Human Body: An Orientation Anatomy & Physiology Chapter 1

Life Functions Maintaining Life Necessary Life Functions Maintain boundaries Move Respond to environmental changes Take in and digest nutrients Carry out metabolism Dispose of waste Reproduce themselves Grow

Life Functions Maintain boundaries Maintain boundaries – an organism internal environment must remain distinct from the external environment Movement Movement – all activities promoted by the muscular system Responsiveness Responsiveness – the ability to sense changes in the environment and then respond to them Digestion Digestion – process of breaking down ingested foodstuffs to simple molecules that can be absorbed into the blood

Life Functions Metabolism Metabolism – all chemical reactions that occur within the body cells Excretion Excretion – process of removing wastes from the body Reproduction Reproduction – Cellular Level: original cell divides producing 2 identical daughter cells that can be used for body growth or repair Organismal Level: when sperm and egg unite producing a fertilized egg which develops into a fetus within the mother’s body Growth Growth – increase in size of a body part or the organism Increase the number of cells

Survival Needs Nutrients Oxygen Water 60 – 80% of body weight Appropriate Temperature Atmospheric Pressure Homeostasis Homeostasis – dynamic state of equilibrium or balance Internal conditions vary but within narrow limits Variable – factor or event being regulated

Divisions of Anatomy Regional Regional – all structures are in a particular region of the body Systemic Systemic– gross anatomy of the body studied system by system Microscopic Microscopic– thin slices of body tissues are examined under the microscope Pathological Pathological– studies structural changes caused by disease

Homeostatic Control Homeostatic Control Mechanisms Homeostatic Control Mechanisms – have at least 3 interdependent components 1. Receptor – some type of sensor that monitors the environment and responds to changes (stimuli) by sending information to the central center 2. Control Center – determines the set point at which a variable is to be maintained, analyzes the input it receives, and determines the appropriate response 3. Effector – provides the means for the central center’s response to the stimulus

Homeostatic Control

Negative Feedback Mechanisms The goal is to prevent sudden, severe changes within the body Maintaining blood glucose levels Regulation of body temperature by nervous system Examples: regulate heartbeat, rate and depth of breath, and blood levels of oxygen, carbon dioxide, and minerals

Homeostatic Control Positive Feedback Mechanisms: Response enhances the original stimulus Change that occurs proceeds in the same direction as the initial disturbance Control infrequent events that do not require continuous adjustments Examples: blood clotting, contractions during the birth of a baby Homeostatic Imbalance Homeostatic Imbalance: disruption of homeostasis causing disease

Language of Anatomy 1. Anatomical Position and Directional Terms a. Anatomical Position a. Anatomical Position: reference point used to describe body parts and position accurately (Standard body position) 1. Human body erect 2. Arms at side 3. Palms forward, thumbs pointed away from the body 4. Feet together * Right and Left – refers to the sides of the person being viewed not those of the observer!

Language of Anatomy Anatomical Position

Language of Anatomy 2. Directional Terms 2. Directional Terms – explains where one body structure is in relation to another a. Superior: toward the head end or upper part; above Inferior: away from head end or toward the lower part, below b. Anterior: toward the front of the body Posterior: toward the back of the body

Language of Anatomy

c. Medial: toward or at the midline of the body Lateral: away from the midline of the body Intermediate: between a more medial and more lateral structure d. Proximal: closer to the origin of the body part or the point of attachment of a limb to the body trunk Distal: farther from the origin of a body part or the point of attachment of a limb to the body trunk e. Superficial: toward or at the body surface Deep: away from the body surface

Language of Anatomy

3. Regional Terms 3. Regional Terms – used to designate specific areas within the major body divisions a. Major Body Divisions 1. Axial – main axis of our body (i.e. head, neck, trunk) 2. Appendicular – consists of appendages or limbs 4. Body Planes and Sections a. Planes a. Planes – cut along a flat surface 1. Sagittal: vertical plane that divides the body into right and left parts Median/Midsagittal: sagittal plan that lies exactly in the midline Parasagittal: offset from the midline

Language of Anatomy 2. Frontal/Coronal: divide the body into anterior and posterior parts 3. Transverse/Horizontal: runs horizontally from right to left, divides the body into superior and inferior parts - Also called a cross section 4. Oblique: cuts made diagonally between the horizontal and the vertical planes

Language of Anatomy

5. Body Cavities and Membranes a. Dorsal Body Cavity a. Dorsal Body Cavity: protects the nervous system organs 1. Cranial Cavity – encases the brain 2. Vertebral Cavity – encases the delicate spinal column b. Ventral Body Cavity b. Ventral Body Cavity : anterior 1. Thoracic – Superior division, surrounded by the ribs and muscles of the chest a. Pleural Cavity: houses a lung b. Mediastinum: contains the pericardial cavity which encloses the heart, surrounds the esophagus, and trachea - separates the lungs into right and left cavities

Language of Anatomy c. Abdominopelvic Cavity: 1. Abdominal Cavity – contains the stomach, intestines, spleen, liver 2. Pelvic Cavity – lies within the bony pelvis, contains the bladder, reproductive organs, and rectum d. Visceral Organs: group of internal organs collectively called viscera e. Diaphragm – dome shaped muscle important in breathing. Separates the thoracic and abdominopelvic cavities.

Language of Anatomy

Abdominopelvic Cavity Quadrants Because the abdominopelvic cavity is quite large, it is often divided into four or more equal regions called quadrants The Four Most Common Quadrants Are: Right Upper Quadrant Right Lower Quadrant Left Upper Quadrant Left Lower Quadrant