Cells and Systems Summary

Cells and Systems

Characteristics of Living Things

To differentiate between living and non-living things, scientists use six key characteristics:

  1. Made of Cells: All living organisms are composed of cells, which are the basic units of life.

  2. Need Energy: Living organisms require energy to sustain life, obtained from the environment through food and nutrients. Plants acquire energy from the sun via photosynthesis, while animals obtain it from their surroundings.

  3. Grow and Develop: Living things grow and develop, replacing worn-out or damaged cells. Development involves changes in body size and shape.

  4. Respond to the Environment: Living organisms react to stimuli in their environment.

    • Stimulus: An event or change in the environment.

    • Response: The organism's reaction to the stimulus.

  5. Reproduce: Living things have the ability to reproduce, ensuring the survival of the species.

  6. Adaptations for Their Environment: Living organisms possess characteristics that allow them to survive in their specific environment.

Examples of Characteristics

  • Cells: Blood cells, lung cells, skin cells, brain cells.

  • Energy: Food, sleeping, nutrients, water, vitamins.

  • Growth & Development: Baby, toddler, child, teen, adult, senior.

  • Reproduction: Babies.

  • Adaptation(s): Standing, walking, talking, learning, memorizing.

Structure vs. Function

Organisms have developed different structures to perform the same functions to stay alive.

  • Structure: A body part designed to perform a specific task (e.g., arm, leg, beak).

  • Function: The purpose of the structure, what it does.

Variations in Structures

Similar organisms often exhibit slight variations in their structures. Charles Darwin studied finches on the Galapagos Islands.

Microscopes

A microscope magnifies or enlarges the images of small objects.

  • Compound Microscope: Uses two or more lenses to magnify the image.

Microscope Parts

  • Eyepiece Lens

  • Objective Lens

  • Coarse Adjustment Knob: Moves the stage up and down for focusing.

  • Fine Adjustment Knob: Moves the stage slightly to sharpen the image.

  • Stage Clips: Hold the slide in place.

  • Diaphragm: Regulates the amount of light passing through the specimen.

  • Light Source: Projects light through the diaphragm.

Magnification

To calculate magnification, multiply the power of the Eyepiece (Ocular Lens) by the Objective Lens.

  • Magnification = Eyepiece \times Objective Lens

  • Example: 10x \times 4x = 40x

  • Example: 10x \times 10x = 100x

  • Example: 10x \times 40x = 400x

The Cell as the Basic Unit of Life

Cells are the smallest known functioning units of life.

  • Tissues: Cells with similar structures and functions organized together.

  • Organs: Tissues working together for a common purpose.

  • Organ System: A group of organs that work together for a common purpose.

  • Organelles: Specialized structures within each cell that carry out specific functions.

Cell Structures

Animal Cell

  • Cell Membrane: Controls the movement of substances in and out of the cell.

  • Nucleus: Controls cell activities and contains DNA.

  • Vacuole: Stores food, waste, and water.

  • Cytoplasm: Contains cell nutrients.

  • Mitochondria: Cell powerhouse, where energy is created.

Plant Cell

  • Cell Membrane: Controls movements in and out of the cell.

  • Nucleus: Controls cell activities and contains DNA.

  • Vacuole: Storage place for food, waste, and water.

  • Cytoplasm: Contains nutrients needed to survive.

  • Mitochondria: Cell powerhouse where energy is created.

  • Cell Wall: Provides support and stability (only in plant cells).

  • Chloroplast: Site for photosynthesis (only in plant cells).

Unicellular vs. Multicellular

Unicellular

  • Made up of only one single cell.

  • Most microscopic organisms (e.g., Mycoplasma).

Multicellular

  • Made up of two or more cells.

  • Plants and animals.

  • Can do multiple tasks and are more complex.

Benefits of Being Multicellular

  • Live in a wide variety of environments.

  • Grow very large.

  • Get energy from a wide variety of foods.

  • Have more complex bodies.

  • Specialize body functions.

Cell Clumping Theory

Single cells that clumped together had a better chance for survival because they were too big for predators to eat. An experiment was conducted to test this theory using Chlorella vulgaris.

Amoeba

  • Common unicellular organisms living in water.

  • Move using pseudopods (false feet).

  • Capture food by surrounding it with pseudopods.

Paramecium

  • Move through water using cilia (hair-like structures).

  • Cilia also help gather food through an oral groove.

Movement of Substances In and Out of Cells

Diffusion

The movement of particles from an area of high concentration to an area of low concentration. The cell membrane acts as a selectively permeable filter.

Selectively Permeable

Membranes that allow particles of one size or type in, but not others.

Osmosis

The movement of water across a selectively permeable membrane from an area of high water concentration to an area of low water concentration.

Effects of Osmosis

Different water concentrations can dramatically affect cells.

  • Hypertonic: Too little water outside, water rushes out.

  • Isotonic: Just right.

  • Hypotonic: Too much water outside, water rushes in.

Cells in Multicellular Organisms

Cells form tissues, tissues form organs, organs work together in organ systems, and systems form an organism. This organization allows the body to work more efficiently.

  • Specialized Cells: Different cells have different appearances and perform different jobs.

Examples of Specialized Cells

  • Nerve Cell: Carries signals all over the body.

  • Muscle Cell: Elastic and stretches to create strength.

  • Skin Cell: Creates a protective layer across the body.

  • Stem Cell: Grows from early embryonic development and can form every type of cell in the body.

Stem Cell Therapy

Stem cells can be used to treat diseases and illnesses.

Digestive System

Organs and Functions

  • Mouth: Food intake and initial digestion (mechanical and chemical).

    • Mechanical Digestion: The actual breaking down of food into very small pieces like chewing Teeth.

    • Chemical Digestion: The breakdown of large particles into smaller ones by using enzymes. Amylase and Saliva.

  • Salivary Glands: Produce saliva and release enzymes.

  • Esophagus: Connects the mouth to the stomach; food is pushed down through peristalsis.

  • Stomach: Food digestion occurs; uses gastric juices.

  • Liver: Produces bile to break down fats.

  • Gall Bladder: Stores bile from the liver.

  • Pancreas: Stores digestive enzymes.

  • Small Intestine: Absorbs nutrients through villi.

  • Large Intestine: Absorbs water and some vitamins and minerals and removes excess wastes.

  • Villi: Tiny projections that increase surface area for nutrient absorption.

  • Microvilli: Further increase surface area for absorption.

  • Capillaries: Tiny blood vessels within each villus, allow for diffusion of nutrients.

Digestive System Illnesses

  • Appendicitis: Blockage inside the appendix leading to increased pressure and inflammation.

  • Crohn’s disease: Swelling of the digestive tract, most commonly the small intestine.

  • Cirrhosis of the liver: Scarring of the liver, often caused by alcoholism.

  • Irritable Bowel Syndrome (IBS): Abnormal Bowel contractions

Respiratory System

Organs and Functions

  • Nose/Mouth: Passageway for air intake.

  • Trachea: Connects the mouth and nose passage to the lungs.

  • Lungs: Collect oxygen for respiration and remove carbon dioxide.

  • Bronchi: Two main branches of the trachea that lead into the lungs.

  • Alveoli: Tiny air-filled sacs in the lungs where gas exchange occurs.

  • Diaphragm: Muscle below the lungs that helps move air in and out.

  • The respiratory system is largely responsible for the intake of oxygen and expelling (or getting rid of) carbon dioxide.

Gas Exchange in Alveoli

Oxygen diffuses into the blood, and carbon dioxide diffuses out of the blood.

Blood entering the lungs is low in oxygen and high in carbon dioxide, whereas air entering the lungs is high in oxygen and low In carbon dioxide.

Respiratory Illnesses

  • Asthma: Inflammation of the bronchioles.

  • Lung disease: Often results from smoking. e.g., Bronchitis, Emphysema and lung cancer.

    • Bronchitis: Narrowing of the Bronchi due to mucus build-up.

    • Emphysema: Smoke from cigarettes damages the lung tissue.

    • Lung cancer: Growth of a tumor or cancerous growth within the lungs

Circulatory System

The circulatory system is the body's transport system, moving nutrients, waste, and other materials.

Organs and Functions

  • Heart: Pumps blood through the body.

  • Arteries: Carry blood away from the heart (high in oxygen).

  • Veins: Carry blood to the heart (low in oxygen).

  • Capillaries: Connect arteries and veins; nutrients and gases diffuse in and out.

Blood Components

  • Blood carries oxygen to the rest of the body.

  • White blood cells fight off invaders, disease, and infection.

  • Platelets help stop bleeding at cuts.

Circulatory Illnesses

  • Atherosclerosis: Build-up of cholesterol in the arteries.

Excretory System

Organs and Functions

  • Kidney: Removes liquid waste from the blood.

  • Ureter: Connects the kidneys to the bladder.

  • Bladder: Stores urine.

  • Nephrons: Microscopic units that remove waste from the blood to produce urine

  • Liver: Removes toxins from the blood.

  • Skin: Removes waste (salts) and helps cool the body down (sweating).

Excretory System Illnesses

  • Kidney (Renal) Failure: Kidneys shut down due to injury, illness, or drug abuse.

  • Dialysis: Process of using a machine to remove waste from the body during poor kidney functioning.

Nervous System

The nervous system receives and responds to information about the body's internal and external environment.

Components

  • Central Nervous System: The brain and the spinal cord.

  • Peripheral Nervous System: Nerves connecting the CNS to the limbs and organs.

Neurons

Cells that carry information through the nervous system.

  • Axon: Sends information to the next cell.

  • Dendrite: Receives information from the previous cell.

  • Sensory Neurons: Carry information from the body to the brain.

  • Motor Neurons: Carry information from the brain to the muscles and organs.

Peripheral System

  • Somatic: Voluntary responses (e.g., walking, talking, eating).

  • Autonomic: Involuntary responses (e.g., breathing, digestion).

Reflex

An autonomic response by the nervous system to a stimulus, bypassing the brain.

Nervous System Illnesses

  • Alzheimer's disease: Affects memory, thinking, and behavior.

  • Parkinson's disease: Affects motor skills and thinking processes.

  • Multiple Sclerosis: Immune system damages neurons, affecting signal transmission.

Developing a Theory for Diseases

First Vaccine

  • Edward Jenner introduced the first vaccine by infecting people with cowpox to immunize them against smallpox.

  • The last case of smallpox reported was in 1979.

Germ Theory

  • Louis Pasteur identified microorganisms as “Germs”.

  • Pasteurization: Heating food to kill microorganisms.

Sterilization

  • Joseph Lister introduced cleanliness and sterilization to surgery.

Nutritional Research

  • James Lind treated sailors with scurvy by feeding them oranges and lemons.

  • Scurvy is caused by a lack of Vitamin C.