Human Physiology Quiz

Course Information

• Course title and code: Human Physiology - PSL223
• Credit hours: 3 hours (2+1)
• Offered in: Public Health and Nursing programs
• Prerequisites:
  • First year Basic Foundation course
  • First year, second semester Biology course

Course Objectives

• Identify physiological terminology
• Understand human body structure at chemical, cellular, tissue, organ, and system levels
• Demonstrate understanding of homeostasis mechanisms
• Plan, perform, and interpret important physiological functions
• Explain the pathophysiological basis of common diseases

Course Assessment

• Quiz: MCQs, 5% (any week before the first midterm)
• 1st Midterm Exam: MCQs, 15% (7th week)
  • Midterm Exam: MCQs; spotting, true/false; fill in the blanks. (8th week)
• 2nd Midterm Exam: MCQs, 15% (11th week)
• Assignment: 10%(12th week)
• Final Practical Exam: Spotting, true/false; fill in the blanks, 15% (after the 15th week)
• Final Theory Exam: MCQs, true/false, fill in the blanks, essay, 25% (after the 15th week)

Learning Resources

• Ross and Wilson's "Anatomy and Physiology in Health and Illness" 12th Edition; ISBN 978-0-7020-5325-2, International ISBN 978-0-7020-5326-9.
• Arthur C. Guyton, update, Textbook of Medical Physiology, W.B. Saunders Company. 2010.
• John B. update; Respiratory physiology The William & Wilkins Company Last edition.
• Cecil Gray John Nunn and J.E. Uttering, update; General Anesthesia, Butterwirths Last edition.

What is Physiology?

• Scientific study of the normal functions of living organisms
• Branches include: Human, Cellular, Cardiovascular, Renal, Respiratory, Gastrointestinal, Neuro, Muscular, Endocrine Physiology

Levels of Organization of the Body

• Chemical
• Cellular
• Tissue
• Organ
• System
• The human

Organ System

• Tissues: Group of cells with similar structure and function
• Organs: Group of tissues performing specialized function
• Composed of at least two tissue types
• Perform specific functions
• Organ system: Collection of organs performing a particular task

Organ Systems (Table 1.1)

• Endocrine: Hypothalamus, pituitary gland, etc.; hormonal communication
• Nervous: Brain, spinal cord, etc.; electrical signals
• Musculoskeletal: Skeletal muscle, bones, ligaments; support, movement
• Cardiovascular: Heart, blood vessels, blood; transport
• Respiratory: Lungs, trachea, etc.; oxygen and carbon dioxide exchange
• Urinary: Kidneys, ureters, etc.; fluid balance and waste removal
• Gastrointestinal: Mouth, stomach, intestines, liver, etc.; digestion and absorption
• Reproduction: Gonads, reproductive tracts; reproduction
• Immune: White blood cells, lymph nodes, etc.; defense
• Integumentary: Skin; protection

Organization of the Body: The Cell

• Cell: Smallest functional unit of life
• Cytology: Study of cells as fundamental units

Plasma Membrane

• Forms cell's outer boundary
• Separates internal environment from external
• Selective barrier
• Cellular communication

Functions of Membrane Proteins

• Ion channels
• Transporters (carrier proteins)
• Receptors
• Enzymes
• Cell-identity markers

Cytoplasm

• Cellular contents between plasma membrane and nucleus
• Cytosol: Fluid portion (mostly water)
• Organelles: Subcellular structures with specific functions

Cytoplasm - 2 Components

• Cytosol: Intracellular fluid; site of chemical reactions, energy release, building block for cellular maintenance, structure, function, growth
• Organelles: Small organs with specialized functions enclosed within a membrane; includes nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, cytoskeleton

Organelles - Nucleus

• Spherical or oval structure
• Most prominent cell feature
• Nuclear envelope: Double membrane separating nucleus from cytoplasm
• Nuclear pores: Openings regulating substance movement between nucleus and cytoplasm
• Nucleolus: Spherical body producing ribosomes
• Chromosomes: Contain hereditary units (genes); control cellular activities and structure

Organelles - Mitochondria

• Known as the "powerhouses" of the cell
• Physiologically active cells (muscles, liver, kidneys, spermatozoa) have more mitochondria
• Double membrane (inner and outer mitochondrial membranes)
• Cristae: Folds of the inner membrane
• Matrix: Large central fluid-filled cavity; responsible for ATP generation via cellular respiration

Organelles - Ribosomes

• Sites of protein synthesis
• Tiny granules composed of RNA and protein
• Synthesize proteins from amino acids using RNA
• Rough ER: Connected to nuclear envelope; series of flattened sacs; produce proteins, presence of ribosomes on the surface
• Smooth ER: Network of membrane tubules; no ribosomes; synthesize fatty acids, steroids; detoxify substances

Organelles - Golgi Complex

• Consists of 3-20 flattened, membranous sacs (cisternae)
• Packages and processes proteins for transport to different destinations
• Proteins transported by vesicles
• Found in all cells, especially those producing and secreting proteins

Organelles - Lysosomes

• Vesicles forming from Golgi complex
• Contain powerful digestive enzymes
• Break down fragments of organelles and large molecules (e.g., RNA, DNA, carbohydrates, proteins)

Organelles - Cytoskeleton

• Extensive network of protein fibers providing structural support
• Microfilaments: Smallest fibers providing structural support and shape (e.g., actin in muscle cells)
• Microtubules: Larger fibers involved in movement of organelles, chromosomes during cell division, and cell extensions (e.g., microvilli, cilia)

Organization of the Body: Tissue

• Tissues: Group of cells with similar structure and function
• Histology: Study of tissue structure and function

Types of Tissues

• Epithelial tissue: Covers body surfaces, lines organs and cavities, forms glands
• Connective tissue: Supports and protects body, binds organs, stores energy, provides immunity
• Muscle tissue: Responsible for movement and force generation
• Nervous tissue: Initiates and transmits nerve impulses to coordinate body activities

Development of Tissues

• Tissues develop from three primary germ layers:
  • Ectoderm
  • Endoderm
  • Mesoderm
• Epithelial tissues derive from all three germ layers
• Connective tissue and most muscle tissues from mesoderm
• Nervous tissue from ectoderm

Epithelial Tissues

• Consists of cells arranged in continuous sheets (single or multiple layers)
• Closely packed
• Cover and line body's surfaces
• Major functions:
  • Protection
  • Secretion
  • Absorption

General Features of Epithelial Cells

• Apical surface: Faces body surface, cavity, lumen, or duct
• Lateral surfaces: Faces adjacent cells
• Basal surface: Opposite of apical layer; adheres to extracellular materials

Covering and Lining Epithelium

• Simple epithelium: Single layer of cells; functions in diffusion, osmosis, filtration, secretion, or absorption
• Pseudostratified epithelium: Appears layered due to varying cell heights; nuclei at different levels
• Stratified epithelium: Two or more cell layers; protects underlying tissues in areas with wear and tear

Simple Epithelium

• Squamous: Flattened cells; rapid substance passage (e.g., heart, blood vessels, alveoli, kidneys)
• Cuboidal: Cube-shaped cells; involved in secretion, absorption, or excretion (e.g., kidney tubules, thyroid)
• Columnar: Rectangular cells; secretion, absorption (e.g., goblet cells, intestines, trachea)

Stratified Epithelium

• Stratified squamous: Multiple layers of flattened cells; protects underlying tissues (e.g., skin, mouth)
• Stratified cuboidal: Multiple layers of cuboidal cells; secretion and absorption (less common)
• Stratified columnar: Multiple layers of columnar cells; protection and secretion (less common)
• Transitional: Variable shape; stretches and recoils (e.g., urinary bladder)

Glandular Epithelium

• Glands: Formed from epithelium, manufacture and secrete a product
• Exocrine glands: Secrete products into ducts; onto skin surface or organ lumen (e.g., sweat, salivary, oil glands)
• Endocrine glands: No ducts; secrete products (hormones) directly into bloodstream

Muscular Tissue

• Consists of elongated cells (muscle fibers or myocytes)
• Uses ATP to generate force
• Classified into three types:
  • Skeletal
  • Cardiac
  • Smooth

Skeletal Muscle Tissue

• Attached to bones
• Striated
• Voluntary movement

Cardiac Muscle Tissue

• Found in the heart
• Striated
• Involuntary movement

Smooth Muscle Tissue

• Found in walls of hollow organs and blood vessels
• Nonstriated
• Involuntary movement

Nervous Tissue

• Consists of two types:
  • Excitable cells (neurons): Initiate, receive, conduct, and transmit information
  • Non-excitable cells (glial cells): Support neurons (e.g., astrocytes, Schwann cells, oligodendrocytes, microglia)

Excitable Cells

• Neurons and muscle fibers exhibit electrical excitability
• Respond to stimuli by producing electrical signals (action potentials)
• Action potentials propagate along plasma membrane for responses
• Neurotransmitters released, causing muscle contraction

Connective Tissue

• Diverse group of tissues
• Characterized by extracellular matrix
• Anchors and connects body structures
• Examples: Bone, tendons, fat, blood

Body Fluid Compartments

• Total body water (70 kg man): ~42 liters
  • Intracellular fluid (ICF): ~28 liters
  • Extracellular fluid (ECF): ~14 liters
  • Plasma: ~3 liters
  • Interstitial fluid (ISF): ~11 liters

Homeostasis

• Ability to maintain a relatively constant internal environment
• Regulated variables include:
  • Temperature
  • Volume
  • Composition

Homeostasis: Terms

• Set point: Expected value of a regulated variable (e.g., body temperature, blood glucose, pH)
• Error signal: Difference between the actual value and the set point

Homeostasis: Components

• Receptors: Sensors detecting stimuli (e.g., thermoreceptors, chemoreceptors, baroreceptors)
• Integrating center: Processes information and regulates responses (often in the brain)
• Effectors: Respond to signals and cause changes (e.g., muscles, glands)
• Signals: Communicate between components (chemical signals or via neurons)

Homeostasis: Negative Feedback

• Regulated variable changes (e.g., body temperature rises)
• Integrating center detects change and activates effectors
• Effectors produce a response to counteract the change (e.g., body temperature decreases)
• Returns the variable to the set point

Homeostasis: Positive Feedback

• Variable changes, causing further change in the same direction
• Continues until a specific point is reached and the process stops (e.g., childbirth)

Homeostasis: Thermoregulation

• Mechanisms: Radiation, conduction, convection, evaporation
• Receptors: Thermoreceptors (central and peripheral)
• Integrating centers: Thermoregulatory centers in the hypothalamus
• Effectors: Sweat glands, skeletal muscles, blood vessels, etc.
• Thermoneutral zone: Range of environmental temperatures where blood flow regulations maintain body temperature

Fever

• Rise in core body temperature accompanying infections
• White blood cells secrete pyrogens (proteins)
• Body temperature set point increases, enhancing immune response