Ch. 1 The Human Body: An Orientation

What is Anatomy and Physiology? Anatomy is the study of the structure & parts of the body Physiology is the study of function at many levels Function always reflects structure What a structure can do depends on its specific form

Levels of Structural Organization Chemical level: atoms and molecules Cellular level: cells and their organelles Tissue level: groups of similar cells Organ level: contains two or more types of tissues Organ system level: organs that work closely together Organismal level: all organ systems

Levels of Structural Organization Smooth muscle cell Atoms 1 Chemical level Molecules Atoms combine to form molecules. 2 Cellular level Cells are made up of molecules. Smooth muscle tissue 3 Tissue level Blood vessels Tissues consist of similar types of cells. Heart Epithelial tissue Smooth muscle tissue Blood vessel (organ) Cardio– vascular system Connective tissue 4 Organ level Organs are made up of different types of tissues. 5 Organ system level 6 Organismal level Organ systems consist of different organs that work together closely. Human organisms are made up of many organ systems.

Survival Needs of Living Organisms Nutrients Chemicals for energy and cell building Carbohydrates, fats, proteins, minerals, vitamins, water Oxygen Essential for energy release (ATP production)

Survival Needs of Living Organisms Water Most abundant chemical in the body Site of chemical reactions Normal body temperature Affects rate of chemical reactions Appropriate atmospheric pressure For adequate breathing and gas exchange in the lungs

Living Organisms Must Maintain Homeostasis Homeostasis is the maintenance of a relatively stable internal environment despite continuous outside changes Homeostatic control mechanisms are responsible for maintaining homeostasis

The Elements of a Homeostatic Control System 3 Output: Information is sent along efferent pathway to effector. 4 Input: Information is sent along afferent pathway to control center. Control Center Afferent pathway Efferent pathway Receptor Effector Receptor detects change. 2 5 Response of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level. 1 Stimulus produces change in variable. IMBALANCE VARIABLE (in homeostasis) IMBALANCE

Components of a Homeostatic Control Mechanism Receptor (sensor) monitors the environment senses stimuli in the environment Control Center receives input from the receptor determines the set point at which a variable is maintained determines the appropriate response

Components of a Control Mechanism Effector receives output from control center provides the means to respond response acts to reduce or enhance the original stimulus (feedback)

Negative Feedback When the response reduces or shuts off the original stimulus this is negative feedback Example: Regulation of body temperature

Temperature-sensitive Temperature-sensitive Control Center (thermoregulatory center in brain) Information sent along the afferent pathway to control center Information sent along the efferent pathway to effectors Afferent pathway Efferent pathway Receptors Temperature-sensitive cells in skin and brain Effectors Sweat glands Sweat glands activated Response Evaporation of sweat Body temperature falls; stimulus ends Stimulus Body temperature rises BALANCE Stimulus Body temperature falls Response Body temperature rises; stimulus ends Receptors Temperature-sensitive cells in skin and brain Effectors Skeletal muscles Efferent pathway Afferent pathway Shivering begins Information sent along the efferent pathway to effectors Information sent along the afferent pathway to control center Control Center (thermoregulatory center in brain) Figure 1.5

Rare in biological systems Example: Positive Feedback When the response enhances or exaggerates the original stimulus this is positive feedback Rare in biological systems Example: Enhancement of labor contractions by oxytocin

The Anatomical Position is used as a frame of reference Body erect Feet slightly apart Palms facing forward

Table 1.1

Table 1.1

Table 1.1

Table 1.1

Table 1.1

Regional Terms Regional Terms: Specify specific areas on the body

Upper limb Acromial Orbital Brachial (arm) Nasal Antecubital Oral Antebrachial (forearm) Cervical Carpal (wrist) Thoracic Axillary Digital Sternal Abdominal Lower limb Umbilical Coxal (hip) Pelvic Femoral (thigh) Inguinal Patellar Crural (leg) Pubic Fibular Tarsal (ankle) Thorax Abdomen Back (Dorsum) (a) Anterior/Ventral Figure 1.5

Upper limb Cephalic Acromial Brachial (arm) Occipital Olecranal Cervical Back (dorsal) Scapular Vertebral Digital Lumbar Sacral Femoral (thigh) Gluteal Popliteal Sural (calf) Fibular Calcaneal Plantar (b) Posterior/Dorsal Figure 1.5

Body Planes and Sections There are Three Anatomical Planes: Sagittal, Frontal, Transverse 1) Sagittal plane Divides body vertically into right and left parts Produces a sagittal section 1a) Midsagittal (median) plane Lies on midline 1b) Parasagittal plane Not on midline

Frontal (coronal) plane Body Planes Frontal (coronal) plane Divides body vertically into anterior and posterior parts Transverse (horizontal) plane Divides body horizontally into superior and inferior parts Produces a cross section

Median (midsagittal) plane Frontal plane Median (midsagittal) plane Transverse plane (a) Frontal section (through torso) (b) Transverse section (through torso, inferior view) (c) Median section (midsagittal) Pancreas Aorta Spleen Left and right lungs Liver Heart Spleen Liver Spinal cord Rectum Intestines Body wall Stomach Arm Vertebral column Subcutaneous fat layer Figure 1.6

There are Two Large Body Cavities: Dorsal and Ventral The Dorsal Body Cavity encloses the CNS Two subdivisions of Dorsal Body Cavity: Cranial cavity Encases brain Vertebral cavity Encloses spinal cord

The Ventral Body Cavity Body Cavities The Ventral Body Cavity Houses soft internal organs (viscera) Two subdivisions (separated by diaphragm): Thoracic cavity Abdominopelvic cavity

Cranial cavity Cranial cavity Dorsal body cavity Ventral body cavity Vertebral cavity Dorsal body cavity Thoracic Cavity Vertebral cavity Ventral body cavity (thoracic and abdominopelvic cavities) Diaphragm Abdominal cavity (contains digestive viscera) Abdomino- pelvic cavity Pelvic cavity (contains urinary bladder, reproductive organs, and rectum) (a) Lateral view (b) Anterior view Figure 1.7

Thoracic Cavity subdivisions: Ventral Body Cavities Thoracic Cavity subdivisions: Two pleural cavities Each houses a lung Mediastinum Contains pericardial cavity Also contains the esophagus and aorta Pericardial Cavity Encloses heart

Abdominopelvic Cavity subdivisions: Ventral Body Cavities Abdominopelvic Cavity subdivisions: Abdominal Cavity Contains stomach, intestines, spleen, and liver Pelvic Cavity Contains urinary bladder, reproductive organs, and rectum

Thoracic cavity Cranial cavity Vertebral cavity Cranial cavity Dorsal body cavity Ventral body cavity Vertebral cavity Thoracic cavity Dorsal body cavity Vertebral cavity Ventral body cavity Diaphragm Abdominal cavity Abdomino- pelvic cavity Pelvic cavity (a) Lateral view (b) Anterior view Figure 1.7

Abdominopelvic Regions Nine Regions within the abdominopelvic area Liver Diaphragm Right hypochondriac region Left hypochondriac region Epigastric region Gallbladder Stomach Right lumbar region Left lumbar region Ascending colon of large intestine Transverse colon of large intestine Umbilical region Small intestine Descending colon of large intestine Cecum Right iliac (inguinal) region Hypogastric (pubic) region Left iliac (inguinal) region Initial part of sigmoid colon Appendix Urinary bladder (a) Nine regions delineated by four planes (b) Anterior view of the nine regions showing the superficial organs Figure 1.12