Flashcards in A&P Chapter 5 Histology & Tissues Deck (84):
1
What is Histology?
The study of cells and tissues and how they are arranged into organs.
This allows us to see how cells are arranged in a particular tissue type and how tissues help form an organ.
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What are the four primary tissue classes?
Epithelial, Connective, Nervous, Muscular
The vast majority of organs and tissues will have all four of the tissue classes.
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Tissues are...
A group of similar cells derived from a common embryonic origin that are arranged in a way that allows them to carry out a particular STRUCTURAL or PHYSIOLOGICAL function.
Tissues = Cells + Extracellular Matrix
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What does extracellular matrix contain? Where is it found?
Protein Fibers, Water, Minerals, Nutrients, and Waste Products
It is found in the spaces between cells.
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How do tissues differ from one another?
In the types of cells that make up the tissue as well as by the type and amount of EXTRACELLULAR MATRIX that surrounds the cells.
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What are the two functions of tissues?
Structural, Ex. Bone supports and protects the body, also allows the muscles to produce movement.
Physiological, Ex. Epithelial tissues lining the digestive system allows the body to absorb nutrients from the foods we eat.
MANY TISSUES HAVE BOTH A STRUCTURAL AND A PHYSIOLOGICAL FUNCTION.
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What are epithelial tissues?
They are a layer of tightly bound cells that are one or more layers thick (1-20) that are bound to a BASEMENT MEMBRANE. They are usually exposed to the outside environment or to the inside of the body.
Examples: Skin, Lining of Digestive System, Lining of Lungs, Lining of Blood Vessels, Etc...
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What does the Basement Membrane do?
It acts as a biological glue that holds cells to connective tissues below it.
The BM is composed of collagen, and avariety of glycoproteins and proteoglycans.
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What are the shapes of epithelial cells?
Squamous, Cuboidal, Columnar
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Describe Squamous cells
Thin, flat looking like a fried egg. Good for exchange of gasses, nutrients, and waste products. Found in lung and blood vessels.
These cells offer short distances between layers/areas therefore they are ideal for the exchange of things.
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Describe Cuboidal cells
Typically square or round, they are found in the lining of ducts of many glands.
You will see a uniform amount of cytoplasm around the nucleus of these cells.
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Describe Columnar cells
Tall and narrow, found lining the intestines. They often have small projections on the exposed (APICAL) surface called MICROVILLI that increase surface area for absorption.
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What are the three functions of Epithelial tissue?
1. Compartmentalization, we find epithelial tissue lining cavities/organs. It serves as a layer between things keeping things in the body seperate.
2. Absorption/Secretion, stuff passes in and out of areas going through the epithelial tissue.
3. Transport/Exchange, Exchange of gasses/waste products. Transportation of nutrients.
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What is one layer of epithelial cells described as?
Simple, one layer is simple. All the cells connect with the basement membrane. Multiple layers is called stratified.
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What are multiple layers of epithelia cells described as?
Stratified, only the bottom layer touches the basement membrane all the upper layers are bound to other cells.
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Describe Pseudostratified columnar and how they look compared to stratified columnar cells.
All the cells are bound to the basement membrane but not all the cells reach the exposed surface. There is only ONE layer of cells, the nuclei will look uneven and not lined up in a single row.
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What are transitional epithelial cells? Where are they found?
This is a specialized type of epithelial cell that transitions between a cuboidal shape and a squamous shape when stretched. The cells transition between the two depending on the movement of the tissue.
Found in the bladder and other organs that need to stretch.
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What are the four types of epithelial tissues?
Simple, Stratified, Pseudostratified columnar, Transitional.
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What types of epithelial cells will microvilli be found on?
Columnar epithelial cells.
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What are goblet cells?
One celled mucous glands.
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Explain keratinized, stratified squamous epithelia. Where is it found?
Keratinized = Dead cells with no nuclei.
Stratified = Many layers of cells.
Squamous = Thin squamous cells.
Many layers of cells, lower cells are alive and dividing, upper cells are dead and filled with keratin.
Found in the pads of the feet, hands, any place where layers are needed to protect against abrasion.
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Explain Non-keratinized stratified squamous epithelia.
Many layers of cells, all alive, CAN SEE THE NUCLEI in all the cells.
Still offers resistance to abrasion like Keratinized stratified squamous cells but exit in other areas of the body like the mouth/vagina.
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Connective tissues derive from?
The mesoderm.
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What are the 6 major functions of connective tissue?
Connection, Connective tissues bind bone to muscle and bones to other bones, they also hold organs in place.
2. Support, Bones help support the body and cartilage supports structures like the nose and ear.
Protection, both PHYSICAL and IMMUNE. Physically connective tissues surround and protect the body. Connective tissues also contain large numbers of LEUKOCYTES AND MACROPHAGES that are immune cells protecting the body from bacteria and viruses.
4. Movement, Bones help move the body with the help of muscle.
5. Storage/Heat Production, Adipose tissue stores energy for later use and preserves/generates heat.
6. Transport, Blood transports gases, nutrients, waste, and hormones to the entire body.
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What are the two types of adipose tissue?
White and Brown.
White adipose is found in adults as stores and helping to provide protection. Most adults have only White Adipose tissue.
Brown adipose is found in infants and is used to produce heat keeping the core body temperature up.
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What are the four types of connective tissue?
Fibrous Connective Tissue, this stuff attaches things together in the body. Ligaments and tendons contain Fibrous C.T.
Cartilage, This rubbery connective tissue supports nose/ear and is found between bones.The intervertebral discs are cartilage as well as the coating on bone ends.
Bone or Osseous tissue, is a rigid connective tissue that protects body organs.
Blood or Fluid Connective Tissue, this is the fluid connective tissue that funtions to transport materials throughout the body.
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Describe Fibrous Connective Tissue what are the 2 types of Fibrous connective tissue?
A diverse type of connective tissue composed of cells, fibers and ground substance.
Loose and Dense
Loose has MUCH more ground substance than fibers/cells.
Dense has MANY more collagen fibers than ground substance and cells.
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What are the four cells found in Fibrous Connective Tissue?
Fibroblasts, the large cells that PRODUCE the fibers and ground substance.
Macrophages, a phagocytic cell that looks for, engulfs and destroys bacteria/viruses.
Leukocytes or WBC's, important part of the immune system that monitors the body for invasion and coordinates immune response. Plasma cells produce ANTIBODIES when a bacteria or virus is detected, Antibodies are proteins that recognize invaders and flag them to be destroyed by Macrophages.
Adipocytes, cells designed to store large vacuoles of fat. The cellular part of adipose tissue.
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What are the three types of Fibers found in Connective Tissue?
Collagenous, made of a protein called Collagen, strong and flexible.
Reticular, collagen fibers coated with GLYCOPROTEINS found inside several organs for structural support, not as common as Collagenous fibers. Found in IMMUNE tissue.
Elastic, Thin fibers made of the protein ELASTIN. These fibers are coiled like a slinky and allow the fibers to stretch. Very important for the elasticity of the skin and lungs.
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What is ground substance?
The stuff in the space between fibers and cells in connective tissues.
Composed of large carbohydrates, proteoglycans, and glycoproteins.
This material cusions and protects the cells of connective tissue.
Many molecules are negativly charged and attract Na+ ions and water.
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How many types of Fibrous Connective Tissue are there?
Five
Three Loose, Areolar, Reticular, and Adipose.
Two Dense, Dense Regular and Dense Irregular.
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Describe Loose Areolar Connective Tissue
Made of many randomly orientated COLLAGEN AND ELASTIN fibers.
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Describe Reticular Connective Tissue
Many randomly oriented RETICULAR fibers with a large number of lymphocytes.
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Describe Adipose Connective Tissue
VERY few fibers, tissue contains MANY adipose cells filled with lipid (fats).
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What cells produce Connective Tissue?
Fibroblasts
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Describe Dense Regular Connective Tissue
Collagen fibers are densely packed and PARALLEL to each other.
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Describe Dense Irregular Connective Tissue
Collagen fibers are densly packed but run in RANDOM directions.
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What is cartilage?
A Flexible, rubbery connective tissue that plays an important supportive role.
Found in the Ears, Nose and between bones of some joints.
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What are the cells that actively make the extracellular matrix of cartilage? What happens when they mature?
Chondroblasts
When they mature and are surrounded by matrix they become Chondrocytes, these exist in cavities called LACUNAE.
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List the three types of Cartilage
Hyaline, Elastic, and Fibrocartilage
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Describe Hyaline Cartilage
It has a clear glossy appearance, it contains many thin collagen fibers that usually can't be seen.
It is usually surrounded by the PERICHONDRIUM made of dense, irregular connective tissue.
Hyaline cartilage is the precursor to Osseous tissue and the fetal skeleton is made of it.
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Describe Elastic Cartilage
It contains many elastin fibers, it provides flexible support for the outer ear and part of the larynx.
Large elastic fibers form a meshwork holding cells and lacunae, this cartilage is ALWAYS covered in a perichondrium.
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Describe Fibrocartilage
It contains many course COLLAGEN BUNDLES rather than random collagen fibers like in hyaline cartilage.
Its a supportive connective tissue that resists compression and absorbs shock.
It's found in the pubic symphisis and makes up the intervertebral discs.
With fibrocartilage the chondrocytes are lined up in rows.
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Where are Lacunae found?
In Cartilage and Osseous connective tissues.
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Describe Osseous Connective Tissue
It is the connective tissue commonly known as Bone.
All bones are covered by a fibrous tissue known as PERIOSTEUM.
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What covers Osseous Tissue?
Periosteum
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What does the Periosteum do?
It serves as an anchor point for the attachment of tendons and ligaments.
Dense connective tissues actually FUSE with the periosteum.
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What are the two types of Osseous tissue?
Spongy Bone, found in the heads of long bones. This tissue is very strong but porous and allows bones to be light weight.
Compact Bone, dense osseous tissue that surrounds spongy bone.
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What are the cells that produce bone?
Osteoblasts.
Once they become enclosed in Lacunae they become Osteocytes.
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What is an Osteon?
A ring of concentric circles (called Lamella)made of osseous matrix that surround a HAVERSIAN CANAL. This canal is where bloodvessels and nerves pass through bone. There are lacunae with osteocytes inside them embedded in the osseous matrix.
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From what embryonic tissue does all other connective tissue come from?
Mesenchyme
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What is the fluid connective tissue?
Blood
It plays an important role in transportation of many substances from immune cells to oxygen/CO2.
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What is the ground substance of Blood?
Plasma, it contains Fibrinogen which form the fibers of blood that help with clotting.
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What are the formed elements of blood?
They are the cells and cell fragments that make up blood.
Erythrocytes (RBC's): Only cells in the body w/o a nucleus. Carrys O2 and CO2 between lungs and body tissues.
Leukocytes (WBC's): 5 different types of cells with specific functions that contribute to immune protection.
Platelets: Cell fragments that are important for the clotting process and directing new blood vessel growth.
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What is special about nervouse tissue?
Excitable tissue that are responsible for carrying out electrical signals called an ACTION POTENTIAL.
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How is an Action Potential generated?
When there is a change in electrical charge across the cell membrane due to the flow of charged ions.
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What makes up the central nervous system?
The Brain and Spinal Cord
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What makes up the peripheral nervous system?
All the nerves in our body, NOT the Brain or Spinal Cord.
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What are the two cells in nervous tissue?
Neurons and Glial Cells
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What is special about Neurons?
They are excitable and are able to transport signals rapidly. They excite other cells. They send/receive signals.
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What do glial cells do?
Support, nourish and protect the neurons.
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What is the cell body of a Neuron called?
SOMA, contains the nucleus and other organelles.
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What part of Neurons receive signals from other Neurons?
Dendrites, they act as the antenna that receive signals.
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What is an axon?
The large nerve fiber that sends out signals to other neurons or eventually to a final organ or tissue.
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What is special about muscle tissue?
It contracts when stimulated.
That contraction exerts force on other tissues and organs. Moves bones, pushes food through the digestive system, controls the blood vessel diameter.
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What are the three types of muscle tissue?
Skeletal, Cardiac, and Smooth
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What is a muscle cell also known as?
A Muscle Fiber.
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What are skeletal muscle fibers made of?
Overlapping Actin and Myosin protein fibers forming STRIATIONS. They are also MULTINUCLEATED.
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What is the only type of muscle that is under consious control?
Skeletal
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What are cardiac muscle cells called? How are they different from skeletal muscle fibers? How are they similar?
Cardiomyocytes, they are much shorter than skeletal muscle fibers and only have one nucleus. They are striated like skeletal muscle fibers.
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What is the clear halo around a Cardiomyocyte nucleus?
Glycogen, the heart needs a constant supply of glucose so it stores extra glycogen here.
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What structure allows the cardiomyocytes to beat in unison?
Intercalated Discs, these are found at the ends of each cell linking one cell to another. This allows signals to pass from one cell to another quickly.
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What types of muscle cells are involuntary?
Cardiac and Smooth
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Which type of muscle is not striated?
Smooth Muscle
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Describe smooth muscle cells
Long cells tapered at the ends. They contain only one nucleus, they are NOT striated.
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Where is smooth muscle found?
In the bronchioles of the lungs, the GI tract, and surrounding blood vessels. The body uses smooth muscle to control many physiological functions like the dialation and constriction of the pupil in your eye.
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Where are the many nuclei of skeletal muscle fibers found?
Near the plasma membrane, on the periphery (the outer edges)
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What do cell junctions do?
Allow nearby cells to communicate and perform coordinated functions. Also allows many cells to come together and form a tissue.
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What are the three types of cell junctions?
Tight Junctions, Desmosomes, and Gap Junctions
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Explain Tight Junctions, What type of tissue are they usually found?
They form tissue barriers by creating a non-permeable barrier between cells by completely surrounding the cells. This means that anything that wants to pass the barrier must go through the cells (transcellular) and not between them (paracellular). This prevents bacteria and viruses from entering through the skin and keeps fluids in proper body cavities.
They are usually found on epithelial tissue.
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Why are desmosomes good? Why are they maybe not so good?
They provide a STRONG attachment holding cells together and prevent against stretching.
They do not prevent things from passing between cells like tight junctions do.
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What attaches an epithelial cell to the basement layer?
A Hemidesmosome
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What are gap junctions?
A pore made of proteins on the surface of a cell called a CONNEXON that meets with the CONNEXON of an adjacent cell.
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