Cells and Tissues Flashcards
- Robert Hooke looks at cork under a microscope
1665
Cell is the basic unit of biological structure and function.
Cell Theory
Mathias Schleiden
1838
Theodore Schwann
1839
Rudolf Virchow
1858
• Entire organism is not merely a group of independent units but rather a living unit subdivided
into cells, which are connected and coordinated into a harmonious whole.
Organismal Theory
Organismal Theory
(1879) Anton de Bary
smallest unit of living structure capable of independent existence,
composed of a membrane-enclosed mass of protoplasm and containing a nucleus.
CELL
are the living structural and functional units enclosed by a membrane.
CELLS
are the living structural and functional units enclosed by a membrane.
CELLS
the study of cellular structure and function
CYTOLOGY
•All organisms are composed of one or more cells
•Chemical reactions of living organisms, including its energy-related
processes and its biosynthetic processes occur within the cell
•Cell contain the hereditary information of the organisms of which they
are part.
Cell Theory (Modern Form)
• First to arise in biological evolution
• Generally solitary with then nuclear material unenclosed in a membrane
Prokaryotic Cells
• Multicellular and provided with a nuclear membrane
• Larger and more complex, with a wider range of diversity and differentiation
Eukaryotic
Cell Functions
• Basic Unit of Life
• Protection and Support
• Movement
• Communication
• Metabolism and energy
release
• Inheritance
Physiologic Properties of Cells
• Excitability
• Conductivity
• Contractility
• Absorption and Secretion
• Excretion
• Respiration
• Growth and Reproduction
• Organization
PRINCIPAL PARTS OF THE CELL
A. Cell Membrane
B. Cytoplasm
C. Nucleus
• Flexible yet sturdy barrier that surrounds and contains the cytoplasm of a cell.
• Fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment
Cell Membrane
the arrangement of molecules within the membrane resembles a sea of lipids containing many types of proteins.
• The lipids act as a barrier to certain substances.
• The proteins act as “gatekeepers” to certain molecules and ions
The fluid mosaic model
Cell Membrane Functions
• Gives shape to the cell
• Separates the cell from its
environment
• Serves as recognition sites
• Serves as selective barrier
Membrane Proteins
A. Integral protein
B. Peripheral protein
C. Glycoprotein
D. Glycocalyx
• extend into or through the lipid bilayer among the fatty acid tails and are firmly embedded in it.
Integral protein
• attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane.
Peripheral protein
• Membrane proteins with a carbohydrate group attached that protrudes into the extracellular fluid
Glycoprotein
• “sugary coating” surrounding the membrane made up of the carbohydrate portions of the glycolipids and glycoproteins
Glycocalyx
The cell is either permeable or impermeable to certain substances.
MEMBRANE PERMEABILITY
means that a structure permits the passage of substances through it.
Permeable
means that a structure does not permit the passage of substances through it.
Impermeable
GRADIENTS ACROSS THE PLASMA MEMBRANE
• Concentration gradient
• Electrical gradient
Electrochemical gradient
is the difference in the concentration of a chemical between one side of the plasma membrane and the other.
Concentration gradient
is the difference in concentration of ions between one side of the plasma membrane and the other.
Electrical gradient
Together, these gradients make up an
Electrochemical gradient
TRANSPORT MECHANISMS ACROSS THE PLASMA MEMBRANE
I. Passive Process
II. Active Process
I. PASSIVE PROCESS
A. Simple diffusion
B. Osmosis
C. Facilitated Diffusion
D. Filtration
Net movement of particles from an area of higher concentration to an area with lower concentration, that is along their concentration gradient
Simple diffusion
Simple diffusion of water through a selectively permeable membrane
Osmosis
Same as simple diffusion but the diffusing substance is attached to a lipid soluble carrier
Facilitated Diffusion
Movement of water and solutes through a semi-permeable membrane from an area with higher hydrostatic pressure to an area with a lower hydrostatic pressure, that is, along a pressure gradient
Filtration
II. ACTIVE PROCESS
A. Active transport
B. Exocytosis
C. Endocytosis
D. Phagocytosis
E. Pinocytosis
F. Receptor Mediated Endocytosis
• Movement of substance through a membrane against a concentration or electrochemical gradient and requires a membrane carrier protein
Active transport
Secretion or ejection of substances enclosed in a membrane vesicle which fuses with the plasma membrane and ruptures
Exocytosis
Engulfed extracellular substance are brought to the cytoplasm in a membrane-limited vesicle
Endocytosis
Cell eating; insoluble substances are engulfed and are enclosed in a vesicle known as “phagosome”
Phagocytosis
Cell eating; insoluble substances are engulfed and are enclosed in a vesicle known as
Phagocytosis
Cell drinking; engulfment of small amount of fluid enclosed in pinocytic vesicles
Pinocytosis
External substances binds to membrane receptors and are engulfed with their receptors
Receptor Mediated Endocytosis
• The protoplasm outside the nucleus which contains the different organelles and
inclusions
• Divided into an outer gel-like ectoplasm and an inner more liquefied endoplasm
• Cytosol: the clear fluid portion in which the particles are dispersed
B. Cytoplasm
FORMED ELEMENTS OF THE CYTOPLASM
I. Organelles
II. Inclusions
III. Cytoskeleton
• Metabolically active internal organs carrying out specific essential functions
Organelles
Metabolically inert accumulations of cell products
Inclusions
• Responsible for the gel-like consistency of the cytoplasm
• Forms the structural support or framework of the cell
Cytoskeleton
I. ORGANELLES
A. Mitochondria
B. Ribosomes
C. Endoplasmic Reticulum
D. Golgi complex
E. Lysosomes
F. Centrosome
G. Cilia and Flagella
II. INCLUSIONS
A. Glycogen
• Storage form of carbohydrates in animal cells
B. Lipid
• Serves as energy source
• For synthesis of membranes
C. Pigments
D. Crystals
• Least common among the inclusions
III. CYTOSKELETON
A. Microfilaments
B. Intermediate filaments
C. Microtubules
• help generate movement and provide mechanical support
• thinnest elements of the cytoskeleton
• Composed of actin & myosin
Microfilaments
thicker than microfilaments but thinner than microtubules
Intermediate filaments
• largest of the cytoskeletal components and are long, unbranched hollow tubes composed mainly of the protein tubulin
Microtubules
• Control center of the cell
• Repository of genes which are the carriers of hereditary traits of an individual
• DNA is the principal nucleic acid of chromatin
Nucleus
• a single molecule of DNA associated with several proteins, contains thousands of hereditary units called genes.
Chromosome
control most aspects of cellular structure and function
Genes
• Shortest period of the cell cycle
• Nuclear division and Cytoplasmic division
CELL DIVISION
-is a group of cells that usually have a common origin in an embryo and
function together to carry out specialized activities.
-may be hard, semisolid, or even liquid in their consistency, a range
exemplified by bone, fat, and blood.
Tissue
is the science that deals with the study of tissues
Histology
is the science that deals with the study of tissues
Histology
is a physician who specializes in laboratory studies of cells and
tissues to help other physicians make accurate diagnoses.
Pathologist
are contact points between the plasma membranes of tissue cells.
CELL JUNCTIONS
are contact points between the plasma membranes of tissue cells.
CELL JUNCTIONS
CELL JUNCTIONS
Examples:
- Tight Junction
- Adherens Junction
- Desmosome
- Hemidesmosome
- Gap/ Communicating Junction
TYPES OF TISSUES
- Epithelial
- Connective
- Muscular
- Nervous
- Also know as Occluding Junctions or Zonula Occludens
-consist of web-like strands of transmembrane proteins that fuse together the outer surface of the adjacent plasma membrane to seal off passageways between adjacent cells
Tight Junctions
contain plaque, a dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments of the Cytoskeleton.
Adherens Junctions
transmembrane glycoproteins that joins the cells.
Cadherins
Note:
• In epithelial cells, adherens junctions often form extensive zones called adhesion
belts because they encircle the cell similar to the way a belt encircles your waist.
• attaches to elements of the cytoskeleton known as
intermediate filaments, which consist of the protein keratin.
Desmosomes
• resemble desmosomes, but they do not link adjacent cells. The name arises from the fact that they look like half of a desmosome
• However, the transmembrane glycoproteins in hemidesmosomes are integrins rather than cadherin.
HEMIDESMOSOMES
• allow the cells in a tissue to communicate with one another.
• membrane proteins called connexins form tiny fluid-filled tunnels called connexons that connect neighboring cells.
GAP JUNCTIONS
ORIGINS OF EPITHELIUM
A. Ectoderm
B. Mesoderm
C. Endoderm
• Epidermidis, glandular appendages of the skin
Ectoderm
Vascular endothelium, kidneys, reproductive tracts
Mesoderm
Intestinal tract, liver, pancreas and lungs
Endoderm
STRUCTURE OF EPITHELIAL TISSUES
• Apical (free) surface
• Lateral surface
• Basal surface
receives cell secretions; they may or may not contain cilia or microvilli
Apical (free) surface
contains the cell junctions
Lateral surface
deepest; adhere to extracellular matrix such as the basement membrane
Basal surface
TYPES OF EPITHELIAL TISSUE
• Covering and lining epithelium
• Glandular epithelium
• forms the outer covering of the skin and some internal organs.
• It also forms the inner lining of blood vessels, ducts, and body cavities, and the interior of the respiratory, digestive, urinary, and reproductive systems.
Covering and lining epithelium
makes up the secreting portion of glands such as the thyroid gland, adrenal glands, and sweat glands.
Glandular epithelium
• Function for secretion, which is accomplished by glandular cells that often lie in
clusters deep to the covering and lining epithelium.
GLANDULAR EPITHELIUM
GLANDULAR EPITHELIUM
• Endocrine glands
• Exocrine glands
secretes hormones that enter the interstitial fluid and then diffuse directly into the bloodstream without flowing through a duct; ductless glands; secretion is inside
Endocrine glands
secrete their products into ducts that empty onto the surface of a covering and lining epithelium such as the skin surface or the lumen of a hollow organ; secretion is outside
Exocrine glands
• Organs with Exocrine and Endocrine glands: pancreas, ovaries, and testes,
STRUCTURAL CLASSIFICATION OF EXOCRINE GLANDS
- Unicellular glands
- Multicellular glands
are single-celled glands.
• **Goblet cells are important unicellular exocrine glands that secrete mucus
directly onto the apical surface of a lining epithelium.
Unicellular glands
are common in exocrine glands composed of many cells that form a distinctive microscopic structure or macroscopic organ.
Multicellular glands
CLASSIFICATION OF MULTICELLULAR EXOCRINE GLANDS
A. Branched or Unbranched
B. Shape of the secretory portions of the gland
C. Functional Exocrine Glands
Branched or Unbranched
• Simple Gland – if the duct of the gland does not branch.
• Compound Gland – if the duct branches
Shape of the secretory portions of the gland
• Tubular Glands – glands with tubular secretory parts
• Acinar Glands – those with rounded secretory portions; also called alveolar glands.
• Tubuloacinar glands – have both tubular and more rounded secretory parts
SIMPLE EXOCRINE GLANDS
A. Simple tubular
B. Simple branched tubular
C. Simple coiled tubular
D. Simple acinar
E. Simple branched acinar
Tubular secretory part is straight and attaches to a single unbranched
duct.
• Example: glands in the large intestine
Simple tubular
Tubular secretory part is branched and attaches to a single
unbranched duct.
• Example: gastric glands
Simple branched tubular
Tubular secretory part is coiled and attaches to a single
unbranched duct.
Simple coiled tubular
Secretory portion is rounded and attaches to a single unbranched duct.
• Example: glands of the penile urethra
Simple acinar
Rounded secretory part is branched and attaches to a single
unbranched duct.
• Example: Sebaceous glands
Simple branched acinar
COMPOUND EXOCRINE GLANDS
-Compound tubular
-Compound acinar
-Compound tubuloacinar
Secretory portion is tubular and attaches to a branched duct.
• Example: bulbourethral (Cowper’s) glands.
Compound tubular
Secretory portion is tubular and attaches to a branched duct.
• Example: bulbourethral (Cowper’s) glands.
Compound tubular
Secretory portion is rounded and attaches to a branched duct.
• Example: mammary glands
Compound acinar
Secretory portion is both tubular and rounded and attaches to a branched duct.
• Example: acinar glands of the pancreas
Compound tubuloacinar
are synthesized on ribosomes attached to rough ER; processed, sorted, and packaged by the Golgi complex; and released from the cell in secretory vesicles via exocytosis.
A. Merocrine Glands
accumulate their secretory product at the apical surface of the secreting cell. Then, that portion of the cell pinches off by exocytosis from the rest of the cell to release the secretion
Apocrine glands
their cells accumulate a secretory product in their cytosol; As the secretory cell matures, it ruptures and becomes the secretory product because the cell ruptures in this mode of secretion.
Holocrine Glands
are one of the most abundant and widely distributed tissues in the body.
Functions:
• They bind together, support, and strengthen other body tissues;
• Protect and insulate internal organs
• Compartmentalize structures such as skeletal muscles
• Serve as the major transport system within the body (blood, a fluid connective
tissue)
CONNECTIVE TISSUES
- is the material located between its widely spaced cells.
• Secreted by connective tissue cells
• It consists of protein fibers and ground substance, the material between the cells and the fibers
• Controls the watery environment via specific proteoglycan molecules.
Extracellular Matrix
CONNECTIVE TISSUE CELLS
- Fibroblasts (fibro-fibers)
- Macrophage (macro- large; -phages eaters)
- Plasma cells
- Mast cells
- Adipocytes
- White blood cells
are large, flat cells with branching processes. They are
present in all the general connective tissues, and usually are the most numerous.
Fibroblasts (fibro-fibers)
develop from monocytes.
Macrophage (macro- large; -phages eaters)
reside in a particular tissue; Eg. Alveolar macrophages in the lungs or
splenic macrophages in the spleen
Fixed Macrophage
have the ability to move throughout the tissue and gather at sites
of infection or inflammation to carry on phagocytosis.
Wondering Macrophage
are small cells that develop from a type of white blood cell called a B lymphocyte.
• Secrete antibodies, proteins that attack or neutralize foreign substances in the body.
• Most plasma cells reside in connective tissues, especially in the gastrointestinal and respiratory tracts.
Plasma cells
are abundant alongside the blood vessels that supply connective tissue. They produce histamine, a chemical that dilates small blood vessels as part of the inflammatory response, the body’s reaction to injury or infection.
Mast cells
also called fat cells are connective tissue cells that store triglycerides (fats).
• They are found deep to the skin and around organs such as the heart and kidneys.
Adipocytes
are not found in significant numbers in normal connective tissues. However, in response to certain conditions they migrate from blood into connective tissues.
White blood cells
gather at sites of infection
Neutrophils
migrate to sites of parasitic invasions and allergic responses
Eosinophils
• The ground substance is the component of a connective tissue between the cells and fibers. The ground substance may be fluid, semifluid, gelatinous, or calcified.
• It supports cells, binds them together, stores water, and provides a medium for
exchange of substances between the blood and cells.
• Component:
• Water and an assortment of large organic molecules (polysaccharides and proteins.
EXTRACELLULAR MATRIX
The polysaccharides include:
• a. Hyaluronic acid
b. Chondroitin sulfate
c. Dermatan sulfate
• d. Keratan sulfate
GROUND SUBSTANCE
-Hyaluronic acid
-Chondroitin sulfate
-Dermatan sulfate
-Keratan sulfate
-Adhesion proteins
is a viscous, slippery substance that binds cells together, lubricates joints, and helps maintain the shape of the eyeballs.
• White blood cells, sperm cells, and some bacteria produce hyaluronidase, an enzyme that breaks apart hyaluronic acid, thus causing the ground substance of connective tissue to become more liquid.
Hyaluronic acid
provides support and adhesiveness in cartilage, bone, skin, and
blood vessels.
Chondroitin sulfate
found in the skin, tendons, blood vessels, and heart valves.
Dermatan sulfate
found in the bone, cartilage, and the cornea of the eye.
Keratan sulfate
found in the bone, cartilage, and the cornea of the eye.
Keratan sulfate
are responsible for linking components of the ground substance
to one another and to the surfaces of cells.
Adhesion proteins
main adhesion protein of connective tissues which binds to both collagen fibers
and ground substance, linking them together.
fibronectin
PROTEIN FIBERS
A. Collagen fibers
B. Elastic fibers
C. Reticular fibers
are very strong and resist pulling forces (tension), but they are not stiff, which allows tissue flexibility.
• The properties of different types of collagen fibers vary from tissue to tissue.
A. Collagen fibers (colla = glue)
are smaller in diameter than collagen fibers, branch and join together to form a fibrous network within a connective tissue.
Elastic fibers
consisting of collagen arranged in fine bundles with a coating of glycoprotein, provide support in the walls of blood vessels and form a network around the cells in some tissues, such as areolar connective tissue (areol- small space), adipose tissue,
nerve fibers, and smooth muscle tissue.
Reticular fibers (reticul = net)
consisting of collagen arranged in fine bundles with a coating of glycoprotein, provide support in the walls of blood vessels and form a network around the cells in some tissues, such as areolar connective tissue (areol- small space), adipose tissue,
nerve fibers, and smooth muscle tissue.
Reticular fibers (reticul = net)
TYPES OF MATURE CONNECTIVE TISSUES
-Dense connective tissues
-Cartilage
contain more fibers, which are thicker and more densely packed, but have considerably fewer cells than loose connective tissues. There are three types: dense regular connective tissue, dense irregular connective tissue, and
elastic connective tissue.
Dense connective tissues
consists of a dense network of collagen fibers and elastic fibers firmly
embedded in chondroitin sulfate, a gel-like component of the ground substance.
• Cartilage can endure considerably more stress than loose and dense connective tissues.
• The strength of cartilage is due to its collagen fibers, and its resilience is due to chondroitin sulfate
Cartilage
cells of mature cartilage occur singly or in groups within spaces called lacunae (sing. Lacuna) in the extracellular matrix.
• Chondrocytes (chondro-cartilage)
covering of dense irregular connective tissue, surrounds the surface of most cartilage and contains blood vessels and nerves and is the source of new cartilage cells.
Perichondrium (peri-around)
Three (3) types of Cartilage:
• 1. hyaline cartilage
• 2. fibrocartilage
• 3. elastic cartilage
are organs composed of several different connective tissues, including osseous tissue, the periosteum, red and yellow bone marrow, and the endosteum
Bones
basic unit of compact bone
• Osteon or Haversian system
• Parts of an Osteon:
• Lamellae
• Lacunae
• Canaliculi
• Central haversian canal
are concentric rings of extracellular matrix that consist of mineral salts (mostly calcium and phosphates),
• Gives bone its hardness and compressive strength, and collagen fibers, which
give bone its tensile strength.
Lamellae (sing. lamella)
are small spaces between lamellae that contain mature
Lacunae (sing. lacuna)
bone cells called
osteocytes
contains blood vessels and nerves.
Central (haversian) canal
lacks osteons. Rather, it consists of columns of bone called trabeculae (little beams), which contain lamellae, osteocytes, lacunae, and
canaliculi.
• Spongy bone
• Description: Compact bone tissue consists of osteons (haversian systems) that
contain lamellae, lacunae, osteocytes, canaliculi, and central (haversian) canals.
• Location: Both compact and spongy bone tissue make up the various parts of
bones of the body.
• Function: Support, protection, storage; houses blood-forming tissue; serves as
levers that act with muscle tissue to enable movement
MATURE CONNECTIVE TISSUE: BONE TISSUE
is a connective tissue with a liquid extracellular matrix and formed elements. The extracellular matrix is called blood plasma.
Blood tissue (or simply blood)
is a pale yellow fluid that consists mostly of water with a wide variety of dissolved substances—nutrients, wastes, enzymes, plasma proteins, hormones, respiratory gases, and ions.
The blood plasma
are flat sheets of pliable tissue that cover or line a part of the body.
Membranes
majority of membranes consist of an epithelial layer and an
underlying connective tissue layer
Epithelial membrane
Principal epithelial membranes
• mucous membranes
• serous membranes
• cutaneous membrane or skin
lines joints and contains connective tissue but no epithelium.
Synovial membrane
lines a body cavity that opens directly to the exterior. line the entire digestive, respiratory, and reproductive tracts, and much of the urinary tract.
Mucous Membranes
lines a body cavity that does not open directly to the exterior (thoracic or abdominal cavities), and it covers the organs that are within the cavity.
SEROUS MEMBRANES
layer attached to and lining the cavity wall;
Parietal layer
– layer that covers and adheres to the organs within the cavity
Visceral layer
secreted by mesothelium; it is a watery lubricant that allows organs
to glide easily over one another or to slide against the walls of cavities.
Serous fluid
serous membrane lining the thoracic cavity and covering the lungs.
Pleura
serous membrane lining the heart cavity and covering the heart
Pericardium
serous membrane lining the abdominal cavity and covering the abdominal
organs
Peritoneum
consist of elongated cells called muscle fibers or myocytes that
can use ATP to generate force.
Muscular Tissues
Muscular Tissues
• Functions:
• Body movements
• Maintain posture
• Generate heat
• Protection
• Classification of Muscular Tissue
• Skeletal Muscular Tissue
• Cardiac Muscular Tissue
• Smooth Muscular Tissue
are sensitive to various stimuli. They convert stimuli into electrical signals called nerve action potentials (nerve impulses) and conduct these action potentials to other neurons, to muscle tissue, or to glands.
Neurons (neuro-nerve) or nerve cells
Most neurons consist of three basic parts
a. Cell body
b. Dendrites
c. Axons
contains the nucleus and other organelles
Cell body
are tapering, highly branched, and usually short cell processes (extensions). They are the major receiving or input portion of a neuron.
Dendrites (dendr-tree)
of a neuron is a single, thin, cylindrical process that may be very long. It is the output portion of a neuron, conducting nerve impulses toward another neuron or to some other tissue
Axon (axo-axis)
do not generate or conduct nerve impulses, these cells do have many important supportive functions.
Neuroglia (-glia-glue)