Unit 1: Homeostasis & the Cell

Question 1

Define physiology.

Answer 1

The study of how systems function in a living organism.

Question 2

Define homeostasis.

Answer 2

The maintenance of relatively stable conditions within the internal environment (body temp, blood sugar levels, blood pH, oxygen and carbon dioxide levels, blood pressure, electrolyte balance, water balance).

Question 3

What are the components of a negative feedback loop?

Answer 3

Control centre (develops a plan to maintain/restore), effector (responds to the plan), regulated variable (regulated through negative feedback loop), sensor (monitors interval environment).

Question 4

How do negative feedback loops maintain homeostasis?

Answer 4

They maintain the variable within a normal range and once the variable reaches its ideal level, it shuts off. The event/effect of a reaction eventually loops back.

Question 5

Define a positive feedback loop.

Answer 5

An increase of both variables. An external event needs to occur in order to break/shut off the loop.

Question 6

What is the organizational hierarchy of the body?

Answer 6

Atoms, macromolecules, organelles, cells/tissues/organs, organ systems, organism.

Question 7

What are the 3 body fluid compartments?

Answer 7

Intracellular fluid, Interstitial fluid, blood plasma fluid.

Question 8

What type of body fluid makes up the majority of the fluid found in the cell?

Answer 8

Intracellular fluid (67%).

Question 9

True or false.
Interstitial fluid has high concentration levels of K.

Answer 9

False. Interstitial fluid has high levels of Na, Ca, and Cl. Intracellular fluid has high levels of K.

Question 10

What is the function of blood plasma fluid?

Answer 10

Allows red and white cells and platelets to circulate around the body. It makes 6.6% of fluid in the body.

Question 11

Which ions are more concentrated outside the cell, and which ions are more concentrated in the cell?

Answer 11

Na, Ca and Cl are more concentrated outside the cell. K is more concentrated in the cell (salty banana).

Question 12

What is the ratio of Na and K ions being pumped into and out of the cell via the Na/K pump?

Answer 12

3 Na in, 2 K out.

Question 13

What are the 6 functions of membrane proteins?

Answer 13

Cell identity marker (cellular identification), cell surface receptor (neurotransmitters and hormones), ion channels (Na/K pump), transporters (movement of molecules across a membrane), enzymes (catalyze reaction, facilitate processes), cell-cell adhesion proteins (cell-cell interactions).

Question 14

What is the difference between facilitated diffusion, active transport and secondary active transport?

Answer 14

Facilitated diffusion allows for passive movements of solutes along their concentration gradient. Active transport is the movement of molecules against their concentration gradient using ATP. Secondary active transport utilizes ion gradients to transport molecules across membranes, driven by energy from gradient-established primary active transport.

Question 15

What are the 5 major ways substances cross the membrane?

Answer 15

Simple diffusion (high to low concentration), facilitated diffusion (the movement of the molecule along it concentration gradient that requires the help of a transport protein), pumps (against concentration gradient), endocytosis, exocytosis.

Question 16

Define osmosis.

Answer 16

The movement of water across a semi-permeable membrane and down its concentration gradient.

Question 17

What is the difference between a solvent and a solute?

Answer 17

A solvent is what is going to be dissolved. A solute is what the solvent is being dissolved in. Together they make a solution.

Question 18

What factors affect the movement of water across membranes?

Answer 18

The permeability of the membrane, the concentration of solutes in the intracellular and interstitial fluids, the pressure gradient across the cell.

Question 19

Chamber A has 300 mM of KCl into 1 kg of water, and chamber B has 200 mM of CaCl2 into 1 kg of water. They are separated by a semi-permeable membrane that only always water to move through. What will happen?

Answer 19

There will be no net movement of water across the membrane because both chambers have a solution of 600 mOsm. Since the two solutions have the same osmolarity, there will be no net movement of water.

Question 20

True or false.
If there are fewer solutes/osmotically active particles, the higher the concentration of water.

Answer 20

True.

Question 21

What is tonicity?

Answer 21

The ability of a solution to cause the movement of water into or out of a cell.

Question 22

What type of solution would be used to rehydrate a patient who is dehydrated?

Answer 22

Hypotonic solution.

Question 22

True or false.
Hypertonic solutions have a low concentration of solutions, therefore resulting in water entering the cell.

Answer 22

False. Hypertonic solutions have a higher concentration of solutes, resulting in water leaving the cell.

Question 23

What 6 factors affect the rate of movement through a cell membrane?

Answer 23

Concentration gradient, electrical gradient, lipid solubility, molecular size, membrane area, composition of lipid barrier.

Question 24

What is the typical resting membrane potential?

Answer 24

-70mV

Question 25

What is the electrical-chemical equilibrium for K?

Answer 25

-90mV

Question 26

What would happen to the cell if the Na/K pump did not work?

Answer 26

The osmolarity would increase, causing water to move into the cell to swell.