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Heart and Ventilatio
Ventilation and Heart rate control
| Question | Answer |
|---|---|
| What is special about Cardiac Muscle: | It is Myogenic, it will beat without signals from the brain. |
| What controls the heart rate: | The sympathetic and Parasympathetic nervous system controlled by the Medulla in the brain. |
| Sympathetic nervous system: | Increases the rate of the heart beating. |
| Which three factors alter the heart rate: | Blood pH, Baroreceptors (blood pressure) and hormonal control. |
| How does blood pH alter heart rate: | As amount of CO2 in the blood rises the pH of the blood lowers, so more O2 is required for respiration, this causes the heart to increase its beating rate to increase the amount of blood flowing to cells. |
| How do Baroreceptors alter the rate of the heart: | As exercise and such undergoes, the muscles squeeze the veins surrounding them, causing more blood to be sent back to the heart, this stretches the veins and arteries so increases heart rate. Receptors in the carotid reduce rate. |
| How do Hormones affect the heart rate: | They can stimulate the nervous system to cause an increase in heart rate. |
| Which part of the brain controls the hear and breathing rate: | The Medulla oblongata |
| Which section of the medulla controls heart rate: | The Cardiovascular Centre. |
| Which section of the medulla controls the breathing rate: | The ventilation centre. |
| Describe the sequence of events involved in one heart beat. | SAN > Atrial Systole > Inhibited by nonconductive collagen fibers > AVN > Bundle of His > Purkyne fibers > Ventricluar Systole. |
| What does an increase in blood pressure in the carotid cause: | A decrease in blood pressure as the Baroreceptors send signals to the medulla which will decrease the heart rate. |
| Describe the events of a single breath: | The inspiratory centre is uninhibited > sends signals to the intercostal muscles and diaphragm causing contraction > volume of lungs increases and air moves in > stretch receptors excite expiratory centre > intercostal muscles relax > Air moves out |
| What detects a change in the CO2 concentration in the blood: | Chemoreceptors in the Carotid and the Aortic bodies. |
| What happens when the pH of the blood is altered: | Chemoreceptors detect the change and will send signals to the medulla, if the pH has decreased (more CO2) the breathing rate will increase to remove the CO2, if the pH increases (less CO2) the breathing rate will decrease to prevent flooding of O2. |
Created by:
mjwilson1988
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