Anatomy and Physiology I Unit 1 Review: An Introduction to the Human Body

Key Concepts

• Anatomy studies the structure of the human body includes gross anatomy (macroscopic) and microscopic anatomy (histology and cytology)
• Physiology examines the functions and processes of the human body at various levels (molecular, cellular, tissue, organ, and system)
• Homeostasis maintains a stable internal environment despite changes in the external environment involves negative feedback mechanisms
  • Negative feedback loops detect deviations from the set point and initiate compensatory responses to restore balance (thermoregulation, blood glucose regulation)
• Anatomical position is the standard reference position for describing the human body standing upright, facing forward, with arms at sides and palms facing forward
• Directional terms describe the relative positions of body parts (superior, inferior, anterior, posterior, medial, lateral, proximal, distal)
• Body planes are imaginary flat surfaces that divide the body into sections (sagittal, frontal, transverse)
• Body cavities are spaces within the body that contain and protect internal organs (dorsal cavity, ventral cavity)

Body Organization and Homeostasis

• Levels of organization in the human body from simplest to most complex: chemical, cellular, tissue, organ, system, organism
• Cells are the basic structural and functional units of life perform specialized functions and work together to maintain homeostasis
  • Cell membrane is a selectively permeable barrier that controls the movement of substances in and out of the cell
  • Cytoplasm contains organelles and serves as the site for many cellular processes (protein synthesis, energy production)
• Tissues are groups of cells with similar structure and function that work together to perform a specific role (epithelial, connective, muscle, nervous)
• Organs are structures composed of multiple tissue types that perform specific functions (heart, lungs, liver, kidneys)
• Systems are groups of organs that work together to carry out a particular function (cardiovascular, respiratory, digestive, urinary)
• Homeostatic mechanisms maintain a stable internal environment includes negative feedback loops and positive feedback loops (childbirth, blood clotting)
  • Receptors detect changes in the internal or external environment and send signals to the control center
  • Control center (often the brain) integrates the information and initiates an appropriate response
  • Effectors (muscles, glands) carry out the response to restore homeostasis

Anatomical Terminology

• Anatomical position is the standard reference position for describing the human body standing upright, facing forward, with arms at sides and palms facing forward
• Directional terms describe the relative positions of body parts:
  • Superior (above) and inferior (below)
  • Anterior (front) and posterior (back)
  • Medial (towards the midline) and lateral (away from the midline)
  • Proximal (closer to the trunk) and distal (farther from the trunk)
  • Superficial (closer to the surface) and deep (farther from the surface)
• Body planes are imaginary flat surfaces that divide the body into sections:
  • Sagittal plane divides the body into right and left halves (midsagittal, parasagittal)
  • Frontal (coronal) plane divides the body into anterior and posterior portions
  • Transverse (horizontal) plane divides the body into superior and inferior portions
• Body cavities are spaces within the body that contain and protect internal organs:
  • Dorsal cavity includes the cranial cavity (brain) and vertebral canal (spinal cord)
  • Ventral cavity includes the thoracic cavity (heart, lungs), abdominal cavity (digestive organs), and pelvic cavity (reproductive organs)

Body Systems Overview

• Integumentary system consists of the skin, hair, nails, and associated glands provides protection, temperature regulation, and sensory reception
• Skeletal system includes bones, cartilage, and ligaments provides support, protection, movement, mineral storage, and blood cell production
• Muscular system consists of skeletal, smooth, and cardiac muscle enables movement, maintains posture, and generates heat
• Nervous system includes the brain, spinal cord, and peripheral nerves coordinates and controls body functions, processes sensory information, and initiates responses
• Endocrine system consists of glands that secrete hormones regulates growth, development, metabolism, and homeostasis
• Cardiovascular system includes the heart, blood vessels, and blood transports nutrients, oxygen, waste products, and hormones throughout the body
• Lymphatic system consists of lymph vessels, lymph nodes, and lymphoid organs (spleen, thymus) helps maintain fluid balance and provides immune defense
• Respiratory system includes the lungs, airways, and associated structures enables gas exchange between the blood and the environment

Levels of Structural Organization

• Chemical level includes atoms, molecules, and compounds that form the basis of all living organisms (water, proteins, carbohydrates, lipids, nucleic acids)
• Cellular level is the basic unit of life cells perform specific functions and work together to maintain homeostasis
  • Prokaryotic cells lack a nucleus and membrane-bound organelles (bacteria)
  • Eukaryotic cells have a nucleus and membrane-bound organelles (animals, plants)
• Tissue level consists of groups of cells with similar structure and function that work together to perform a specific role
  • Epithelial tissue covers body surfaces and lines cavities provides protection, secretion, and absorption
  • Connective tissue supports and connects other tissues includes bone, cartilage, blood, and adipose tissue
  • Muscle tissue enables movement and generates force includes skeletal, smooth, and cardiac muscle
  • Nervous tissue transmits electrical signals and processes information includes neurons and glial cells
• Organ level is composed of multiple tissue types that work together to perform a specific function (heart, lungs, liver, kidneys)
• System level consists of groups of organs that work together to carry out a particular function (cardiovascular, respiratory, digestive, urinary)
• Organismal level is the highest level of organization includes all systems working together to maintain life and homeostasis

Cell Structure and Function

• Cell membrane is a selectively permeable phospholipid bilayer that controls the movement of substances in and out of the cell
  • Fluid mosaic model describes the structure of the cell membrane with embedded proteins and carbohydrates
  • Transport proteins facilitate the movement of specific molecules across the membrane (channels, carriers)
• Cytoplasm is the gel-like substance within the cell that contains organelles and serves as the site for many cellular processes
• Nucleus is the control center of the cell contains genetic material (DNA) and directs cellular activities
  • Nuclear envelope is a double membrane that separates the nucleus from the cytoplasm
  • Nucleolus is a dense region within the nucleus where ribosomal RNA is synthesized
• Endoplasmic reticulum (ER) is a network of membrane-bound channels involved in protein and lipid synthesis, transport, and storage
  • Rough ER has ribosomes attached and is involved in protein synthesis and modification
  • Smooth ER lacks ribosomes and is involved in lipid synthesis, detoxification, and calcium storage
• Golgi apparatus is a stack of flattened membrane sacs that modifies, packages, and sorts proteins and lipids for transport to their final destination
• Mitochondria are the powerhouses of the cell generate ATP through cellular respiration
• Lysosomes are membrane-bound organelles that contain digestive enzymes break down and recycle cellular waste and foreign materials
• Cytoskeleton is a network of protein filaments that provides structure, support, and movement within the cell includes microfilaments, intermediate filaments, and microtubules

Tissues and Organs

• Epithelial tissue covers body surfaces and lines cavities provides protection, secretion, and absorption
  • Simple epithelium consists of a single layer of cells (squamous, cuboidal, columnar)
  • Stratified epithelium consists of multiple layers of cells (squamous, cuboidal, columnar)
  • Glandular epithelium is specialized for secretion includes exocrine glands (sweat, salivary) and endocrine glands (thyroid, adrenal)
• Connective tissue supports and connects other tissues includes bone, cartilage, blood, and adipose tissue
  • Loose connective tissue has a loose arrangement of fibers and cells (adipose tissue, areolar tissue)
  • Dense connective tissue has a high proportion of fibers and provides strength and support (tendons, ligaments)
  • Specialized connective tissue includes bone, cartilage, and blood
• Muscle tissue enables movement and generates force includes skeletal, smooth, and cardiac muscle
  • Skeletal muscle is attached to bones and is under voluntary control
  • Smooth muscle is found in the walls of hollow organs and is involuntary
  • Cardiac muscle is found in the heart and is involuntary with a unique structure
• Nervous tissue transmits electrical signals and processes information includes neurons and glial cells
  • Neurons are the functional units of the nervous system consist of a cell body, dendrites, and an axon
  • Glial cells support and protect neurons includes astrocytes, oligodendrocytes, and Schwann cells
• Organs are structures composed of multiple tissue types that perform specific functions
  • Example: the stomach is an organ that consists of epithelial tissue (lining), smooth muscle tissue (walls), and connective tissue (submucosa)

Practical Applications and Lab Work

• Microscopy is the use of microscopes to observe cells, tissues, and other small structures
  • Light microscopy uses visible light and lenses to magnify specimens up to ~1000x
  • Electron microscopy uses a beam of electrons to magnify specimens up to ~1,000,000x provides higher resolution but requires special preparation
• Histology is the study of tissues and their structure uses microscopy and staining techniques to visualize and identify different tissue types
  • Hematoxylin and eosin (H&E) staining is a common technique that stains nuclei blue and cytoplasm pink
  • Special stains can be used to highlight specific components (collagen, elastic fibers, mucins)
• Dissection is the process of cutting and separating tissues to study their structure and relationships
  • Cadaver dissection is the dissection of a preserved human body provides a detailed understanding of anatomy
  • Virtual dissection uses computer software and 3D models to simulate the dissection process
• Imaging techniques allow for the visualization of internal structures without invasive procedures
  • X-rays use electromagnetic radiation to create images of dense structures (bones, teeth)
  • Computed tomography (CT) uses X-rays and computer processing to create detailed cross-sectional images
  • Magnetic resonance imaging (MRI) uses strong magnetic fields and radio waves to create detailed images of soft tissues
  • Ultrasound uses high-frequency sound waves to create real-time images of internal structures
• Physiology experiments investigate the functions and processes of the human body
  • Measuring vital signs (heart rate, blood pressure, respiratory rate, temperature) provides information about homeostasis and overall health
  • Electrophysiology studies the electrical properties of cells and tissues (ECG, EEG, EMG)
  • Biochemical assays measure the levels of specific molecules in body fluids (glucose, hormones, enzymes)