Variations in Heart Rate and Breathing Rate Flashcards
Why does your breathing and heart rate increase with exercise?
- When exercise, muscles contract more freq. which means use more energy.
- To replace energy your body needs to do more aerobic respiration, so needs to take in more oxygen and breathe out more CO2.
When exercising, how does your body increase the amount of oxygen entering body?
- Increase breathing rate and depth - to obtain more oxygen and get rid of more CO2.
- Incr. heart rate to deliver oxygen (and glucose) to muscles faster and remove extra CO2 produced by incr. rate of respiration in muscle cells.
How does exercise trigger an increase in breathing rate?
- During exercise, level of CO2 in blood increases. This decreases pH of blood.
- Chemoreceptors in medulla, aortic bodies and carotid bodies are sensitive to pH changes in blood.
- If chemeoreceptors detect a decrease in blood pH, they send nerve impulses to medulla, which sends more frequent nerve impulses to intercostal muscles and diaphragm.
- This increases rate and depth of breathing. Causes gaseous exchanges to speed up.
- CO2 levels drop and extra O2 is supplied to muscles.
What is the definition for ‘heart rate’?
How quickly the heart is beating. It’s the number of beats per unit of time, usually a minute.
What is stroke volume?
The volume of blood leaving the left ventricle with EACH BEAT.
What is cardiac output and how is it calculated?
The total volume of blood pumped by the ventricle every MINUTE. Cardiac Output (dm3min-1) = Stroke Volume (dm3) x Heart rate (min-1)(bpm)
What is the heart rate controlled by?
The cardiovascular control centre in the medulla in the brain.
What happens to the heart rate when blood pH decreases?
- Increase in pH (caused by incr. in CO2) is detected by chemoreceptors.
- Chemoreceptors send nerve impulses to the medulla.
- Medulla sends nerve impulses to the SAN to incr. heart rate.
What happens to the heart rate when blood pressure increases?
- Pressure receptors in aorta wall and carotid sinuses detected changes in bp.
- If the pressure is too high, pressure receptors send nerve impulses to cardiovascular centre which sends impulses to SAN to slow down heart rate.
- If pressure too low, pressure receptors send nerve impulses to cardiovascular centre which sends nerve impulses to SAN to speed up heart rate.
What nerve [system] is responsible for speeding up heart rate when pH falls?
Sympathetic nerve.
What causes pH in the blood to fall?
Lactate and CO2 levels raising.
What nerve [system] is responsible for slowing down the heart rate when demand for O2 and removal of CO2 reduces?
Vagus nerve.
