Chemical Control 7.3

Question 1

Metabolism

Answer 1

chemical reactions that occur inside an organism to maintain life.
*Catabolic reactions;
Break down organic matter
Release energy
*Anabolic reactions;
Build organic matter
Store energy

Question 2

Enzymes

Answer 2

Proteins that speed up metabolic reactions.
Without enzymes, reactions would be to slow to maintain life
We have around 700 enzymes in our body.
Enzymes are not used up in a reaction
Enzyme activity is modelled through the lock and key method. Each enzyme has a specific substrate that they interact with.

Question 3

homeostasis

Answer 3

is a process that maintains a constant internal environment within an organism so that cells and systems can function properly despite changes to the external environment.
managed by the nervous system and the endocrine system.

Question 4

endocrine system

Answer 4

comprised of glands that produce and secrete hormones

1.The hypothalamus receives information from thermoreceptors on the skin / inside the body
2.It signals the pituitary gland that secretes thyroid stimulating hormone (TSH) to control the thyroid gland
3.The thyroid gland controls the release of the hormone thyroxine into the bloodstream

Thyroxine increases the metabolic rate of target cells -> increases body temperature.
*If the body is too warm,
-less thyroxine will be released
-lower metabolic rate
-body temp drops back to 37oC
*If the body is too cold,
-more thyroxine will be released
-increase metabolic rate
-body temp increases to 37oC

Question 5

hormones

Answer 5

chemical messengers secreted by endocrine glands into the bloodstream.
Hormones only affect specific target cells that have a receptor for that hormone on the cell membrane.
needed in small quantities and are used for:
growth,
development,
temperature control

Question 6

Hypothalamus

Answer 6

a region in the brain that constantly checks our internal environment.
If a change is detected, then the hypothalamus will trigger the nervous system and endocrine system to act

Question 7

Regulating body temperature model

Answer 7

Body Temp falls
| ^
> |
Blood vessels constrict
so heat is conserved Normal body temp
More thyroxine secreted |
| ^
>
Heat is retained

                                       Body temp rises       
        ^                                              |
        |                                              > Normal body temp      Blood vessels dilate
        |                          
        ^                            Less thyroxine secreted
                                                        |
                                                        <
                                     Heat lost to environment

Question 8

regulating Body Temperature

Answer 8

Humans are endotherms (warm-blooded):
We can generate our own heat through metabolic reactions
We need a stable body temperature to function properly (~37oC)
Maintaining a constant body temperature is known as thermoregulation.

Question 9

Thermoregulation

Answer 9

Homeostasis processes
involve negative feedback loops
The outcome of the loop will decrease the initial stimulus and return body back to its ideal condition

Question 10

Temperature control in nervous system

Answer 10

When a drop in temperature is detected, the hypothalamus will send a nerve impulse to trigger shivering in muscles around the vital organs which moving muscles increase internal body temperature. And, send a nerve impulse to trigger blood vessels near the skin become narrower. This is called vasoconstriction as less blood flowing to the skin reducing heat lost to the environment.

When a rise in temperature (>37oC) is detected, the hypothalamus will send a nerve impulse to trigger sweating. As sweat evaporates, it cools the body. And, send a nerve impulse to trigger blood vessels near the skin become wider. This is called vasodilation as more blood flowing to the skin increases heat loss to the environment, which makes your face red.