module 5 - 13.1 coordination

Question 1

what are the biological levels of organisation?

Answer 1

1. cell
2. tissue
3. organ
4. organ system
5. organism

Question 2

what is the basic idea of communication and coordination?

Answer 2

any change in an organisms internal or external environment means that the organism must respond correctly to these changes to stay alive

Question 3

what are communication systems?

Answer 3

• animals react to changes in their environment by using neuronal and hormonal communication systems to bring about the correct response
• plants respond to changes in their environment by using hormonal systems

Question 4

what is coordination?

Answer 4

• organs and organ systems in multicellular life cannot remain alive in isolation as they rely on other organs and other organ systems to stay alive
• as a result coordination between organs and organ systems are required to ensure an organism survives

Question 5

what is homeostasis?

Answer 5

• the coordination of organs to maintain a constant internal environment
• allows optimal functioning for the organism and includes many variables being kept within certain pre-set limits (within homeostatic ranges)

Question 6

which variables are controlled within homeostasis?

Answer 6

• core temperature
• blood glucose concentration
• blood iron concentration
• blood calcium concentration
• blood sodium and potassium concentration
• cerebrospinal fluid concentrations
• neurotransmitter concentrations
• blood gases
• arterial blood pressure
• blood water potential (osmotic pressure)
• blood pH

Question 7

what coordinates the actions of the whole organism?

Answer 7

• nervous and hormonal systems
• this relies on coordination and communication at a cellular level called CELL SIGNALLING

Question 8

how do cells communicate with each other?

Answer 8

by releasing chemicals that affect a target cell(s)

Question 9

what can cell signalling include?

Answer 9

• between cells locally (e.g. within a tissue or at a synapse)
• between cells at greater distances (e.g. a cell in the pancreas controlling a cell in the liver)

Question 10

why is cell signalling important?

Answer 10

it is a fundamental property of all cellular life

Question 11

how are cell signals carried?

Answer 11

carried by signal molecules that are released by one cell and move to make contact with another cell

Question 12

what are the 2 types of signalling molecules?

Answer 12

1. signalling molecules that enter the cell
   - generally small and hydrophobic e.g. thyroxine hormone
   - insoluble in water
2. **signalling molecules that bind to cell surface receptors
   - generally large and hydrophobic e.g. hormones like ADH
   - soluble in water

Question 13

how are signalling molecules secreted?

Answer 13

secreted by cells by exocytosis (ATP transports vesicles, then vesicles bind with outer membrane, release neurotransmitters)

Question 14

what are cell signals detected by?

Answer 14

receptors

Question 15

how can receptors operate?

Answer 15

1. receptor is a protein molecule and interacts with light, mechanical pressure or temperature
2. receptor is a protein molecule and the signal molecule binds to receptor molecules binding site

Question 16

what are cell surface receptors?

Answer 16

transmembrane proteins that change shape of conformation when their specific signal binds to them

Question 17

when a cell surface receptor’s specific signal binds to it, what could it lead to?

Answer 17

• ions crossing the cell surface
• receptor becomes a catalyst on the cytoplasmic side, causes cAMP to be made as second messenger
• receptor becomes catalyst on cytoplasmic side and produces new chemical

Question 18

what are intracellular receptors?

Answer 18

• proteins that change shape when their signal molecule binds to them
• they’re for signal molecules that cross the surface membrane