Biology: Cell Theory and Tumors

Cell Theory

• All living organisms are composed of one or more cells.
• Cells are the fundamental units of structure and function in living things.
• Cells arise from pre-existing cells.

Types of Tumors

• Benign Tumors: Cells remain clustered together and typically do not seriously harm surrounding tissues. They can, however, physically crowd nearby cells and tissues, impacting normal function.
• Malignant Tumors: Cells form a mass that disrupts the normal function of neighboring cells and tissues. They may destroy surrounding tissues and are cancerous.
• Metastasis: Malignant cancer cells detach from the original tumor and move to other parts of the body, creating new tumors. This is a significant cause of cancer deaths.

Stem Cells

• Multipotent (adult): Stem cells found in adults, they can differentiate into a limited range of cell types (e.g., blood, muscle).
• Pluripotent ("embryonic"): Obtained from the blastocyst stage of embryonic development (around 120 cells from IVF). These stem cells can generate numerous different cell types.
• Totipotent: Fertilized egg (up to the 8-cell stage) which under suitable conditions can yield a viable embryo.
• Induced pluripotent stem cells (iPS cells): Differentiated adult cells that can be reprogrammed to a pluripotent state.

Reasons for Cell Division

• Growth: Cells divide to enable organisms to increase in size by creating more cells.
• Repair: Cells divide to mend damaged or injured tissue.
• Replacement: Cells divide to replace old or worn-out cells.

Cancer Causes

• DNA Mutations: Disruption of the cell cycle due to changes in DNA.
• Environmental Carcinogens: Substances like tobacco smoke and UV radiation.
• Hereditary Factors: Genes that predispose to certain cancers (e.g., breast, colon).

Prokaryotes and Eukaryotes

• Prokaryotes: Single-celled organisms without a nucleus or membrane-bound organelles (e.g., bacteria).
• Eukaryotes: Organisms with cells containing a nucleus and membrane-bound organelles (e.g., plants, animals, fungi).

Osmosis and Diffusion

• Diffusion: Movement of particles from high to low concentration.
• Osmosis: Movement of water across a semi-permeable membrane.
• Semi-permeable membrane: Allows some substances to pass through while inhibiting others.
• Hypertonic Solution: Higher solute concentration outside the cell compared to inside. Water moves out, causing cell shrinkage.
• Hypotonic Solution: Lower solute concentration outside the cell compared to inside. Water moves in, causing cell swelling or bursting.
• Isotonic Solution: Equal solute concentration inside and outside the cell. Water moves in and out equally, maintaining cell size.

Stem Cells (Definition and Types)

• Definition: Undifferentiated cells capable of dividing and differentiating into specialized cell types.
• Types: Embryonic stem cells (can form any cell type) and adult stem cells (limited to a specific type like blood or muscle)
• Importance: Used in disease research, treatment development, and regeneration of damaged tissue.

Cancer (Definition, Causes, and Traits)

• Definition: Uncontrolled cell growth and division due to mutations.
• Causes: Inherited factors, aging, and harmful substances like smoking, UV light.
• Cancer Cell Traits: Uncontrolled growth, avoidance of immune system, spreading to other areas, tissue damage.

Types of Tumors (Benign and Malignant, Metastasis)

• Metastatic: Cancerous tumors spreading to other body regions.
• Benign: Non-cancerous tumors staying in one location..
• Malignant: Cancerous tumors disrupting neighboring tissue functions.

Detecting and Screening for Cancer

• Methods such as MRI and CT scans.
• ABCDE Rule: Used in identifying potential cancers in moles. (Asymmetry, Border, Color, Diameter, Evolving)

Cancer Treatments

• Surgery: Removal of tumors (limited by size/accessibility).
• Chemotherapy: Use of drugs to kill rapidly dividing cells (potential for tissue damage).
• Radiation: Damaging cancer cell DNA.
• Biophotonics: Laser-based cancer cell targeting.

Animal and Plant Cells (Similarities and Differences)

• Similarities: Cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, and similar processes like mitosis and cellular respiration.
• Differences:
• Animal Cells: Lack a cell wall, chloroplasts, and a large central vacuole; generally rounded.
• Plant Cells: Have a rigid cell wall, chloroplasts for photosynthesis, and a large central vacuole; often rectangular shaped.

Stages of Mitosis

• Interphase: DNA replication, cell's normal functions occur.
• Prophase: Chromosomes condense, nuclear envelope breaks down, spindle fibers form.
• Metaphase: Chromosomes align at the cell's center, spindle fibers attach.
• Anaphase: Sister chromatids separate, pulled to opposite poles.
• Telophase: Chromosomes uncoil, new nuclear envelopes form.
• Cytokinesis: Cytoplasm divides, creating two separate cells (different mechanisms in animal and plant cells).

Enzymes and Enzyme Locations

• Amylase: Found in saliva, digests carbohydrates.
• Pepsin: Located in the stomach, digests proteins.
• Trypsin: Found in the small intestine, continues protein digestion.
• Lipase: Found in the small intestine, digests fats/lipids.

Digestion Process

• Chemical Digestion: Enzymes break down food into absorbable components.
• Mechanical Digestion: Physical breakdown of food to increase surface area for enzymes. (e.g., teeth, stomach churning).

Human Organ Systems

• Digestive:

• Mouth: Chews food, saliva contains amylase.

• Esophagus: Transports food to the stomach.

• Stomach: Mechanical and chemical digestion (acid and enzymes).

• Small Intestine: Nutrient absorption.

• Large Intestine: Water absorption, waste formation.

• Accessory Organs: Assist digestion without touching food.

• Liver: Produces bile.

• Gallbladder: Stores bile.

• Circulatory:

• Heart: Pump for blood.

• Blood: Fluid carrying oxygen, nutrients, and waste.

• Blood Vessels: Arteries, veins, capillaries.

• Blood Components: Blood plasma (90% water), red blood cells (carry oxygen), white blood cells (fight disease), platelets (blood clotting).

• Respiratory:

• Nose/Mouth: Air intake.

• Trachea: Air passage (cartilage rings for support).

• Bronchi: Air conduits into lungs.

• Bronchioles: Smaller branches within the lungs.

• Alveoli: Site of gas exchange (oxygen in, carbon dioxide out).

• Diaphragm: Muscle aiding in breathing.

• Musculoskeletal:

• Bones: Support, protection, mineral storage, blood cell production.

• Ligaments: Connect bones.

• Cartilage: Cushions joints..

• Tendons: Connect muscles to bones.

• Muscles: Contract to cause movement. work in pairs for agonist/antagonist action.

• Nervous:

• Central Nervous System (CNS): Brain, spinal cord; information processing.

• Peripheral Nervous System (PNS): Nerves connecting CNS to body.

• Neurons: Transmit electrical signals.

• Myelin: Fatty covering on some neurons for faster signal transmission.

• Sensory Receptors: Photoreceptors (light), thermoreceptors (temperature), chemoreceptors (chemicals), mechanoreceptors (pressure), nociceptors (pain).

• Spinal Cord: Reflex actions & communication between brain and body.

• Lungs (Respiratory): Large surface area (alveoli) maximizing gas exchange.

• Small Intestine (Digestive): Villi and microvilli increasing absorptive surface area.

• Capillaries (Circulatory): Extensive network facilitating gas, nutrient, and waste exchange.

• Skin (Integumentary): Large surface area allowing for temperature regulation and environmental sensing.

• Brain (Nervous): Convolutions (gyri and sulci) increasing surface area for neuron density and function.

Systems Working Together

• Respiratory and Circulatory: Oxygen delivery to cells and CO2 removal.
• Musculoskeletal: Movement.
• Nervous: Controls and coordinates.
• Digestive and Circulatory: Food breakdown and nutrient transport.
• Gas Exchange in Lungs: Oxygen diffuses into blood; CO2 diffuses out. Alveoli (thin-walled sacs) maximize gas exchange area.
• Circulatory System - Blood Flow: Two paths: Pulmonary (heart to lungs, oxygenation), Systemic (body, oxygen delivery).

Respiratory System Issues

• Tuberculosis (TB): Bacterial lung infection.
• Lung Cancer: Often linked to smoking.
• Vaping: Potential long-term lung damage.
• COVID-19: Respiratory illness caused by a virus.

Musculoskeletal System Issues

• Osteoporosis: Weakened bones due to calcium loss.
• Leukemia: Cancer affecting bone marrow blood production.

Reflexes

• Involuntary, quick muscle responses to stimuli for protection or movement.

Nervous System Diseases/Disorders

• Concussion: Brain injury from trauma, diagnosed by imaging scans.
• Multiple Sclerosis: Immune system attacks myelin. Symptoms involve weakness, mobility issues.
• Paralysis: Severe spinal cord injury leading to movement loss.

Climate Change

• Greenhouse gases: Trap heat in Earth's atmosphere.
• Greenhouse effect: Natural process keeping Earth warm.
• Climate change: Long-term alterations in weather patterns (temperature, rainfall, storms).
• Climate change vs. global warming: Global warming is a cause (rise in Earth's average temperature). Climate change encompasses local effects from these global changes.
• Climate vs. weather: Climate is the long-term average weather; weather is current atmospheric conditions.
• Evidence of Global Warming:
• Increase in CO2 levels from pre-industrial era.
• Ice cores showing CO2 increase linked to industrialized activities.
• Increased CO2 correlates with rising temperatures.
• Climate Change Activities:
• Activities like burning fossil fuels (coal, oil, gas), deforestation, industrial activities are increasing CO2 concentrations.
• CO2 steadily increased from 280 ppm to over 420 ppm, a high in 800,000 years.
• CO2 traps more heat causing warming, glacier melt, sea-level rise, extreme weather.