Chapter 7.3 Chemical Control

Question 1

Metabolism

Answer 1

Metabolism refers to the chemical reactions that occur inside an organism to maintain life.

Question 2

Catabolic Reactions

Answer 2

Breaks down organic matter, and releases energy.

Question 3

Anabolic Reactions

Answer 3

It builds up organic matter, and stores energy.

Question 4

Enzymes

Answer 4

Proteins that speed up metabolic reactions, and are not used up in a reaction. Without enzymes reactions would be slow to maintain life. We have around 700 enzymes in our body.

Question 5

Homeostasis

Answer 5

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.
Use negative feedback loops.

Question 6

Endocrine System

Answer 6

Made up of glands that produce and secrete hormones – chemical messengers.

Question 7

Hormones

Answer 7

Hormones are 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.

Question 8

What are hormones used for?

Answer 8

Hormones are needed in small quantities and are used for:
growth,
development,
temperature control etc.

Question 9

Hypothalamus

Answer 9

The hypothalamus is 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 10

Thermoregulation

Answer 10

Maintaining a constant body temperature is known as thermoregulation.

Question 11

How is thyroxine made?

Answer 11

Hypothalamus receives information from thermoreceptors, then signals the pituitary gland that secretes thyroid stimulating hormone to control the thyroid gland. The thyroid gland controls the release of the hormone thyroxine into the bloodstream.

Question 12

What does thyroxine do?

Answer 12

Thyroxine increases the metabolic rate of target cells which increases body temperature.

Question 13

What is a stable body temperature?

Answer 13

~37oC

Question 14

Vasoconstriction

Answer 14

Vasoconstriction is when the hypothalamus sends a nerve impulse triggers blood vessels near skin to become narrower.
Less blood flowing to the skin reducing heat lost to the environment.

Question 15

How is shivering formed?

Answer 15

The hypothalamus sends a nerve impulse to trigger shivering in muscles around the vital organs - moving muscles increase internal body temperature.

Question 16

How is sweating formed?

Answer 16

The hypothalamus sends a nerve impulse to trigger sweating - as sweat evaporates, it cools the body.

Question 17

Vasodilation

Answer 17

Vasodilation is when the hypothalamus sends a nerve impulse triggers blood vessels near skin to become wider.
More blood flowing to the skin increases heat lost to the environment - turns ur face red!