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1The Human Body: An Orientation

Yong Jeong, MD, PhD

Department of Bio and Brain Engineering

The Human Body—An Orientation

Anatomy

Study of the structure and shape of the body and its parts

Physiology

Study of how the body and its parts work or function

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Anatomy—Levels of Study

Gross anatomy

Large structures

Easily observable

Figure 14.1

Anatomy—Levels of Study

Microscopic Anatomy

Very small structures

Can only be viewed with a microscope

Figure 14.4c–d

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Levels of Structural Organization

Figure 1.1

Smooth muscle cellMolecules

Atoms

Smoothmuscletissue

Epithelialtissue

Smoothmuscletissue

Connectivetissue

Bloodvessel(organ) Cardio-

vascularsystem

Cellular levelCells are made up of molecules

Tissue levelTissues consist ofsimilar types of cells

Organ levelOrgans are made upof different typesof tissues

Organ system levelOrgan systems consist of differentorgans that work together closely

Organismal levelHuman organismsare made up of manyorgan systems

Chemical levelAtoms combine toform molecules

http://www.zygotebody.com/#nav=2.31,81.5,250

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Figure 1.2a

Organ System Overview

Integumentary

Forms the external bodycovering

Protects deeper tissue frominjury

Helps regulate body temperature

Location of cutaneousnerve receptors

Figure 1.2b

Organ System Overview

Skeletal

Protects and supportsbody organs

Provides muscleattachment for movement

Site of blood cellformation

Stores minerals

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Figure 1.2c

Organ System Overview

Muscular

Produces movement

Maintains posture

Produces heat

Organ System Overview

Nervous

Fast-acting controlsystem

Responds to internal andexternal change

Activates muscles andglands

Figure 1.2d

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Organ System Overview

Endocrine

Secretes regulatoryhormones

Growth

Reproduction

Metabolism

Figure 1.2e

Figure 1.2f

Organ System Overview

Cardiovascular

Transports materials in bodyvia blood pumped by heart

Oxygen

Carbon dioxide

Nutrients

Wastes

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Organ System Overview

Lymphatic

Returns fluids to blood vessels

Cleanses the blood

Involved in immunity

Figure 1.2g

Organ System Overview

Respiratory

Keeps blood supplied with oxygen

Removes carbon dioxide

Figure 1.2h

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Organ System Overview

Digestive

Breaks down food

Allows for nutrient absorption into blood

Eliminates indigestible material

Figure 1.2i

Organ System Overview

Urinary

Eliminates nitrogenous wastes

Maintains acid-base balance

Regulates water and electrolytes

Figure 1.2j

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Organ System Overview

Reproductive

Produces offspring

Figure 1.2k–l

Interrelationships Among Body Systems

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Necessary Life Functions

Maintain boundaries

Movement

Locomotion

Movement of substances

Responsiveness

Ability to sense changes and react

Digestion

Break-down and absorption of nutrients

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Necessary Life Functions

Metabolism—chemical reactions within the body

Produces energy

Makes body structures

Excretion

Eliminates waste from metabolic reactions

Reproduction

Produces future generation

Growth

Increases cell size and number of cells

Survival Needs

Nutrients

Chemicals for energy and cell building

Includes carbohydrates, proteins, lipids, vitamins, and minerals

Oxygen

Required for chemical reactions

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Survival Needs

Water

60–80% of body weight

Provides for metabolic reaction

Stable body temperature

Atmospheric pressure

Must be appropriate

Homeostasis

Homeostasis—maintenance of a stable internal environment

A dynamic state of equilibrium

Homeostasis is necessary for normal body functioning and to sustain life

Homeostatic imbalance

A disturbance in homeostasis resulting in disease

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Figure 1.4

Changedetectedby receptor

Stimulus:Produceschangein variable

Input:Informationsent alongafferentpathway to

Receptor (sensor) Effector

Variable(in homeostasis)

Response ofeffector feedsback toinfluencemagnitude ofstimulus andreturns variableto homeostasis

Controlcenter

Output:Information sentalong efferentpathway to activate

cf: Steady state

Biomedical Engineering © Mark Saltzman 2009

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cf: Equilibrium

Maintaining Homeostasis

The body communicates through neural and hormonal control systems

Receptor

Responds to changes in the environment (stimuli)

Sends information to control center

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Maintaining Homeostasis

Control center

Determines set point

Analyzes information

Determines appropriate response

Effector

Provides a means for response to the stimulus

Feedback Mechanisms

Negative feedback

Includes most homeostatic control mechanisms

Shuts off the original stimulus, or reduces its intensity

Works like a household thermostat

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Feedback Mechanisms

Positive feedback

Increases the original stimulus to push the variable farther

In the body this only occurs in blood clotting and during the birth of a baby ?

The Language of Anatomy

Special terminology is used to prevent misunderstanding

Exact terms are used for

Position

Direction

Regions

Structures

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Figure 1.5a

Regional Terms

Anterior body landmarks

Regional Terms

Posterior body landmarks

Figure 1.5b

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Directional Terms

Table 1.1 (1 of 3)

Directional Terms

Table 1.1 (2 of 3)

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Directional Terms

Table 1.1 (3 of 3)

Body Planes and Sections

Figure 1.6

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Body Planes and Sections

A sagittal section divides the body (or organ) into left and right parts

A median, or midsagittal, section divides the body (or organ) into equal left and right parts

A frontal section divides the body (or organ) into anterior and posterior parts

A transverse, or cross, section divides the body (or organ) into superior and inferior parts

Rostral (beak) vs. caudal (tail): embryology base

Superior vs. inferior

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Body Cavities

Dorsal body cavity

Cranial cavity houses the brain

Spinal cavity houses the spinal cord

Ventral body cavity

Thoracic cavity houses heart, lungs and others

Abdominopelvic cavity houses digestive system and most urinary system organs

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Body Cavities

Figure 1.7

Abdominopelvic Quadrants

Figure 1.8a

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Abdominopelvic Regions

Figure 1.8b

Abdominopelvic Major Organs

Figure 1.8c