Human Anatomy Section 1

Basic Terminology

Anatomy: Internal and external structure and the physical relationships between body parts; the

practice of dissection is used to identify and study anatomical structures

Anatomy Example: Two organs that are sequenced one after the other (stomach & small intestine)

Morphology: The scientific study of the external form/shape the body has because of how

organs and systems “fit” together (because of complementarity of their shapes);

the sculpting of the body

Morphology Example: The curvature of the spine due to the positioning of the intervertebral discs as well as the ligaments and muscles attached to the spine

Physiology: How living organisms perform the vital chemical functions necessary to sustain life

Physiology Example: Physiological processes maintain homeostatic balance with regard to how body systems interact and are dependent on each other

Physiology Example: Nerves sending impulses to the smooth muscles of the intestine so that digesting food moves through the intestinal tract

Pathology: The scientific study of disease processes (their causes & effects) in the body

Pathology Example: Cancer cells developing and spreading through otherwise healthy tissue

Structural Levels of Organization

Atom: The smallest, complete unit of an element (matter); most atoms do not have a complete

valence (outer) energy level, therefore they react (bond) with other atoms to stabilize the

respective valence levels

Molecule: The smallest, complete unit of a compound or diatomic substance resulting from

chemical bonding

Molecule Example: Melanin in the skin

Cell: The smallest, complete unit of structure & function in the body

Cell Example: A melanocyte

Tissue: A grouping of similar cells that are interconnected and work together to perform a

common function

Tissue Example: The Epidermis of the skin

Organ: A group of different types of tissues that work collectively on a common function

Organ Example: The skin, as composed of the epidermis, dermis and subdermis (hypodermis)

System: A network of different organs, each doing their own respective job(s), yet still working

together on a broader, common function

System Example: The integumentary system; the skin, including its accessory structures such as hair follicles, sensory and pain receptors, oil glands and sweat glands

Organism: The entire body (usually multicellular) with each of its systems working in an

integrated way to maintain homeostasis (relatively constant internal environment)

Organism Example: The entire body (usually multicellular) with each of its systems working in an integrated way to maintain homeostasis (relatively constant internal environment)

1st level of organization: Atom

2nd level of organization: Micro-molecule

3rd level of organization: Macromolecule

4th level of organization: Organelle

5th level of organization: Cell

6th level of organization: Tissue

7th level of organization: Organ

8th level of organization: Organ System

9th level of organization: Organism

Feedback Mechanisms

Positive Feedback: Occurs when the initial stimulus produces a response that exaggerates or enhances the stimulus; this occurs over a more extended period of time to complete a particular body function before eventually returning to homeostasis (stimulus is increased)

Positive feedback Example: Childbirth

Negative feedback : Occurs when (an) effector(s), which is/are activated by a control center, either oppose(s) or eliminate(s) the original stimulus; this occurs as rapidly as possible to return the situation to homeostasis quickly (stimulus is decreased)

Negative feedback Example : Temperature Regulation

Stimulus : A change in surroundings that the receptor notices (something that evokes a reaction)

Receptor : A body structure that monitors changes in a controlled condition and sends input to a control center

Control center : Will process the information (compare the variable in relation to a set point) and activate effectors

Effector : The component in a feedback system that causes a change to reverse the situation and return the value to the normal range (output)

Variable : The factor or event being regulated

Afferent : Communication flows toward the control center from the receptor (stuff towards the body)

Efferent: Information flows from the control center to the effector (stuff away from the body)

Characteristics of Life

Maintaining life : Maintaining Boundaries, Movement, Irritability (responsiveness), Digestion, Metabolism (Anabolism & Catabolism), Excretion (Elimination), Growth/Development, Reproduction (Mitotic cell division & Meiotic cell division)

Survival needs: Food/Nutrients, Oxygen/cellular respiration, Appropriate body temperature, Appropriate pH conditions, Atmospheric pressure

Directional Terms

Superior : Located in the upper region of, or above something else; if body orientation if vertical, superior can also mean “toward the head”

Superior Example : The human brain is ___ to the spinal cord

Inferior : Located in the lower region of, or below something else; if body orientation is vertical, inferior can also mean “toward the feet”

Inferior Example: The human spinal cord is ___ to the brain

Anterior : Located in front of , or ahead of something; forward:most region of something

Anterior Example : A dog’s head is at the ____ end of its body

Posterior: Located in back of something, or behind something; hind:most region of something

Posterior Example : The ____ pituitary lies behind the anterior pituitary

Ventral : Located toward the belly or underside of the body

Ventral Example : A fish’s pectoral and pelvic fins are on the ___ surface of its body

Dorsal : Located on the back surface of something

Dorsal Example : A person’s shoulder blades are on the dorsal/posterior surface of the body (in vertical orientation, ___ and posterior are synonymous)

Medial : Located toward the midline of the body

Medial Example : The big toe is on the ____ side of the foot

Lateral : Located toward the right or left side of the body; located away from the midline of the body

Lateral Example : The eyes lie ___ to the nose

Intermediate : Part way between lateral and medial

Intermediate Example : The cheek is ____ to the mouth and the ear

Proximal : Located toward, or nearest the trunk of the body; located nearest the point of origin of one of its parts

Proximal Example : The knee is ___ to the foot

Distal : Located away from, or farthest from the trunk or the point of origin of a body part

Distal Example : The hand is ___ to the elbow

Superficial : Located nearest the outer surface of something

Superficial Example : The skin of the body is ___ to the musculature

Deep : Located underneath, or farther away from the outer body surface

Deep Example : The femur bone of the thigh is deep to the hamstrings and quadriceps (quads)

muscle groups that surround/cover it