Unit 1- The Human Body: An Orientation

Anatomy

Anatomy

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

Gross Anatomy

large, easily observable structures

Microscopic Anatomy

structures too small to be seen by the naked eye such as cells and tissues; view with a microscope

Physiology

study of how the body and its parts function; structure determines what functions can occur

Levels of Structural Organization

atoms, cells, tissues, organs, organ systems, organisms

Integumentary system

forms the external body covering (skin, hair fingernails) which:

• waterproofs the body

• protects deeper tissue

• produces vitamin D

• excretes salt in perspiration

• helps regulate body temp

• is the location of the cutaneous nerve receptors

Skeletal system

Made up of bones, cartilages, ligaments, and joints which:

• provides muscle attachment for movement

• protects organs

• stores minerals (calcium)

• is the site of blood cell formation

Muscular system

skeletal muscles contract which produces motion and heat

Nervous system

fast acting control system that consists of the brain, spinal cord, nerves, and sensory receptors which:

• responds to internal and external stimuli

• sensory receptors detect changes

• messages sent to CNS which assesses info and activates effectors (muscles and glands)

Endocrine system

slow acting control system made up of glands which:

• secretes chemical molecules, called hormones, into the blood

• hormones control body functions like growth, reproduction, and use of nutrients

Endocrine Glands

• pituatary gland

• thyroid and parathyroids

• adrenal gland

• thymus

• pancreas

• pineal gland

• ovaries and testes

Cardiovascular system

made up of heart and blood vessels which:

• pumps blood (heart)

• transports blood containing O2 and CO2, nutrients, and hormones to tissues (blood vessels)

• also transports white blood cells and chemicals to protect from foreign invaders

Lymphatic system

includes lymphatic vessels, lymph nodes, and lymphoid organs which:

• complement the cardiovascular system by returning leaked fluids to bloodstream

• cleanses blood

• houses white blood cells that are involved in immunity

Respiratory system

includes nasal passages, pharynx, larynx, trachea, bronchi, and lungs which:

• exchange gases with blood through air sacs in the lungs

• supplies body with O2

• removes CO2

Digestive system

includes oral cavity (mouth), esophagus, stomach, small and large intestines, rectum, and accessory organs which:

• breaks down food

• allows for nutrients to be absorbed into the blood

• eliminates indigestible material as feces

Urinary system

includes kidneys, ureters, urinary bladder, and urethra which:

• eliminates nitrogenous waste

• maintains acid-base balance

• regulates water and electrolyte balance

• helps regulate normal blood pressure

Reproductive system

Males - testes, scrotum, penis, accessory glands, and duct system

Females - ovaries, uterine tubes, uterus, and vagina

• Also plays role in growth and development as well as reproduction

Necessary life functions

maintaining boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth, nutrients, oxygen, water, normal body temperature, and atmospheric pressure

Maintaining boundaries

separate the inside from the outside

Movement

locomotion and movement of substances

Responsiveness

ability to sense changes and react

Digestion

breakdown and absorption of nutrients

Metabolism

chemical reactions within the body that break down complex molecules into smaller ones, and builds larger molecules from smaller ones

Excretion

eliminates waste from metabolic reactions through urine, feces, or sweat

Reproduction

cellular level - new cells used for growth and repair

organismal level - reproductive system handles the task

Growth

increases cell size (until split) or body size; hormones

Nutrients

chemicals used for energy and cell building (carbohydrates, proteins, lipids, vitamins, and minerals)

Oxygen

required for chemical reactions (to produce ATP and keep cells alive) and works through cooperation of the respiratory and cardiovascular systems

Water

makes up 60-80% of body weight, most abundant chemical, provides fluid base for body secretions and excretions

Normal body temperature

37 degrees C or 98.6 F; below causes chemical reactions to slow and stop and above causes them to proceed too rapidly

Atmospheric pressure

must be appropriate for gas exchange and for respiratory system to function

Anatomical position

standard body position, terminology refers to position regardless of actual position

• stand, feet parallel, arms at sides, palms facing forward, thumbs away from body

Directional terms

explain the location of one body structure in relation to another

• superior, inferior, anterior, posterior, medial, lateral, intermediate, proximal, distal, superficial, and deep

Superior (cranial or cephalic)

toward head or upper part of a structure or the body, above

Inferior (caudal)

away from head or toward the lower part of a structure, below

Anterior (ventral)

toward or at front of body

Posterior (dorsal)

toward or at backside of body

Medial

toward or at midline of body, inner side

Lateral

away from midline, outer side

Intermediate

between more medial and more lateral structure

Proximal

close to origin of body part, point of attachment to link to body trunk

Distal

farther from origin of body part

Superficial (external)

toward or at body surface; usually referencing injuries

Deep (internal)

away from body surface; usually referencing injuries

Body planes and sections

sagittal, median, frontal, and transverse

Sagittal

divides body/organ into left and right

Median (midsagittal)

divides body into equal left and right parts

Frontal (coronal)

divides into anterior and posterior (front and back)

Transverse (cross)

divides into superior and inferior (top and bottom)

Dorsal

made up of cranial cavity and spinal cavity; encased in bone (spinal bones)

Cranial cavity

houses brain and is protected by the skull

Spinal cavity

houses spinal cord and is protected by the vertabrae

Ventral

made up of the thoracic and abdominopelvic cavities divided by the diaphragm

Thoracic cavity

superior to mediastinum and houses heart, lungs, and other organs which are protected by rib cage

Mediastinum

houses heart, trachea, and other organs

Abdominopelvic cavity

inferior to the diaphragm

• superior abdominal has stomach, liver, and other organs protected by trunk muscles

• inferior pelvic contains reproductive organs, bladder, and rectum protected by pelvis

• has 4 quadrants and 9 regions

Homeostasis

maintenance of relatively stable internal conditions; imbalance results in disease; mostly controlled by nervous and endocrine systems

3 homeostatic control mechanism components

receptor, control center, and effector

Receptor

responds to changes in environment and sends info to the control center along an afferent pathway

Control center

determines set point, analyzes info, and determines an appropriate response

Effector

provides a means for response to stimuli from information received from efferent pathway

Negative feedback

shuts off or reduces the intensity of the original stimulus; most homeostatic control mechanisms; think thermostat

Positive feedback

increases the original stimulus to push the variable farther and occurs at faster rate; rare in human body (blood clotting and labor)