Lecture 4

Question 1

describe and compare 2 types of passive cell transport

Answer 1

• Diffusion/ osmosis
• directly across the membrane
• Hydrophobic molecules and small uncharged polar molecules
• facilitated diffusion
• trough a membrane channel or transporter (water trough an aquaporin)
• Large uncharged polar molecules and ions

Question 2

describe and compare 2 types of active cell transport

Answer 2

Primary and secondary active transport

Primary

• ATP is used directly for the process
• Transports substances against their electrochemical gradient
• creates electrochemical gradients

Secondary
- uses electrochemical gradients created by primary active transports
- the movement of one substance down its gradient (downhill) drives the movement of another substance against its gradient (uphill)
Na+/ K+ ATPase pump

Diffusion happens whenever there is a gradient it goes from neuron to neuron

Question 3

describe bulk transport (flow) and give an example of how bulk transport and cell transport work together.

Answer 3

Bulk transport

• Fast over long distances (diffusion is fast over short distances, from neuron to neuron)
• passive process down pressure gradients (eg. blood flow)
• requires pressure gradients to be created (eg. heart contraction)

bulk and cell transport team up

• bulk transport (flow) occurs in organ systems to transport substance to and from cells
• cell transport occurs trough the cell membrane to transfer substances into cells, and wastes out of cells.

Question 4

define homeostasis and list and describe the 5 examples given, of variables the body tries to keep in balance

Answer 4

Homeostasis - Balance

• a balanced internal environment
• many variables need to be kept within a set range to ensure cells can function

the 5 examples given

• blood glucose (primary fuel)
• blood pressure (meassure of acidicity)
• blood pH (ratio of solutes to water)
• blood osmolarity (average blood pressure within the arteries)
• blood temperature (core body temp)

imbalance

• as cells function they use nutrients and produce waste and heat
  eg. growth, reproduction, exercise, stress and illness

Question 5

describe two types of control systems the body uses to maintain homeostasis

Answer 5

1. Feedforwards
   (preparation before)
2. Negative feedback
   (correction after)

Question 6

describe and give an example of each of the 4 parts of a negative feedback control loop.

Answer 6

stimulus-> sensor-> control centre-> effector-> stimulus