Download Unit #1 notes

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.