Homeostasis + Cells & Molecules

Question 1

Define homeostasis

Answer 1

Similar condition, as energy demand increases, supply of substrate required to prevent disturbance in system also does

Question 2

Role of systems in homeostasis

Answer 2

Cardiovascular System – delivers O2 and nutrients to cells, removes waste from cells
Respiratory System – acquires O2, disposes of CO2
Gastrointestinal System – acquires nutrients, disposes of waste
Renal System – disposes of waste
Musculoskeletal System – sources nutrients, removes us from danger, protects from threat
Immune System – protects us from infe ction
Nervous System – coordinates other systems
Endocrine System – coordinates other systems, major role in allowing cellular access to nutrients that have been absorbed

Question 3

Principles of negative feedback control systems

Answer 3

• Does not prevent condition but regulates it

Question 4

Feed forward system

Answer 4

• Additional receptors permit system to anticipate change and activate response easier

Question 5

• Positive feedback

Answer 5

Sets off train of events that leads to larger disturbance than original

Question 6

Daily water balance in man

Question 7

Different body fluid compartments

Answer 7

1. Intracellular fluid 28L
2. Interstitial fluid 11L
3. Plasma 3L

Question 8

• Importance of nature barriers whichseparate the body compartments

Answer 8

• Body can only survive if eat is in maintained by cell membrane + water regulated by osmosis

Question 9

Define the dilution principle

Answer 9

• C= mv
• V = m/c

Question 10

Describe the structures present in all cell types

Answer 10

Cytoplasm, ribs some + cell membrane

Question 11

Prokaryotic cels

Answer 11

• Lack of nuclear membrane + no nuclear bound organelles

Question 12

Eukaryotic cells

Answer 12

• Nuclear membrane → humans, algae, fungi

Question 13

Apoptosis vs necrosis

Answer 13

• Apoptos’s = controlled programmed cell death
• necrosis = death of cells in response injury or infection

Question 14

Major elements used to construct Human biomolawles

Answer 14

H, c, N, 0,

Question 15

Importance of functional groups + molecular configuration in biomolecular function

Question 16

Five kinds of chemical reactions in living organisms

Answer 16

1. Redox reactions
2. Making and breaking c-c bonds
3. Internal arrangements
4. Group transfers
5. Condensation + hydrolysis reactions

Question 17

Hydrophobic molecules

Answer 17

• Lipids, steroid hormones, fat soluble vitamins + arrange themselves to minimise contact w/water

Question 18

Hydrophilic moleures

Answer 18

• Alcohol, sugars etc. - water splits to form screen around ions

Question 19

Rules of thermodynamics

Answer 19

1. Energy can be converted from on form to another but total energy of the universe remains constant
2. All energy transformations lead to more disorder in the universe

Question 20

Define gibes free energy

Answer 20

• Spontaneous reactions can occur of a system gives up energy +/ becomes more random + increases in entropy

Question 21

Reaction coupling

Answer 21

• Energetically unfavourable reaction is driven by an energetically favourable reaction, net free energy change is less than zero

Question 22

What does the extracellular fluid compartment consist of?

Answer 22

• Plasma
• interstitial fluid

Question 23

• Basic structure of membranes

Answer 23

• Capillary wall separates plasma from ISF
• cell membrane separates cells from ECF
  (Water passes freely between compartments via aquaporin channels)

Question 24

1.na, 2. K, 3. Protein content in fluid compartments

Answer 24

Plasma = High low High
Interstitial fluid = High, low, low
Intracellular fluid = low High High

Question 25

5 membrane protein functions

Answer 25

1. Receptors 2. Transport 3. Enzymes 4. Maintenance of cell structure (anchorage) 5. Communication

Question 26

Function of receptors

Answer 26

- Integral to membrane structure - allow communication of extraculular signals - ligand binds (ligand-receptor complex ) triggers cellular response

Question 27

Function of Transporter proteins

Answer 27

Integral proteins that allow movemen of ions: 1. Channel proteins- create a pore through the membrane which molecules flow through 2. Transporters- open to ICF + ECF but never at the same time

Question 28

Function of enzymes

Answer 28

- Catalyse chemical reactions_ enzymatic part may be on external part of membrane

Question 29

Function of structural proteins

Answer 29

- Anchor cell membrane to intracellular skeleton, extracellular matrix and other cells - dysfunction or loss can lead to serious debility e.g. Duchenne's muscular dystrophy

Question 30

Function of communication proteins

Answer 30

- Communicating extracellular signals to intraceuular environment

Question 31

Protein content of membranes

Answer 31

1. Myelin; insulator around myelinated nerve fibres (protein content =18%) 2. Plasma membrane have typically 50% 3. Membranes involved in energy transduction 75% - The more functions a a membrane was the higher the protein content

Question 32

Endocytosis

Answer 32

- Invagination of cell membrane to form a vesicle which disintegrates on the inside of the membrane, releasing contents into cell

Question 33

Exocytosis

Answer 33

- Proteins manufactured in lets are released by exocytosis

Question 34

What is diffusion

Answer 34

- Process by which gas or substance in solution expands to fill all the available volume: molecules spread from regions of nigh concentration to low concentration

Question 35

What is the difference between passive + facilitated diffusion

Answer 35

- A passive: substance moves directly through lipid bilayer - B facilitated - requires assistance from membrane proteins to cross lipid bilayer

Question 36

Passive diffusion

Answer 36

- Molecules must be: small, uncharged + lipophilic (hydrophobic) ~ it not they will recursive facilitated diffusion

Question 37

What does osmosis mean?

Answer 37

- Het movement of water from regions of high conc. To low

Question 38

What is osmolarity?

Answer 38

- Describes number of particles in solution

Question 39

Tonicity

Answer 39

- Number of non-penetrating particle in solution ( toxicity is more important as it determines cell volume)

Question 40

Hypo-osmotic

Answer 40

- Solution with fewer total particles than normal ECF are hypo-osmotic

Question 41

Hyper-osmotic

Answer 41

- Greater number of total particles than ECF are hyper-osmotic

Question 42

What is tonicity?

Answer 42

- Total number of non-penetrating solute particles

Question 43

How does ATP provide energy?

Answer 43

Hydrolysis = ADP + pi