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ANATOMY AND PHYSIOLOGY
‘Pre’-View Chapter 1 Outline
Objectives
Define anatomy and physiology
Describe the levels of structural organization
Life processes of human body
Define homeostasis
Describe the components of feedback system
Anatomical terminology
Medical imaging
An Introduction to the Human Body
• Anatomy
– science of structure
– relationships revealed by dissection (cutting apart)
– imaging techniques
• Physiology
– science of body functions
– normal adult physiology studied in this text
– some genetic variations described
• Subdivisions of A & P = Table 1.1
Clinical Observational Techniques
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Palpation
– feel body surface with hands
• pulses and breathing rates
•
Auscultation
– listen to body sounds with stethoscope
• abnormal fluid in lungs
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Percussion
– tap on body surface and listen to echo
• air in intestines
Levels of Organization
• Chemical
• Cellular
• Tissue
• Organs
• System Level
• Organismic Level
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Levels of Structural Organization
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Chemical Level
– atomic and molecular level
Cellular level
– smallest living unit of the body
Tissue level
– group of cells and the materials surrounding them that work together on one task
– 4 basic tissue types
• epithelium, muscle, connective tissue, and nerve
•
Organ level
– grouping of 2 or more tissue types into a recognizable structure with a specific
function.
•
Organ system
– collection of related organs with a common function
– sometimes an organ is part of more than one system
•
Organismic level
– one living individual.
Interaction of Organ Systems
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All major body systems will be examined
Interaction of different systems of the body
– skin produces vitamin D needed for calcium absorption and bone growth
– bone marrow produces cells which help the skin resist infection.
Life Processes
• Metabolism = sum of all chemical processes
– breakdown of large molecules into small
– building new structural components (proteins)
– providing chemical energy for cells
• Responsiveness
– detect & respond to changes in internal or external environment
– some typical responses
• muscle contraction, electrical signals, hormone or glandular secretion
• Movement at any structural level
– the body, an organ, a cell or cell component
• Growth
– increase in number or size of cells or the material found between cells
• Differentiation
– specialization of cells for a specific function
– stem cells give rise to cells that specialize
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Reproduction
– formation of new cells or new individuals
Autopsy
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Postmortem examination of body by dissection
Purpose
– confirm or determine cause of death
– support findings of other tests
– provide information on effects of drug usage
– educate healthcare students
– reveal congenital defects
Homeostatis
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Maintaining the internal environment within physiological limits
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Process named by Walter Cannon, 1871-1945
First described by French physiologist,
1813-1878
Example
– blood glucose level is kept within narrow range 70-110/100ml
Homeostasis of Body Fluids
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Delineation of fluid compartments
– intracellular fluid (ICF) = within cells
– extracellular fluid (ECF) = outside cells
• intercellular fluid = tissue fluid =
interstitial fluid
• plasma = fluid portion of blood
Composition of fluids change as
substances move between
compartments
– nutrients, oxygen, ions and wastes move in both directions across capillary walls
Control of Homeostasis
• Homeostasis is continually being disrupted by
– external stimuli or
• intense heat, cold , and lack of oxygen
– internal stimuli
• psychological stresses
• exercise
• Disruptions are usually mild & temporary
• If homeostasis is not maintained, death may result
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Neural and Endocrine Controls
• Process of maintaining a controlled condition
– sensory receptors detect change in a monitored variable
– nervous system and/or endocrine system responds
• Example of control of blood gas level
– exercise increases blood CO2 levels
– sensory receptors detect change
– nervous system increases heart and breathing rates to remove excess CO2
– adrenal gland releases epinephrine to increase heart and breathing rates
Components of Feedback Loop
• Receptor
– monitors a controlled condition
• Control center
– determines next action
• Effector
– receives directions from the control center
– produces a response that changes the controlled condition
Negative & Positive Feedback Loops
• Negative feedback loop
– original stimulus reversed
– most feedback systems in the body are negative
– used for conditions that need frequent adjustment
– body temperature, blood sugar levels, blood pressure
• Positive feedback loop
– original stimulus intensified
– seen during normal childbirth
Homeostasis of Blood Pressure
• Pressure receptors in walls of certain arteries detect an increase in BP
– Blood Pressure = force of blood on walls of vessels
• Brain receives input and signals heart and blood vessels
• Heart rate slows and arterioles dilate (increase in diameter)
• BP returns to normal
Positive Feedback during Childbirth
• Stretch receptors in walls of uterus send signals to the brain
• Brain releases hormone (oxytocin) into bloodstream
• Uterine smooth muscle contracts more forcefully
• More stretch, more hormone, more contraction etc.
• Cycle ends with birth of the baby & decrease in stretch
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Homeostatic Imbalances
• Disorder = abnormality of function
• Disease = homeostatic imbalance with distinct s/s
– Symptoms = changes in body function felt by the patient such as nausea, dizziness
– Signs = changes in body function that can be observed by the doctor such as rash
or fever
• Diagnosis = skill of distinguishing one disease from another
• Epidemiology = how disease is transmitted
• Pharmacology = how drugs used to treat disease
Basic Anatomical Terminology
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•
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Anatomical position
Regions of the body
Anatomical planes, sections and directional terms
Anatomical Position
• Standardized position from which to describe directional terms
– standing upright
– facing the observer, head level
– eyes facing forward
– feet flat on the floor
– arms at the sides
– palms turned forward
• Prone position = lying face down
• Supine position = lying face up
Common Regional Names
• Clinical terminology based on a Greek or Latin root word.
Planes and Sections
• A plane is an imaginary flat surface that passes through the body.
• A section is one of the 2 surfaces (pieces) that results when the body is cut by a plane
passing through it.
Sagittal Plane
• Sagittal plane
– divides the body or an organ into left and right sides
• Midsagittal plane
– produces equal halves
• Parasagittal plane
– produces unequal sides (“unequal halves”)
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Other Planes and Sections
• Frontal or coronal plane (pink)
– divides the body or an organ into front (anterior) and back (posterior) portions
• Transverse(cross-sectional) or horizontal plane (green/teal)
– divides the body or an organ into upper (superior) or lower (inferior) portions
• Oblique plane
– some combination of 2 other planes
Planes and Sections of the Brain
(3-D anatomical relationships revealed)
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Horizontal Plane
Frontal Plane
Midsagittal Plane
Major Directional Terms
• See Definitions page 14
Superior or Inferior
• Superior
– towards the head
– The eyes are superior to the mouth.
• Inferior
– away from the head
– The stomach is inferior to the heart.
Dorsal or Ventral
• Dorsal or Posterior
– at the back of the body
– The brain is posterior to the forehead.
• Ventral or Anterior
– at the front of the body
– The sternum is anterior to the heart.
Medial and Lateral
• Medial
– nearer to the midline of the body
– The heart lies medial to the lungs.
• Lateral
– farther from the midline of the body
– The thumb is on the lateral side of the hand.
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Proximal and Distal
• Proximal
– nearer to the attachment of the limb to the trunk
– The knee is proximal to the ankle.
• Distal
– farther from the attachment of the limb to the trunk
– The wrist is distal to the elbow.
Dorsal Body Cavity
• Near dorsal surface of body
• 2 subdivisions
– cranial cavity
• holds the brain
• formed by skull
– vertebral or spinal canal
• contains the spinal cord
• formed by vertebral column
• Meninges line dorsal body cavity
Ventral Body Cavity
• Near ventral surface of body
• 2 subdivisions
– thoracic cavity above diaphragm
– abdominopelvic cavity below diaphragm
• Diaphragm = large, dome-shaped muscle
• Organs called viscera
• Organs covered with serous membrane
Abdominopelvic Cavity
• Inferior portion of ventral body cavity below diaphragm
• Encircled by abdominal wall, bones & muscles of pelvis
Thoracic Cavity
• Encircled by ribs, sternum, vertebral column and muscle
• Divided into 2 pleural cavities by mediastinum
• Mediastinum contains all thoracic organs except lungs
Mediastinum
• Midline wall of tissue that contains heart and great vessels, esophagus, trachea and
thymus.
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Serous Membranes
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Thin slippery membrane lines body cavities not open to the outside
– parietal layer lines walls of cavities
– visceral layer covers viscera within the cavities
Serous fluid reduces friction
Pleural & Pericardial Cavities
• Visceral pleura clings to surface of lungs --- Parietal pleura lines chest wall
• Visceral pericardium covers heart --- Parietal pericardium lines pericardial sac
Peritoneum
• Visceral peritoneum -- serous membrane that covers the abdominal viscera
• Parietal peritoneum --- serous membrane that lines the abdominal wall
Abdominopelvic Regions & Quadrants
• Describe locations of organs or source of pain
• Tic-tac-toe grid or intersecting lines through navel
Medical Imaging
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Allows visualization of structures without surgery
Useful for confirmation of diagnosis
Examples of imaging techniques
Conventional Radiography
• A single burst of xrays
• Produces 2-D image on film
• Known as radiography or xray
• Poor resolution of soft tissues
• Major use is osteology
Computed Tomography (CT Scan)
• Moving x-ray beam
• Image produced on a video monitor of a cross-section through body
• Computer generated image reveals more soft tissue detail
– kidney & gallstones
• Multiple scans used to build 3D views
Digital Subtraction Angiography (DSA)
• Radiopaque material injected into blood vessels
• Before and after images compared with a computer program
• Image of blood vessel is shown on a monitor
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Ultrasound (US)
• High-frequency sound waves emitted by hand-held device
• Safe, noninvasive & painless
• Image or sonogram is displayed on video monitor
• Used for fetal ultrasound and examination of pelvic & abdominal organs, heart and
blood flow through blood vessels
Magnetic Resonance Imaging (MRI)
• Body exposed to high-energy magnetic field
• Protons align themselves relative to magnetic field
• Pulse of radiowaves used to generate an image on video monitor
• Can not use on patient with metal in their body
• Reveals fine detail within soft tissues
Positron Emission Tomography (PET)
• Substance that emits positively charged particles is injected into body
• Collision with negatively charged electrons in tissues releases gamma rays
• Camera detects gamma rays & computer generates image displayed on monitor