Polymers of the 20 common amino acids joined together by a peptide bond. Human peptide bonds always occur at cis because this form is more stable. The amount of rotation of the bonds is restricted to the side chains (r groups) at either side of the peptide bond. In general, the more bulkier, the more restricted the rotation.
Represents the sequence of amino acids in a peptide chain including the disulfide bonds and post-translational changes.
Represents the twisting and folding of the neighboring amino acids in the polypeptide chain. It is stabalized by hydrogen bonds -ex alpha helix
Refers to the three dimensional shape of the polypeptide chain. It is supported by several types of bonds as disulfide bridges, hydrogen, ionic, and hydrophobic interaction
ex- B-pleated sheet
Arrangements of individual polypeptide bonds relative to one another.
Comprised of a nitrogenous base (purine or pyrimidine) a pentose sugar (rib or dexyrib) and a phosphate group. A specific sequence of purines and pyrimidines encode the genetic info of the human cell.
Levels of Complexity of Cells
Atomical, Molecular, Compound, Cellular, Tissues, Organs, Systems
Process for exporting substances from the cell
(eg. neurotransmitters, hormones, digestive enzymes)
eg. antibodies crossing the placenta
Gel like fluid in which the cells metabolic reactions occur. Contains suspended particles, minute filaments, and tubules
Specialized structures related with cell growth, repair, and maintenance.
Internal network of proteins inside the cytoplasm involved in locomotion, phagocytosis, and cell wall strength.
Rod like structure composed of actin filaments that provides support and movement assisting in cell shape.
Largest of the cytoskeletal components. Cylindrical structure consists of tubulin. Major function is assembly of centromeres during cell division.
Mainly composed of microtubules. Both structures are motile but only the flagella allows for locomotion.
Flagella and Cilia
Largest Organelle. Is enclosed in a bi-layer membrane continuous with the ER. It harbors the genetic blueprints that directs cell division and production of proteins. Its nucleoli is involved in the production of rRNA.
Membrane bound network of channels providing surface area for chemical reactions
Related with synthesis of lipids and detoxification of drugs.
Synthesis for proteins to be exported
Cytoplasmic site for protein translation and assembly. Some are free in the cytoplasm, while others are attached to the ER. 2 subunits Large 80's, and Small 30's
Membrane enclosed cisternae where proteins and lipids are packaged into secretory vesicles for export or insertion into the cell membrane.
Specialized vesicles which contain digestive enzymes for breakdown of nutrients and foreign bodies. Involved in Autophagy.
Specialized vesicles which contains enzymes for oxidation of organic substances.
Cytoplasmic and nuclear organelle involved in the destruction of unneeded or damage proteins
Organelle in which energy is produced during cellular respiration.
Include normal endogenous compounds and storage of nutrients- ex lipofusin, melanin, glycogen
An iron storage compound found within the cell. Is brown colored)
Grandular yellow-brown pigmented granules composed of lipid-containing residues of lysosomal digestion.
Sequence of events through which a cell undergoes complete division with a final product of two identical cells
Is the cell cycle similar in all cells?
No, it depends on the types of cells.. but it does have similar events.
Cells which proceed through the cell cycle from one mitosis to the next proliferating throughout its life.
Continuously dividing (labile) cells
Surfaces of the skin, oral cavity, vagina, cervix
Ducts of endocrine and exocrine glands
GI tract, Uterus, Fallopian tubes, Transitional epithelium of the urinary tract and the hematopoietic cell.
Quiescent (stable) cells
Demonstrate low level of reproduction under adequate stimuli promotes rapid increase in cell division.
ex- Hepatocytes, pancreatic, kidney, endothelial and smooth muscle cells
Nondividing (permanent) cells
Cells which exited cell cycle at some point during intrauterine (fetal) development and will not undergo further mitotic division during post natal life
ex- nerve cells, cardiac cells (myocytes) and to some extent the skeletal muscle cells.
Somatic cells are in:
Germ cells are in:
What is the cell cycle composed of
Duplication of genetic component (mitosis)
Cytoplasmic division (cytokinesis)
Cell cycle process- 3 phases
Phase between cell division
Cell engages in growth, metabolism, and production of substances required for division
(No chromosomal replication)
Synthesis and replicayion of new DNA and associated proteins
Cell engages in growth, metabolism, and production of substances required for division
-No chromosomal replication-
4 phases of Mitosis
The longest phase
Condensation of chromatin fibers becomes the chromosomes.
The nucleoli disappears and the nuclear enveope break down.
The mitotic spindle is formed developing three types of microtubules
The mitotic spindle attaches to the chromosomes and distributes them to opposite poles
3 types of microtubules formed by the mitotic spindle
The centromeres line up in exact center of mitotic spindle (equatoral plane region)
The splitting and separation of centromeres and movement of sister chromatids toward opposite poles.
The shortest phase
Begins when chromosomal movement stops. The chromosomes begin to uncoil and two nuclear envelopes forms and the mitotic spindle breaks up.
Cytoplasmic division between the two daughter cells
1. Ability to stimulate cells into division by using mitogens (PHA)
2. Chemical agents that are toxic for mitotic spindle arresting cell division during mitosis
3. Use of hypotonic solutions
4. In vitro culture of human cells
5. Availability of different staining techniques
Which cells may be used for karyotyping?
Any cells that may be promoted into division can be used.
The most common cells or tissues used for karyotuping
1. Amniocytes (12-16 weeks in pregnancy)
2. Chorionic villi (earlier in pregnancy, when the mom hase undergone more then 2 spontaneous abortions)
3. Bone Marrow
4. Special studies for studying malignant processes
Have 46 chromosomes
22 Autosome (pairs) - alike in both sexes
1 pair of sex chromosomes
XX = female
Composed of 2 chromatids joined by a centromere or central are of condensation
P= short arm
Q = long arm
How are human chromosomes identified
By their characteristics in 8 groups A-H
Location of centromere
Presence of satelites
When a chromosome is stained, a specific set of band patterns is observed
Organized procedure for matching and alining the identical chromosome pairs.
It will always state the chromosomal complement and sex.
Clinical application of Karyotyping
Detect structural abnormalities of a chromosome
Detect numerical variation associated with specific syndromes which allows for early (inutero) diagnosis of chromosomal abnormalities.
The electrochemical difference between the intracellular and extracellular environment is maintained by what?
The cell membrane
A Resting Membrane Potential is formed by what?
The inside surface is relatively negative charged than the extracellular space producing a voltege difference or...
membrane potential/ diffusion potential
Main Cations in membrane
Main Anions in membrane
Factors contributing in the production of a resting membrane potential (3)
1- Unequal distribution of ions across the membrane
2- Relative membrane permeability for Na+, K+, and Cl-
3. Permeability is 50-100x greater for K+ than for Na+
The 2 types of electrical signals that muscle and neurons use
1- Graded potentials (for short distance communication)
2- Action potentials
Electrical signals produced by neurons and muscles rely on these 4 types of ion channels
Mechanically gated channels
These gates are randomly opened or closed to maintain the electrochemical difference (diffusion potential)
eg- cell membrane allows leakage of K+ to maintain electrochemical difference
Leakage gated channels
Open in response to direct change in membrane channels. Gives neurons and muscle fibers the property of excitability (ability to respond to certain stimuli producing impulses)
Voltage gated channels
Work in responce to specific chemical stimulii changing membrane permeability
Ligand gated channels
2 types of ligand gated channels
1- Direct (Acetylcholine) - Opens channels for Na+, K+, and Ca++
2- Indirect - Work via membrane protein (protein G) as second messenger system
Work in response of vibration, pressure (sound), stretching (pacinian corpuscle), and light (photoreceptors)
Mechanically gated channels
When a stimulus occurs in ligand gated or mechanically gated channels, it produces a small deviation from the membrane potential producing:
-Occurs in a localized region of the membrane, travels for a short distance, and dies out.
Electrical signal produced in excitable cells under proper stimulation leading to a sequence of rapidly occuring events that results in:
Depolarization and Repolarization
Decrease and eventual reversal of membrane potential. Requires a stimuli to depolarize the resting potential to a critical value (threshold)
-depends on Na+ channels (open)
going up the curve
Restauration of resting state
Depends on K+ channels which do not exhibit an inhibitory state
-Na+ channels close, K+ channels open- down the curve
The time during which an excitable cell cannot generate another action potential.
Time in which a second action potential can be initiated by a superthreshold stimulus. Coincides with a period of voltage gated K+ channel open after inactivated Na+ channels have returned to resting state
Relative Refractory Period
Concincides with the period of Na+ channels activation and inactivation
Absolute refractory period
Propagation of Action Potential
Electrical impulse travel dependent on positive feedback.
Since the membrane is refractory behind the leading edge of the Action Potential, it only moves in one direction.
Follows the All or none principle
What is directly related to the diameter of the fiber and the presence or absence of myelin?
Speed of impulse
Myelinated large diameter fibers conducting the fastest impulses
Small myelinated fibers
Small unmyelinated fibers
Occurs in muscle fibers and unmylinated axons
Occurs in myelinated fibers, is more energy efficient, and travel time is faster
The transference of the signal or synapses in human cells occurs in 2 different forms:
Occur through gap junctions "connexons"
Allows for faster communication and synchronization
Chemical synapses (2 things)
1- One way transmission
2- Promotes a response in post-synaptic target
Which neurotransmitters are Inhibitory
Gaba and Serotonine
Which neurotransmitters are Excitatory
Acetylcholine (cholinergic neurons)
Norepinepherine (adrenergic neurons)
Graded potential characteristics
Amplitude- Variable sizes, dependent on strength to start it
Channels- different types
Location- mainly in dendrites
Refractory Period- none
Action potential characteristics
Amplitude- same size
Channels- Voltage gated ion
Location- arise at triggered zone propagating along the axon.
Refractory period- Present
Body is upright
Body is laying face down
Body is lying face up
Skull and face
Supports the head and attaches to trunk
Chest, abdomen, and pelvis
Attaches to trunk (shoulder, armpit, and arm)
Attaches to trunk (buttock, thigh, leg, ankle, and foot)
Nearer or at the Front of the body
Anterior/ ventral / frontal
Nearer or at the Back of the body
Toward the head
Away from the head
Nearer to the attachment of a limb to the trunk
Farther from the attachment of a limb to the trunk
Farther from the midline
Nearer to the midline
Imaginary flat surfaces that pass through the body parts
Planes and Sections
A vertical plane that divides the body into right and left sides
Divides the body into equal right and left sides
Divides the body into unequal right and left sides
Divides the body or an organ into anterior and posterior portions.
Frontal or Coronal plane
Divides the body or an orgain into superior and inferior portions.
Also, cross sectional or horizontal plane
Passes through the body or an organ at an angle
-Between transverse and sagittal or between transverse and frontal
Spaces within the body that help protect, separate, and support the internal organs
Formed by the cranial bones
Protects the brain
Formed by bones of vertebral column
Contains the spinal cord
Layers of protective tissue that line the cranial cavity and vetebral canal.
Thoracic Cavity is formed by:
Muscles of the chest
Vertebral column (thoracic portion)
2 cavities within the thoracic cavity
Extends from the diaphragm to the groin
Stomach, Spleen, Liver, Gallbladder, Small and Large Intestine
Urinary Bladder, Inernal organs of reproductive system, and portions of the large intestine.
Nine Abdominopelvic Regions
R & L Hypochondriac
Epigastric and Hypogastric
Right and Left Lumbar
Right and Left Inguinal
Vertical and horizontal likes that pass through the umbilicus
RUQ, LUQ, RLQ, LLQ
Middle ear cavities
An organized aggregation of cells that function in a collective manner
Sites that mediate electric coupling between cells. Also permit the prederential passage of small molecules from cell to cell.
Intercellular channels that permit the free passage between the cells of ions and small molecules.
They are cylinders constructed form the 6 copies of transmembrane proteins called connexins.
Permit changes in membrane potential to pass from cell to cell.
Ex- heartbeat, electrical synapses in
4 tissue types
A Pas positive + recation means:
The presence of polysaccharides
Description of Pseudostratified epithelia
all cells rest on the basement membrane,
only some cells reach the free surface,
Actually, a simple epithelium. (stratisfied should have two or more layers)
Has limited Distrubtion in the body
Reflects the role of stem cells in maintaining a stable population of cells to balance cell turnover.
ex- Pseudostratisfied columnar
epithelium of the trachea
Epithelia involved in secretion and/or absorbtion are typically what type:
Simple or Pseudostratisfied
What are Goblet cells?
Single cells in the epithelium that have secretory function. They secrete a mucous substance.
Are unicellular glands.
What are the characteristics of a Secretory Cell
Have a well developed ER
A Golgi apparatus to fulfill their function
Vesicles and granules
Multiple join together to form multicellular glands
Most in humans are cuboidal columnar
Ex- cells of epithelium of GI tract that
secrete digestive enzymes and gastric acid, or Meibomian glands in the eyelid
that secrete sebum to lubricate and protect the eye.
3 ways that exocrine glands release their products
Cells that secrete products via this method form membrane-bound secretory vesicles internal to the cell.
These are moved to the apical surface where the vesicles coalesce with the membrane on the apical surface to release the product.
Most common- Most glands release their products this way.
In glands that release the product via this method, the apical portions of cells are pinched off and lost during the secretory process.
This results in a secretory product that contains a variety of molecular components including those of the membrane.
Mammary Glands release their products in this manner.
The type of secretory release that involves cell death.
The secretory cells is released and as it breaks apart, the contents of the cell become the secretory product.
This mode of secretion results in the most complex secretory product.
Some sweat glands in the axillae, pubic areas, and areoli of breasts use this method.
Sebaceous glands are also this type
Secretory cells of endocrine glands that can release their substance into the adjacent cells or surrounding tissue rather than into the bloodstream.
Function is _____ signaling
Ex- growth factors, clotting factors.
Overproduction of some of these growth factors have been linked to the development of cancer.
Secretory cells that also release their hormones into the surrounding cells in the tissue.
The chemical agent, or hormone, affects cells of the same type.
The function is _________ signaling
A form of signaling in which a cell secreated a hormone (or chemical messenger) that binds to autocrine receptors on the same cell, leading to changes in the cell.
Examples- T cell lymphocytes
Cytokine interleukin 1- in monocytes
What are Macula Adherens
A focal junction- a spot in the cell membrane where adhesion occurs.
What are Zonula Adherens?
A Band junction- the area of adhesion that surrounds cell membanes.
Usually found adjacent to zonla occlusions
Found in the intercellular junctions of the RPE
Between the Muller cells of the Retina
At the Myoid portion of the photoreceptors of the retina forming the outer limiting membrane of the retina.
Differences in Macula and Zona Occludens
Both are associated with a keratin-based cytoskeleton.
Macula possess specific transmembane receptors of the integrin family that link the cell to the extracellular matrix on the outside of the cell and the microfilament system on the inside.
Zonula has members of a family of calcium ion-dependent cell adhesion molecules, called Ca-adherens, that mediate attachment between cells at junctions.
What the Macula and Zonula Occludens do:
They join cells together or to the extracellular matrix.
Transduce signals into and out of the cell, including proliferation, migration, and differentiation.
Some components can shuttle to and from the nucleus where they are thought to play a role in regulating gene
What are Desmosomes
Same as macula adherens but:
There is a “cellular bridge”
Present an electron-dense intercellular material parallel to the cell membrane, forming a line.
Present numerous tonofilaments in the cytoplasm oriented at right angle with respect to the cell junction
Found in the epidermis, corneal epithelium, optic cup epthelium, and the CNS.
What are Hemidesmosomes
A special type of desmosomes found at the base of epithelial cells
Fasten the epithelium to the basement membrane
How are fibers organized in the dense regular connective tissue? (tendons)
The fibers are all aligned in a single direction, conferring tensile strength primarily in that direction.
Function of Mast cells?
Secretory alarm cells. Upon the slightest disturbance, they release chemical signals which diffuse through the surrounding ground substance and trigger the process of inflammation.
What is the secretion of the Osteoblasts?
deposit a matrix of Type-1 collegen and also release calcium, magnesium, and phosphate ions that combine within the collagenous matrix into crystalline mineral, known as bone mineral.
What are Osteoclasts?
macrophage relatives which dissolve bone matrix.
What are the Haversian canals
the central canal where the concentric lamellae (the osteon’s concentric layers of mineralized matrix) are deposited.
(compact bone has these)
What are Volkmann canals?
Known as perforating holes, are microscopic structures found in compact bone. They run within the osteons perpendicular to the Haversian canals, interconnecting the latter with each other and the periosteum. They usually run at obtuse angles to the Haversian canals and contain anastomosing vessels between Haversian capillaries. They also carry small arteries throughout the bone.
Direct Function of bone tissue
Support for muscles, organs, and soft tissue
Leaverage and movement
Protection of vital organs
Calcium phosphate storage
Indirect Function of Bone tissue
Hemopoiesis- formation of blood cells by the bone marrow interspersed within the spongy bone.
Main blood production is in the spleen and liver
What is Epithelioid tissue? Examples
They are interstincial cells of leydig of the testis
Examples: luteal cells of the ovary, parenchyma of adrenal glands, epithlioreticular cells of thymus