SCIENCE 8 U1 & U7

Respiration

A characteristic of living things; it is a series of chemical reactions that happen inside every living cell to release energy from food

Aerobic respiration

The specific kind of respiration that happens inside cells using oxygen

Respiratory system

The group of organs (including the lungs) that work together to take oxygen out of the air and get rid of carbon dioxide

Trachea (Windpipe)

The main tube that carries air down into the lungs

Cartilage

Strong rings of tissue around the trachea and bronchi that keep the tubes open and prevent them from collapsing

Bronchus (plural

bronchi): The two main branches of the trachea, with one bronchus going into each lung

Bronchiole

Several smaller tubes that the bronchi divide into, allowing air to reach deep into the lungs

Air sac

Tiny structures at the end of bronchioles where gas exchange occurs

Larynx (Voicebox)

A wider part at the top of the trachea containing the vocal cords

Vocal cords

Bands of muscle stretched across the larynx that vibrate to produce sound

Alveoli

Another name for the air sacs in the lungs

Analogy

A model (like using agar jelly holes) used to represent a real biological structure to help explain how it works

Capillaries

Very tiny blood vessels wrapped tightly around the alveoli

Diffusion

The process where gas particles move freely from an area of high concentration to an area of low concentration; this is how oxygen moves into the blood and carbon dioxide moves into the air sacs

Gas exchange

The process inside the air sacs where oxygen enters the blood and carbon dioxide leaves it

Haemoglobin

A red pigment in red blood cells that combines with oxygen to transport it

Inspired air

Air that is breathed in

Expired air

Air that is breathed out

Limewater

A liquid used to test for carbon dioxide; it turns cloudy when the gas is present

Glucose

A type of sugar that acts as an energy store; it is the fuel used by cells during respiration

Mitochondria

Tiny structures inside cells where the chemical reaction for aerobic respiration takes place

Equation for Aerobic Respiration

glucose+oxygen→carbon dioxide+water

Blood plasma

The liquid, pale yellow part of the blood that is mostly water; it transports blood cells, glucose, and carbon dioxide

Red blood cells

Unusual cells that lack a nucleus and mitochondria to make more room for haemoglobin to carry oxygen

Oxyhaemoglobin

A bright red compound formed when haemoglobin combines with oxygen in the lungs

White blood cells

Cells larger than red blood cells that have a nucleus; they defend the body against pathogens

Pathogens

Microscopic organisms, such as bacteria and viruses, that can cause illness

Antibodies

Chemicals produced by white blood cells that stick to pathogens to kill them or glue them together

Nutrients

Substances in food (such as protein, carbohydrate, and fat) that the body needs to stay healthy

Carbohydrate

A nutrient (like starch or sugar) used by cells to release energy during respiration

Starch

A type of carbohydrate found in foods like rice; the body breaks it down into glucose

Protein

A nutrient essential for making new cells for growth and repair, as well as making haemoglobin and antibodies

Fats and Oils

Nutrients that provide energy and are used to make cell membranes; fats are solid at normal temperatures, while oils are liquid

Vitamins

Nutrients needed in only small amounts to prevent illness

Vitamin A

Helps the eyes work well in the dark and assists white blood cells in fighting pathogens

Vitamin C

Keeps skin strong, heals wounds, and maintains healthy blood vessels and bones; a deficiency causes scurvy

Vitamin D

Helps the body absorb calcium for strong bones and teeth; a deficiency causes rickets

Minerals

A group of nutrients (like calcium and iron) needed in small amounts for various body functions

Anaemia

A health condition that can result from a lack of certain minerals or vitamins

Balanced diet

Eating the right amounts of the six types of nutrients every day to maintain health

Fibre

A substance (mostly cellulose) from plant cell walls that cannot be digested but is necessary to keep the digestive system moving

Constipation

A condition where the digestive system slows down because of a lack of fibre, causing waste to collect inside the body

Skeleton

A structure of bones that supports the body and protects organs

Exoskeleton

A skeleton found on the outside of the body, common in insects

Joints

Places where two bones meet, allowing the skeleton to move

Hinge joints & example

Joints that allow back-and-forth movement in one direction, like a door hinge (e.g, the elbow)

Ball-and-socket joints & example

Joints that allow movement in a complete circle, where a ball-shaped bone fits into a cup-shaped socket (e.g, the shoulder)

Muscles

Specialized cells that can contract (get shorter) to pull on bones and create movement

Tendons

Tough cords that attach muscles to bones; they do not stretch

Biceps

The muscle on the front of the upper arm that contracts to bend the arm at the elbow

Triceps

The muscle on the back of the upper arm that contracts to straighten the arm

Antagonistic muscles

A pair of muscles that work together in opposite ways; when one contracts, the other relaxes to move a bone