Introduction to physiology

Question 1

What is physiology?

Answer 1

Science of life

Question 2

What is the purpose of physiology?

Answer 2

• How the body works
• How living organisms adapt to different environments - e.g. temperatures, altitudes
• What goes wrong in disease (pathophysiological conditions)
• How to treat diseases
• How to maintain health

Question 3

What is the process by which the internal environment is kept at a constant state?

Answer 3

Homeostasis

Question 4

Why is the internal environment described as being ‘constant’ and not ‘equilibrium’?

Answer 4

As there is still energy being input into the system?

Question 5

Why is the lungs, GI tract (the lumen) & urinary tract still considered part of the external environment?

Answer 5

As there is a layer of epithelial cells along that create a barrier.

Question 6

Is the cardiovascular system and blood vessels considered part of the internal environment or the external environment?

Answer 6

Internal environment

Question 7

What is included as extracellular fluid?

Answer 7

Interstitial fluid, transcellular fluid & blood plasma

Question 8

What is interstitial fluid?

Answer 8

Fluid outside blood vessels that surrounds all of your cells

Question 9

What is blood plasma?

Answer 9

Found within blood vessels

Question 10

Why do females have a lower % body weight that is fluid?

Answer 10

Because women have more fat tissue, whereas men have more muscle tissue. Muscle tissue has a higher % of water content.

Question 11

What is osmolality?

Answer 11

Total concentration of all particles that are free in a solution

Question 12

What is the units used to measure osmolality?

Answer 12

mOsm - millisomoles per kg of water

Question 13

Describe the osmolality between blood plasma, interstitial fluid & intracellular fluid

Answer 13

All the same

Question 14

What is the advantage of the osmolality being the same between blood plasma, interstitial fluid & intracellular fluid?

Answer 14

Prevents movement of water into or out of the cell:
- too much water = cell would shrink
- too much water = swelling cell

Question 15

Describe the sodium, chloride, potassium & calcium levels in the extracellular fluid

Answer 15

HIGH:
- sodium
- chloride

LOW:
- potassium
- calcium

Question 16

Describe the sodium, chloride, potassium & calcium levels in the intracellular fluid

Answer 16

HIGH:
- potassium
- calcium

LOW:
- sodium
-chlorine

Question 17

Describe how the body fluid compartments are separated (blood plasma through to intracellular)

Answer 17

Blood plasma - capillary endothelium - interstitial fluid - cell (plasma) membrane - intracellular membrane

Question 18

Describe the features of the cell membrane

Answer 18

• phospholipid bilayer
• amphipathic (hydrophobic & hydrophilic parts)
• hydrophilic head (polar & interacts with water)
• hydrophobic tail (non-polar & interacts poorly with water)

Question 19

What is the role of cholesterol in the cell membrane?

Answer 19

Regulates fluidity

Question 20

Describe what 2 properties of molecules make them impermeable across the cell membrane

Answer 20

• Large molecules (proteins & nucleic acids)
• Charged, water soluble molecules (e.g. ions)

Question 21

What type of molecule is permeable across the cell membrane?

Answer 21

• hydrophobic molecules
  (lipid-soluble) e.g. O2, CO2 & steroid hormones

Question 22

What type of molecules are partially permeable to crossing the cell membrane?

Answer 22

Uncharged, polar molecules (water, glucose)
- small charged molecules find it easier to enter than large charged molecules.

Question 23

How do membrane proteins allow polar molecules to travel across the cell membrane?

Answer 23

Prevents the molecules from coming in contact with the hydrophobic core of the bilayer

Question 24

What are intracellular vital parameters that are important to regulate?

Answer 24

• glucose
• ATP
• ions (e.g. Ca2+, K+, Na+)
• pH (H+)

Question 25

What are extracellular vital parameters that are important to regulate?

Answer 25

• plasma levels of oxygen
• plasma levels of nutrients e.g. glucose
• plasma levels of electrolytes e.g. Ca2+, K+, Na+, H+ (pH)

Question 26

What are whole body vital parameters that are important to regulate?

Answer 26

• arterial blood pressure
• blood volume
• core temperature

Question 27

Describe the relationship between blood volume & blood pressure

Answer 27

More blood volume = higher blood pressure

Question 28

What are the 4 features of a negative feedback loops?

Answer 28

1. Receptors
2. Control center
3. Output signal
4. Effector

Question 29

Describe the role of receptors in negative feedback loops

Answer 29

Sense the vital parameter (input)

Question 30

Describe the role of the control center in negative feedback loops

Answer 30

Compares input against a SET POINT (usually found in hypothalamus & brain stem)

Question 31

Where is the SET POINT in the control center (regarding negative feedback of vital parameters)?

Answer 31

Hypothalamus & brain stem

Question 32

Describe the role of the output signal in negative feedback loops

Answer 32

Signal from control center to effector (can use neural mechanisms/endocrine mechanisms e.g. hormone)

Question 33

What 2 mechanisms can be used as an output signal?

Answer 33

• Neural mechanisms
• Endocrine mechanisms

Question 34

Describe the role of the effector in the negative feedback loops

Answer 34

Enables a change to return vital parameter

Question 35

What can an effector act on in order to return vital parameter?

Answer 35

Glands

Question 36

What is extrinsic regulation?

Answer 36

Regulation via neural mechanism (brain) or endocrine system (e.g. hormones).

Question 37

What is intrinsic regulation?

Answer 37

Cells can switch genes on and off as a form of intrinsic regulation