Lecture 1 - Cellular Homeostasis

Question 1

Homeostasis

Answer 1

Maintenance of a stable internal environment of the body.

Question 2

What are the three components of homeostasis?

Answer 2

1. Receptor
2. Integrator
3. Effector

Question 3

Receptor

Answer 3

Senses the change
Ex. free nerve ending

Question 4

Integrator

Answer 4

Receives the information, judges the appropriate response and stimulates the response.
Ex. brain

Question 5

Effector

Answer 5

Restores the balance.
Ex. a muscle or a gland

Question 6

What type of feedback maintains homeostasis?

Answer 6

Negative feedback

Question 7

Negative feedback

Answer 7

Occurs when a change in a regulated variable triggers a response which reverses the initial change and brings the regulated variable back to the set-point. Regulates homeostasis.

“Change the variable back to its original state”

Question 8

Positive feedback

Answer 8

Occurs when a change in a variable triggers a response which causes more change in the same direction.

“Enhance the original stimulus in the same direction”

Question 9

Hydrophobic, fat soluble substances ___ pass through the membrane.

Answer 9

CAN

Question 10

Hydrophilic substances do ___ pass through the membrane.

Answer 10

NOT

Question 11

Diffusion

Answer 11

Random movement of particles of a solute from an area of higher concentration to an area of lower concentration.

Passive transport.

Question 12

The net rate of diffusion across the membrane is affected by?

Answer 12

1. Concentration gradient
2. Thickness of barrier
3. Area of membrane
4. Solubility of the substrate in lipid

Question 13

Osmosis

Answer 13

Spontaneous net movement of water through a semipermeable membrane into region of higher solute concentration.

Diffusion of water from a region of high water molecules (dilute) to a region of fewer water molecules (concentrated).

Question 14

Bulk flow

Answer 14

Movement via differential pressure changes.

Ex. blood in arteries, veins, capillaries, air in trachea, gut contents, secretions in secretory ducts.

Question 15

Is extracellular space + or - charged?

Answer 15

Positively

Question 16

Is intracellular space + or - charged?

Answer 16

Negatively

Question 17

Where are Na+/K+ Pump found?

Answer 17

Found in excitable tissue.
Pumps 2 Na+ ions out of the cell and 2 K+ ions into the cell against a concentration gradient.

Ex. nerves, muscle

Question 18

Exocytosis

Answer 18

The membrane bound vesicle from the cytoplasm makes contents with the plasma membrane. The membranes fuse and the contents spill into the extracellular fluid.

Ex. release of neurotransmitter by a neuron.

Question 19

Endocytosis

Answer 19

Substances collect along the surface of the plasma membrane. The membrane surrounds the substances and engulfs, fusing the membrane and creating a membrane vesicle.

Ex. cholesterol uptake by cells.