Characteristics of Living Things

• Living things have specific characteristics and structures that help them perform functions.

Characteristics of Living Things

• All living things are made of cells
• Require energy to function
• Grow and develop over time
• Respond to stimuli from their environment
• Reproduce to create new individuals
• Adapt to changes in their environment

Cells

• Cells are the basic units of life
• All living things are made up of at least one cell.
• Non-living things are not made of cells.
• Cells can be found in things that were once alive
  • example, a tree stump, which requires a microscope to observe its cells.

Energy

• All organisms need energy to survive
• Organisms obtain energy from their environment
• Organisms use energy for growth, development, and reproduction
• Nutrients are substances that provide energy
• Many chemical processes occur inside cells
  • Some processes consume energy
  • Other processes create energy.
  • Organisms need a balance of energy-creating and energy-using cells.
• Metabolism is the sum of all processes occurring in an organism

Organs

• Organs are composed of tissues, which are made of cells
• Each organ has its own specific function
• Organs work together to form an organ system

Structure & Function

• Structure indicates how something is built or arranged
• Function is how something works
  • Example: The heart's multiple chambers and valves help pump blood

Response to Stimuli

• Stimuli are changes in an organism's environment
• An organism responds to these changes
  • Example: Immediately removing your hand from a hot stove.

Adaptations

• Adaptations are changes or adjustments that help an organism survive
• Behavioral adaptations are learned actions or behaviors
  • Example: Birds flying south during colder times to avoid freezing
• Structural adaptations are physical features that aid survival
  • Example: Polar bears have sharp claws and large paws.
• Physiological adaptations are internal processes that improve survival
  • Example: Scorpions use poison when stinging.

The Microscope

• Microscopes help to see clear images that are 0.1 mm or larger.
• Compound light microscopes use two lenses (objective and ocular) to magnify specimens

Microscope Parts and Functions

• Ocular lens (eyepiece): Provides 10x magnification
• Objective lens: Usually 3-4 lenses with magnifications like 4x, 10x, and 40x
• Light source: Transmits light through the specimen
• Focus mechanism: Coarse and fine focus knobs for adjusting focus
• Stage: The flat platform where the specimen is placed.
• Fiber optics: Technology that allows light to pass through a flexible tube and be used inside & outside of the body

Cells

• Cells are the basic unit of life
• Cells rarely work alone in organisms
• All organisms are made of at least one cell
• Cells with similar structure & function are organized into tissue

Organization of Living Things

• Tissues work together to form an organ
• Many organs together make up an organ system

Cell Parts and Functions

• Cell membrane: Protects the cell and controls what enters and exits.
• Nucleus: Contains genetic material (DNA) and controls cell activities.
• Cytoplasm: A jelly-like substance that holds the organelles in place.
• Mitochondria: Produces energy for the cell, is also the powerhouse of the cell
• Ribosomes: Makes proteins for the cell to function.
• Vacuole: Stores water, nutrients, and waste.
• Cytoskeleton: Provides the cell's shape.
• Chloroplasts (in plant cells): Capture sunlight for photosynthesis

Preparing Slides for Microscope

• Gather the specimen
• Place a drop of water on the bottom part of the slide.
• Place the specimen on top of the water
• Cover the specimen with a plastic film

Viewing Cells

• Within each cell are organelles: specialized structures.Organelles carry out specific functions.

Organ Systems

• Epithelial tissue serves a primary role in organ systems

Respiratory System

• Takes in oxygen and releases carbon dioxide.
• The diaphragm helps move air by contracting and relaxing.
• Lungs contain Bronchi
  • The trachea splits into two bronchi, each leading to a lung.
  • Bronchi branch into bronchioles, leading to alveoli.
  • Alveoli are tiny air sacs where oxygen and carbon dioxide exchange occurs through diffusion between air and blood
  • Capillaries, tiny blood vessels, surround the alveoli
    • Gas, nutrient, and waste exchange occurs in the capillaries
    • Gases pass between alveoli and capillaries through a thin membrane
• Inhalation: Diaphragm contracts, chest expands, lungs fill with air, oxygen absorbed
• Exhalation: Diaphragm relaxes, chest contracts, air is pushed out of the lungs

Nose

• Air enters through the nose (or mouth if breathing through the mouth) and is filtered.
• Trachea (windpipe) leads into the lungs.

Digestive System

• Digests and breaks down food.
• Digestion begins in the mouth (mechanical digestion, chewing).
• Food moves through the pharynx and esophagus (peristalsis).
• Chemical digestion occurs in the stomach (HCL and enzymes)
• Liver: Essential for fat digestion and removing toxins.
  • The liver produces bile, stored in the gallbladder
    • Bile is the substance that breaks down fats
    • Gallbladder sends bile to the small intestine when needed
• Nutrients are absorbed in the small intestine.
• Feces goes to the large intestine.
  • Absorbs water and electrolytes.

Nervous System

• Controls functions by sending and receiving messages.

Central Nervous System

• Brain: Receives external stimuli from the 5 sense and internal stimuli from the organ systems.
  • Cerebellum: Controls balance and coordination
  • Cerebrum: Thinking, memory, and voluntary actions.
• Medulla: Involuntary actions (heart rate, pupils dilating etc)
• Spinal cord: Connects the brain to the peripheral nervous system and controls reflexes
  • Interneuron: Connects one neuron to another

Peripheral Nervous System

- Sensory Neurons: Send messages from the body (organs) to the brain (CNS).
- Motor Neurons: Send messages from the brain (CNS) to the body (organs).
- Autonomic Nervous System: Controls involuntary responses to stimuli.
- Somatic Nervous System: Controls voluntary responses to stimuli (blood pressure, heart rate etc).

Neurons

• Specialized cells that send and receive messages.
  • Dendrites: Sends messages.
  • Axon: Receives messages.

Reflexes

• Sensory and motor neurons work together to create automatic responses quickly

Excretory System

• The excretory system processes cell waste (ammonia)
  • Liver converts ammonia to urea.
    • Ammonia is very toxic
    • Urea is less toxic, but still bad
    • Urea goes back into the bloodstream and makes its way to the kidneys
• Kidneys filter blood (nephrons):
  • When urea enters the kidneys, millions of nephrons filter it
  • Clean blood is recirculated.
  • Waste (urine) goes to the ureter and the bladder where it is stored until expelled through the urethra

Skin

• The skin is the largest organ of the body.
• Your skin contains thousands of tiny sweat glands.
• These sweat glands remove salt from your blood to keep you cool.

Skeletal System

• Bones protect organs and provide a frame for the body.

Circulatory System

• Transports oxygen, blood, hormones, and waste.
• Blood:
  • Plasma: Liquid that contains water, protein, hormones, and waste.
  • White blood cells: Part of the immune system, fight infections
  • Red blood cells:
    • Contain hemoglobin.
    • Carry oxygen to other parts of the body and carbon dioxide to the lungs
  • White blood cells:
    • Defend against harmful bacteria and viruses
    • Responsible for healing wounds (clotting)

Blood Vessels

• Arteries carry oxygenated blood away from the heart
  • High-pressure vessels
• Veins carry deoxygenated blood back to the heart
  • Low-pressure vessels
  • Pulmonary vein carries oxygenated blood from lungs

Heart

• The heart pumps blood
• Ventricles and atriums are chambers of the heart
  • Atriums receive blood and ventricles pump out blood Right atrium
    • Receives deoxygenated blood from the body.
  • Right ventricle
    • Pumps deoxygenated blood into the lungs.
  • Left atrium
    • Receives oxygen.
• Left ventricle
  • Pumps oxygenated blood throughout the body.
• Aorta: The largest artery in the body that carries oxygenated blood from the left ventricle to the rest of the body
• Superior vena cava: A large vein that carries deoxygenated blood from the top of the body to the right atrium.
• Inferior vena cava: The largest vein that carries deoxygenated blood from the bottom of the body to the right atrium.
• Pulmonary artery: Brings blood from the right ventricle to the lungs.
• Pulmonary vein: Brings blood from the lungs to the left atrium.

Medical Advances

People Who Made a Difference

• The first vaccine
  • Edward Jenner
  • Jenner used cowpox to fend off smallpox
    • Jenner observed that Milkmaids that had cowpox were immune to smallpox
    • This lead him to start infecting people with cowpox which made people immune to smallpox
• Louis Pasteur:
  • A French Chemist
  • He discovered that germs cause infectious diseases.
  • Hired to study why beer and wine were soiling during production -Louis Pasteur discovered that microorganisms caused spoilage during fermentation. -Louis Pasteur Discovered that yeast converts sugars into alcohol and carbon dioxide.
• Joseph Lister:
  • An English Surgeon
  • Many of his patients died from infections
  • Lister sterilized surgical tools before surgery so people stopped dying from infections

Osmosis

• Osmosis is the movement of water particles from low concentration to high concentration solutions
  • The goal is to balance the concentration of the solute on both sides of the membranes
• Selectively permeable membrane:
  • Only allows certain molecules to pass.
    • The cell membrane helps maintain balance by controlling what enters and leaves the cell.