Communication and Homeostasis, 5.1 Flashcards Preview

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Flashcards in Communication and Homeostasis, 5.1 Deck (28):
1

What conditions do living organisms need to maintain inside their cells? Why?

Suitable pH, suitable temperature, aqueous environment and freedom from toxins and excess inhibitors. As they affect enzyme acitivity.

2

Examples of a changing external enviroment

Changes externally put a stress on the living organism such as the temperature changing

3

Examples of a changing internal enviroment

Metabolic activities of cells, they use resources and produce waste which could be toxic, eg if CO2 is allowed to build up it will alter the pH

4

Cell Signalling

The way in which cells communicate with each other

5

What is the neuronal system?

Network of neurons, signal across synapse junctions, conduct signals quickly

6

What is a hormonal system?

Use the blood to transport signals, endocrine organs secrete hormones, hormones are detected by target cells with specific receptors

7

What makes a good communication system?

Covers whole body, enable communication between cells, communication is specific, rapid response, short and long term responses

8

Homeostasis

Maintaining a constant internal environment despite changes in internal and external factors. Within narrow limits.

9

Negative Feedback

Conditions in the body are brought back to the optimum, it reverses the change

10

What occurs during negative feedback?

Receptor detects the change (stimulus) and sends an input to the coordination center, the coordination center sends an output to the effectors which respond

11

Positive Feedback

Mechanism that increases the change taking the system further away from the optimum

12

Why is positive feedback more dangerous?

It destabilizes the system and is harmful

13

An example of positive feedback

During pregnancy, oxytocin is release to stretch the cervix more and more until to baby is born

14

Stimulus

Change in environment causing a response

15

Response

Change in behavior or physiology

16

Ectotherm

Organism that relies on external sources of heat to maintain body temperature

17

Ectotherm response to being too cold

Move into a sunny area, lie on a warm surface, expose a larger SA to the sun

18

Ectotherm response to being too hot

Move out of the sun, move underground, reduced body surface exposed to the sun

19

Ectotherm advantages

Less food used in respiration, more energy used in growth, need to find less food, won't overheat as easily

20

Ectotherm disadvantages

Less active in cool temperatures, at risk from predators in the cold

21

Endotherm

Organism that uses heat from metabolic reactions to maintain body temperature as chemical reactions can be exergonic

22

Endotherm response to being too cold

Sweat glands release less sweat, hairs stand up, vasoconstriction, increased respiration in the liver, skeletal muscles contract (shivering)

23

Endotherm response to being too hot

Sweat glands secrete more sweat, hairs lie flat, increased panting, less respiration in the liver,
vasodilation

24

Endotherm advantages

Maintain a constant body temperature, remain active at cold temperatures, inhabit colder parts of the planet

25

Endotherm disadvantages

Most energy used to maintain body temperature, need more food, lower proportion of energy used for growth

26

What happens if the temperature rises?

Molecules gain kinetic energy, move faster, are more likely to collide and more likely to collide with sufficient energy, rate of reaction increases, however, structure of proteins and enzymes can be affected

27

Where are temperature receptors?

In the hypothalamus, detect core body temperature

28

What is the sensory cell that detects changes in external temperatures?

Thermoreceptor