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2 components of basement membrane:

Basal lamina: bottom of epithelial cell
Reticular lamina:
Top of underlying connective tissue cell.
*both glue cells together, anchor blood vessels, and provide a barrier btw epithelia and underlying tissue


The cells of Connective Tissue Proper

Aka general connective tissue. Has resident cells which stay put, and migrant cells that travel where needed:
Fibroblasts = most common. mature cell w/ properties of an immature cell. Produce collagen.
Adipocytes= fat cells. Cytoplasm stores lipids.
Mast cells= cells of the immune system. Degranulate when stimulated, causing inflammation
Phagocytes= also immune cells ingest stuff via phagocytosis
Other immune cells= vary


Endocrine gland

secrete hormones directly into the blood to communicate with distant cells.


A tissue is a group of structurally and functionally related cells and their external environment that together perform common functions. All tissues share the following two basic components:

1. A discrete population of cells related in structure and function
2. Extra cellular matrix


4 types of simple epithelia

Simple Squamous: very thin layer, fried egg appearance. Adapted for rapid transport of oxygen, CO2, fluid, and ions. Found in lungs

Simple Cuboidal: cube shaped w/ large central nulcleus. Often appears as a tube. Provides rapid diffusion. Found in kidney tubules.

Simple Columnar: Tall rectangular, nucleus in basal portion. Often have microvilli for greater absorbtion. Found in small intestine. If ciliated, found in uterine tube and respiratory passages.

Pseudostratified Columnar: appears to be stratified, but isn't. Ciliated. Found in nasal cavity and respiratory tract


Describe tissue repair

Tissue repair happens differently for different tissues. In the case of regeneration, dead and damaged cells are replaced with cells of the same type, and tissue regains its full function. In the case of fibrosis, fibroblasts divide by mitosis and fill in the wound with collagen. The result of fibrosis is scar tissue, a type of dense irregular connective tissue. It doesn't regain its full function.


3 parts of a neuron

1. Cell body/soma
2. Axon: sends signals
3. Dendrite: receives signals


Muscle tissue

Cells can contract and generate force. Little ECM btw cells


Loose connective tissue. What its made of, where it is, what is its function?

Aka areolar. Main component is ground substance, the 3 types of protein fibers, and adipocytes. Deep to epithelium, lining body cavities. Function is support, and delivery of oxygen and nutrients to epithelial tissue above. Contains blood vessels and immune cells.


Transport across simple epithelia

paracellular transport: btw cells
transcellular transport: through cell.


Describe the transport into other tissues feature of epithelial tissue

epithelial tissues are selectively permeable allowing substances to pass. Example is in the small intestine where nutrients must pass the intestinal epithelium to the blood.


Types of tissue that regenerate

Cells that undergo mitosis usually regenerate. Example: epithelial, smooth muscle, and most connective tissue (minus cartilage).


two methods for secreting products used by exocrine glands

Merocrine secretion= exocytosis
Holocrine secretion= accumulation of product in cell released upon cell death. Seen in sebaceous glands of skin.


Describe the sensation feature of epithelial tissue

most epithelia are supplied with nerves that detect changes in internal and external environment. Also epithelia form taste buds.


Blood and its cellular components

ECM is fluid, called plasma.
1. erythrocytes aka red blood cells transport oxygen
2. leukocytes aka white blood cells function in immunity.
3. Blood also contains platelets for clotting


Describe the protection feature of epithelial tissue

it protects by making a continuous surface shielding underlying tissue. Ie: skin epithelium makes hard keratin enabling resistance to injury. Epithelial tissue gets damaged and dies, but mitosis is rapid to replace it.


3 types of specialized connective tissue

1. Cartilage
2. Bone
3. Blood


Types of dense connective tissue, and what are their functions?

Aka fibrous. Main component is protein fibers. 3 types:
1. Dense irregular. disorganized collagen bundles. Strong. Resists tension in 3 planes. Found in dermis.

2. Dense regular. Collagen fibers arranged parallel. Resists tension in 1 plane. Tendons & ligaments.

3. Dense regular elastic: allows for strength and stretch. Contains elastic fibers. Found in walls of organs that need to stretch like large blood vessels and certain ligaments.


Exocrine Glands

release their products onto the apical surfaces of the epithelium, onto the external surface of the body, or into a hollow organ that opens to the outside of the body through an epithelial-lined duct.


Reticular Tissue

Made of reticular fibers that form fine networks to support small structures like blood vessels and lymphatic vessels


Types of stratified epithelia

keratinized stratified squamous: apical layers are dead. Filled w/ hard keratin that protects. Makes our skin.

Non-keratinized stratified squamous: all layers are alive. found in areas of high mechanical stress that need moisture ie: mouth, throat, anus, vagina.

Stratified cuboidal: rare. lines ducts of sweat glands

Stratified columnar: also rare. Found in urethra & cornea

Transitional Epithelia: Has a unique shape, made to stretch. Found only in the urinary system. Lines kidney, ureters, urinary bladder, and urethra


The functions of ECM

strength, anchoring cells in place, and regulating cell activity


Goblet cell

A unicellular gland that secretes mucus



The study of the normal structure of tissues


What is Epithelial tissue?

Sheets of tightly packed cells. No visible ECM. Cover or line almost all body surfaces/cavities. Some form glands. Avascular tissue, gets oxygen and nutrient from tissue below, so thickness limited.


The 2 major components of ECM

Ground substance - glycosaminoglycans, proteoglycans, and glycoproteins

Protein fibers - collagen fibers, elastic fibers, and reticular fibers


4 types of connective tissue proper

1. Areolar - deep to the skin, lines body cavities/hollow organs.
2. Dense
a. regular: forms tendons and ligaments
b. irregular: forms joint capsuls
c. elastic: aorta
3. Reticular: spleen and lymph nodes
4. Adipose: part of hypodermis


Membrane-like structures

1. Cutaneous: Lines the outside of the body. Outermost layer is called epidermis. Innermost layer is called dermis.

2. Mucus membranes: line body passages and hollow organs that open to outside of body, like mouth, resp. passages, nose, digestive tract, male/female reproductive tracts.



Made of chondroblasts (immature) and chondrocytes (mature and mostly inactive). Mostly avascular. Gets blood supply from perichondrium. There are 3 types of cartilage:
1. Hyaline aka articular: most abundant, glass-like due to predominance of ground substance. Covers ends of bones, joints.
2. Fibrocartilage: contains large amounts of collagen fibers. Very strong. Vertebral discs.
3. Elastic: limited to external ear and voice box. Filled w/ elastic fibers allowing tissue to vibrate.


Types of tissue that undergo fibrosis

skeletal muscle, cardiac muscle, and nervous tissue (specifically neurons).


Describe the secretion feature of epithelial tissue

epithelial cells form glands which secrete substances like oil or hormone ect.


Functions of Adipose Tissue

insulation, warmth, shock absorption, and protection. Major energy reserve in body.


Other factors affecting tissue repair

nutrition, and blood supply


3 types of muscle tissue

All 3 of these turn the chemical energy of ATP into the mechanical energy of movement.
1. Skeletal: striated cells appear as long muscle fibers. multinucleate. Voluntary muscle control.
2. Cardiac: striated, short and thick. Uninucleate. Contain intercalated discs. Involuntary muscle control.
3. Smooth: smooth, flat cells with single nucleus. Present in nearly every hollow organ. Involuntary muscle control.


True membranes

Do not open to the outside of the body.

1. Serous membranes: line pleural, pericardial, and peritoneal cavities. Contain mesothelium (a layer of simple squamous). basement membrane, and connective tissue.
2. Synovial membranes: line joints. No epithelium, but rather 2 types of connective tissue. Synoviocytes secrete synovial fluid..


Connective Tissue Functions

1. connecting and binding
2. support (from bone and cartilage)
3. protection
4. transport (via blood, which is a connective tissue)


Describe the immune defense feature of epithelial tissue

provides a barrier for invading microorganisms. Also immune system cells are scattered throughout epithelial tissue.


Epithelia is classified by what 2 characteristics:

Simple: Single layer. Adapted for transportation of substances btw tissues. Some have microvilli for increased surface area, and some are ciliated to move stuff along. 4 Types.

Stratified: More than one layer of cells that create thick protective barriers. Best suited for areas of high mechanical stress.


What is bone made of, and what is its function?

Made of the 3 resident cells: osteoblasts, osteocytes, and osteoclasts. supports the body, protects our vital organs, provides attachments for the muscles that allow for movement, stores calcium, and houses bone marrow, which produces blood cells and stores fat. Bone ECM is composed of about 35% organic components consisting of collagen fibers and ground substance called osteoid. The remaining 65% of ECM is inorganic calcium phosphate crystals.


3 types of cell junctions:

Tight junctions: aka occluding junctions. Makes space btw cells impermeable. “locking proteins”
Desmosomes: increases resistance of tissue to mechanical stress. Integral linker proteins
Gap junctions: allows small substances to move from one cell to another. Protein channels


Where ECM of epithelial cells is located

Basement membrane beneath cells


Connective tissue

Cellular Velcro that connects all other tissues together. ECM is prominent feature. Function: bind, support, protect, and allow transport of substances thru body.


The 4 major tissue types

1. Epithelial
2. Connective
3. Muscle
4. Nervous


what are protein fibers made of?

Made of:
Collagen: fibers are composed of multiple repeating subunits that form a white fibrous protein that is resistant to tension (pulling and stretching forces) and pressure.

Elastic fibers: fibers, composed of the protein elastin surrounded by glycoproteins, has the property of extensibility that allows the fiber to stretch up to one and a half times its resting length without breaking. Once stretched, these fibers return to their resting length, a property called elasticity.

Reticular fibers: fibers, a thin, short collagen fiber, form a meshwork or scaffold that support the cells and ground substance of many tissues. They form a web-like structure in organs like the spleen that help trap foreign cells.


What is a membrane composed of? What are their functions?

a thin sheet of one or more tissues that lines a body surface or cavity. Contain a superficial epithelial layer and a connective tissue layer, sometimes containing smooth muscle. Function: anchor organs, serve as barriers, function in immunity, and secrete substances.


Ground substance

made of
1. glycosaminoglycans (GAGs), example of gradient, draws water out of cells and traps it in ECM.
2. proteoglycans, makes ECM firm, and make a barrier for diffusion thus protecting underlying tissue.
3. cell-adhesion molecules (CAMs)Makes cells sticky.


2 types of muscle cells:

Both of these are excitable, and can respond to electrical and chemical stimulation:

1. Striated muscle cells: areas where myofilaments overlap and create a striped look.

2. Smooth muscle cells: myofilaments are in irregular bundles, so no striations are visible.


what is a gland?

is a structure that forms and secretes a product


2 main cell types of nervous tissue

Neurons: send and receive signals. Do not undergo mitosis
Neuroglial: smaller, supportive cells “nerve glue” undergo mitosis


5 distinguishing characteristics of epithelial tissue

1. polarity
2. specialized contacts
3. supported by connective tissues
4. avascular but innervated
5. regeneration