EMPA Flashcards
(39 cards)
What does the autonomic nervous system do?
Controls and regulates the involuntary activities of internal muscles and glands
What are the two divisions of the autonomic nervous system?
- Sympathetic nervous system
2. Parasympathetic nervous system
What 3 things does the sympathetic nervous system do?
- Stimulates effectors to speed activity up
- Acts like an emergency controller when we exercise strenuously
- Heightens awareness, preparing for the fight or flight response
What 3 things does the parasympathetic nervous system do?
- Inhibits effectors, so slows down activity
- Controls activity under normal resting conditions
- Conserves energy and replenishes the reserves
What are changes to the heart rate controlled by?
The region of the brain called the medulla oblongata
What are the two centres of the medulla oblongata?
- A centre that increases heart rate, linked to the sinoatrial node by the sympathetic nervous system
- A centre that decreases heart rate, linked to the sinoatrial node by the parasympathetic nervous system
Where are chemoreceptors found?
In the wall of the carotid arteries which serve the brain
What are chemoreceptors sensitive to?
Changes in the pH of the blood that result from changes in carbon dioxide concentration. In solution, carbon dioxed forms an acid and lowers pH
Describe in 5 steps the control by chemoreceptors?
- When blood has high carbon dioxide levels, pH is lowered
- Chemoreceptors in cartorid arteries and aorta detect this and increase nervous impulses to medulla oblongata
- The centre increases impulses via sympathetic nervous system to sinoatrial node to increase heart rate
- Increased blood flow leads to more carbon dioxide being removed by lungs, so level in blood returns to normal
- Medulla oblongata reduces impulses to sinoatrial node, decreasing heart rate to normal
What 2 things do the pressure receptors do when blood pressure is higher than normal?
- They transmit a nervous impulse to the centre in the medulla oblongata to decrease heart rate
- This sends impulses via parasympathetic nervous system to sinoatrial node of the heart to decrease heart rate
What 2 things do the pressure receptors do when blood pressure is lower than normal?
- Transmit a nervous impulse to centre in medulla oblongata to increase heart rate
- This centre sends impulses via sympathetic nervous system to sinoatrial node to increase heart rate
What is the test to see if carbon dioxide is present?
Limewater test
What is the null hypothesis?
No difference between the amount of carbon dioxide and holding breath
What is homeostasis?
The maintenance of a constant internal environment
What 3 things is it important for homeostasis to maintain?
- Temperature
- pH
- Glucose
What do homeostatic systems respond by when they detect a change?
Negative feedback
What three things do homeostatic systems involve?
- Receptors
- Communication system
- Effectors
What do receptors and effectors do in homeostasis?
Receptors detect when a level is too high or low and the information is communicated via the nervous or hormonal system
Effectors counteract the change to bring the level back to normal
In homeostasis, what is negative feedback?
Mechanism that restores the level to normal
What happens to enzymes if blood pH is too high or low?
They become denatured
Why does homeostasis involve multiple negative feedback systems?
Gives it more control over changes in internal environment to increase or decrease a level to return it to normal
Describe what happens during positive feedback?
Effectors respond to further increase the level away from its normal level
In 3 steps, what happens to enzymes if blood pH is too high or low?
- They become denatured
- So, hydrogen bonds are affected, changing shape of active site, so it longer works as a catalyst
- Metabolic reactions are less effective
What do some changes, such as Hypothermia or a injury trigger?
Positive feedback system