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Flashcards in EMPA Deck (39):

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?

1. Sympathetic nervous system
2. Parasympathetic nervous system


What 3 things does the sympathetic nervous system do?

1. Stimulates effectors to speed activity up
2. Acts like an emergency controller when we exercise strenuously
3. Heightens awareness, preparing for the fight or flight response


What 3 things does the parasympathetic nervous system do?

1. Inhibits effectors, so slows down activity
2. Controls activity under normal resting conditions
3. 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?

1. A centre that increases heart rate, linked to the sinoatrial node by the sympathetic nervous system
2. 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?

1. When blood has high carbon dioxide levels, pH is lowered
2. Chemoreceptors in cartorid arteries and aorta detect this and increase nervous impulses to medulla oblongata
3. The centre increases impulses via sympathetic nervous system to sinoatrial node to increase heart rate
4. Increased blood flow leads to more carbon dioxide being removed by lungs, so level in blood returns to normal
5. 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?

1. They transmit a nervous impulse to the centre in the medulla oblongata to decrease heart rate
2. 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?

1. Transmit a nervous impulse to centre in medulla oblongata to increase heart rate
2. 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?

1. Temperature
2. pH
3. Glucose


What do homeostatic systems respond by when they detect a change?

Negative feedback


What three things do homeostatic systems involve?

1. Receptors
2. Communication system
3. 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?

1. They become denatured
2. So, hydrogen bonds are affected, changing shape of active site, so it longer works as a catalyst
3. Metabolic reactions are less effective


What do some changes, such as Hypothermia or a injury trigger?

Positive feedback system


Describe what happens during positive feedback?

Effectors respond to further increase the level away from its normal level


What is the optimum pH for an enzyme

pH 7


What controls body temperature in mammals?

The part of the brain called the hypothalamus


What is the concentration of glucose in the blood normally at?

90 mg per 100 cm(3 cubed)


What are animals either classed as depending on how they control their body temperature?

Ecotherms - can't control body temperature internally, so have to do it by behaviour such as reptiles basking in sun/ sitting in shade

Endotherms - can control body temperature by homeostasis or behaviour


What and where does the hypothalamus receive information from?

Receives information about internal and external temperatures from the thermoreceptors


Name the 5 organs of the human gas exchange system?

1. Trachea
2. Bronchi
3. Bronchioles
4. Alveolus
5. Diaphragm


Describe what happens in 6 steps during inspiration?

1. Diaphragm contracts and flattens
2. External intercostal muscles contract
3. Ribs move upwards and outwards
4. Thorax cavity volume increases
5. Pressure in lungs decreases
6. Air moves into lungs


Describe in 6 steps what happens during expiration?

1. Diaphragm relaxes and domes
2. External intercostal muscles relax
3. Ribs move down and inwards
4. Thorax cavity volume decreases
5. Pressure in lungs increases
6. Air is forced out of the lungs


Give 4 ways the alveoli is efficient gas exchange?

1. Alveoli epithelium and capillary endothelium wall are thin with a single layer of cells = short diffusion pathway
2. Large number of alveoli and pulmonary capillaries = large surface area
3. Ventilation and circulation = maintained concentration gradient
4. = Fast diffusion


Name 4 diseases of the lungs?

1. Emphysema
2. Tuberculosis
3. Asthma
4. Fibrosis


In 9 steps, explain what happens during tuberculosis?

1. Bacteria transmitted in droplets, such as sneezing and coughing
2. Bacteria engulfed by phagocytes
3. Bacteria encased in tubercle in wall of lungs
4. Bacteria is dormant and not replicating
5. If immunosuppressed, bacteria is activated and replicates
6. Bacteria destroys alveoli
7. Leading to scar tissue and fibrosis
8. Damage leads to less diffusion, surface area and increases distance
9. Damage allows bacteria to enter blood, spreading to other organs


Explain in 7 steps what happens during emphysema?

1. Alveoli beak down
2. Less surface area, increased diffusion distance
3. Loss of elastin, so reduced elasticity
4. Lungs cannot expand and recoil
5. Reduced diffusion gradient
6. Less oxygen enters blood
7. Less respiration and less ATP produced


Explain in 5 steps what happens in fibrosis?

1. Scar tissues form on epithelium on lungs
2. Alveolar walls thicken
3. Longer diffusion pathway
4. Scarred tissue reduces surface area
5. Reduced elasticity to expand and recoil, effecting respiration


Describe in 4 steps what happens with asthma?

1. Asthma is the irritation and inflammation of airways
2. Epithelial cells secrete large quantities of mucus
3. Fluid leaves capillaries and enters airways
4. Smooth muscle in bronchioles contracts and constricts airways