introduction to physiology. the six levels of organization chemical level –atoms cell level tissue...
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Introduction to Physiology
The Six Levels of Organization
• Chemical level– Atoms
• Cell Level
• Tissue Level– A tissue is a group of similar cells and the
materials surrounding them
• Organ Level– An organ is composed of 2+ tissue
types that perform the same functions
• Organ System Level– Organ system is a group of organs that
have a common function (11 major organ systems)
• Organism Level
Homeostasis
• Existence and maintenance of a constant internal environment
• Mechanisms keep body temperature near an ideal normal range called set points.
– The points need to remain in a normal range.
Negative Feedback• Negative means that any deviation from
the set point is made smaller or resisted
• Regulates most body systems
• There are three components– Receptor– Control center– Effector
Receptor
• Monitors the value of some variables
• Detects changes and sends message to the brain
• Example: Blood pressure
Control Center
• Establishes the set points around which the variable is maintained
• Receives messages and tells body how to react
Effector
• Can change the value of the variable
• Example: Sweat, raise/lower blood pressure
Positive Feedback• Rare
• Creates a deviation further from the normal set point
• Example: Natural birth
Body Positions• Anatomical position
– Face directed forward– Upper limbs hanging to the side, palms
facing forward
• Supine– A person lying face upwards
• Prone– A person lying face downwards
Directional terms of the trunk• Superior = Cephalic
– Up, towards the head
• Inferior = Caudal
– Down, towards the “tail”
• Posterior =Dorsal
– Back side
• Anterior = Ventral– Front, belly side
Directional terms of the trunk
• Medial– Towards the midline
• Lateral– Away from the midline
Directional terms of the limbs
• Proximal
– Nearest the point of attachment
• Distal
– Furthest from the point of attachment
Planes• Sagittal
– Separates a body into a left and right
– Midsagittal/Median• Separates body into equal left and right
halves
– Parasagittal• Unequally divides left and right sides
• Transverse = Horizontal
– Horizontally divides body into superior and inferior portions (top and bottom)
• Frontal = Coronal
– Vertically divides body into anterior and posterior portions (front and back)
– Face remains intact
Body Cavities• The trunk contains 3 large cavities:
– Thoracic
• Surrounded by rib cage
• Partition called the mediastinum separates left and right parts
• Mediastinum contains the heart, thymus, trachea, esophagus
• Abdominal cavity
– Contains most of the digestive tract
• Pelvic cavity
– Located within the pelvic bones
• The pelvic and abdominal cavities are not physically separated and are sometimes called the abdominopelvic cavity
Serous Membranes
• Membrane that lines trunk cavities and organs
• Serous membranes are made of 2 layers:–Visceral serous is in contact with
internal organs–Parietal serous lines the walls of the
cavity
• The thoracic cavity contains 3 serous membrane – lined cavities:
–1 Pericardial cavity
–2 Pleural cavities
The Pericardial Cavity
• Surrounds the heart
• The visceral pericardium touches and covers the surface of the heart, which is contained within the parietal pericardium.
The Pleural Cavities
• Surrounds each lung
• Each lung is covered by visceral pleura, which is contained within a parietal pleura.
The Peritoneal Cavity
• Covers the abdominopelvic cavity
• Each organ is covered by a visceral peritoneum, which is located within the parietal peritoneum.