Anatomy

This essay has a total of 5905 words and 47 pages.

Anatomy



‘Overview of Anatomy & Physiology’

Anatomy - is the study of the structure of the body parts & their
relationship to one another.
Physiology - concerns with the function of the body’s structural
machinery - how the body works.
Topics of Anatomy
Gross Anatomy - is the study of the large body structures visible to the
naked eye. It can be approached in different ways.
Regional Anatomy - is the study of all the structures in one particular
region.
Systematic Anatomy - is when anatomy is studied system by system.
Surface Anatomy - is the study of the internal structures as they relate
to the overlying skin surface.
Microscopic Anatomy - is the study of structures too small to be seen
without a microscope.
Topics of Physiology
They are usually divided into operations of specific organ systems.
The Principle of Complementarity of structure & Function - Anatomy &
Physiology are taught together because the functions always reflect the
structure.
Levels of structural organization
Chemical level - this includes atoms & molecules.
Cellular level - is the smallest unit of living things.
Tissue level - are groups of similar cells that have a common function.
Organ level - an organ is at least two tissues that perform a specific
function of the body.
Organ System level - organs that work together to accomplish a
specific function.

Homework (pgs. 4-5) February 5,1999

‘Summary of the Body’s Organ Systems’

Integumentary System - forms of the external body covering; protects
deeper body tissue from injury; synthesizes vitamin D; site of
cutaneous (pain, pressure, ect.) receptors, & sweat & oil glands.
Skeletal System - protects & supports body organs; provides the
framework the muscles use to cause movement; blood cells are formed
within bones; stores minerals.
Muscular System - allows manipulation of the environment,
locomotion, & facial expression; maintains posture; produces heat.
Nervous System - fast-acting control system of the body; responds to
internal & external changes of the body by activating appropriate
muscles & glands.
Endocrine System - glands secrete hormones that regulate processes
such as growth, reproduction, & nutrient use (metabolism) by body
cells.
Cardiovascular System - Blood vessels transport blood, which carries
oxygen, carbon dioxide, nutrients, ect.; the heart pumps blood.
Lymphatic System/Immunity - Picks up fluids leaked from blood
vessels & returns it to the 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.
Respiratory System - keeps blood constantly supplied with oxygen &
removes carbon dioxide; the gaseous exchange occurs through the
walls of the air sacs of the lungs.
Digestive System - breaks down food into absorbable units that enter
the blood for distribution to the body cells; indigestible foodstuffs are
eliminated as feces.
Urinary System - eliminates nitrogenous waste from the body;
regulates water, electrolytes, & the acid-based balance in the blood.
Male Reproductive System - overall function is the production of
offspring. Testes produce sperm & male sex hormones; ducts & glands
aid in delivery of sperm to the female reproductive tract.
Female Reproductive System - overall function is the production of
offspring. Ovaries produce eggs & female sex hormones; remaining
structures serve as sites for fertilization & the development of the
fetus. Mammary glands of female breast produce milk to nourish the
newborn.





















Classwork (pgs. 6-8) February 8, 1999

‘Maintaining Life’

Necessary Life Functions
Maintaining Boundaries - keeps its internal environment separate
from the external environment (ex.- skin or cell membrane).
Movement - all activities promoted by the muscular system; on the
cellular level, muscle cells contracting is called contractility.
Responsiveness - irritability is the ability to sense changes in the
environment & then respond to them.
Digestion - is the process of braking down ingested food into simple
molecules that can be absorbed into the blood.
Metabolism - all chemical reactions that occur within the body.
Excretion - is the process of removing wastes from the body; usually
refers to urine.
Reproduction - the making more of an organism; occurs asexually
(one) or sexually (two).
Growth - an increase in size.
Survival Needs
The goal of the body system is to maintain life. There are several factors
that need to be present, like:
Nutrients - these contain the chemical substances used for energy &
cell building.
Oxygen - chemical reactions in the body require oxygen.
Water - is the single most abundant substance in your body.
Homeostasis
Homeostasis - is the body’s ability to maintain a relatively stable internal
condition, even though the outside world changes. There are three factors
in the homeostatic control organism:
Receptor - sensor that monitors the environment.
Control Center - analyzes input it receives & determines the
appropriate action.
Effector - provides the means to the response.




























Classwork (pgs. 8-13, & 16) February 9, 1999

‘Positive & Negative Feedback’

Most of the homeostatic control mechanisms are negative feedback
mechanisms. The net effect is that the output of the system shuts off the
original stimulus (ex.- heat & air conditioning in houses & glucose
regulating pgs. 9 -10, fig. 1.5}).
Positive feedback mechanisms, (often referred to as cascades) the result
or response enhances the original stimulus so that the output (activity) is
accelerated pg. 11, fig. 1.6}.
Regional Terms
Used to designate specific areas within the major body divisions.
Axial - part that makes up the main axis of the body; head, neck, &
truck.
Appendicular - part that consists of the appendages or limbs; arms &
legs.
Body Planes
In the study of Anatomy, the body is often sectioned along a flat surface
called a plane. A section is named for the plane along which it is cut.
Sagittal plane - a vertical plane that divides the body into left & right
halves.
Median or Midsagittal plane - a vertical plane that lies directly in the
center (midline) of the body
Frontal or Coronal plane - a vertical plane that divides the body into
anterior & posterior parts.
Transverse or Horizontal plane - a horizontal plane that divide the
body into superior & inferior parts; also called a cross section.
Body Cavities
Within the axial portion of the body are two large cavities. They are closed
to the out side & each contains internal organs.
Dorsal Body Cavity - contains two divisions.
Cranial cavity - within which the brain is encased by the skull.
Vertebral or Spinal cavity - runs within in the bony vertebral &
encloses the spinal cord.
Ventral Body Cavity - contains two divisions.
Thoracic cavity - surrounded by the ribs.
Pleural cavities - each houses a lung, & the medial mediastinum.
Pericardial cavity - within the mediastinum, encloses the
heart, & surrounds the thoracic organs (esophagus, trachea,
ect.)
Abdominopelvic cavity - a dome-shaped muscle important in
breathing.
Abdominal cavity - contains the stomach, spleen, liver,
intestines, & other organs.
Pelvic cavity - contains the bladder, rectum, & reproductive
organs.















Homework (pgs. 11-12, & 14) February 9, 1999

‘Homeostatic Imbalance’

Homeostasis is so important that most disease is regarded as a result of
its disturbance, a condition called homeostatic imbalance. As we age, our
body organs & control systems become less efficient. As a result, our
internal environment becomes less & less stable. These events place us at
an even greater risk for illness & produce the changes we associate with
aging.
Another important source of homeostatic imbalance occurs in certain
pathological situations when the usual negative feedback mechanisms are
overwhelmed & destroyed by the positive feedback mechanisms take over.
Some instances of heart failure reflect this phenomenon.

‘Anatomical Position & Directional Terms’

To describe body parts & position accurately, we need an initial reference
point & must use indications of direction. The anatomical reference point
is a standard body position called anatomical position. In this position,
the body is erect with feet together. The terms ‘right’ & ‘left’ refer to those
sides of the cadaver or the person being viewed - not to those of the
observer.
Directional terms allow us to explain exactly where one body structure is
in relation to another. Anatomical terminology saves words & is less
ambiguous; anatomical meanings are very precise.
Orientation & Directional Terms
Superior (cranial) - toward the head end or upper part of a structure
or the body; above. Example: The head is superior to the abdomen.
Inferior (caudal) - away from the head end or toward the lower part of
a structure or the body; below. Example: The navel is inferior to the
chin.
Anterior (ventral) - toward or at the front of the body; in front of.
Example: The breastbone is anterior to the spine.
Posterior (dorsal) - toward or the back of the body; behind. Example:
The heart is posterior to the breastbone.
Medial - toward or at the midline of the body; on the inner side of.
Example: The heart is medial to the arm.
Lateral - away from the midline of the body; on the outside of.
Example: The arms are lateral to the chest.
Intermediate - Between a more medial & more lateral structure;
Example: The collarbone is intermediate between the breastbone & the
shoulder.
Proximal - Closer to the origin of the body part or the point of
attachment of a limb to the body trunk. Example: The elbow is proximal
to the wrist.
Distal - farther from the origin of the body part or the point of
attachment of a limb to the body trunk. Example: The knee is distal to
the thigh.
Superficial - Toward or at the body surface. Example: The skin is
superficial to the skeletal muscles.
Deep - away from the body surface; more internal. Example: The lungs
are deep to the skin.







Classwork (pg. 17) February 10, 1999

‘Body Cavities & Membranes’

Membranes in the Ventral Body Cavity
The walls of the ventral body cavity & the outer surfaces of the organs it
contains are covered by serous membrane. The one lining the cavity wall
is the parietal serosa, which folds on itself to form the visceral serosa pg.
17, fig. 1.10} for all the cavities.
Other cavities
Oral & Digestive cavity - oral cavity, commonly called the mouth
Nasal cavity - located within & posterior to the nose.
Orbital cavities - house the eyes & present them in an anterior
position.
Middle Ear cavities - carved into the temporal bone of the skull lie just
medial to the eardrum; contain tiny bones that transmit sound
vibrations.
Synovial cavities - are joint cavities; enclosed within fibrous capsules
that surround freely movable joints of the body (ex.- elbow & knee
capsules).











Classwork (pgs. 109-113, 119,132, 134 ) February 12, 1999

‘Types of Tissues’

Histology is the study of tissues, it complements the study of gross
anatomy. Tissues are groups of cells that are similar in structure &
perform a common function. Tissues are organizations of similar cells
that are surrounded & often embedded in a nonliving intercellular material
called a matrix.
Four Principle Types of Tissues
Epithelial tissue - is a sheet of cells that covers & protects the body
surface; lines body cavities; moves substances in & out of the blood; &
forms some glands.
Connective tissue - supports the body & connects body parts; found
everywhere in the body.
Muscle tissue - produce most types of body movement.
Nervous tissue - most complex body tissue; specializes in
communication between various parts of the body.
Functions of the Epithelial Tissue
Protection - the skin protects the body from mechanical, chemical, &
invading bacteria.
Sensory Functions - skin, nose, eyes. & ears.
Excretion - found in the lining of the kidneys tubule makes it possible.
Filtration - also in kidneys; filters blood so it can be excreted.
Secretion - secretes hormones, mucus, digestive juices, & sweat.
Absorption - found in the lining of the gut & respiratory tract. This
allows for absorption of nutrients from the gut; & exchange of gases
between the lungs & heart.
Classification of Epithelia
Each epithelium is given two names. The first name indicates the # of cell
layers present; the second describes the shape of its cells.
Simple Epithelia
The simple epithelia are concerned with absorption, secretion, & filtration.
Protection is not one of their specialties.
Simple Squamous Epithelium - their cells are flattened laterally & their
cytoplasm is spares; in a surface view, it resembles a tiled floor,
perpendicularly they resemble fried eggs. This epithelium is found were
filtration or the exchange of substances by rapid diffusion is a priority.
Simple Cuboidal Epithelium - consists of a single layer of cubical cells &
its spherical nuclei is stained darkly; looks like a string of beads when
viewed microscopically. It functions are excretion & absorption.
Simple Columnar Epithelium - seen a as a single layer of tall, closely
packed cells, aligned like soldiers in a row. Mostly associated with
absorption & secretion. It lines the digestive tract from the stomach to
the rectum.
Pseudostratified Columnar Epithelium - cells vary in height & rest on
the basement membrane, but only the tallest reach the apical surface
of the epithelium; the nuclei are located at different levels above the
basement, thus giving a false (pseudo) impression. They secrete &
absorb substances.












Homework (pgs. 109-110) February 12, 1999

‘Special Characteristics of Epithelium’

Epithelial tissues have many characteristics that distinguish them from
other tissues types.
Cellularity. - Epithelial tissue is composed almost entirely of
close-packed cell. Only a tiny amount of extracellular material lies in
the narrow spaces between them.
Specialized contacts. - Epithelial cells fit closely together to form
continuous sheet. Adjacent cells are bound together at many points by
lateral contacts, including tight junctions & desmosomes.
Polarity. - All epithelia have an apical surface, a free surface exposed
to the body exterior or the cavity of an internal organ, & an attached
basal surface. All epithelia exhibit polarity, meaning that cells near the
apical surface differ from those at the basal surface in both structure &
function.
Although some apical surfaces are smooth & slick, most have
microvilli, finger like extensions of the plasma membrane. Microvilli
tremendously increase the exposed surface area, & in epithelia that
absorb or secrete substances, the microvilli are often so dense that the
cell apices have a fuzzy appearance called a brush border. Some
epithelia, such as that lining the trachea, have motile cilia that propel
substances among their surfaces.
Lying adjacent to the basal surface of an epithelium is a thin
supporting sheet called the basal lamina. This noncellular, adhesive
sheet consists largely of glycoproteins secreted by the epithelial cells.
Functionally, the basal lamina acts as a selective filter; that is, it
determines which molecules diffusing from the underlying connective
tissue will be allowed to enter the epithelium. The basal lamina also
acts as a scaffolding along which epithelial cells can migrate to repair a
wound.
Supported by connective tissue. - All epithelial sheets rest upon & are
supported by connective tissue. Just deep to the basal lamina is the
reticular lamina, a layer of extracellular material containing a fine
network of collagen protein fibers that “belong to” the underlying
connective tissue. Together the two laminae form the membrane
basement. The basement membrane reinforces the epithelial sheet,
helping it to resist stretching & tearing forces, & defines the epithelial
boundary.
An important characteristic of cancerous epithelial cells is their
failure to respect this boundary, which they penetrate to invade the
tissue beneath.
Innervated but avascular. - Although epithelium is innervated (supplied
by nerve fibers), it is avascular (contains no blood vessels). Epithelial
cells are nourished by substances diffusing from blood vessels in the
underlying connective tissue.
Regeneration. - Epithelium has a high regenerative capacity. Some
epithelia are exposed to friction & their surface cells removed by
abrasion. Others are damaged by hostile substances in the external
environment (bacteria, acid, smoke). As long as epithelial cells receive
adequate nutrition, they can replace lost cells rapidly by cell division.









Classwork (pgs. 115-118) February 16, 1999

‘Stratified & Glandular Epithelia’

Stratified Epithelia
Stratified epithelia consists of two or more cell layers.
Stratified Squamous Epithelium - is the most widespread of the
stratified; found in the exterior part of the skin.
Stratified Cuboidal & Stratified Columnar - are rare; usually found in
large ducts & some glands.
Transitional Epithelium - found in the lining of urinary organs.
Transitional epithelium can change shape in order to stretch.
Glandular Epithelia
Epithelium of the glandular type is specialized for secretory activity. All
glands are classified as exocrine or endocrine.
Exocrine glands - discharge their secretory products into ducts (ex.
salivary glands)
Endocrine glands - are ductless; they discharge their secretions
directly: hormones.
Multicellular exocrine glands have two structural elements: ducts &
secretory units. On the basis of their duct structures they are either
simple glands - single unbranched ducts or compound glands - that have a
branched duct. Then they are further described according to their
secretory parts:
Tubular - forms tubes.
Alveolar - small flask like sacs.
Tubuloalveolar - both.
Functional Classifications of Exocrine Glands.
Methods by which they discharge. Three types:
Apocrine Glands - collect their products near the tips of the cell & then
they release into a duct by pinching of (ex. mammary glands).
Holocrine Glands - collect inside the cells & then they rupture (ex.
sedaceous (oil) glands).
Merocrine Glands - discharge directly through the cell membrane (ex.
salivary glands).



























Homework (pgs. 119) February 16, 1999

‘Unicellular Exocrine Glands’

Unicellular exocrine glands are single cells scattered in am epithelial sheet
amid cells with other functions. They have no ducts. In humans, all such
glands produce mucin, a complex glycoprotein that dissolves in water
when secreted. Once dissolved, mucin forms mucus, a slimy coating that
both protects & lubricates surfaces. The only important unicellular glands
in humans are the goblet cells found sprinkled in the columnar epithelium
cells lining the intestinal & respiratory tracts. Although unicellular glands
probably outnumber multicellular glands, unicellular glands are the less
well known of the two glands types.


















Classwork (pgs. 119, 122-126) February 17, 1999

‘Connective Tissue’

Connective Tissue is the most abundant tissue. Its major functions are:
Binding & Support
Protection
Insulation & Blood
Transportation
Common Characteristics of Connective Tissue
Common origin - derived from the mesoderm.
Degrees of vascularity; some are vascularized, others are not.
Extracellular matrix - this separates the living cells of the tissue.
Two Classes of Connective Tissue
The first is divided into four groups.
Loose Ordinary Tissue (Areolar) - found between other tissues or
other organs; used in connection; it is a fluid.
Adipose Tissue (Fat) - found under the skin & as padding at various
points. Used for protection, insulation, & a reserve for food.
Reticular Tissue - slender branching of reticular fibers forms the
framework for the spleen, lymph nodes, & bone marrow; look like
little strings that run in all directions.
Dense Fibrous Tissue - tendons & ligaments; they are bundles or
callagenous fibers in parallel rows in a fluid matrix; they are thicker
strings that run in one direction.
The second class of connective tissue contains cartilage - has qualities
intermediate between dense fibrous connective tissue & bone. It is
avascular (no bloods run through it) & has no nerves.
Hyal

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