The Human Body: An Orientation Chapter 1 Part 2

Necessary Life Functions Survival Needs Homeostasis Maintaining Life Necessary Life Functions Survival Needs Homeostasis

Necessary Life Functions Maintaining Boundaries Inside must be distinct from outside Movement Locomotion Movement of substances Responsiveness AKA “irritability” Ability to sense changes in environment and respond Digestion Breakdown and delivery of nutrients Metabolism Chemical reactions within body cells Excretion Removes wastes from body and requires many organs Reproduction Production of future generation Growth Increasing of cell size and number

Survival Needs Nutrients Oxygen Taken in via diet Give energy and maintain cells Chemicals for energy and cell building Includes carbohydrates, proteins, lipids, vitamins, and minerals Oxygen Required for chemical reactions

Survival Needs (con’t) Water Obtained through diet Lose by evaporation from lungs, skin, and excretion 60 – 80% of body weight Provides for metabolic reactions Normal (stable) body temperature Atmospheric pressure – must be appropriate

Indicates a dynamic state of equilibrium, or balance. Homeostasis Describes the ability to maintain relatively stable internal condition even though the outside world changes continuously. Indicates a dynamic state of equilibrium, or balance.

Homeostatic Control Mechanisms Communication in the body is accomplished chiefly by the nervous and endocrine systems. Variable – factor or event being regulated Receptor – sensor that monitors the environment and respond to changes Control center – analyzes the input it receives and then determines the appropriate response Effector – provides a means for response to the stimulus

Negative Feedback Mechanism The output of the system shuts off the original stimulus or reduces its intensity. This mechanism causes the variable to change in a direction opposite to that of the initial change, returning it to its “ideal” value. All negative feedback systems have the same goal: to prevent sudden severe changes.

Positive Feedback Mechanism The result of response enhances or exaggerates the original stimulus so that the activity is accelerated. “Positive” because the change occurs in the same direction as the initial disturbance, causing the variable to deviate further and further from the original value. Control infrequent events that don’t require continuous adjustments!!

The Language of Anatomy Special terminology is used to prevent misunderstanding Exact terms are used for: Position Direction Regions Structures

Anatomical Position Anatomical reference point Body is erect with feet slightly apart “Standing at attention” pose Palms face forward and thumbs point away from body

Directional Terms Allow us to explain exactly where one body structure is in relation to another.

Orientation and Directional Terms Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Orientation and Directional Terms Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Regional Terms Used to designate specific areas within the major body divisions. Two divisions: Axial part – head, neck, and trunk Appendicular part – limbs

Body Landmarks Anterior

Body Landmarks Posterior

Body Planes Plane – flat surface Most frequent body planes: Sagittal Plane Vertical plane that divides body into right and left Midsagittal – exactly on midline Parasagittal – offset from midline Frontal Plane Divides body into anterior and posterior AKA “coronal” plane Transverse Plane Horizontal plane Divides into superior and inferior parts

A section is a cut along a plane.

Body Planes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Body Cavities

Axial portion of the body: Dorsal Body Cavity Ventral Body Cavity

Dorsal Body Cavity Protects nervous system 2 Subdivisions: Cranial cavity – encases brain Vertebral cavity – encases spinal cord

Ventral Body Cavity 2 Subdivisions: Thoracic cavity is subdivided into pleural cavities, the mediastinum, and the pericardial cavity Surrounds ribs and muscles Pleural cavity – houses lungs Pericardial cavity – houses hearts, esophagus and trachea Mediastinum – contains the pericardial cavity, and surrounds the remaining thoracic organs

Ventral Body Cavity 2 Subdivisions: (con’t) Abdominopelvic cavity Separated from thoracic cavity by the dome-shaped diaphragm It is composed of two subdivisions Abdominal cavity – contains stomach, intestines, spleen, and liver, and other organs Pelvic cavity – lies within the pelvis and the contains bladder, reproductive organs, and rectum

Membranes in the Ventral Body Cavity Serosa (serous membrane) Thin, double-layered membrane Parietal serosa – membrane lining cavity walls Visceral serosa – covers organs Serous fluid Separates serous membranes Allows sliding without friction

Ventral Body Cavity Membranes Parietal serosa covering the body walls Visceral serosa covering the internal organs Serous fluid separates the serosae

Other Body Cavities Oral and digestive Nasal Orbital Middle ear Mouth and cavities of the digestive organs Nasal Located within and posterior to the nose Orbital House the eyes Middle ear Contains bones (ossicles) that transmit sound vibrations Synovial Joint cavities

Abdominopelvic Regions 1. Right Hypochondriac: Liver, gall bladder, small intestine, ascending colon, transverse colon, right kidney 2. Epigastric: Esophagus, stomach, liver, pancreas, small intestine, transvers colon, right and left adrenal glands, pancreas, right and left kidneys, right and left ureters, spleen 3. Left Hypochondriac: Stomach, tip of liver, tail of pancreas, small intestines, transverse colon, descending colon, pancreas, left kidney, spleen 4. Right Lumbar: Tip of liver, gall bladder, small intestine, ascending colon, right kidney 5. Umbilical: Stomach, pancreas, small intestine, transverse colon, pancreas, right and left kidneys, right and left ureters

Abdominopelvic Regions (con’t) 1. Right Hypochondriac: Liver, gall bladder, small intestine, ascending colon, transverse colon, right kidney 2. Epigastric: Esophagus, stomach, liver, pancreas, small intestine, transvers colon, right and left adrenal glands, pancreas, right and left kidneys, right and left ureters, spleen 3. Left Hypochondriac: Stomach, tip of liver, tail of pancreas, small intestines, transverse colon, descending colon, pancreas, left kidney, spleen 4. Right Lumbar: Tip of liver, gall bladder, small intestine, ascending colon, right kidney 5. Umbilical: Stomach, pancreas, small intestine, transverse colon, pancreas, right and left kidneys, right and left ureters

Abdominopelvic Regions

Abdominopelvic Quadrants Quadrants are named according to subject’s pt. of view Right upper Left upper Right lower Left lower