Study sheet: Human Anatomy and Cell Biology

📋 Course Outline

1. Anatomy Physiology and Organization
2. Anatomical Position and Directions
3. Body Systems and Life Processes
4. Homeostasis and Feedback Control
5. Cell Structure and Discovery
6. Cell Organelles and Their Functions
7. Cell Membrane and Transport
8. Cell Junctions and Communication

📖 1. Anatomy Physiology and Organization

🔑 Key Concepts & Definitions

• Anatomy : The branch of science that deals with the structure of the human body and the relationships between its different parts.
• Physiology : The branch of science that deals with the normal functions and working of the human body and its different parts.

📝 Essential Points

• 🔄 The levels of organization progress as follows:
  1. Atoms
  2. Molecules
  3. Cells
  4. Tissues
  5. Organs
  6. Organ systems
  7. Organism

💡 Memory Hook

Anatomy asks what and where; physiology asks how.

📖 2. Anatomical Position and Directions

🔑 Key Concepts & Definitions

• Anatomical position : The standard reference position used to describe the relationships between body parts, with the person standing upright, facing forward, arms beside the body, feet together or slightly apart, and toes pointing forward.

★ Must-know

📌 The sagittal plane divides the body into right and left parts, the coronal or frontal plane divides it into anterior and posterior parts, and the transverse or horizontal plane divides it into upper and lower parts.

• The principal directional terms are:
  • Anterior or ventral
  • Posterior or dorsal
  • Medial
  • Lateral
  • Proximal
  • Distal
  • Superior or cranial
  • Inferior or caudal
  • Superficial

Further detail

📌 The midsagittal or median plane divides the body into equal right and left halves, whereas the parasagittal plane divides it into unequal right and left parts.

💡 Memory Hook

A person standing upright, facing forward, with arms beside the body and toes forward.

📖 3. Body Systems and Life Processes

🔑 Key Concepts & Definitions

• Metabolism : Metabolism is the sum of all chemical processes occurring in the body and includes anabolism, which builds substances, and catabolism, which breaks substances down.
• Homeostasis : The process by which the body maintains a relatively stable internal environment despite changes in the external environment.

★ Must-know

• The eleven human body systems are the integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive systems.

Further detail

• Normal body temperature is 37°C, and the course gives blood pH as 7.88–7.45.

💡 Memory Hook

Metabolism, respiration, reproduction, responsiveness, movement, growth, homeostasis.

📖 4. Homeostasis and Feedback Control

🔑 Key Concepts & Definitions

• Feedback system : A mechanism that maintains homeostasis by continuously monitoring and correcting changes in the internal environment.

📝 Essential Points

• A feedback system operates through a receptor or sensor, a control centre, an effector, and a response.

💡 Memory Hook

Stimulus → receptor → control centre → effector → response.

📖 5. Cell Structure and Discovery

🔑 Key Concepts & Definitions

• Cell : The basic structural and functional unit of life.
• Plasma membrane : A thin, flexible, elastic, selectively permeable barrier that separates the internal components of the cell from the external environment.

📝 Essential Points

• The cell was first observed by Robert Hooke in 1665.

• The first living cell was observed by Antonie Van Leeuwenhoek.

💡 Memory Hook

Membrane → cytoplasm → organelles → nucleus.

📖 6. Cell Organelles and Their Functions

🔑 Key Concepts & Definitions

• Cytoplasm : The gel-like substance between the plasma membrane and nucleus that contains cytosol, organelles, and dissolved substances.
• Nucleus : The nucleus is generally spherical or oval, acts as the control centre of the cell, and contains genetic material in the form of chromatin.

📝 Essential Points

• Ribosomes are small structures made of RNA and proteins and are the sites of protein synthesis.

📌 Smooth endoplasmic reticulum lacks ribosomes and helps synthesize lipids, whereas rough endoplasmic reticulum contains surface ribosomes and helps synthesize and transport proteins.

• The Golgi apparatus consists of flattened membrane-bound sacs and modifies, sorts, and packages proteins and lipids while forming secretory vesicles and lysosomes.

💡 Memory Hook

Specialized organelles → specialized cellular functions.

📖 7. Cell Membrane and Transport

🔑 Key Concepts & Definitions

• Passive transport : Passive transport moves substances across the cell membrane from higher to lower concentration without requiring cellular energy or ATP.
• Active transport : Active transport moves substances across the cell membrane against the concentration gradient, from lower to higher concentration.

★ Must-know

📌 A phospholipid has a hydrophilic part that attracts water and a hydrophobic part that repels water.

• Simple diffusion moves molecules from higher to lower concentration without carrier proteins, facilitated diffusion uses specific carrier or channel proteins, and osmosis moves water through a selectively permeable membrane.

Further detail

• The plasma membrane is composed of approximately 50–60% proteins, 40% lipids, and 1–10% carbohydrates.

📌 Primary active transport directly uses ATP, whereas secondary active transport uses energy stored in an ion concentration gradient and may move substances in the same or different direction.

💡 Memory Hook

Passive transport follows the concentration gradient; active transport opposes it.

📖 8. Cell Junctions and Communication

🔑 Key Concepts & Definitions

• Tight junction : A seal between cells that prevents leakage of substances and is commonly found in intestinal epithelial cells.
• Gap junction : A gap junction forms small channels between adjacent cells that allow ions and small molecules to pass directly for cell-to-cell communication and is important in cardiac muscle cells.

★ Must-know

• Desmosomes are strong cell-to-cell anchoring junctions that attach cells through intermediate filaments and provide resistance to stretching, especially in skin and cardiac muscle.

Further detail

• An adherens junction connects cells through actin filaments, provides mechanical strength, helps maintain cell shape, and supports cell-to-cell adhesion.

• Hemidesmosomes attach cells to the basement membrane by connecting intermediate filaments to the extracellular matrix.

💡 Memory Hook

Tight junctions seal; anchoring junctions attach; gap junctions communicate.

📊 Synthesis Tables

Anatomy and Physiology

Feature	Anatomy	Physiology
Main concern	Structure	Function
Question	What and where	How
Example	Structure of the heart	How the heart pumps blood

Membrane Transport

Type	Direction	Energy or proteins
Simple diffusion	Higher to lower concentration	No ATP or carrier proteins
Facilitated diffusion	Higher to lower concentration	Carrier or channel proteins; no ATP
Osmosis	Higher to lower water concentration	Selective membrane; no ATP
Primary active transport	Lower to higher concentration	Direct ATP use
Secondary active transport	Against a concentration gradient	Ion-gradient energy