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Chapter 1

The Human Body

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Introduction

• Anatomy: the study of the structure of the body

• Physiology: the study of the function of the body parts

• Pathology: the study of the disease of the body

• Basic reference systems– Directions, planes, cavities, structural units

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Terms of Direction

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Terms of Direction (cont’d.)

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Planes

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Planes (cont’d.)

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Cavities

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Cavities (cont’d.)

• Dorsal– Cranial, spinal

• Ventral– Thoracic, abdominopelvic

• Parietal: walls of a cavity

• Visceral: covering on an organ

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Cavities (cont’d.)

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Structural Units

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Structural Units (cont’d.)

• Cells– Smallest units of life– Perform all activities necessary to maintain

life• Metabolism, assimilation, digestion, excretion,

reproduction

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Structural Units (cont’d.)

• Tissues – Made up of different types of cells– Epithelial: covers and protects– Connective: binds and supports other tissues– Muscle: movement– Nervous: connects sensory structures to

motor structures

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Structural Units (cont’d.)

• Organs– Cells integrated into tissues– Serve a common function– Examples

• Liver• Stomach

• System is a group of organs

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Structural Units (cont’d.)

• Integumentary system– Organs

• Skin, hair, nails, sweat glands, sebaceous glands

– Functions• Protection, insulation, regulation of water and

temperature

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Structural Units (cont’d.)

• Skeletal system– Organs

• Bones, cartilage, membranous structures

– Functions• Movement, blood production, fat and mineral

storage, protection

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Structural Units (cont’d.)

• Muscular system– Organs

• Muscles, fasciae, tendon sheaths, and bursae

– Functions• Movement, pushing food and blood, contracting

heart

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Structural Units (cont’d.)

• Nervous system– Organs

• Brain, spinal cord, cranial and peripheral nerves, sensory and motor structures

– Function• Control and regulation, interpreting stimuli

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Structural Units (cont’d.)

• Endocrine system– Organs

• Endocrine glands

– Function• Works with nervous system to regulate chemical

aspects of the body

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Structural Units (cont’d.)

• Cardiovascular system– Organs

• Heart, arteries, veins, capillaries

– Function • Transport substances to and from cells

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Structural Units (cont’d.)

• Lymphatic/immune system– Organs

• Lymph nodes, lymph vessels, thymus gland, spleen

– Functions• Drains tissues of excess fluids, transports fats,

develops immunities

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Structural Units (cont’d.)

• Respiratory system– Organs

• Nasal cavities, pharynx, larynx, trachea, bronchi, lungs

– Function• O2 > CO2 exchange in the blood

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Structural Units (cont’d.)

• Digestive system– Organs

• Alimentary canal: mouth, esophagus, stomach, small and large intestines, rectum and anus

• Associated glands: salivary, liver, pancreas

– Functions• Convert food into absorbable substances,

eliminates wastes

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Structural Units (cont’d.)

• Urinary system– Organs

• Kidneys, ureters, bladder, urethra

– Functions• Chemical regulation of blood• Formation and elimination of urine• Maintenance of homeostasis

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Structural Units (cont’d.)

• Reproductive system– Organs

• Women: ovaries, uterine tubes, uterus, vagina• Men: testes, seminal vesicles, prostate gland,

penis, urethra

– Functions• Maintains sexual characteristics and perpetuates

the species

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Homeostasis

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Homeostasis (cont’d.)

• Maintenance of the body’s internal environment– Within varying narrow limits

• Negative feedback loop

• Examples– Blood sugar levels– Body temperature

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Homeostasis (cont’d.)

• Blood glucose– Levels rise dramatically after meal– Cells take in glucose– Pancreas secretes insulin

• Moves glucose into liver for storage as glycogen

– Between meals, pancreas secretes glucagon• Turns glycogen into glucose and returns it to blood

– Thus, glucose levels remain nearly constant

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Homeostasis (cont’d.)

• Body temperature– Hypothalamus detects increase in body

temperature– Causes sweating

• Water evaporates and body is cooled

– Blood vessels dilate to bring blood near body surface

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Homeostasis (cont’d.)

• Body monitors deviations in homeostasis– Negative feedback loop

• Responses that revise disturbances to body’s condition

– Positive feedback• Increase in function in response to stimulus• Uterine contractions during labor

• Organ systems help control internal environment

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Summary

• Discussed the four basic reference systems of body organization (directions, planes, cavities, and structural units)

• Discussed organization of the body into different structural levels (cells, tissues, organs, systems, human organism)

• Discussed homeostasis and mechanisms for maintaining it