Physiology Week 1

Question 1

ICF is found where? ECF?

Answer 1

ICF: within the cell
ECF: bathes and surrounds the cells

Question 2

Another word for homeostasis that describes a stable internal environment

Answer 2

Dynamic equilibrium

Question 3

What are the cells requirements?

Answer 3

Maintain functional integrity, perform organ function, and contribute to organism’s survival

Question 4

Define homeostasis.

Answer 4

Ability of the body to maintain a relatively stable internal environment despite external variances

Maintenance of steady states in the body by coordinated physiological mechanisms

Question 5

Total volume of body water and its distribution

Answer 5

42L total
2/3: intracellular (40%)
1/3: extracellular (20%); 
    3/4: interstitial/lymph
    1/4: plasma

Note: water is 50% and 60% of body weight for women and men, respectively

Question 6

What is transcellular fluid?

Answer 6

Fluids outside of normal compartments; I.e. CSF, digestives fluids, and mucus

Question 7

Sodium extracellular electrolytes range

Answer 7

136-145 mmol/L (mEq/L)

Question 8

Potassium extracellular electrolyte range

Answer 8

3.5 - 5 mmol/L (mEq/L)

Question 9

Intracellular sodium range

Answer 9

6 - 14 mmol/L (mEq/L)

Question 10

Intracellular potassium electrolyte range

Answer 10

154 mmol/L (mEq/L)

Question 11

Osmolarity of body fluid compartments

Answer 11

290 mOsm

Question 12

Homeostasis requires __________, while equilibrium does not

Answer 12

Energy expenditure

Question 13

What is steady state?

Answer 13

Maintenance of a state that does not change with time that usually required energy expenditure

Question 14

Define equilibrium

Answer 14

Two compartments that have the same amount and free energy; bonnet energy transfer between compartments

Question 15

What is the relationship between steady state and homeostasis?

Answer 15

Steady state is the means by which homeostasis is maintained

Question 16

Steady state or equilibrium:
A) water
B) ECF
C) ICF

Answer 16

A) equilibrium
B) steady state
C) steady state

Question 17

Feedback mechanisms are what kind of loops? Feedforward?

Answer 17

Feedback: CLOSED
Feedforward: OPEN

Question 18

Negative feedback vs positive feedback

Answer 18

Negative: opposes original change
Positive: amplifies original change until an end point in reached

Question 19

Which of the following variable is not controlled by homeostasis?
A. Blood pressure
B. Blood glucose
C. Heart rate 
D. Arterial PO2
E. Blood pH

Answer 19

C. Heart rate; HR is and effector, not a variable

Question 20

What is significant about negative feedback mechanism of blood glucose?

Answer 20

Pancreas B-cells are the sensor, comparator, and effector. There is no CNS involvement.

Question 21

What are the 4 set point deviations?

Answer 21

1. 24 hr cycle: circadian rhythm
2. Environmental changes: altitude
3. Protective response: fever
4. Aging/pathological changes: atheramatous plaques (accumulation of degenerative materials)

Question 22

What is redundancy?

Answer 22

More than one mechanism to control an important variable

Question 23

Mechanisms of hypovolemic shock

Answer 23

Aortic arch/carotid sinus:

1. hypothalamus/posterior pituitary -> ADH: wafer reabsorption & vasoconstriction
2. Medulla oblongata -> sympathetic output & parasympathetic decrease: vast constriction & increase in heart rate contractual it’s

Kidney/JG cells:
1. Angiotensin/angiotensin II-> adrenal cortex -> aldosterone : Na+ resorption

Question 24

Result of deficient homeostatic mechanism

Answer 24

Disease: negative feedback becomes positive feedback leading to disastrous consequences

Ex. Chronic heart failure: CO falls -> body retains fluid -> increase of load -> inc. chance of failure