Chapter 4 Tissues Flashcards
What are tissues?
A group of cells with a common embryonic origin that function together to carry out specialized activities
What is histology?
The science that deals with the study of tissues
What are pathologists?
Specialize in laboratory studies of cells and tissues for diagnoses
What are 4 types of tissues?
- Epithelial
- Connective
- Muscular
- Nervous
What is Epithelial Tissue?
Covers body surfaces and lines hollow organs, body cavities, ducts, and forms glands
What are connective tissues?
Protects, supports, and binds organs, while also storing energies such as fat, providing immunity
What is muscular tissues?
Generates the physical force needed to make body structures move and generate body heat
What is nervous tissues?
Detects changes in body and responds by generating nerve impulses
Tissues of the body develop from what three primary germ layers?
Endoderm, Mesoderm, and Ectoderm
What type of tissue develops from all three germ layers?
Epithelial
All Connective tissues and most muscle tissues derive from what?
Mesoderm
Nervous tissue develops from what?
Ectoderm
What are cell junctions?
Contact points between the plasma membranes of tissue cells
What are the 5 most common types of cell junctions?
- Tight junctions
- Adherens
- Desmosomes
- Hemidesmosomes
- Gap Junctions
What are tight junctions?
Web-like strands of transmembrane proteins
What do tight junctions do?
Fuse cells together and seal off passageways between adjacent cells. (This helps retard the passage of substances between cells and leaking into the blood or surrounding tissues)
Where are tight junctions common?
epithelial tissues of the
1. stomach
2. Intestines
3. urinary bladder
What are Adherens Junctions?
Dense layer of proteins called Plaque, which resist separation of cells during contractile activities
Where is Adherens Junctions located?
inside the plasma membrane attached to both membrane proteins and microfilament of the cytoskeleton
What are Cadherins?
Transmembrane glycoproteins which insert into the plaque and join cells
What are adhesion belts ?
In epithelial cells they encircle the cell
What is the Desmosomes?
- They contain plaque and cadherins that extends into the intercellular space to attach adjacent cells together.
- They also prevent epidermal cells from separating under tension and cardiac muscles cells from pulling apart during contraction
Desmosomes plaques attaches to intermediate filaments that contain what ?
A protein called keratin
What are hemidesmosomes?
They resemble half a desmosome and do not link adjacent cells but anchor cells to the basement membrane
What do Hemidesmosomes contain?
A transmembrane glycoprotein called integrin
What do Integrins do?
Attach to intermediate filaments and the protein laminin present in the basement membrane
What are gap junctions? and what do they do?
Plasma membranes which are separated by a very narrow intercellular gap. They also connect neighboring cells via tiny fluid filled tunnels called connexons
What happens in the gaps of Gap junctions?
Communication of cells via ions, nutrients, waste, chemical and electrical signals which travel through the connexons from one cell to another
What are the 3 major functions of epithelial tissues?
- Selective barrier that regulates the movement of materials in and out of the body
- Secretory surfaces that release products onto the free surface
- Protective surfaces against the environment
How are the cells of epithelial tissues arranged?
- Cells are closely packed and held tightly together
- functions in covering and lining the body
- has a free surface
- can be arranged in continuous sheets, single sheets, or multiple layers
Do Epithelial tissues have their own nerve supply?
Yes
Epithelial tissues are avascular, what does that mean?
They lack their own blood supply
In Epithelial tissues how do they get nutrients and eliminate waste?
Blood vessels in the connective tissues take care of that
What does the cell division rate for epithelial tissue look like?
High rate of cell division
What type of role does the Epithelial tissue play in the body?
Numerous roles such as protection and filtration
What are two different types of Epithelium Tissue?
- Covering and lining epithelium
- Glandular Epithelium
What is covering and lining epithelium?
Outer covering of skin and some internal organs
What is Glandular epithelium?
Secreting portion of glands (thyroid, adrenal, and sweat glands)
What are different kinds of Simple epithelium?
- Simple squamous epithelium
- Simple cuboidal epithelium
- Simple Columnar epithelium
- Pseudostratified Columnar epithelium
What are simple squamous epithelium?
Simple layer of cells that resemble a tiled floor on the surface
Where are simple squamous epithelium found generally?
At sites for filtration or diffusion
What are different kinds of simple squamous epithelium/ covering and lining epithelium?
Endothelium and Mesothelium
What are endothelium’s ?
They type of simple squamous that lines the heart, blood vessels, and lymphatic vessels
What are mesothelium’s?
The type of epithelial layer of serous membranes such as the pericardium, pleura, or peritoneum
What do endothelium and mesothelium have in common?
They are both derived from embryonic mesoderm
What is a simple columnar epithelium?
- Cuboidal shaped sells
- Cell nuclei are round and centrally located
- Found in the thyroid gland and kidneys
- functions in secretion and absorption
- Column shaped cells
- oval nuclei near the base
- nonciliated and ciliated
What are nonciliated simple columnar epithelium?
Contains columnar cells with microvilli at their apical surface and goblet cells.
What do Nonciliated simple columnar epitheliums cells do?
Prevent the destruction of the stomach lining by acidic gastric juices. They do this by secreting mucus which serves has a lubricant for the lining of digestive, respiratory, reproductive, and urinary tracts
What are ciliated simple columnar epithelium?
Columnar epithelial cells with cilia at the apical surface
Where are ciliated simple columnar epithelium cells usually found?
In the respiratory tract, goblet cells are interspersed among ciliated columnar epithelia
What do ciliated simple columnar epithelium cells do?
Secretes mucus on the surface traps inhaled foreign particles. Beating cilia moves particles to the throat for remove by coughing, swallowing, or sneezing. Cilia also move oocytes to the uterine tubes
What are pseudostratified columnar epithelium?
Covering and lining epithelium cells which appear to have several layers due to nuclei which are at various depth. However, all cells are attached to the basement membrane in a single layer but do not extend to the surface
What do the pseudostratified columnar epithelium do?
Ciliated cells secrete mucus and bear cilia. The non ciliated cells lack cilia and goblet cells
What are stratified epithelium?
Two or more layers of cells
In terms of stratified epithelium what affects the shape of the cells in the apical layer?
- stratified squamous epithelium
- stratified cuboidal epithelium
- stratified columnar epithelium
- transitional epithelium
What are stratified squamous epithelium?
Several layers of cells that are flat in the apical layer
What are some special characteristics of the Stratified Squamous epithelium
- New cells are pushed up towards the apical layer
- As cells move further from the blood supply, they dehydrate, harden, and die
What are Stratified cuboidal epithelium
Fairly rare type of epithelium where the apical layers are cuboidal and functions in protection.
What are stratified columnar epithelium?
Very uncommon columnar cells in apical layer. Basal layers has shortened, irregular shaped cells which functions in protection and secretion
Where is transitional epithelium normally found?
Urinary system
What kind of appearance does the transitional epithelium have?
Variable appearance. In a relaxed state, cells appear cuboidal and upon stretching cells become flattened and appear squamous.
What are the benefits of transitional epithelium?
Ideal for hollow structure subjected to expansion
What are two types of glandular epithelium?
- Endocrine
- Exocrine
What is the largest portion of glandular tissue made of?
Simple cuboidal epithelium
What are endocrine glands?
Ductless glands which secrete hormones directly into the bloodstream with the function of maintaining homeostasis
What are some examples of endocrine glands?
Thyroid gland and pituitary glands
What are exocrine glands
Glands on the skin surface or lumen of a hollow organ which secrete products into ducts that empty onto the surface of epithelium.
What are some examples of secretions of exocrine glands?
Mucus, sweat, oil, earwax, saliva, and digestive enzymes
What are some examples of exocrine glands?
Sudoriferous glands
What is connective tissue?
Most abundant and widely distributed tissue in the body
What are the functions of connective tissue?
- Binds tissues together
- Supports and strengthens tissue
- Protects and insulates internal organs
- Compartmentalize and transport
- energy reserves and immune responses
What are different types of connective tissues?
- Cartilage
- Ligaments
- Tendons
- Bones
- Liquid - blood/lymph
What are all connective tissues made of?
- extracellular matrix
- Specialized cells
What are different types of extracellular matrix?
- Ground substance
- Protein fibers
What are extracellular matrix?
The material located between the cells, which consist of extracellular protein/ protein fibers and ground substances
Is connective tissue highly or lowly vascular?
Highly
What kind of origin does the extracellular matrix of connective tissue have?
Embryonic origin: mesenchyme cells
All extracellular matrix of connective tissue is supplied with nerves with the exception of which?
cartilage and tendon, both have little or no blood supply or nerves
What are fibroblasts?
connective tissues cells which secrete fibers and components of ground substance
What are adipocytes (fat cells)?
Connective tissues cells which store triglycerides (fats)
What are Mast cells?
Connective tissues cells which produce histamine
What are white blood cells
Connective tissue which deal with immune response. Examples are neutrophils and eosinophils
What are macrophages?
Cells which engulf bacteria and cellular debris by phagocytosis
What are plasma cells?
Connective tissue cells which secrete antibodies
What does the ground substance in connective tissues extracellular matrix do?
Functions to support and bind cells, store water, and allow exchange between blood and cells
- Fluid
- Semifluid
- Gelatinous
- Calcified
What are examples of fibers?
- Collagen fibers
- Elastic fibers
- Reticular fibers
What are embryonic connective tissue?
Mesenchyme and mucous connective tissue
What are 5 types of mature connective tissue?
- loose connective tissue
- Dense connective tissue
- Cartilage
- Bone tissue
- Liquid connective tissue
What are examples of Loose connective tissue?
- Areolar
- Adipose
- Reticular
What are different types of dense connective tissue?
- dense regular
- dense irregular
- Elastic
What are different types of cartilage?
- Hyaline
- Fibrocartilage
- Elastic cartilage
What are two types of connective tissue?
Blood and lymph
What is cartilage?
A dense network of collagen fiber’s and elastic fibers firmly embedded in chondroitin sulfate
What is chondrocytes?
Mature cartilage cells found in the spaces called lucunae
What is Perichondrium?
Covering of dense irregular connective tissue that surrounds the cartilage?
What are the two layers of the perichondrium?
- outer fibrous layer
- Inner cellular layer
What is the repair rate of cartilage?
Slow, due to avascular nature
What are two patterns of cartilage growth?
- interstitial growth
- Appositional growth
What is interstitial growth?
Growth from within the tissue which occurs in childhood and adolescence
What is Appositional growth?
Growth at the outer surface of the tissue, which occurs later in life and continues through adolescence
What is blood tissue?
A liquid blood connective tissue with liquid extracellular matrix called blood plasma
What are membranes?
Flat sheets of pliable tissue that cover or line a part of the body
What are epithelial membranes?
a combination of an epithelial layer and an underlying connective tissue layer
What are examples of Epithelial membranes?
Mucous, serous, and cutaneous membranes
What are synovial membranes?
Lines joints and contains connective tissue but not epithelium
What are muscular tissue?
Consists of elongated cells called muscle fibers or myocytes
What are three classifications of muscle tissue?
- Skeletal tissue
- Smooth muscle
- cardiac muscle
What two principle cells are nervous tissue consisting of?
- Neurons or nerve cells
- Neuroglia
What are excitable cells?
Neurons and muscle fibers which exhibit electrical excitability
What is it mean when excitable cells exhibit electrical excitability?
The ability to respond to certain stimuli by producing electrical signals such as action potentials?
Action potentials propagate along a nerve or muscle plasma membrane to cause what kind of response?
Release of neurotransmitters or muscle contractions
What two types of tissues repair based on severity of damage?
Regeneration or fibrosis
What is the steps of tissue repair?
- Inflammation
- Organization
- Regeneration and fibrosis
Extracellular components also change with what?
Age
