section 1. (3+ 4) describe homeostasis as the process by which organisms maintain a relatively stable internal environment+ 2 stages of homeostasis Flashcards Preview

Biology Topic 1: Maintaining a Balance > section 1. (3+ 4) describe homeostasis as the process by which organisms maintain a relatively stable internal environment+ 2 stages of homeostasis > Flashcards

Flashcards in section 1. (3+ 4) describe homeostasis as the process by which organisms maintain a relatively stable internal environment+ 2 stages of homeostasis Deck (14):
1

Define homeostasis

the maintenance of an organism at a constant or near constant state of internal conditions

2

What are the two stages of homeostasis?

1. detecting a change in the internal environment
2. Organism then counteracts these changes in order to maintain a stable environment

3

What are the organs which detect changes called?

receptors

4

Where is the osmoreceptor located and what does it detect?

- location: brain (hypothalamus)
- detects: Water content of blood

5

Where is the thermoreceptor located and what does it detect?

- location: hypothalamus
- detects: temperature of the blood

6

Where is the baroreceptor located and what does it detect?

- location: Large blood vessels near the heart
- detects: Blood pressure

7

Where are the Islets of Langerhans located and what do they detect?

- located: pancreas
- detects: glucose level of blood

8

What does the effector do?

completes the response to the determined issue

9

What is a stimulus-pathway response example?

o Baroreceptor detects an increase in blood pressure:
o This information is then sent to the heart and the heart rate decreases- hence lowering blood pressure

10

What is a typical stimulus-response pathway?

stimulus → receptor → modulator → effector → response (and then back again)

11

What is a negative feedback response mechanism?

Negative feedback is a reaction that causes a decrease in function- the organism tries to return conditions to normal (most bodily functions are negative response feedback)

12

What is an example of a negative feedback mechanism?

Human body temperature - The hypothalamus of a human responds to temperature fluctuations and responds accordingly. If the temperature drops, the body shivers to bring up the temperature and if it is too warm, the body will sweat to cool down due to evaporation (referenced above)

13

What is a positive feedback mechanism?

The response to a change from a set level to continue to move away from the set level even further.

14

What is an example of a positive feedback mechanism?

o Stimulus to urinate, once mechanoreceptors in the bladder detect the bladder filling up, it causes contractions of the muscles- we feel the need to urinate.
o As the bladder becomes more distended, further contractions occur, feels more urgent.