Weekly Quizzes Homeostasis Flashcards
True or False? The controlled variable is changed by altering the diameter of arterioles.
True
Which of the following statements is INCORRECT?
Fever is not an example of hyperthermia.
The set point for body temperature changes across the day.
Fever is caused by a change in the set point for body temperature.
Allowing the controlled variable to move away from the set point always has adverse effects.
Allowing the controlled variable to move away from the set point always has adverse effects.
If a person had an adrenal tumour that was producing excessive amounts of cortisol what with their blood levels of CRH and ACTH be?
Excessive cortisol produced by an adrenal tumour would feedback on the hypothalamus to suppress CRH and on the anterior pituitary to suppress ACTH. The low levels of CRH will also suppress ACTH production.
True or False? The controller is in the medulla oblongata.
True
Excessive levels of cortisol in the blood could be due to disease and hypothalamus, or the pituitary gland, or the adrenal gland.
If a person had a hypothalamic tumour that was producing excessive amounts of CRH, what would their blood levels of ACTH and cortisol be?
Excess production of CRH by tumour would cause excessive production of ACTH. Excessive production of ACTH would cause excessive production of cortisol.
The response to the decrease in blood pressure that occurs when we stand up is an example of what type of feedback?
When we stand up our blood pressure falls due to the effects of gravity. That’s why we may feel dizzy when we stand up. The homeostatic system that returns BP to normal is a negative feedback system-it is responding after a change in the controlled variable has occurred to return the controlled variable to its normal level.
What is the efferent pathway?
The hormone insulin
After eating our blood glucose increases, resulting in the release of insulin. Insulin allows glucose transporters to be inserted in the cell membrane. Why are glucose transporters required to get glucose into the cell.
Glucose is water soluble so it will not be able to pass directly through the phospholipid bilayer of the cell membrane.
What type of homeostatic mechanism is this?
This is a negative feedback system. Eating increases the blood glucose concentration resulting in the movement of glucose into cells to restore the normal blood glucose concentration
True or False? Fever is caused by a change in the set point for body temperature.
True
true or false? The concentration of sodium ions is very high in the extracellular fluid.
It’s true. Comparatively speaking the concentration of sodium is much higher in the extracellular fluid than in the intracellular fluid.
Which of the following statements is INCORRECT regarding the control system for blood pressure?
The blood pressure is the set point.
The controller is in the medulla oblongata.
The efferent pathway is the autonomic nervous system.
The controlled variable is changed by altering the diameter of arterioles.
The blood pressure is the set point.
The blood pressure is the controlled variable. The target value for blood pressure is the set point
If a person had a pituitary tumour that was producing excessive amounts of ACTH what would their blood levels of CRH and cortisol be?
A pituitary tumour producing excessive amounts of ACTH would stimulate excessive production of cortisol. The cortisol would feedback on the hypothalamus and suppress production of CRH.
Is the following statement true or false? Positive feedback systems will slow the rate of increase in body temperature in a hypothermic patient put in front of a blazing fire.
Its false - it would be a feedforward system that would have that effect. Feedforwards systems are why we need to warm hypothermic patients in a conservative way.
Hypertension is excessively high blood pressure. The suffix -capnia refers to carbon dioxide levels in the blood. What word would describe an excessive amount of carbon dioxide in the blood?
Hypercapnia
What is the relationship between the concentration of sodium and potassium ions in the intracellular and extracellular fluid?
Sodium and potassium will always be opposite; intracellular and extracellular fluid will always be opposite.
The concentration of sodium is high in the extracellular fluid; the concentration of potassium ions is low; the concentration of sodium in the intracellular fluid is low whereas the potassium concentration is high.
The levels of carbon dioxide in the blood should be controlled to stay within the normal range. We adjust ventilation to achieve this control. If a person’s ventilation is excessive their CO2 levels will fall. What would you call this increase in ventilation?
Hyperventilation
What is the controlled variable?
The blood glucose concentration
Describe the important differences in the composition of the intracellular and extracellular fluid.
The key thing to remember is that sodium and potassium are always opposite and the ICF and ECF are always opposite. If you remember that the sodium concentration is high in the extracellular fluid then you know that
the potassium concentration in the extracellular fluid is low (because sodium and potassium are always opposite)
the sodium concentration intracellular fluid is low (because ICF and ECF are always opposite).
