CNS And The Hormonal Control Of The Heart Flashcards
What is the sympathetic system?
A part of the autonomic nervous system that speeds up heart rate.
What is the parasympathetic system?
A part of the autonomic nervous system tat decreases heart rate.
What is the medulla oblongata and what does it do?
It is the most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate.
What are chemoreceptors and what do they do?
They are tiny structures in the carotid arteries and aortic arch that detect changes in blood acidity caused by an increase or decrease in the concentration of carbon dioxide.
What are baroreceptors and what do they do?
They are special sensors in tissues in the aortic arch, carotid sinus, heart and pulmonary vessels that respond to changes in blood pressure to either increase or decrease heart rate.
What are proprioceptors and what do they do?
They are sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement.
What is adrenaline and what does it do?
Adrenaline is a stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in heart rate.
What is stroke volume?
The volume of blood pumped out by the heart ventricles in each contraction.
What is the diastole phase?
When the heart relaxes to fill with blood.
What is ejection fraction?
It is the percentage of blood that is pumped out by the left ventricle per beat.
What does the sympathetic nervous system do?
- Increases Heart rate by releasing adrenaline.
- Adrenaline increases the strength of ventricular contraction which then increases stroke volume.
- Noradrenaline aids the spread of electrical impulse throughout it the heart increasing HR
- Increased metabolic activity causes increased concentration of CO2 and lactic acid, decreasing pH of blood.
- These changes are picked up by chemoreceptors and inform the sympathetic centre to increase HR to plush out the waste products.
- This results in an increased cardiac output.
What does the parasympathetic nervous system do?
Releases acetylcholine which slows the spread of impulses throughout the heart. resulting in a lower heart rate.
What are the characteristics of you body when using the parasympathetic nervous system?
Constricted pupils, stimulates saliva, slower heart beat, constricted airways, stimulates activity of the stomach, inhibits release of glucose; stimulates gallbladder, stimulates the activity of the intestines and contracts the bladder.
What are the characteristics of the body when using the parasympathetic system?
Dilated pupils, inhibits salivation, increased heartbeat, relaxed airways, inhibit activity of stomach, stimulates release of glucose; inhibits gallbladder, inhibits use of intestines, secrets epinephrine and norepinephrine, relaxes the bladder.
What is the hormonal control mechanism and what does it do?
Hormones can also have an effect on heart rate. The release of adrenaline during exercise is known as hormonal control. Adrenaline is a stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise. It stimulates the SAN (pacemaker) which results in an increase in both the speed and force of contraction, thereby increasing cardiac output. This results in more blood being pumped to the working muscles so they can receive more oxygen for the energy they need.
