An Orientation and Introduction Chapter 1: The Human Body… An Orientation and Introduction

Figure 1.1 Levels of structural organization. Organelle Atoms Molecule Smooth muscle cell Cellular level Cells are made up of molecules. 2 Chemical level Atoms combine to form molecules. 1 Smooth muscle tissue Cardiovascular system 3 Tissue level Tissues consist of similar types of cells. Heart Blood vessels Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelial tissue 4 Organ level Organs are made up of different types of tissues. 6 Organismal level The human organism is made up of many organ systems. Organ system level Organ systems consist of different organs that work together closely. 5

Figure 1.2 Examples of interrelationships among body organ systems. Digestive system Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces) Respiratory system Takes in oxygen and eliminates carbon dioxide Food O2 CO2 Cardiovascular system Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs Blood CO2 O2 Urinary system Eliminates nitrogenous wastes and excess ions Heart Nutrients Interstitial fluid Nutrients and wastes pass between blood and cells via the interstitial fluid Integumentary system Protects the body as a whole from the external environment Feces Urine

Figure 1.3a The body’s organ systems and their major functions. Hair Skin Nails (a) Integumentary System Forms the external body covering, and protects deeper tissues from injury. Synthesizes vitamin D, and houses cutaneous (pain, pressure, etc.) receptors and sweat and oil glands.

Figure 1.3b The body’s organ systems and their major functions. Bones Joint (b) Skeletal System Protects and supports body organs, and provides a framework the muscles use to cause movement. Blood cells are formed within bones. Bones store minerals.

Figure 1.3c The body’s organ systems and their major functions. Skeletal muscles (c) Muscular System Allows manipulation of the environment, locomotion, and facial expression. Main- tains posture, and produces heat.

Figure 1.3d The body’s organ systems and their major functions. Brain Nerves Spinal cord (d) Nervous System As the fast-acting control system of the body, it responds to internal and external changes by activating appropriate muscles and glands.

Figure 1.3e The body’s organ systems and their major functions. Pineal gland Pituitary gland Thyroid gland Thymus Adrenal gland Pancreas Testis Ovary (e) Endocrine System Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.

Figure 1.3g The body’s organ systems and their major functions. Red bone marrow Thymus Lymphatic vessels Thoracic duct Spleen Lymph nodes (g) Lymphatic System/Immunity Picks up fluid leaked from blood vessels and returns it to blood. Disposes of debris in the lymphatic stream. Houses white blood cells (lymphocytes) involved in immunity. The immune response mounts the attack against foreign substances within the body.

Figure 1.3f The body’s organ systems and their major functions. Heart Blood vessels (f) Cardiovascular System Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood.

Figure 1.3h The body’s organ systems and their major functions. Nasal cavity Pharynx Bronchus Larynx Trachea Lung (h) Respiratory System Keeps blood constantly supplied with oxygen and removes carbon dioxide. The gaseous exchanges occur through the walls of the air sacs of the lungs.

Figure 1.3i The body’s organ systems and their major functions. Oral cavity Esophagus Liver Stomach Small intestine Large intestine Rectum Anus (i) Digestive System Breaks down food into absorbable units that enter the blood for distribution to body cells. Indigestible foodstuffs are eliminated as feces.

Figure 1.3j The body’s organ systems and their major functions. Kidney Ureter Urinary bladder Urethra (j) Urinary System Eliminates nitrogenous wastes from the body. Regulates water, electrolyte and acid-base balance of the blood.

Figure 1.3k-l The body’s organ systems and their major functions. Mammary glands (in breasts) Prostate gland Ovary Penis Testis Ductus deferens Scrotum Uterine tube Uterus Vagina (k) Male Reproductive System (l) Female Reproductive System Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn.

Information sent along efferent pathway to effector. Figure 1.4 Interaction among the elements of a homeostatic control system. Output: Information sent along efferent pathway to effector. 4 Input: Information sent along afferent pathway to control center. 3 Control Center Afferent pathway Efferent pathway 2 Receptor Effector 5 Receptor detects change. Response of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level. 1 Stimulus produces change in variable. BALANCE

Temperature-sensitive Temperature-sensitive Figure 1.5 Regulation of body temperature by a negative feedback mechanism. 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)

1 occurs in blood vessel wall. Positive feedback cycle is initiated. 3 Figure 1.6 Summary of the positive feedback mechanism regulating formation of a platelet plug. Break or tear occurs in blood vessel wall. 1 Positive feedback cycle is initiated. 3 Released chemicals attract more platelets. 2 Platelets adhere to site and release chemicals. Positive feedback loop Feedback cycle ends when plug is formed. Platelet plug forms. 4

Figure 1.7 Regional terms used to designate specific body areas. Cephalic Cephalic Frontal Otic Orbital Occipital (back of head) Nasal Oral Upper limb Mental Acromial Cervical Cervical Brachial (arm) Thoracic Antecubital Sternal Olecranal Back (dorsal) Axillary Antebrachial (forearm) Scapular Mammary Carpal (wrist) Vertebral Abdominal Umbilical Lumbar Manus (hand) Pelvic Pollex Sacral Inguinal (groin) Metacarpal Palmar Gluteal Digital Perineal (between anus and external genitalia) Lower limb Coxal (hip) Pubic (genital) Femoral (thigh) Patellar Popliteal Crural (leg) Sural (calf) Fibular or peroneal Pedal (foot) Thorax Tarsal (ankle) Abdomen Calcaneal Back (Dorsum) Metatarsal Digital Plantar Hallux (a) Anterior/Ventral (b) Posterior/Dorsal

Median (midsagittal) plane Figure 1.8 Planes of the body with corresponding magnetic resonance imaging (MRI) scans. 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 1.9 Dorsal and ventral body cavities and their subdivisions. Cranial cavity Cranial cavity (contains brain) Dorsal body cavity Ventral body cavity Vertebral cavity Superior mediastinum Dorsal body cavity Thoracic cavity (contains heart and lungs) Pleural cavity Pericardial cavity within the mediastinum Vertebral cavity (contains spinal cord) 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 1.11 The four abdominopelvic quadrants. Right upper quadrant (RUQ) Left upper quadrant (LUQ) Right lower quadrant (RLQ) Left lower quadrant (LLQ)

Figure 1.12 The nine abdominopelvic regions. Liver Diaphragm Right hypochondriac region Left hypochondriac region Epigastric region Gallbladder Stomach Transverse colon of large intestine Right lumbar region Left lumbar region Ascending 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

Table 1.1 Orientation and Directional Terms (1 of 3)

Table 1.1 Orientation and Directional Terms (2 of 3)

Table 1.1 Orientation and Directional Terms (3 of 3)