Deoxygenated blood is pumped from the heart to the lungs, where it passes through capillaries surrounding the alveoli to exchange carbon dioxide for oxygen.
Osmosis is the net movement of water from a dilute solution to a more concentrated solution across a partially permeable cell membrane.
Ventilation means moving air in and out of the lungs, which requires a difference in air pressure.
Adult stem cells are found in certain adult tissues such as bone marrow, skin, and the lining of the intestine, and have lost the ability to differentiate into any type of cell but can form a number of specialized tissues.
The tobacco mosaic virus is a virus that infects plant cells, particularly tobacco plants, interfering with their ability to produce chloroplasts and causing discoloration of the leaves.
Cilia are tiny hair-like structures that sweep mucus and trapped particles out of the airways towards the mouth, helping to keep the airways clean.
The excretory system, including the kidneys, filters toxic waste materials from the blood.
Extracellular enzymes are enzymes that are secreted out of cells to break down food into soluble substances for absorption.
Emphysema is a lung disease caused by smoking that damages the walls of the alveoli, leading to enlarged air spaces and reduced surface area for gas exchange, resulting in less oxygen in the blood.
COPD is a progressive disease characterized by chronic bronchitis and emphysema, for which there is no cure.
Mitosis is the type of cell division in multicellular organisms where a single fertilised egg cell divides into two, then four, and so on, under the control of genes.
The diaphragm contracts to pull down into a flattened shape during inhalation, increasing the volume of the thorax and lowering pressure, while it relaxes during exhalation, allowing the thorax volume to decrease.
The function of the digestive system is to digest food and absorb the digested products into the blood.
Breathing is the mechanical process of moving air in and out of the lungs, while respiration is the chemical process of energy release from food.
The reproductive system produces sperm in males and eggs in females, and allows for the development of the embryo.
Plasmids are small circular rings of DNA found in the cytoplasm of some bacteria, carrying some of the bacterium’s genes and important for genetic engineering.
A concentration gradient is the difference in concentration of a substance between two areas, which drives the movement of molecules during diffusion.
The thorax is the part of the body enclosed by the ribcage, containing the lungs and heart, and separated from the abdomen by the diaphragm.
The reproductive structure of a mushroom is called a fruiting body.
Invertebrates are animals that lack a vertebral column or backbone.
A virus is a microscopic infectious agent that can only reproduce by entering a host cell and taking over its genetic machinery, and it does not exhibit the normal characteristics of living organisms except for reproduction.
Intercostal muscles are the muscles located between the ribs that assist in the process of breathing by helping to expand and contract the ribcage.
Stem cell therapy is the use of stem cells to treat or prevent a disease, or to repair damaged tissues.
Protoctists are a mixed group of organisms that do not fit into the categories of plants, animals, or fungi, and most are microscopic single-celled organisms.
Saprotrophic nutrition is a mode of feeding where an organism absorbs nutrients from dead organic material, with digestion occurring outside of the organism.
An alveolus is a small air sac in the lungs where gas exchange occurs, surrounded by capillaries that facilitate the diffusion of oxygen and carbon dioxide.
Evidence from studies in the 1950s indicated a link between smoking and lung cancer, showing that a greater proportion of lung cancer patients were smokers compared to a control group.
Fungi are multicellular or unicellular organisms that do not contain chloroplasts and cannot photosynthesize.
The net movement of carbon dioxide is out of the cell, as its concentration is higher inside the cell than outside.
Pleural membranes form a continuous envelope around the lungs, creating an airtight seal and separating the thorax from the lungs.
The gas exchange system includes the lungs, which exchange oxygen and carbon dioxide.
Algae are protoctists that have chloroplasts and can carry out photosynthesis; most are unicellular, but some, like seaweeds, are multicellular.
A hypha is a fine thread-like filament that makes up the structure of fungi, such as mushrooms and moulds.
Active transport is the movement of substances against a concentration gradient, using energy from respiration.
Specialised exchange surfaces are parts of animals or plants that are adapted for the exchange of materials, having a large surface area in proportion to their volume.
The intercostal muscles contract to move the ribs upwards and outwards during inhalation, and pull the ribs down and in during exhalation.
An organ system is a group of different organs working together to perform a specific function in the body.
Smoking destroys the cilia, which prevents them from effectively protecting the lungs from infections.
During inhalation, the pressure in the thoracic cavity becomes lower than the outside atmosphere, allowing air to be drawn into the lungs.
The structure of alveoli is important because it maximizes surface area for gas exchange, allowing efficient absorption of oxygen and removal of carbon dioxide.
Guard cells have a special shape that creates a pore between them, facilitating gas exchange in leaves.
A vertebrate is an animal that has a vertebral column, or backbone.
Glycogen is a compound in which animals store carbohydrate in their cells.
Selectively permeable refers to the ability of the cell surface membrane to control which chemicals can pass in and out of the cell.
Alveoli are microscopic air sacs where gas exchange with the blood takes place.
Exhalation is the process where air is pushed out of the lungs, involving the contraction of internal intercostal muscles and the relaxation of the diaphragm, which becomes dome-shaped, increasing pressure in the thoracic cavity.
The internal intercostals are primarily used for deep (forced) breathing out, such as during exercise.
Mucus is a sticky liquid secreted by cells in the airway lining that traps dirt and bacteria, helping to keep the airways clean.
Bacteria are small single-celled organisms with a simpler structure than eukaryotic cells, typically ranging from 1 to 5 μm in length.
An organ is a collection of several tissues carrying out a particular function, such as the heart or leaves in plants.
The maximum resolution of a light microscope is about 200 nanometres (nm).
The rough endoplasmic reticulum is a system of membranes covered with ribosomes, serving as the site of protein synthesis.
The host cell provides the genetic machinery that the virus hijacks to replicate itself, ultimately leading to the death of the host cell.
The diaphragm is a muscular sheet that separates the thorax from the abdomen and plays a crucial role in ventilation by contracting and relaxing to facilitate breathing.
The most common form of stem cell therapy is the use of bone marrow transplants, which are used to treat patients with conditions such as leukaemia.
Amoeba is a type of protozoan protoctist that lives in pond water and resembles animal cells.
Mitosis allows all cells of the body to have the same genes, but different proteins are produced to enable cells to function differently.
Bacteria, along with fungi, are important decomposers that recycle dead organisms and waste products in the soil and elsewhere.
A virus particle is composed of a core of genetic material (either DNA or RNA) surrounded by a protein coat and lacks a nucleus or cytoplasm.
Chitin is a chemical that makes up the cell walls of fungi, differing from the cellulose found in plant cell walls.
The net movement of oxygen is into the cell, as respiration uses up oxygen, creating a concentration gradient from outside to inside the cell.
Pleural fluid acts as lubrication, preventing the surfaces of the lungs from sticking to the chest wall during breathing.
Smoking can damage the lungs and impair their function, leading to respiratory diseases and conditions such as coronary heart disease.
'Eukaryotic' means 'having a nucleus', referring to organisms whose cells contain a nucleus and membrane-bound organelles.
Mycelium is the whole network of hyphae that forms the vegetative part of a fungus, typically found underground.
A flagellum is a structure that propels some bacteria through water by corkscrew-like movements; a single one is called a flagellum.
Ribosomes are about 25 nanometres (nm) in diameter.
A stem cell is a cell that has the ability to divide many times by mitosis while remaining undifferentiated and can later differentiate into specialized cells such as muscle or nerve cells.
'Adapted' means that the structure of a cell or an organism is suited to its function, often used to describe how organisms are suited to their environment.
During inhalation, the volume of the thorax increases, causing a slight drop in pressure inside the thorax compared to the outside air, allowing air to enter the lungs.
Alveoli are tiny air sacs in the lungs that facilitate gas exchange by bringing air and blood very close together over a large surface area, allowing for the absorption of oxygen and removal of carbon dioxide.
The gas exchange system facilitates the exchange of oxygen and carbon dioxide between the air in the lungs and the blood.
The endocrine system consists of glands that secrete hormones, which act as chemical messengers.
Tissues are groups of cells with a similar function, such as muscle tissue, which contains specialized muscle cells for contraction.
Genes control the process of differentiation, determining which proteins are produced and thus how cells function differently.
The thin layer of fluid allows oxygen to dissolve before it passes through the alveolar wall into the blood, facilitating efficient gas exchange.
Carbon dioxide diffuses from the blood into the alveolus because there is a higher concentration of carbon dioxide in the blood than in the air within the lungs.
Embryonic stem cells are found in the early stage of development of the embryo and can differentiate into any type of cell.
AIDS is not a disease but a syndrome characterized by a set of symptoms caused by the immune system's damage due to HIV, making individuals more susceptible to other diseases.
The circulatory system, including the heart and blood vessels, transports materials around the body.
Peptidoglycan is a complex compound of sugars and proteins that makes up the bacterial cell wall, providing protection and maintaining cell shape.
Bronchitis is a lung disease that blocks normal air flow, causing difficulty in breathing, often due to irritation and increased mucus production in the airways.
A pathogen is an organism that causes disease; many common diseases in animals and plants are caused by bacteria or viruses.
A key function of a cell membrane is to separate cell functions into different compartments to prevent them from occurring together.
HIV (Human Immunodeficiency Virus) is a virus that attacks the immune system, leading to AIDS (Acquired Immune Deficiency Syndrome), which is a collection of symptoms resulting from the immune system's damage.
Prokaryotic cells are simpler cells that lack a nucleus, mitochondria, or chloroplasts, and are primarily represented by bacteria.
Diffusion is the net movement of particles (molecules or ions) from a region of high concentration to a region of low concentration, i.e. down a concentration gradient.
The rate of diffusion is affected by the concentration gradient, surface area to volume ratio, distance, and temperature.
The bronchial tree refers to the highly branching network of air passages in the lungs, starting from the trachea and dividing into bronchi and bronchioles, eventually leading to alveoli.
Inhalation is the process where air enters the lungs, facilitated by the contraction of external intercostal muscles and the diaphragm, which flattens to create lower pressure in the thoracic cavity.
Respiration is the biochemical process of oxidizing food substances, such as glucose, to release energy, which requires a continuous supply of oxygen.
In the trachea, cartilage forms incomplete C-shaped rings that support the airway and keep it open.
The nervous system consists of the brain, spinal cord, and nerves, which coordinate the body’s actions.
Differentiation is the process by which developing cells become specialized to carry out particular roles, controlled by genes.
Resolution is the ability to distinguish two points in an image as being separate.
The diffusion gradient for oxygen exists because the air in the alveolus has a higher concentration of oxygen than the blood entering the capillaries, causing oxygen to diffuse into the blood.
The host is the living cell in which a virus reproduces; viruses can only reproduce inside living cells.
The nervous system coordinates movement in animals, allowing them to move from place to place.
Alveoli are tiny air sacs in the lungs where gas exchange occurs, allowing oxygen to enter the blood and carbon dioxide to be removed.
Many people object morally to using cells from embryos for medical purposes, despite the potential to cure many diseases.
Plasmodium is a protoctist that acts as an agent of disease, specifically causing malaria.
The approximate percentage of oxygen in exhaled air is 16%, compared to 21% in atmospheric air.
In prokaryotic cells, the genetic material (DNA) is organized in a single chromosome that is loose in the cytoplasm, forming a circular loop.
Xylem vessels are dead, hollow cells in plants that carry water up the stem and have strengthening rings.
A nerve cell (neurone) has an elongated part called an axon, which is responsible for carrying nerve impulses.
A capsule is an additional protective layer outside the bacterial cell wall, providing extra protection to the bacterium.
