Year 8 Science: Respiration, Cell Biology, and the Respiratory System

Unit 1: Respiration and Blood - 1.1 The human respiratory system - 1.2 Breathing - 1.3 Gas exchange - 1.4 Respiration - 1.5 Circulatory system
Unit 4: Ecosystem - 4.1 The Sonoran Desert - 4.2 Different ecosystems - 4.3 Intruders in an ecosystem - 4.4 Bioaccumulation
Unit 7: Nutrition, Smoking, and Bones - 7.1 Nutrients - 7.2 A balanced diet - 7.3 Growth, development and health - 7.4 Moving the body

Definition of a Cell: The cell is the smallest basic unit of life.
Structure of a Plant Cell: - A: Cell wall: The rigid outer layer providing structural support. - B: Cell membrane: Controls the movement of substances in and out of the cell. - C: Cytoplasm: The jelly-like substance where chemical reactions occur. - D: Nucleus: Contains genetic material and controls cell activities. - E: Sap vacuole / Vacuole: Large organelle containing cell sap. - F: Chloroplast: Found in plant cells exposed to sunlight. Contains a green substance called chlorophyll. This is the site where plants perform photosynthesis to make their food. - G: Mitochondria (singular: mitochondrion): Present in all plant cells. These are the organelles where energy is released from food through respiration.
Structure of an Animal Cell: - W: Cell membrane: The outer boundary of the cell. - X: Cytoplasm: The site of cellular activities. - Y: Mitochondria: The site of energy release. - Z: Nucleus: The control center of the cell.

Specialized Cell Types: - Red blood cells: specialized for transport; lack a nucleus to maximize space for hemoglobin (noted components: cytoplasm and cell membrane). - Neurones (Nerve Cells): Specialized for transmitting electrical impulses. Key features include the dendrite and the axon. - Ciliated cell: Features tiny hair-like structures called cilia on the surface, along with a cell membrane, cytoplasm, and nucleus. - Root hair cell: Specialized plant cell for water absorption. Components include a cell wall, cell membrane, cytoplasm, a large vacuole with cell sap, and a nucleus.
Levels of Biological Organization: - Tissue: A group of similar cells working together. - Organ: A structure made of many different tissues working together to perform a task. - Organ system: A group of organs that carry out a particular function. - Organism: A living thing that may contain many different organ systems, organs, and tissues.

Living organisms are distinguished from non-living things by seven life processes, often remembered by the acronym MRS GREN:

Movement: Living organisms can move.
Respiration: Food is broken down inside cells to provide energy.
Sensitivity: Living organisms are sensitive to changes going on around them (response to stimuli).
Growth: All living organisms grow throughout their lifespan.
Reproduction: Living organisms can produce young/offspring.
Excretion: Living organisms get rid of waste materials, such as carbon dioxide ( $CO_2$ ).
Nutrition: The intake of nutrients. Plants feed by photosynthesis, while animals (e.g., bears) eat meat or other organic matter.

Definition: Respiration is the release of energy by the breaking down of glucose. This process takes place in the mitochondria of all living cells.
The Role of Energy (ATP): Life processes (MRS GREN) require energy in the form of ATP (adenosine triphosphate). Examples of ATP use include: - Muscle contraction. - Nerve cell stimulation. - Growth and repair.
Word Equation for Respiration: $\text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy (ATP)} + \text{heat energy}$
Chemical Equation for Respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy (ATP)} + \text{heat energy}$

Internal Structures and Components: - Nose and Mouth: Entrances for air. - Larynx (Voicebox): Located at the top of the trachea. - Trachea (Windpipe): The main airway leading to the lungs, reinforced with rings of cartilage to prevent collapse. - Bronchus (plural: Bronchi): The two main branches off the trachea leading into each lung. - Bronchioles: Smallest branches resulting from the division of bronchi. - Alveoli (Air Sacs): Tiny sacs at the end of bronchioles where gas exchange occurs. - Lungs: The main organs of the respiratory system. - Diaphragm: A large sheet of muscle at the base of the chest cavity involved in breathing. - Intercostal Muscles: Muscles located between the ribs (including internal and external intercostal muscles) that assist in expanding and contracting the chest. - Rib Bones: Protect the chest cavity.
Anatomical Mapping (Label List): - A: Larynx - B: Alveolus (Alveoli) - C: Trachea - D: (Left) Bronchus (Bronchi) - E: Bronchiole(s) - F: Intercostal muscles - G: Ribs - H: Diaphragm

Question 1: Write down the structures that the air passes through as it moves down into your lungs in the correct order. - Response: Air enters through the Nose/Mouth $\rightarrow$ Larynx (Voice box) $\rightarrow$ Trachea (Windpipe) $\rightarrow$ Bronchus/Bronchi $\rightarrow$ Bronchiole/Bronchioles $\rightarrow$ Alveolus/Alveoli (Air sac).
Question 2: Write the same structures in the order in which air passes through them as it moves out of your lungs and back into your surroundings. - Response: Air leaves the Alveolus/Alveoli (Air sac) $\rightarrow$ Bronchiole/Bronchioles $\rightarrow$ Bronchus/Bronchi $\rightarrow$ Trachea (Windpipe) $\rightarrow$ Larynx (Voice box) $\rightarrow$ Nose/Mouth.