped by one ventricle each time it contracts
What are ECGs used for?
Doctors compare to normal trace to diagnose abnormal heart rhythms
What is breathing rate
Breaths taken a minute
Define myogenic
Can contract and relax without reviving signals from neurones
Function of Prukyne fibres
Carry signal to muscular walls of ventricles causing them to contact from the bottom up
What is the QRS complex?
Contraction (DP) of ventricles
What is the T wave
Relaxation (RP) of ventricles
Where is the Sino-atrial node?
Wall of right atrium
What’s the equation for cardiac output
Co (cm3/ min) = heart rate (bpm) X stroke volume
Describe expiration
- Stretch receptors detect inflated lungs
- Send impulse to medulla
- Nerve impulse sent to relax diaphragm and intercostal muscles
Describe breathing in (inspiration)
- Intercostal muscles, pulling ribs up
- Diaphragm contracts (flattens)
- This increase volume in lungs, bringing pressure to lower than environment
How does the medulla oblongata respond to information from receptors
Processes then sends impulses along sympathetic or parasympathetic nerve to SAN
What is the P wave
Depolarisation (contraction) of the atria
What is the function of the bundle of His
- Muscle fibres conduct electricity to finer fibres called Purkyne fibres
How does exercise trigger an increase in breathing rate
- More Co2 in blood, lowers pH
- Chemoreceptors in medulla and aorta sensitive to pH change
- Impulse sent to medulla, causing it to send more frequent impulses to intercostal and diaphragm
- Co2 drops , pH returns to normal
