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UNIT 1 The Human Body: An Orientation
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Overview of Anatomy and Physiology
Anatomy – the study of the structure of body parts and their relationships to one another Gross or macroscopic Regional – all structures in one part of the body Systemic – each system individually Surface – study of internal structures as they relate to skin above Microscopic Cytology - study of cells Histology - study of tissues Developmental Embryology - study of the body before birth
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Overview of Anatomy and Physiology
Physiology – the study of the function of the body’s structural machinery Considers the operation of specific organ systems: Renal physiology – kidney function Neurophysiology – workings of the nervous system Cardiovascular physiology – operation of the heart and blood vessels Focuses on the functions of the body, often at the cellular or molecular level
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Principle of Complementarity
Function always reflects structure and form fits function! What a structure can do depends on its specific form. A change in anatomy can have a significant effect on physiology. Ex: sickle cell anemia
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Levels of Structural Organization
Chemical – atoms combined to form molecules Molecular – made of several chemicals Cellular – cells are made of molecules Tissues – consists of similar types of cells Organs – made up of different types of tissues Organ systems – consists of different organs that work closely together Organism – made up of the organ systems
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Levels of Structural Organization
A malfunction at any level has serious consequences to levels built upon it. Example: cystic fibrosis
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Levels of Structural Organization
Figure 1.1
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Anatomical road map
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Directional Terms (body structures in relation to another)
Superior – toward head Inferior – away from head Anterior – toward the front Posterior – toward the back of the body Medial – toward the midline Lateral – away from the midline Intermediate – between a more medial and lateral structure
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Directional Terms Proximal – closer to the origin of a limb on the body Distal – further from the origin of a limb on the body Superficial – toward the surface Deep – away from the surface
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Practice using Directional Terms
The wrist is _____________ to the hand. The sternum (breastbone) is ___________ to the spine. The brain is ______________ to the spinal cord. The kidneys are ___________ to the liver. The nose is ______________ to the cheekbones. The thumb is _____________ to the fingers.
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ANSWERS The wrist is ___PROXIMAL__________ to the hand.
The sternum (breastbone) is __ANTERIOR_________ to the spine. The brain is ___SUPERIOR___________ to the spinal cord. The kidneys are ___INFERIOR________ to the liver. The nose is __MEDIAL__________ to the cheekbones. The thumb is ____LATERAL_________ to the fingers.
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More Practice using Directional Terms
The ___________ is posterior to the ______________. The ___________ is intermediate between the ________________and the _____________. The_______________ is superficial to the ___________________. The _________________ is deep to the ________________. The _________________ is distal to the _________________.
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Regional Terms (visible landmarks on surface of body)
Axial – head, neck, and trunk Appendicular – appendages or limbs LABEL REGIONAL ANATOMY ON DIAGRAM
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Figure 1.7b
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Locate the following pulse points on your body:
Radial pulse Brachial pulse Carotid pulse Femoral pulse Popliteal pulse Pedal pulse
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Body Planes and Sections
Sagittal – divides the body into right and left parts Midsagittal – sagittal plane that lies on the midline Frontal or coronal – divides the body into anterior and posterior parts Transverse or horizontal (cross section) – divides the body into superior and inferior parts Oblique section – cuts made diagonally
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Body Planes Figure 1.8
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Planes On what plane could your desk be cut to yield a usable seat? Explain your answer.
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Body Cavities The body has two major cavities: Dorsal Cavity
Divided into two parts Cranial – skull and brain Vertebral – runs down the vertebral column and encases spinal cord and vertebrae Ventral cavity Houses the internal organs (viscera), and is divided into two subdivisions: thoracic and abdominopelvic
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Figure 1.9
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Ventral Cavity The ventral cavity is further divided into two parts:
Thoracic Divided into three parts: Pleural cavities – each houses a lung Mediastinum – contains the pericardial cavity, and surrounds the remaining thoracic organs Pericardial – encloses the heart
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Ventral Cavity, Continued
Abdominopelvic Separated from the superior thoracic cavity by the diaphragm Divided into two parts Abdominal cavity – contains the stomach, intestines, spleen, liver, and other organs Pelvic cavity – lies within the pelvis and contains the bladder, reproductive organs, and rectum
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Ventral Body Cavity Membranes
Parietal serosa covers the body walls Visceral serosa covers the internal organs Serous fluid separates the serosae Figure 1.10
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Other Body Cavities Oral and digestive – mouth and cavities of the digestive organs Nasal –located within and posterior to the nose Orbital – house the eyes Middle ear – contain bones (ossicles) that transmit sound vibrations Synovial – joint cavities
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Necessary Life Functions
Maintaining boundaries – internal environments never contact external environments Movement – locomotion, propulsion (peristalsis), and contractility Responsiveness – ability to sense changes in the environment and respond to them Digestion – breakdown of ingested foodstuff
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Necessary Life Functions
Metabolism – all the chemical reactions that occur in the body Excretion – removal of wastes from the body Reproduction – continuing a species; offspring Growth – increase in size of a body part or of the organism
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Survival Needs Nutrients – chemical substances used for energy and cell building Oxygen – needed for metabolic reactions Water – provides the necessary environment for chemical reactions Normal body temperature – provide safe environment for chemical reactions to take place Atmospheric pressure – required for proper breathing and gas exchange in the lungs
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Organ Systems of the Body
Integumentary system Composed of the skin, sweat glands, oil glands, hair, and nails Forms the external body covering - protects deep tissue from injury
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Organ Systems of the Body
Skeletal system Composed of bone, cartilage, and ligaments Protects and supports body organs Provides the framework for muscles Site of blood cell formation Stores minerals
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Organ Systems of the Body
Muscular system Composed of muscles and tendons Allows for movement Maintains posture Produces heat
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Organ Systems of the Body
Nervous system Composed of the brain, spinal column, and nerves Is the fast-acting control system of the body Responds to stimuli by activating muscles and glands
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Organ Systems of the Body
Cardiovascular system Composed of the heart and blood vessels The heart pumps blood The blood vessels transport blood throughout the body
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Organ Systems of the Body
Lymphatic system Composed of red bone marrow, thymus, spleen, lymph nodes, and lymphatic vessels Picks up fluid leaked from blood vessels and returns it to blood Disposes of debris in the lymphatic stream Houses white blood cells involved with immunity
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Organ Systems of the Body
Respiratory system Composed of the nasal cavity, pharynx, trachea, bronchi, and lungs Keeps blood supplied with oxygen and removes carbon dioxide
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Organ Systems of the Body
Digestive system Composed of the oral cavity, esophagus, stomach, small intestine, large intestine, rectum, anus, and liver Breaks down food into absorbable units that enter the blood Eliminates indigestible foodstuffs as feces
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Organ Systems of the Body
Urinary system Composed of kidneys, ureters, urinary bladder, and urethra Eliminates nitrogenous wastes from the body Regulates water, electrolyte, and pH balance of the blood
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Organ Systems of the Body
Reproductive system Main function is the production of offspring Also produces sex hormones Males - testosterone Females - estrogen
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Organ System Interrelationships
Each organ system depends upon another The integumentary system protects the body from the environment Digestive and respiratory systems take in nutrients and oxygen
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Organ System Interrelationships
Nutrients and oxygen are distributed by the blood Wastes are eliminated by the urinary and respiratory systems Figure 1.3
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Homeostasis Homeostasis
The ability to maintain a relatively stable internal environment despite outside forces The internal environment of the body is in a dynamic state of equilibrium Many systems interact to maintain homeostasis
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Homeostatic Control Mechanisms
How is homeostasis controlled? Receptor monitors the environment for changes When change occurs, a control center sets the point at which the variable is maintained An effector responds to the stimulus
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Homeostatic Control Mechanisms
Figure 1.4
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Negative Feedback In negative feedback systems, the output shuts off the original stimulus Example: Regulation of blood glucose levels Figure 1.5
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Other Negative Feedback Examples
heart rate blood pressure breathing rate blood levels of oxygen, carbon dioxide, nutrients, and minerals Most control mechanisms are negative feedback loops.
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Positive Feedback In positive feedback systems, the output enhances or exaggerates the original stimulus Example: Regulation of blood clotting, contractions in childbirth, lactation Figure 1.6
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