Physiological Mechanisms of Health and Disease PDF

Physiological Mechanisms of Health and Disease Week 1 Homeostasis, Body Organization, and Components Outline Introduction General class format Assignments/grading Expectations Homeostasis Body Organization and compartments Instructors Dr. Moreira-Bou...

Physiological Mechanisms of Health and Disease Week 1 Homeostasis, Body Organization, and Components Outline Introduction General class format Assignments/grading Expectations Homeostasis Body Organization and compartments Instructors Dr. Moreira-Bouchard They/He Email: [email protected] Office: CRC - Sargent 514b Office Hours: Tuesdays 11am-12pm Dr. Roberts She/Her Email: [email protected] Office: CRC - Sargent 423 Office Hours: Wednesdays 2-3pm General Class Format Where to find information Blackboard Syllabus Updated grades Lecture slides Assignment submission Additional content Grade Breakdown Exams (2) - 50% Reports (2) - 50% Exams There will be a midterm and a final Each exam will only cover the information since the last exam Case Reports There will be two case reports In the case report you will explain The case report will: Explain the relevant pathophysiology of a provided infectious or noninfectious bodily insult that results in disease Examine the epidemiology and non-physiological factors that could result in the given condition Provide at least one potential solution at the individual level Provide at least one potential solution at the population level Rubric will be provided on Blackboard Body Organization Type General Characteristics General Functions 1. Epithelial Cellular, polar, attached, avascular, Covers Surfaces, inside and out innervated, highly regenerative 2. Connective Diverse types, protein, cellular Protects, binds together, supports components 3. Muscle Contractile, responds to Movement stimulation 4. Nervous Neurons: excitable, high metabolic Neurons: controls activities, rate, extreme longevity, process info nonmitotic Glial cells: support and protect Glial cells: nonexcitable, mitotic neurons Epithelial Cells and Tissues Specialized for selective secretion and absorption of ions and organic molecules Add protection epithelium  Epithelial Cells and Tissues Superficial skin and inner lining of organs, cavities, blood vessels Made up almost entirely by cells Avascular epithelium epithelium 13 Epithelial Cells and Tissues Anchored to basement membrane at the basolateral side Interior facing side called apical side Each side often performs unique functions Tight junctions – hold together cells on lateral surface Connective Tissues Diverse group of tissues that connect body parts together Common features of Connective tissue: Cells are not in contact with each other, surrounded by fluid or matrix This makes the extracellular matrix around cells ECM – provides structure for cellular attachments and allows for movement of chemical messengers to regulate cellular activities Highly vascularized Protein fibers add structure and strength 15 Types of Connective Tissue Fibrous (proper) connective tissue (several sub-types) Loose connective tissue (ex. collection of cells and fibers underlying epithelial layer) Dense connective tissue (ex. tendons and ligaments) Adipose (fat) tissue Supportive connective tissue Bone Cartilage Fluid connective tissue (blood) 16 Connective Tissues 3 basic components Cells fibroblasts (fiber-creaters) Scattered adipocytes (fat cells) Some resident and some wandering immune cells Protein fibers Collagen (majority), Elastic and Reticular Ground substance thin gel in proper connective tissue firm gel in cartilage impregnated with inorganic salts in bone 17 Fibers found in Connective Tissue Collagen fibers: made of the protein collagen (main component of leather and glue) Tough, flexible, resists stretching In dissection, collagen has a glistening, pearly white appearance Very common 18 Fibers found in Connective Tissue Elastin fibers: Stretchy like rubber bands Imparts the ability to stretch and recoil back to original shape 19 Fibers found in Connective Tissue Reticular fibers: made of type III collagen Forms a net-like structure Found in: endocrine glands, liver, lymph organs 20 Supporting Connective Tissues: Cartilages Cartilage in Cartilages in external ear nose Articular cartilage of a joint Costal cartilage Cartilage in intervertebral disc Pubic symphysis Meniscus (padlike cartilage in knee joint) Articular cartilage of a joint Cartilages Hyaline cartilages Elastic cartilages Fibrocartilages Supporting Connective Tissues: Cartilages Cartilage connective tissue Cartilage is weaker than bone, but more flexible and resilient Contains: water, collagen and cells Cells: Chondroblasts: produce the matrix of cartilage Once they make enough matrix to encase themselves in lacunae they become Chondrocytes: mature cartilage cells that maintain the matrix 22 Cartilage Matrix Avascular (this is an exception to the theme that connective tissue is typically vascular) Matrix is mostly water (60%-80%) Resistant to compression – meaning it doesn’t damage easily from compression Compression helps maintain cartilage by promoting fluid movement to cells (due to avascular nature) Vulnerable to twisting and bending (tears easily) 23 Types of Cartilage Hyaline-most abundant Trachea, larynx, joints, ends of bones (epiphyseal plates) fetal skeleton Fibrocartilage-shock absorbing Resists stretch and compaction Found in intervertebral discs, knee joints, pelvis Elastic Cartilage-stretchy Contains branched elastin fibers Found in ear, end of nose, epiglottis 24 Bone Bone connective tissue Also contains periosteum connective tissue and cartilage connective tissue Ground Substance is rigid due to deposition of minerals in the matrix: calcification/mineralization Collagen fiber framework is essential for this process Collagen fibers Calcium and phosphoro us minerals 25 Muscle Cells and Tissues – Functional Characteristics Contractility - ability to shorten Excitability Receives a stimulus Responds with the generation of an electrical impulse What is the other type of tissue that can do this? Extensibility – ability to be stretched Elasticity – ability to recoil to resting length after being stretched 3 Types of Muscle Tissue Cardiac muscle Found only in the heart Contract as a unit Slow and steady rate of contraction Innervated by autonomic nervous system Mononucleated Striated 3 Types of Muscle Tissue Smooth muscle Shorter cells Contract as a unit Very slow and sustainable contraction Innervated by autonomic nervous system Mononucleated 3 Types of Muscle Tissue Skeletal muscle Produce voluntary movements Contract as multiple units Contraction speed can vary Force generation can vary Innervated by somatic nervous system Multinucleated Striated Neurons and Nervous Tissue Two types of cells Neurons: conduct nerve impulses from one part of body to another High metabolic rate-need lots of glucose and oxygen Extreme longevity-most last the lifetime of an individual Non-mitotic* (exceptions: olfactory bulb, hippocampus) Glial Cells: Smaller Mitotic No nerve impulses, but protect and nourish neurons 30 Synapse Between Neurons A junction between neurons may contain many synapses due to each cell having many dendrites 31  Glial Cells Support, nourish & protect neurons Mop up excess K+ to help maintain extracellular environment Aid in recovery from injury 32 Organs and Organ Systems Organs are composed of two or more tissue types arranged in different patterns Organs and Organ Systems System Major Organs or Tissues Primary Functions Circulatory Heart, blood vessels, blood Transport of blood throughout the body Digestive Mouth, salivary glands, pharynx, Digestion and absorption of nutrients and esophagus, stomach, small and intestines, water, elimination of waste anus, pancreas, liver, gallbladder Endocrine All glands or organs that secrete Regulation and coordination of many hormones activities in the body Immune White blood cells and their organs of Defense against pathogens production Integumentary Skin Protection against injury and dehydration, defense against pathogens, regulation of body temperature Lymphatic Lymph vessels and lymph nodes Fluid balance, immune defense, absorption of fats Organs and Organ Systems System Major Organs or Tissues Primary Functions Musculoskeletal Cartilage, bone, ligaments, tendons, Support, protection, and movement of body; joints, skeletal muscle production of blood cells Nervous Brain, spinal cord, peripheral nerves and Regulation and coordination of activities in ganglia, sense organs the body, detection and response to changes in the internal and external environments, states of consciousness, learning, memory, emotion, etc. Reproductive Tests, penis, ovaries, fallopian tubes, Production of sperm/eggs, transfer of sperm, uterus, vagina, mammary glands, and provision of nutrient dense environment for associated ducts/glands, developing embryo/fetus Respiratory Nose, pharynx, larynx, trachea, bronchi, Exchange of carbon dioxide and oxygen, lungs regulation of hydrogen ion concentration Urinary Kidneys, ureters, bladder, urethra Regulation of plasma composition through controlled excretion of ions, water, and organic wastes Body Fluid Compartments Body fluid refers to watery solution of dissolved substances like oxygen, nutrients, and wastes Fluid is present within and around all cells of the body and within the blood vessels Two main components: Intracellular and Extracellular fluid Body Fluid Compartments Extracellular fluid has similar compositions across the body Exception – plasma contains higher protein concentration Intracellular fluid solute concentrations vary to aid in unique cellular activities Compartmentalization of the body allows for different concentrations across cells Homeostasis SPH EH 710 Week 1 Jesse D. Moreira-Bouchard, PhD What is homeostasis? The tendency toward a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes Maintenance of a “status quo” by physiological feedback mechanisms Feedback Loop: an internal physiological monitoring and response system that uses its own output as part, or all, of its future input Positive feedback loop: will drive a system further from homeostasis in a goal-oriented manner Negative feedback loop: will help a system maintain homeostasis by returning it to its set point when it deviates Negative Feedback Generally cause by feedback inhibition Many biochemical pathway end products cause inhibition of their own synthesis This conserves energy and resources Positive feedback What variables are maintained in homeostasis? Body temperature Blood volume Blood pressure Blood pH Blood oxygen concentration Ion balance Glucose levels Homeostatic variability Dynamic constancy Since a variable in homeostasis isn’t EXACTLY the same all the time, but is within a range that is acceptably deviated from average, we say it is in dynamic constancy Homeostatic control systems These are the sets of physiologic systems in place to maintain our internal environment Equilibrium: a particular variable is not changing but no input of energy is necessary to maintain the constancy Steady state: a particular variable is not changing but energy is needed to sustain the constancy Homeostatic control system Resetting of physiologic setpoints Often associated with disease states Ex: body temperature is allowed to increase in infectious illness, producing a fever Ex: blood pressure sensors become less sensitive in hypertension, and blood pressure rests higher Fundamental Components of Feedback Loops Thermoregulation Let’s practice What would happen in the previous example if the body temperature was raised above normal? Come draw! Clinical Case Jamie is 35 weeks pregnant and goes into labor Induction of labor began when the amniotic sac ruptured (water broke) and the baby’s head began pushing on the cervix The pushing caused sensory nerves in the cervix to signal to the hypothalamus, a control center in the brain, to release oxytocin, causing contraction of the uterus, pushing the baby’s head further into the cervix Further pushing causes more sensory nerve firing, releasing more oxytocin, and so on, until the baby is fully delivered Clinical Case Jamie is 35 weeks pregnant and goes into labor Induction of labor began when the amniotic sac ruptured (water broke) and the baby’s head began pushing on the cervix The pushing caused sensory nerves in the cervix to signal to the hypothalamus, a control center in the brain, to release oxytocin, causing contraction of the uterus, pushing the baby’s head further into the cervix Further pushing causes more sensory nerve firing, releasing more oxytocin, and so on, until the baby is fully delivered Clinical Case You were sitting on the couch relaxing, when your mom called to remind you that you should have taken the chicken out of the freezer for dinner. Startled, you jumped up, causing a spike in your blood pressure. Your baroreceptors in your carotid arteries detected the elevated blood pressure, and signaled to your medulla to activate the parasympathetic nucleus, the NTS. The NTS signaled down parasympathetic nerves to your heart to slow it back down, lowering your blood pressure back to normal. Clinical Case You were sitting on the couch relaxing, when your mom called to remind you that you should have taken the chicken out of the freezer for dinner. Startled, you jumped up, causing a spike in your blood pressure. Your baroreceptors in your carotid arteries detected the elevated blood pressure, and signaled to your medulla to activate the parasympathetic nucleus, the NTS. The NTS signaled down parasympathetic nerves to your heart to slow it back down, lowering your blood pressure back to normal. Anticipatory/Feedforward Regulation A change in a variable is predicted and, as such, prevented, before it can occur When thermosensitive neurons in the skin, which monitor the room temperature, detect that it is cold, they will signal to the body to conserve heat by constricting blood vessels close to the skin and shunting blood to the central organs. This prevents heat loss before it even happens Signals in Homeostasis Circadian Rhythms Circadian Rhythms Zeitgeber – a rhythmically occurring natural phenomenon that acts as a cue to the body to entrain physiological processes For us, this is the sun Entrainment – setting of the actual hours of the biological rhythm When there is sunlight, our eyes transmit a signal to the Suprachiasmatic Nucleus (SCN) which will then use the nervous system’s connections all over the body to ”tell” the organs what time it is