A&P
Anatomy and Physiology
Anatomy and physiology are branches of biology concerned with:
The form (anatomy) and functions (physiology) of the body.
Types of anatomy:
Gross anatomy: Study of structures visible to the naked eye.
Microscopic anatomy: Structures that are not visible without magnification.
Cytology: Study of individual cells.
Histology: Study of tissues.
Physiology
Physiology subdivisions named according to:
Organism involved: human physiology, plant physiology.
Organizational level: molecular physiology, cellular physiology.
Systemic function: respiratory physiology, neurophysiology, cardiovascular physiology.
Characteristics of Life
Autopoiesis: Living organisms are self-organized and self-maintaining.
Cell theory: If an organism is composed of one or more cells, it is considered alive.
Metabolism: The sum total of all physical and chemical reactions occurring in the living body.
Levels of Organization
Chemical Level
The organization of chemical structures separates living material from nonliving material.
Atoms, molecules, and macromolecules, when organized, yield living matter known as cytoplasm.
Organizational Levels in the Human Body
Chemical Level: Atoms, molecules.
Cellular Level: Cells, organelles (e.g., mitochondria, Golgi apparatus, endoplasmic reticulum).
Tissue Level: Groups of cells.
Organ Level: Organs with distinct functions (e.g., heart, lungs).
Organ System Level: Systems performing complex functions (e.g., cardiovascular, respiratory).
Organism Level: The complete living entity that is greater than the sum of its parts.
Anatomical Position
The anatomical position serves as a standard reference position:
Body erect with arms at sides, palms facing forward.
Head and feet pointing forward.
Bilateral Symmetry
Bilateral symmetry: Balanced proportions with correspondence of size and shape between body parts on opposite sides of the body.
Ipsilateral structures: On the same side of the body.
Contralateral structures: On opposite sides of the body.
Anatomical Directions: Directional Terms
Superior: Towards the head; upper; above.
Inferior: Lower; below.
Anterior: Front; in front of.
Posterior: Back; in back of.
Medial: Towards the midline of the body.
Lateral: Towards the side; away from the midline.
Proximal: Nearer the trunk of the body or nearest the point of origin.
Distal: Farthest from the trunk or the point of origin.
Superficial: Nearer the surface.
Deep: Farther away from the body surface.
Body Planes and Sections
Sagittal planes: Lengthwise plane running front to back, dividing the body into right and left.
Coronal planes: Lengthwise plane running side to side, dividing the body into anterior and posterior.
Transverse planes: Crosswise plane dividing the body or body parts into upper and lower.
Body Cavities
Dorsal Cavities
Cranial cavity: Contains the brain.
Spinal cavity: Contains the spinal cord.
Ventral Cavities
Thoracic cavity: Contains the lungs and heart, subdivided into:
Right and left pleural cavities.
Mediastinum (space between lungs containing the heart).
Abdominopelvic cavity: Further divided into:
Abdominal cavity (upper portion).
Pelvic cavity (lower portion).
Major Body Cavities
Dorsal body cavities: cranial and spinal.
Ventral body cavities: thoracic and abdominopelvic.
Abdominopelvic Quadrants
Right Upper Quadrant (RUQ)
Left Upper Quadrant (LUQ)
Right Lower Quadrant (RLQ)
Left Lower Quadrant (LLQ)
Abdominopelvic Regions
Right hypochondriac region
Epigastric region
Left hypochondriac region
Right lumbar region
Umbilical region
Left lumbar region
Right iliac (inguinal) region
Hypogastric region
Left iliac (inguinal) region.
Body Regions
Axial subdivision: Head, neck, torso (trunk).
Appendicular subdivision: Upper extremity, lower extremity.
Interaction of Structure and Function
The complementarity of structure and function is a critical concept; anatomical structures often appear designed for specific functions due to their unique size, shape, or brain location.
Homeostasis
Learning Objectives - Lesson 2.1: Homeostasis
Define homeostasis.
Explain the importance of homeostatic control mechanisms and the operation of negative and positive feedback loops.
Define the three levels of homeostatic control.
Homeostasis
Homeostasis: The relatively constant states maintained by the body.
Examples of Homeostasis
Temperature regulation: Body maintains around 37°C (98.6°F).
Blood carbon dioxide level regulation: Maintains necessary levels for efficient gas exchange.
Blood glucose level regulation: Insulin and glucagon maintain blood sugar within a narrow range.
Homeostatic Control Mechanisms
Devices for maintaining or restoring homeostasis through feedback control loops, including:
Sensor mechanism: Detects changes.
Integrating (control) center: Processes information and determines response.
Effector mechanism: Carries out response to restore balance.
Feedback: Information returning from the effector to the sensor.
Feedback Systems
Negative Feedback:
Inhibitory effect that stabilizes physiological variables.
Produces actions opposite to changes that activated the system; responsible for maintaining homeostasis.
Common in biological systems (e.g., thermoregulation).
Positive Feedback:
Stimulatory effect that amplifies or reinforces change.
Tends to disrupt homeostasis and is less common than negative feedback (e.g., childbirth).
Chemistry of Life
Learning Objectives - Lesson 3.1: Chemistry of Life
Explain the importance of understanding basic chemistry in the study of life processes.
Describe the relationship between elements, compounds, atoms, and molecules.
List the major elements and major mineral elements in the human body.
Discuss atomic structure and explain the influence of electron shells.
Compare and contrast the three major types of chemical bonds.
Describe the types of chemical reactions occurring in living materials.
Define metabolism; explain the difference between catabolism and anabolism.
Discuss the properties of water in living organisms.
Explain the concept of pH and its relationship to acids, bases, and salts.
Elements and Compounds
Matter: Anything that occupies space and has mass, composed of elements.
Element: A substance that cannot be broken down into simpler substances.
26 elements are known to be essential for life.
Compound: A combination of two or more elements.
Atomic Structure
Atoms contain three types of subatomic particles:
Protons (p): Positively charged; found in the nucleus.
Neutrons (n): Neutral charge; found in the nucleus.
Electrons (e): Negatively charged; orbit around the nucleus.
Properties of Atoms
Atomic number: Number of protons in the nucleus.
Mass number: Total number of protons and neutrons.
Energy levels: Regions around the nucleus where electrons reside, obeying the octet rule for stability.
Chemical Bonds
Chemical bonds connect atoms to form molecules. Two main types:
Ionic bonds: Involve the transfer of electrons; results in ion formation.
Example: Sodium chloride (NaCl).
Covalent bonds: Involve the sharing of electrons between atoms.
Example: Water (H₂O).
Hydrogen Bonds
Weak bonds formed due to polar covalent molecules with unequal charge distribution.
Critical for the structure of proteins and nucleic acids (DNA, RNA).
Chemical Reactions
Include:
Synthesis reactions: Two or more substances combine to form a more complex product (A + B → AB).
Decomposition reactions: A compound breaks down into simpler reactants (AB → A + B).
Exchange reactions: Components of the reactants are rearranged (AB + CD → AC + BD).
Reversible reactions: Can proceed in both directions.
Metabolism
Catabolism: Metabolic pathways that break down larger molecules into smaller units, releasing energy.
Anabolism: Metabolic pathways that construct molecules from smaller units, requiring energy intake (such as the synthesis of proteins).
Properties of Water
Polarity: Allows for hydrogen bonding, making it an excellent solvent.
High specific heat: Enables temperature regulation.
High heat of vaporization: Critical for thermoregulation through perspiration.
Acids and Bases
Acids: Substances that donate hydrogen ions (H+) to solutions.
Bases: Substances that accept H+ or release hydroxide ions (OH-).
pH Scale
Measures acidity or alkalinity; ranges from 0 (most acidic) to 14 (most alkaline) with 7 being neutral.
Biomolecules
Learning Objectives - Lesson 4.1: Biomolecules
Identify the four major groups of organic substances in the body.
Discuss the function of carbohydrates and their types.
Describe the types of lipids and their major functions.
Explain the role of structural and functional proteins.
Describe the four levels of protein structure.
Compare the structures of DNA and RNA.
Describe how ATP releases energy and its role in the cell.
Discuss relationships between biomolecule abnormalities and diseases.
Organic Molecules
Organic molecules: Compounds that contain carbon and are essential to life; include:
Carbohydrates
Lipids
Proteins
Nucleic acids
Carbohydrates
Commonly referred to as sugars and starches:
Monosaccharides: Simple sugars (e.g., glucose).
Disaccharides: Two monosaccharides joined (e.g., sucrose).
Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen).
Lipids
Water-insoluble organic molecules critical for biological functions:
Triglycerides: Composed of glycerol and fatty acids.
Types:
Saturated fats: Solid at room temperature; raise LDL cholesterol.
Unsaturated fats: Liquid; raise HDL cholesterol, beneficial for heart health.
Phospholipids: Structural components of cell membranes, possessing hydrophobic tails and hydrophilic heads.
Proteins
Composed of amino acids; functions include:
Catalytic (enzymes), structural (collagen), transport (hemoglobin).
Amino acids can be essential (must be consumed) or nonessential (can be produced by the body).
DNA and RNA
Deoxyribonucleic acid (DNA): Contains genetic information; composed of nucleotides. Base pairs:
Adenine (A) with Thymine (T), Cytosine (C) with Guanine (G).
Ribonucleic acid (RNA): Involved in protein synthesis, contains Uracil (U) instead of Thymine.
ATP (Adenosine Triphosphate)
Functions as the energy currency of cells; releases energy upon hydrolysis to ADP and inorganic phosphate.
Cell Structure
Learning Objectives - Lesson 5.1: Cells, Membranes, and Organelles
Discuss the cell structure.
Describe the molecular structure and function of cell membranes.
Identify and discuss cell organelles.
Discuss the structure and function of the nucleus and chromatin.
Describe the cytoskeleton and associated organelles.
List types of direct cell connections.
Cell Structure
Cells are the basic unit of life, vary in size and function.
Plasma Membrane
Composed of a bilayer of phospholipids with embedded proteins, controlling nutrient and waste passage.
Fluid Mosaic Model: Illustrates dynamic nature of the membrane.
Cytoplasm
Contains organelles suspended in cytosol (the liquid matrix).
Nuclear Structure
Contains DNA within a double membrane (nuclear envelope) with nuclear pores for transport.
Nucleolus: Produces ribosomal RNA.
Organelles
Mitochondria: Energy production via ATP synthesis through cellular respiration.
Ribosomes: Synthesizes proteins; found free in the cytoplasm or attached to the rough endoplasmic reticulum (RER).
Golgi Apparatus: Modifies, sorts, and packages proteins from the RER.
Lysosomes: Digestive organelles that break down cellular waste.
Smooth Endoplasmic Reticulum (SER): Synthesizes lipids and detoxifies harmful metabolic byproducts.
Cytoskeleton: Provides structural support, facilitates cell movement and division (microfilaments, intermediate filaments, microtubules).
Cell Connections
Tight junctions: Prevent leakage between cells.
Desmosomes: Provide adhesion between cells.
Gap junctions: Allow communication between neighboring cells.
Cell Function
Learning Objectives - Lesson 6.1: Passive and Active Transport Processes
Discuss passive transport processes: diffusion, osmosis, facilitated diffusion, and filtration.
Discuss active transport mechanisms: pumps and vesicles.
Explain enzymes' roles in metabolism and the process of cellular respiration.
Transport Mechanisms
Passive Transport
Does not require energy.
Diffusion: Movement of solutes from high to low concentration.
Osmosis: Diffusion of water across a selectively permeable membrane.
Facilitated Diffusion: Uses carrier proteins to assist molecules across the membrane down their concentration gradient.
Filtration: Movement of water and solutes through a membrane due to pressure differences.
Active Transport
Requires cellular energy (ATP).
Primary Active Transport: Directly uses ATP (e.g., Na+/K+ pump).
Secondary Active Transport: Utilizes energy from primary transport to move other substances against their concentration gradient.
Vesicular Transport: Includes endocytosis (for bringing materials into the cell) and exocytosis (for exporting materials out of the cell).
Cellular Respiration
A process that converts biochemical energy from nutrients into ATP, involving:
Glycolysis: Anaerobic process in which glucose splits into two pyruvate molecules, generating ATP.
Citric Acid Cycle (Krebs Cycle): Processes pyruvate in the mitochondria, producing electron carriers.
Electron Transport System (ETS): Transfers electrons, yielding ATP and water.
Cell Growth and Development
Learning Objectives - Lesson 7.1: Cell Growth and Development
Discuss gene control of protein synthesis.
Cell Growth and Reproduction
Fundamental functions of living organisms, comprising:
Cell life cycle: Growth and reproduction depend on genetic information in DNA to synthesize proteins required for survival.
Protein Synthesis
DNA: Genetic material that encodes proteins.
A gene consists of approximately 1000 nucleotide pairs coding for an RNA transcribed from a gene, which translates to a polypeptide.
Transcription: mRNA synthesis from the DNA template.
Translation: Synthesis of proteins from mRNA at ribosomes.
Introduction to Tissues
Learning Objectives - Lesson 8.1: Introduction to Tissues
Define tissue and discuss four principal types.
Explain the extracellular matrix (ECM).
Discuss regeneration of tissues and major body membranes.
Tissues
A tissue is a group of similar cells performing a specific function.
Matrix: Nonliving intercellular material.
Types of Tissue
Four principal types:
Epithelial tissue: Covers body surfaces, lines cavities, and forms glands.
Connective tissue: Supports, binds, and protects other tissues and organs.
Muscle tissue: Responsible for movement.
Nervous tissue: Transmits signals to coordinate functions.
Epithelial Tissue Characteristics
Limited amount of matrix material.
Avascular and capable of reproduction.
Connective Tissue Characteristics
Composed mostly of ECM, which determines its physical properties:
Collagenous fibers: Provide strength.
Elastic fibers: Provide flexibility.
Reticular fibers: Form a supportive mesh.
Muscle Tissue Types
Skeletal muscle: Striated and voluntary.
Smooth muscle: Non-striated and involuntary.
Cardiac muscle: Striated and involuntary, found only in the heart.
Nervous Tissue Components
Neurons: Specialized cells that transmit signals.
Neuroglia: Supportive cells that assist neurons.
Blood and Muscle Tissue
Learning Objectives - Lesson 9.2: Blood and Muscle Tissue
Compare bone and cartilage in terms of function and structure.
Discuss blood as tissue and its functions.
Identify characteristics of muscle tissue types and nervous tissue types.
Bone Tissue
Uniquely hard and strong; supports, protects, and allows muscle attachment; serves as a reservoir for minerals.
Osteocytes are the mature cells embedded in calcified matrix.
Blood Tissue
Considered a liquid tissue, composed of:
Plasma (liquid matrix).
Formed elements: red blood cells, white blood cells, and platelets.
Muscle Tissue Types
Skeletal muscle: Voluntary, striated fibers.
Smooth muscle: Involuntary, non-striated fibers in walls of hollow organs.
Cardiac muscle: Involuntary, striated fibers found in the heart, coordinated contractions.
Nervous Tissue Structure
Composed of neurons (conducting cells) and neuroglia (supportive cells).
Neurons consist of a cell body, axons, and dendrites.
Anatomical Position and Symmetry\n- Anatomical Position: The reference standard where the body is erect, arms are at the sides with palms facing forward, and the head and feet point forward.\n- Bilateral Symmetry: Balanced proportions on opposite sides of the body.\n- Ipsilateral: Structures located on the same side of the body.\n- Contralateral: Structures located on opposite sides of the body.\n\n#### Directional Terms and Body Planes\n- Directional Terms:\n - Superior / Inferior: Above / below.\n - Anterior / Posterior: Front / back.\n - Medial / Lateral: Toward the midline / toward the side.\n - Proximal / Distal: Nearer to / farther from the point of origin or trunk.\n - Superficial / Deep: Closer to / farther from the surface.\n- Body Planes:\n - Sagittal: Divides into right and left.\n - Coronal (Frontal): Divides into anterior and posterior.\n - Transverse (Horizontal): Divides into upper and lower parts.\n\n#### Body Cavities and Abdominal Regions\n- Dorsal Cavities: Cranial (contains the brain) and Spinal (contains the spinal cord).\n- Ventral Cavities:\n - Thoracic: Includes pleural cavities (lungs) and the mediastinum (heart).\n - Abdominopelvic: Divided into the abdominal cavity (digestive organs) and pelvic cavity (reproductive and urinary organs).\n- Abdominal Quadrants: RUQ, LUQ, RLQ, LLQ.\n- Abdominal Regions: Right/Left hypochondriac, Epigastric, Right/Left lumbar, Umbilical, Right/Left iliac, Hypogastric.\n\n#### Levels of Organization and Body Systems\n- Levels: Atoms \(\to\) Molecules \(\to\) Organelles \(\to\) Cells \(\to\) Tissues \(\to\) Organs \(\to\) Organ Systems \(\to\) Organism.\n- Body Systems: Include integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive systems.\n\n#### Homeostasis and Feedback Loops\n- Homeostasis: The maintenance of relatively constant internal states (e.g., temperature at , blood glucose levels).\n- Negative Feedback: Inhibitory; produces response opposite to the change to stabilize the system (most common).\n- Positive Feedback: Stimulatory; amplifies or reinforces the change (e.g., labor contractions during childbirth).\n\n#### Chemistry of Life\n- Atoms: Composed of protons (p+), neutrons (n), and electrons (e-).\n - Atomic Number: Number of protons in the nucleus.\n - Mass Number: Sum of protons and neutrons.\n - Atomic Weight: Average mass of all isotopes of an element.\n- Bonds:\n - Ionic: Transfer of electrons between atoms.\n - Covalent: Sharing of electron pairs.\n - Hydrogen: Weak attraction between polar molecules.\n\n#### Biomolecules\n- DNA: Deoxyribonucleic acid; double-helix containing genetic info. Base pairs: Adenine-Thymine (A-T) and Cytosine-Guanine (C-G).\n- Amino Acids:\n - Essential: Must be obtained through diet.\n - Non-essential: Can be synthesized by the body.\n- Lipids: Specifically Phospholipids which form a bilayer in cell membranes with hydrophilic heads and hydrophobic tails.\n\n#### Cell Structure and Organelles\n- Plasma Membrane: Phospholipid bilayer controlling transport.\n- Nucleus: Contains DNA and coordinates cell activities.\n- Mitochondria: Powerhouse of the cell, produces ATP.\n- Ribosomes: Protein synthesis.\n- Golgi Apparatus: Modifying and packaging proteins.\n- Lysosomes: Digestion of waste.\n- Endoplasmic Reticulum (ER): Rough ER (protein synthesis/transport) and Smooth ER (lipid synthesis/detoxification).\n\n#### Transport Processes\n- Passive Transport: No energy required, moves down concentration gradients.\n - Diffusion: Movement of solutes.\n - Osmosis: Movement of water across a membrane.\n - Facilitated Diffusion: Uses proteins.\n - Channel-mediated: Gated or non-gated pores.\n - Carrier-mediated: Transporters that change shape to move specific molecules.\n- Active Transport: Requires ATP (energy) to move substances against gradients (e.g., Na+/K+ pump, vesicular transport like endocytosis/exocytosis).\n\n#### Tissues and Characteristics\n- Major Tissue Types:\n - Epithelial: Forms sheets, covers surfaces, lines cavities; avascular and high regeneration rate.\n - Connective: Most abundant; contains significant Extracellular Matrix (ECM) with collagenous, elastic, or reticular fibers.\n - Muscle: Specialized for contraction (Skeletal, Smooth, Cardiac).\n - Nervous: Specialized for communication (Neurons and Neuroglia).
1. Anatomical Reference and Body Layout
Anatomical Position and Symmetry
Anatomical Position: The standard body reference position characterized by:
Body erect with arms at the sides.
Palms facing forward with thumbs pointing away from the body.
Head and feet pointing forward.
Bilateral Symmetry: A body plan where the right and left sides are mirror images of each other.
Ipsilateral: Refers to structures located on the same side of the body (e.g., the right lung and right kidney).
Contralateral: Refers to structures on opposite sides of the body (e.g., the left arm and right leg).
Body Planes and Directional Terms
Body Planes: Imaginary flat surfaces used to section the body:
Sagittal: Runs lengthwise (front to back), dividing the body into right and left sides.
Coronal (Frontal): Runs lengthwise (side to side), dividing the body into anterior (front) and posterior (back) portions.
Transverse (Horizontal): Runs crosswise, dividing the body into superior (upper) and inferior (lower) portions.
Directional Terms:
Superior / Inferior: Above / below.
Anterior (Ventral) / Posterior (Dorsal): Front / back.
Medial / Lateral: Toward the midline / toward the side (away from midline).
Proximal / Distal: Nearer to / farther from the trunk or point of origin.
Superficial / Deep: Nearer to / farther from the body surface.
Body Cavities and Abdominal Divisions
Dorsal Cavities: Located at the posterior of the body:
Cranial cavity: Encased by the skull, contains the brain.
Spinal cavity: Encased by the vertebrae, contains the spinal cord.
Ventral Cavities: Located at the anterior of the body:
Thoracic cavity: Divided into the Mediastinum (central region containing the heart, trachea, and esophagus) and Pleural cavities (containing the lungs).
Abdominopelvic cavity: Subdivided into the Abdominal cavity (liver, stomach, intestines) and the Pelvic cavity (bladder, reproductive organs, rectum).
Abdominal Regions and Quadrants:
Four Quadrants: Right Upper (RUQ), Left Upper (LUQ), Right Lower (RLQ), Left Lower (LLQ).
Nine Regions:
Upper: Right hypochondriac, Epigastric, Left hypochondriac.
Middle: Right lumbar, Umbilical, Left lumbar.
Lower: Right iliac (inguinal), Hypogastric, Left iliac (inguinal).
2. Levels of Organization and Body Systems
Levels of Organization
Chemical Level: Atoms (e.g., Carbon) and Molecules (e.g., ).
Cellular Level: Organelles (e.g., mitochondria) and the basic unit of life, the Cell.
Tissue Level: Groups of similar cells performing a common function.
Organ Level: Structures composed of different tissues working together (e.g., Heart).
Organ System Level: Groups of organs working to meet a physiological need (e.g., Cardiovascular system).
Organism Level: The total human body.
Major Body Systems
Integumentary: Protection, temperature regulation.
Skeletal: Support, protection, mineral storage.
Muscular: Movement, heat production.
Nervous: Fast-acting control and coordination via electrical signals.
Endocrine: Slower control via hormones.
Cardiovascular: Transport of nutrients, gases, and waste.
Lymphatic: Immunity and fluid balance.
Respiratory: Gas exchange ( and ).
Digestive: Nutrient breakdown and absorption.
Urinary: Waste excretion and water/electrolyte balance.
Reproductive: Production of offspring.
3. Homeostasis and Feedback Control
Homeostasis: The ability of the body to maintain a relatively stable internal environment (e.g., blood glucose levels, body temperature at ).
Feedback Control Loop Components:
Sensor: Detects the change in the environment.
Integrating Center: Analyzes information and determines a response.
Effector: Executes the response to change the internal environment.
Negative Feedback: Inhibitory. It reverses the direction of the initial change to stabilize the system (e.g., sweating to lower body temperature).
Positive Feedback: Stimulatory. It reinforces or amplifies the initial change, moving the system further from the baseline (e.g., oxytocin release during labor).
4. Chemistry of Life and Biomolecules
Atomic Structure and Properties
Atoms: Composed of protons (), neutrons (), and electrons ().
Atomic Number: The number of protons in an atom; defines the element.
Mass Number: The sum of protons and neutrons in the nucleus.
Atomic Weight: The average mass of all naturally occurring isotopes of an element.
Molecules: Two or more atoms held together by chemical bonds.
Chemical Bonds
Ionic Bonds: Result from the complete transfer of electrons from one atom to another, creating ions (e.g., ).
Covalent Bonds: Formed when atoms share pairs of electrons to achieve stability.
Hydrogen Bonds: Weak attractive forces between a slightly positive hydrogen atom and a slightly negative atom (like oxygen) in another molecule.
Essential Biomolecules
DNA (Deoxyribonucleic Acid): The genetic blueprint of the cell found in the nucleus. It is a double-stranded helix. Base pairs include:
Adenine (A) pairs with Thymine (T).
Cytosine (C) pairs with Guanine (G).
Amino Acids: The building blocks of proteins.
Essential: Cannot be made by the body; must be consumed via diet.
Non-essential: Can be synthesized by the body from other materials.
Phospholipid Bilayer: The primary component of the cell membrane.
Hydrophilic heads: Water-loving; face the exterior and interior fluid.
Hydrophobic tails: Water-fearing; face inward, away from fluid.
5. Cell Structure and Transport
Organelles
Nucleus: The control center containing genetic material (chromatin/DNA).
Mitochondria: The "powerhouse" where cellular respiration produces ATP.
Ribosomes: Small structures responsible for protein synthesis.
Golgi Apparatus: Modifies and packages proteins for secretion or use within the cell.
Lysosomes: Contain digestive enzymes to break down waste or foreign particles.
Endoplasmic Reticulum (ER):
Rough ER: Studded with ribosomes; involved in protein synthesis and transport.
Smooth ER: Involved in lipid synthesis and detoxification.
Transport Mechanisms
Passive Transport (No energy/ATP required):
Diffusion: Movement of solutes from high concentration to low concentration.
Osmosis: The movement of water through a selectively permeable membrane toward a higher solute concentration.
Facilitated Diffusion: Movement assisted by membrane proteins.
Channel-mediated: Uses gated or non-gated water-filled pores (hydrophilic).
Carrier-mediated: Transporters bind to the substrate, change shape, and release it on the other side.
Active Transport (Requires ATP):
Moves substances against their concentration gradient (e.g., the pump).
6. Major Tissues and Their Characteristics
Epithelial Tissue:
Forms sheets that cover surfaces or line cavities.
Characterized by very little extracellular matrix (ECM).
Avascular (no blood vessels) but has a high capacity for regeneration.
Connective Tissue:
The most abundant and diverse tissue type.
Characterized by a large amount of Extracellular Matrix (ECM) relative to cells.
ECM contains fibers: Collagenous (strength), Elastic (flexibility), and Reticular (mesh support).
Muscle Tissue:
Specialized for contraction and movement.
Includes Skeletal (voluntary/striated), Smooth (involuntary/non-striated), and Cardiac (involuntary/striated).
Nervous Tissue:
Specialized for communication and sensing.
Consists of Neurons (conducting cells) and Neuroglia (supportive cells).