Biology Chapter on Cells and Systems

Characteristics of Living Things

• Living organisms produce and consume energy to function
• Metabolism encompasses all chemical reactions essential for life processes
• Anabolism is the building of complex molecules from simpler ones
• Catabolism is the breakdown of complex molecules into simpler ones
• Living organisms grow and repair themselves, often specializing according to function
• Mechanisms exist to fix malfunctioning cells
• Adaptation is the ability to respond to environmental changes
• Homeostasis is a vital process to maintain a stable internal environment
• Reproduction allows for the creation of new organisms (either cellular or organismal level)

Levels of Organization in the Body

• Chemical level: Atoms and molecules form the basic building blocks of the body
• Cellular level: Cells are the fundamental units of life, each performing specific functions in tissues
• Tissue level: Similar cells grouped together form tissues, performing common functions
• Organ level: Two or more tissue types working together form organs with specialized roles
• System level: Various organs cooperate to accomplish a complex set of functions
• Organismal level: All structural levels interact to maintain the organism's overall functions

Cell Theory

• All organisms are composed of one or more cells
• Cells are the fundamental unit of life and carry out essential biological functions
• Cells originate only from previously existing cells
• Heredity information directs the creation of biomolecules and enables reproduction

Cells Are the Living Unit of Life

• Cells are the fundamental building blocks of tissue
• Cells maintain homeostasis
• All cells share basic components: membrane, genetic material, and cytosolic fluid
• Specialized organelles within human cells lead to compartmentalization and complexity
• Gene expression leads to cell specialization

Cell Differentiation

• Cells develop unique features and functions during specialization
• Cell specialization is often irreversible in differentiated cells
• All cells start as unspecialized totipotent stem cells
• As tissues develop, stem cells differentiate to perform specific functions

Tissues

• Tissues are groups of similar cells with a shared structure and function
• Four basic tissue types: Epithelial, Connective, Muscle, Nervous
• Each tissue type performs specific roles critical for organ function

Integrating Tissues: Organs

• Organs are structures composed of 2 or more tissue types working together
• Different tissues cooperate within organs to produce complex functions

Intro to the Organ Systems

• Integumentary System: Skin, hair, nails, glands contribute to protection and temperature regulation
• Nervous System: Brain, spinal cord, nerves facilitate detection of internal and external stimuli and physiological responses
• Musculoskeletal System: Bones, muscles, cartilage, tendons, and ligaments provide support, protection, and mobility along with blood cell production

Intro to the Organ Systems (cont. 1)

• Respiratory System: Nasal passages, trachea, lungs facilitate gas exchange
• Cardiovascular System: Heart, blood vessels, and blood move materials throughout the body
• Immune and Lymphatic Systems: Lymphoid organs and cells contribute to defending against pathogens
• Endocrine System: Glands release hormones coordinating growth, metabolism, and other physiological processes

Intro to the Organ Systems (cont. 2)

• Urinary System: Kidneys, ureters, bladder, and urethra maintain fluid balance and excrete waste
• Digestive System: Mouth, esophagus, stomach, intestines, and associated organs digest food and process nutrients
• Reproductive System: Organs (male and female) facilitate reproduction

Regional Anatomical Terms

• Main Regions: Axial (head, neck, trunk) and Appendicular (arms, legs, girdles)
• Specific Regions: Detailed divisions within the main regions

The Body Cavities

• Cavities are hollow spaces within the body, containing organs or holding them in place
• Posterior aspect cavities (cranial and vertebral) are completely encased in bone
• Ventral cavity is larger and is anteriorly placed, divided into thoracic and abdominopelvic regions

Serosa

• Serous membranes form thin, double-layered sacs surrounding organs in the ventral body cavity
• Parietal layer lines the cavity wall, visceral layer covers the organ
• Serous fluid between these layers reduces friction

The Thoracic Cavity

• Primarily the chest cavity, encased by ribs and chest muscles
• Contains three divisions: pleural cavities (surrounding the lungs), mediastinum (between the lungs), and pericardial cavity (surrounding the heart)

The Abdominopelvic Cavity

• Divided into two cavities: The superior abdominal cavity and the inferior pelvic cavity
• Contains organs of the digestive system, excretory system and reproductive systems

Abdominopelvic Regions

• The abdominopelvic region is divided into four quadrants and nine regions based on anatomical landmarks
• Quadrant and region divisions are used for easier anatomical reference

Directional Terms

• Anatomical directional terms describe locations of body structures relative to each other
• Anterior/Posterior, Superior/Inferior, Medial/Lateral, Proximal/Distal, Superficial/Deep are key concepts

Body Planes and Sections

• Anatomical position (upright, arms at side, palms forward) is the reference point
• Planes (coronal, transverse, midsagittal) are used for dividing the body into sections

Homeostasis

• Ability to maintain relatively stable internal conditions despite external changes
• Dynamic state of equilibrium
• Crucial for physiological function
• Homeostasis is achieved through regulatory feedback mechanisms

Homeostasis (components)

• Variable: The substance or physiological process being regulated
• Stimulus: Initiates the homeostatic process
• Receptor: Detects the change in the variable
• Controller: Integrates input from the receptor and directs an appropriate response
• Effector: Brings about the changes needed to restore homeostasis
• Set point: The normal range for the variable

Negative v. Positive Feedback

• Negative feedback loops reverse a change, maintaining a set point
• Positive feedback loops enhance a change
• Common examples of homeostasis regulation mechanisms