Intro to Physiology

Question 1

What is the internal environment?

Answer 1

The carefully regulated fluid environment that cells need in order to function - must remain stable despite changes in external environment

Question 2

How is the internal environment maintained?

Answer 2

Homeostasis - active process requiring energy

Question 3

What is part of the external environment?

Answer 3

Digestive system, respiratory system, urinary system

Question 4

What makes up the internal environment and why?

Answer 4

Cardiovascular system, interstitial fluid, intracellular fluid - does not directly interact with external environment

Question 5

What is the capillary endothelium?

Answer 5

Between blood and interstitial fluid

Question 6

What is the plasma membrane?

Answer 6

Between interstitial fluid and intracellular fluid

Question 7

What makes up the extracellular fluid?

Answer 7

Blood and interstitial fluid

Question 8

What is interstitial fluid?

Answer 8

Any fluid not in blood vessels or cells

Question 9

What is osmolality?

Answer 9

Total concentration of all particles that are free in a solution - vital parameter that must be controlled

Question 10

What is the body’s osmolality?

Answer 10

290 mOsm (milliosmoles per kg of water) in all compartments to avoid movement of water by osmosis

Question 11

What happens if osmolality is disrupted?

Answer 11

Cells may swell/burst or shrink

Question 12

How are ions distributed between ICF and ECF?

Answer 12

Na+ Higher in ECF
K+ Lower in ECF
Cl- Higher in ECF
Ca2+ Higher in ECF

Question 13

What does amphipathic mean?

Answer 13

Has both hydrophobic and hydrophilic parts

Question 14

What are the properties of a hydrophobic head?

Answer 14

Polar
Interacts with water
Sits on outside of membrane

Question 15

What are the properties of a hydrophilic tail?

Answer 15

Non-polar
Interacts poorly with water
Sits on inside of membrane

Question 16

How is a phospholipid structured?

Answer 16

Hydrophilic phosphate head
Hydrophobic lipid tails
(Ethanolamine, Phosphate, Glycerol, Fatty acids)

Question 17

What other molecules make up the cell membrane?

Answer 17

Cholesterol
Proteins

Question 18

What is the selective permeability of cell membranes?

Answer 18

Impermeable to: Large molecules e.g. proteins nucleic acids, charged water soluble substances e.g. ions
Permeable to: Hydrophobic molecules e.g. O2, CO2, steroid hormones
Partially permeable to: uncharged, polar molecules e.g. H2O, urea, glucose

Question 19

What is the function of membrane proteins?

Answer 19

Provide specific channels and carriers - allows polar molecules (ions, sugars, AA, water) to pass through, avoiding hydrophobic core of bilayer

Question 20

What is homeostasis?

Answer 20

Maintains the steady state of vital parameters

Question 21

What are the body’s vital parameters?

Answer 21

Oxygen in blood plasma
ATP in ECF
Volume of plasma and ICF (affects BP)
Ion concentrations
Arterial BP
Core body temperature
Glucose

Question 22

What is an example of an external change?

Answer 22

Temperature change

Question 23

What is an example of an internal change?

Answer 23

Running - muscles need more oxygen

Question 24

What are the basic components of a negative feedback loop?

Answer 24

1) Steady state disrupted
2) Receptors sense vital parameter
3) Control centre compares input against a set point (hypothalamus, brainstem)
4) Output signal from control centre to effector (via neural mechanisms - ANS, or via endocrine system - hormones)
5) Effector enables a change to return the vital parameter (sweat glands, skeletal muscle, cardiac muscle)

Question 25

What is an example of a negative feedback loop?

Answer 25

Thermoregulation

Question 26

What are the properties of negative feedback loops?

Answer 26

Physiological adjustment always opposite direction to disturbance
Returns parameters to original level
Redundancy - there are multiple mechanisms present for many vital parameters in case one fails