Biology - Module 5.1 - Communication & Homeostasis

What are the required conditions for cells to function

Suitable Temperature
Suitable pH
Freedom from toxins & excess inhibitors
Aqueous environment that keeps substrate & products in solution

Why do conditions need to be maintained

Enzymes - cellular reactions rely on enzymes to function. Without them, organisms wouldn’t be able to function

Define Stimulus

A change in the internal or external environment of an organism

Define Response

The way in which the organism changes its behaviour or physiology in reaction to a stimulus

Features of a good communication system

Covers the whole body
Enables cells to communicate with each other
Enables specific communication
Enables rapid communication
Enables both short term & long term responses

Define Homeostasis

The maintenance of the internal environment, in a constant state, despite external changes

What are the four parts of a control system

Sensory Receptors Cells - detect any deviation from the set point
Communication System - Coordinates information from various sources & sends instructions to effectors
Effector Cells - Brings about necessary changes to return system to set point
Feedback Loop - informs the receptor of changes to the system brought about by the effector

Describe a Negative Feedback Loop

A process that brings about a reversal on any change in conditions. It maintains an optimum, steady state

Describe s Positive Feedback Loop

A process that increases any change detected by the receptors. Destabilises the system & so tends to be harmful

Define Homeotherm

Any organism able to maintain an almost constant body temperature - either by endo/ectothermic reactions

Define Endotherm

An organism that uses internal sources of heat to maintain body temperature

Define Ectotherm

An organism that uses external sources of heat to maintain body temperatureA

Advantages of being Ectothermic

Less food required for energy
More energy can be used for growth/repair
Can survive longer without food

Disadvantages of being Ectothermic

More at risk from climate change
Climate & seasons can affect ability to move
Greater risk of predation if not got enough energy

Advantages of being Endothermic

Easier to maintain body temperature
Less prone to being affect by temperature
Activity is possible when cold - can inhabit colder climatesD

Disadvantages of being Endothermic

Requires lots of energy for heat
Requires lots of food
Less energy used for growth

Which body components are involved in body temperature change

Hypothalamus - thermoregulatory centre
Skin
Skeletal Muscles
Liver