Unicellular Organisms: Good and Bad

• Unicellular organisms are tiny, single-celled organisms that can either benefit or harm the body.

Helpful Unicellular Organisms

• Some, like gut bacteria, aid in food breakdown, digestion, and prevent harmful bacteria.
• These "good" microorganisms are essential for a healthy digestive and immune system.

Harmful Unicellular Organisms

• Others, such as certain bacteria and parasites, can lead to infections and diseases.
• Harmful bacteria can cause infections like food poisoning and parasites can cause sickness.
• These organisms invade the body, replicate, and damage tissues, resulting in illness.
• Maintaining a balance between beneficial and harmful microorganisms is crucial for health.

Unicellular Organism Traits

• A unicellular organism is a living entity consisting of a single cell.
• This single cell performs all functions necessary for survival like growth, reproduction, and metabolism.
• Examples: Bacteria (e.g., Escherichia coli), Protozoa (e.g., Amoeba, Paramecium), Some algae (e.g., Chlamydomonas), Some fungi (e.g., Yeast).
• Unicellular organisms rely entirely on their single cell to conduct all life processes.

Multicellular Organism Traits

• A multicellular organism is a living entity consisting of more than one cell.
• These specialized cells collaborate to perform various functions, including digestion, movement, and respiration.
• Examples: Humans and animals (e.g., dogs, birds, fish), Plants (e.g., trees, flowers, grass), Fungi (e.g., mushrooms).
• They possess organized structures like tissues, organs, and organ systems enabling them to perform complex functions that unicellular organisms cannot.

Gas Exchange: Humans

• Humans breathe using their lungs.
• They inhale oxygen (O2) from the air, which enters the lungs and diffuses into the bloodstream.
• Oxygen is transported to cells for energy production.
• Cells produce carbon dioxide (CO2) as a byproduct, which is carried back to the lungs and exhaled.

Gas Exchange: Earthworms

• Earthworms breathe through their moist skin, not lungs.
• Oxygen from the air dissolves in the mucus on their skin and diffuses directly into their bloodstream.
• Similarly, carbon dioxide from their bodies diffuses out through the skin into the air.

Gas Exchange: Connections

• Humans and earthworms both rely on gas exchange to breathe, but they do it in different ways.
• Humans exhale carbon dioxide, which is released into the air.
• Plants absorb this CO2 during photosynthesis and release oxygen back into the air.
• Earthworms, living in the soil, absorb this oxygen through their skin for respiration.
• They then release CO2, which contributes to the cycle.
• Humans, earthworms, and plants are interconnected in the oxygen-carbon dioxide cycle.

Definitions

• Invertebrate: An animal without a backbone.
• Vertebrate: An animal with a backbone.
• Fungi: Organisms obtaining nutrients from dead/decaying matter and unable to perform photosynthesis; absorb nutrients.
• Protist: Organism neither plant nor animal, shares characteristics of both; usually unicellular, can be multicellular.
• Bacteria: The most basic unicellular organisms; lack a nucleus. Movement: Changing the shape of an organism; characteristic of all living things.
• Locomotion: Moving from one place to another in the environment; characteristic of animals, animal-like protists, and some bacteria, but not plants or fungi.

Main Organs

• Five main organs—brain, heart, lungs, liver, and kidneys—maintain body function.
• Each organ belongs to a system and interacts with others to maintain homeostasis (stable internal environment).

Brain

• Brain (Nervous System): The Control Center.
• Sends/receives signals to regulate body functions.
• Controls movement, breathing, heartbeat, and digestion by communicating with other organs.
• Works with heart and lungs to ensure oxygen reaches brain cells.

Heart

• Heart (Circulatory System): The Pump.
• Pumps oxygen-rich blood from lungs to the body.
• Delivers nutrients/oxygen to cells; removes waste.
• Works with lungs, brain, and kidneys to regulate blood flow/oxygen levels.
• Example: when blood pressure drops, the heart beats faster to circulate more oxygen.

Lungs

• Lungs (Respiratory System): Oxygen Supply.
• Takes in oxygen, removes carbon dioxide from the body.
• Oxygen is transferred to the bloodstream, which the heart pumps to the brain and body.
• Works with the heart to ensure cells get enough oxygen.
• Example: The lungs increase breathing rate during exercise to provide more oxygen to the blood.

Liver

• Liver (Digestive System & Detoxification): The Filter.
• Processes nutrients from food and stores energy.
• Removes toxins from the blood.
• Works with the heart and kidneys to clean blood and regulate sugar levels.
• Example: After eating, the liver stores excess sugar and releases it when needed for energy.

Kidneys

• Kidneys (Excretory System): Waste Removal.
• Filters blood to remove waste/extra fluids, producing urine.
• Helps regulate blood pressure/water balance.
• Works with heart and liver to maintain a clean, balanced bloodstream.
• Example: If the body is dehydrated, the kidneys retain more water instead of producing urine.

Organ Communication

• During exercise:
• Brain signals muscles to move; tells the heart to pump faster.
• Heart increases blood flow to deliver more oxygen.
• Lungs work harder to bring in more oxygen.
• Liver releases stored energy to fuel muscles.
• Kidneys filter out waste and maintain fluid balance.
• All five organs constantly communicate to keep the body functioning.

Unicellular organisms are single-celled entities that can impact health. Some, like gut bacteria, aid digestion. Others, such as harmful bacteria and parasites, can cause infections and diseases. Understanding the balance between them is crucial.