1.1 Describe the levels of structural organization that make up the human body
ANP1105: (pp. 3-4) Topic 1 Notes
Structural Organization of
the Human 1.2 Cells: summarize the major organelles and structures found in cel(pp.83-96) Body (2
1.1. Describe the levels of structural organization that make up the human body
1.1.1. Define: atom, molecule, organelle, cell, tissue, organ, organ system; give an example of each and localize
each in the hierarchy of anatomical structure
1. Chemical Level: Atoms combine to form molecules.
a. Atoms: smallest particle of an element with all the properties of that element. Parts include:
neutrons, protons, electrons
b. Molecules: the smallest amount of a substance that exist alone= a combination of atoms. Ex.
H2O, C 6 12 6
2. Cellular Level: Cells are made up of molecules
a. Organelle: molecules associate in specific was to form organelles basic components of living
cells. Ex. Nucleus, Mitochondria
b. Cell: Fundamental structural and functional unit of a living thing; cells vary widely in size and
shape, reflecting unique functions in the body.
3. Tissue Level: Tissues consist of groups of similar cells that have a common function. There are 4 types of
a. Epithelium: pertaining to a primary tissue that covers the body surface, lines its internal cavities,
and forms glands.
b. Muscle: a contractile organ consisting of a special bundle of muscle tissue, which moves a
particular bone, part or substance of the body.
c. Connective: a primary tissue; form and function vary extensively. Functions include support,
storage, protection, and binding, connect or separates other tissues and organs.
d. Nervous: main component of the nervous system—brain, spinal cord, and branching peripheral
nerves—which regulates and controls bodily functions. Composed of neurons.
4. Organ Level: Structure composed of at least 2 (usually 4) tissue types that preform a specific function for
a. EX. HEART: composed of muscle tissue (cardiac muscle) contracts pumping blood, nervous
tissue, which conducts the heart’s electrical signals to make it contract in a coordinated manner
and epithelium tissue, mostly from the blood vessels which supply the heart muscle with oxygen
5. Organ System Level: organs that work closely with one another to accomplish a common purpose. Ex:
a. Nervous System: responds to internal and external changes by activating appropriate muscles
and glands. Organsbrain, nerves, spinal cord.
b. Urinary System: eliminates wastes from body, regulates H O2 electrolytes and acid-base balance
of the blood. Organs kidney, ureter, bladder, urethra.
6. Organismal Level: the human organism is made up of man organ systems.
1.2. Cells: describe the major structures found in body cells
1.2.1. Define the following cytological terms: cell, nucleus, cytoplasm, plasma membrane, semi-permeable
• Cell: structural unit of all living things
• Nucleus: (1) Control center of a cell; contains genetic material; (2) clusters of nerve cell bodies in the
• Cytoplasm: The cellular material surrounding the nucleus and enclosed by the plasma membrane.
1 • Plasma Membrane: Membrane; composed of phospholipids, cholesterol, and proteins, that encloses cell
contents; outer limiting cell membrane.
• Semi-Permeable: A membrane that allows certain substances to pass while restricting the movement of others; also
called differentially permeable membrane.
1.2.2. Define: cytosol, organelle, cell inclusion; list, recognize the structure, and indicate the functions of each of
the following organelles: mitochondrion, peroxisomes, endoplasmic reticulum, Golgi apparatus, lysosome
• Cytosol: Viscous, semitransparent fluid substance of cytoplasm in which other elements are suspended.
• Organelle: Small cellular structures that preform specific metabolic functions for the cell as a whole.
• Cell inclusion: any foreign matter or residual elements of the cytoplasm that are enclosed within a cell.
They are metabolic products of the cell (for example, granules or crystals)
Organelle Structure Function
Mitochondria Rod-like, double-membrane Site of ATP synthesis;
structures; inner membrane powerhouse of the cell.
folded into projections
Peroxisomes Membranous sacs of The enzymes detoxify a
catalase and oxidase number of toxic
enzymes. substances. The most
catalase, breaks down
Endoplasmic Smoot Membranous system of Site of lipid and steroid
Reticulum h sacs and tubules; free of (cholesterol) synthesis,
ribosomes. lipid metabolism, and drug
Rough Membranous system Sugar groups are attached
enclosing a cavity, the to proteins within the
cistern, and coiling through cisterns. Proteins are
the cytoplasm. Externally bound in vesicles for
studded with ribosomes. transport to the Golgi
apparatus and other sites.
External face synthesizes
Ribosomes Dense particles consisting The site of protein
of two subunits, each synthesis.
composed of ribosomal
RNA and protein. Free or
attached to rough
Golgi Apparatus A stack of flattened Packages, modifies, and
membranes and associated segregates proteins for
vesicles close to the secretion from the cell,
nucleus. inclusion in lysosomes,
and incorporation into the
Lysosomes Membranous sacs Sites of intracellular
containing acid hydrolases. digestion.
2 **SEE PAGES 94-94 FOR FURTHER CLARIFICATION**
1.2.3. Name and briefly describe the 3 types of cytoskeletal filaments; define centriole and distinguish between a
cilium and a flagellum
Cytoskeleton: is an elaborate network of rods running through the cytosol and hundreds of accessory
proteins that link these rods to other cell structures.
• Acts as a cell’s “bone,” “muscles,” and “ligaments” by supporting cellular structures and providing
the machinery to generate various cell movements.
Three types of cytoskeletal filaments:
a. The thinnest elements of the cytoskeleton, are semi-flexible strands of the protein actin7nm
b. Nearly all cells have a fairly dense cross-linked network of microfilaments, called the terminal
web, attached to the cytoplasmic site of their membrane. The web strengthens the cell surface,
resists compression, and transmits force during cellular movements and shape changes.
c. Most microfilaments are involved in cell motility or changes in cell shape.
d. Ex. Actin filaments interact with another protein, unconventional myosin to generate contractile
forces in a cell
i. This interaction also forms the cleavage furrow that pinches one cell into 2 during cell
e. Except in muscle cells, where they are highly developed, stable, and long-lived, actin filaments
are constantly breaking down and re-forming from smaller subunits whenever and wherever they
3 are needed.
2. Intermediate filaments
a. Tough, insoluble protein fibers that resemble woven ropes. Made of twisted units of tetramer (4)
b. Are the most stable and permanent of the filaments and have a high tensile strength.
c. They attach to desmosomes and their main function is to act as an internal guy-wires to resist
pulling forces exerted on the cell.
d. Numerous types of intermediate filaments as protein composition is different for each cell type
they’re different names. Ex. Neurofilaments in nerve cells, keratin filaments in epithelial cells.
a. Hollow tubes of spherical protein subunits called tubulins25nm
b. Most microtubules radiate from a small region of cytoplasm near the nucleus called the
centrosome or cell center.
c. They are constantly growing out from the centrosome, disassembling, and then reassembling at
the same or different sites.
d. Determine the overall shape of the cell, as well as the distribution or cellular organelles.
e. Mitochondria, lysosomes, and secretory vesicles attach to the microtubules like ornaments
hanging. Tiny protein machines called motor proteins continually move and reposition the
organelles along the microtubules.
• Centriole: Paired cylindrical bodies, each composed of nine triplets of microtubules. As part of the
centrosome, organize a microtubules network during mitosis (cell division) to form the spindle and asters.
Form the bases of cilia and flagella.
• Cilium: Short cell-surface projections; each cilium composed of 9 microtubules surrounding a central pair.
Coordinated movement creates a unidirectional current that propels other substances across cell
• Flagellum: Like cilium, but longer; on example in humans is the sperm cell. Propels the cell.
1.2.4. Briefly describe the structural organization of the nucleus demonstrating your understanding of the terms:
nuclear envelope, nuclear pore, nucleolus, chromatin
• Nuclear Envelope
o The nucleus is bounded by the nuclear envelope separated by a fluid-filled space.
o The outer nuclear membrane is continuous with the rough ER of the cytoplasm and is studded
with ribosomes on its external face.
o The inner nuclear membrane is lined by the nuclear lamina, a network of lamins that maintains
the shape of the nucleus and acts as a scaffold to organize DNA in the nucleus.
o Selectively permeable; separates the nucleoplasm from the cytoplasm and regulates passage of
the substances to and from the nucleus
o The nuclear envelope encloses a jelly like fluid called nucleoplasm in which other nuclear
elements are suspended.
• Nuclear Pore
o At various points the nuclear envelope is punctuated with nuclear pores
o Nuclear pore complex lines each pore forming an aqueous transport channel and regulates entry
and exit of molecules and large particles into and out of the nucleus.
o Are the dark staining spherical bodies found within the nucleus where ribosomal subunits are
o Are not membrane bound.
o 1-2 nucleoli per nucleus
4 • Chromatin
o A system of bumpy threads weaving through the nucleoplasm.
o Composed of:
30% DNA; our genetic material
60% globular histone proteins, which package and regulate the DNA
10% RNA chains, newly formed or forming
o Fundamental subunits nucleosomes which consist of flattened disc shaped cores or clusters of
eight histone proteins connected like beads on string by a DNA molecule
o Histones provide a physical means for packing the very long DNA molecules.
They also plan an important role in gene regulation
o When a cell is preparing to divide, the chromatin threads coil and condense enormously to form
short, bar-like bodies called chromosomes.
Chromosomes compactness prevents the delicate chromatin strands from tangling and
breaking during the movements that occur during cell division.
1.3. Tissues: Describe the different tissues of the human body
1.3.1. Define tissue and demonstrate how the organization of cells into tissues contributes to overall homeostasis
• Tissue (tissue= woven) are groups of cells that are similar in structure and perform a common or related
• Individual body cells are specialized, with each type performing specific functions that help maintain
homeostasis and benefit the body as a whole.
• When a particular group of cells is indispensible, its injury or loss can disable or even destroy the body.
• Histology: the study of tissues and their cellular organization
1.3.2. List the 4 primary types of tissues
1. Epithelial Tissue: Covers
a. Forms boundaries between different environments, protects, secretes, absorbs, filters.
i. Lining of digestive tract organs and other hollow organs
ii. Skin surface (epidermis)
2. Connective Tissue: Supports
a. Supports, protects, binds other tissues together
iii. Fat and other soft padding tissue
3. Nervous Tissue: Controls
a. Internal communication
ii. Spinal cord
4. Muscle Tissue: Movement
a. Contracts to cause movement
i. Muscles attached to bones (skeleton)
ii. Muscles of heart (cardiac)
iii. Muscles of walls of hollow organs (smooth)
1.3.3. Define epithelial tissue and list 6 functions associated with various types of epithelia
5 • Epithelial Tissue: Sheet of cells that covers a body surface or lines a body cavity. Creates boundaries.
1. Covering and lining epithelium
a. Which forms the outer layer of skin; dips into and lines the open cavities of the urogenital,
digestive, and respiratory systems; and covers the walls and organs of the closed ventral
2. Glandular Epithelium
a. Which fashions the glands of the body
• Functions associated:
o Protection: mechanical, chemical, infectious—skin
o Absorption—GI Tract
o Sensory Reception—Taste buds, olfactory membranes
1.3.4. List and demonstrate your understanding of 7 special structural characteristics of epithelial tissue
a. Composed almost entirely of cells. The cells are close and only a small amount of extracellular
material lies in the narrow spaces between them.
2. Specialized Contacts
a. Except for glandular epithelia, epithelial cells fit closely together to form continuous sheets.
b. Lateral contacts, including tight junctions and desmosomes, bind adjacent cells together at many
c. These tight junctions help keep proteins in the apical region of the plasma membrane from
diffusing into the basal region, and thus help to maintain epithelial polarity.
a. All epithelial cells have apical surface, an upper free surface exposed to the body exterior or the
cavity of an internal organ, and a lower attached basal surface.
i. The two surfaces differ in both structure and function
b. Some apical surfaces are smooth and slick, most have microvilli, (ex. lining of intestines) which
increase surface area. In epithelial cells that absorb or secrete substances, the microvilli are
often so dense that the cell apices have a fuzzy appearance called a brush border. Other
epithelia (ex. Trachea) have motile cilia that propel substances across their surface.
4. Basil Lamina
a. Adjacent to the basal surface of an epithelium is a thin supporting sheet.
b. Noncellular, adhesive sheet consists largely of glycoproteins secreted by the epithelial cells plus
some fine collagen fibers.
c. It acts as a selective filter that determines which molecules diffusing from the underlying
connective tissue are allowed to enter the epithelium.
d. It also acts as scaffolding along which epithelial cells can migrate to repair a wound.
5. Supported by connective tissue
a. All epithelial tiss