Exam 2 Study Guide Flashcards
How is epithelial tissue classified?
Classified as simple or stratified.
Also classified as covering and lining epithelium if it covers a surface or lines a cavity.
Classified as glandular epithelium if it composed of glands.
Differentiate between endocrine and exocrine glands and give an example.
Exocrine glands secrete products through ducts (epithelial tube that directs secretions to the surface). ex. sweat gland
Endocrine glands have no ducts and secrete hormones directly into the bloodstream. ex. thyroid gland
Differentiate between merocrine and holocrine secretion and give an example.
Merocrine secretion is when products are produced by cells lining the secretory unit. Product is loaded into a secretory vesicle within the cells and then released into the lumen of the secretory unit by exocytosis. Product leaves secretory unit to move up the duct to the surface of the epithelium.
Examples are sweat glands, salivary glands, part of the pancreas.
Holocrine secretion is more aggressive. The secretory unit itself is filled with cells that produce the product, but the cells rupture to release their secretion to the duct along with cell fragments to be secreted onto the epithelial surface.
Examples are sebaceous or oil glands.
What are the types of fibers found in connective tissue and their functions?
Synthesized by fibroblasts in CT proper.
Collagen, elastic, and reticular fibers.
Collagen is strong and functions to resist stretching or tension.
Elastic fibers give tissues flexibility and want to be stretched.
Reticular fibers are very short and fine fibers and they tend to provide the supporting mesh to support other cells (present in bone marrow).
What is the composition of ground substance?
Everything else in the EC matrix except fibers, could be fluid or sugars or proteins.
What are the different types of cells that produce and maintain the matrix of connective tissue?
Fibroblasts, chondroblasts, osteoblasts, or blood cells formed from hematopoietic stem cells.
Blast cells are considered immature cells, when they mature they become cytes. Ex. Fibrocytes.Cells may revert back to blast version to build more.
Exception: blood cells are formed from hematopoietic stem cells.
Other cells: mast cells, adipocytes, WBC, macrophages.
Differentiate between the different types of cells and describe where they can be found. (fibroblasts vs. chondroblasts vs. osteoblasts)
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Compare and contrast the three types of muscle tissue as to location, structure, characteristics, and function.
General muscle: highly cellular cells that are close in proximity and functions for movement, muscle cells also known as fibers. Also extremely vascularized because of activity levels.
Muscle fibers are filled with protein rods called myofilaments (actin and myosin). Specific patterns, allow for tension in muscle.
Skeletal: long, cylindrical multinucleate cells (needed to control all the cellular activity), appears striped or has striations. Striations result from overlapping organization of actin and myosin.
Under the control of somatic NS.
Cardiac muscle: branching cells, typically mono nucleated, has intercalated discs and less organized actin and myosin that form faint striating.
Interacalated discs: cell junctions that contain two junctions, gap junctions and desmosomes.
Under involuntary control or autonomic NS.
Smooth muscle: small spindle shaped cells, uninucleate, does not appear striated because actin and myosin organizations is not as precise. Functions to propel substances through passageways. Lining hollow organs, stomach, intestines, ureters.
Also under control of autonomic NS
What are the two general cell types within nervous tissue and what are the differences between them as described in lecture?
Nervous tissue: functions for control. Most abundant cell types in NT is neurons because they are electrically active.
Glia or glial cells are supporting cells. Not electrically active; they cannot send or receive impulses.
Describe the general structure of the skin.
Composed of 2 main layers
epidermis is composed of stratified squamous epithelium, avascular, highly mitotic.
Dermis is highly vascular, where dermal vascular plexus is located.
Subcutaneous layer- not part of the integument, made of adipose and aereolar CT. functions for cushioning, insulation and anchoring skin to underlying structures.
Skin is not uniform, thickness and distribution of components varies
composed of dense irregular CT. dermal vascular plexus, sensory NS structure, sweat and oil glands, and hair follicles.
What are the layers of the epidermis? What happens in each layer?
Epidermis is composed of stratified squamous epithelium. Keratinocytes, epidermal dendritic cells, melanocytes, tactical cells (cutaneous sensation).
Stratum corneum: dead cells with glycolipids in between to prevent water movement; cornified cells slough off with abrasion.
Stratum lucidum: thin transparent layer, areas of thick skin, composed of cells that are dead and identical to above layer- stratum corneum. Adds hardiness to the regions that are subject to high abrasion.
Stratum granulosum: typically 1-5 layers of keratinocytes, last layer of living cells. Keratinization process begins here. Keratinization is when cells flatten out and all organelles are removed. They do this to make room for keratohyaline and lamellar granules to add to the skin. Organelles are ingested by lysosomes.
Keratohyaline granules are regions of high abundance of keratin molecules.
Lamellar granules: filled with glycolipids- prevent water loss and water entry.
Stratum spinosum: contains young keratinocytes, go from being round to flat, have junctions called desmosomes between keratinocytes. Desmosomes are very evident. Also has epidermal dendritic cells patrolling searching for foreign invaders. Mark any foreign material for destruction to activate an immune response.
Stratum basale: deepest layer of the epidermis, single row of highly mitotic cells, where keratinocytes are first formed. 10-20% of cells in this layer are melanocytes. All humans have the same number of melanocytes, but some are more active than others.
As stratum basale cells synthesize new cells, old ones get bumped up to the stratum spinous.
What is a keratinocyte? What other cells are found in the epidermis? What are their functions?
Specialized hardy cells, filled with strong fibrous protein called keratin.
Melanocytes
epidermic dendritic cells patrol the epidermis, if something is found, they will mark to for destructions.
Dermal macrophages: participates in phagocytosis, in the deeper dermis. Engulf pathogens engulfs anything that is missed by dendritic cells.
What type of connective tissue is found within the dermis?
Papillary: superficial layer, made up of aereolar CT
Reticular: deeper layer that makes up majority of skin, dense irregular CT.
Differentiate between sudoriferous and sebaceous glands as to location, structure and function.
suderiferous glands (sweat glands) cover the entirety of the skin, they are more numerous than sebaceous glands.
eccrine and apogrine glands
sebaceous glands vary in size, multicellular exocrine glands, but duct empties into a hair follicle instead of the skin surface. secretory unit is filled with cells which produce the product sebum and release sebum by holocrine secretion.
sebum is composed of a lot of lipids and cell fragments from holocrine secretion.
functions to soften skin and lubricate hair and has antibacterial agents.
synthesis questions on the test about different glands!
Differentiate between eccrine and apocrine sudoriferous glands as to function and location.
eccrine (merocrine) glands most numerous sweat glands they are multicellular exocrine glands, produce a hypotonic filtrate (has fewer solutes than blood) of blood which is 99% water. contains salts, metabolic wastes (urea uric acid), and an antibacterial agent called dermcidin.
product is produced by cells of the secretory ducts, then released by merocrine secretion to the lumen.
function of eccrine sweat glands is for temperature regulation when sweat is secreted onto surface of skin and evaporated, body heat is dissipated.
other function is antibacterial. eccrine sweat is pH 4-6 which slows replication, and an antibacterial dermcicin.
apocrine sweat glands are few in number, around 2000 in the human body.
present in axillary and anogenital areas.
multicellular exocrine glands that secrete product by merocrine secretion.
apocrine sweat glands sometimes empty secretion into a hair follicle.
product is thicker (more proteins and more lipids) than eccrine glands.
function is somewhat unknown, does not function for temp regulation, functions as sexual scent glands, and responsible for BO because of the presence of lipids and proteins which decompose on the skin surface.
Discuss the three levels of burns and the characteristics of each level.
causes of burns are heat, electricity, radiation, or toxic chemicals.
these cause proteins in skin to denature or unfold which can lead to cell death.
first degree burn is only damaging the epidermis, associated with redness, pain, and slight edema. heals in 2-5 days.
second degree burn is when entire epidermis is lost, and papillary layer of the dermis is damaged. associated with redness and pain and blisters.
typically heals in 2-4 weeks. may not scar, but risk of infection is present because dermal vascular plexus is in the dermis.
third degree cover the entirety of skin, epidermis and dermis are lost. nerve endings and blood vessel network could be destroyed causing loss of fluids. not associated with severe pain, scarring usually results, treated with skin grafts (healthy skin is put on top of burn skin so stratum basal can help regenerate skin.
What is the immediate danger with a severe burn? After the initial crisis, what is the next danger?
dermal vasulcar plexus is destroyed in a severe burn, which leads to loss of fluids (dehydration and electrolyte imbalance which possibly leads to renal failure and circulatory shock.
treatment is to replace fluids.
the next danger is infection.
Describe the three different types of skin cancers in terms of appearance, origin and severity. Which is the most deadly?
predominately caused by UV radiation in sunlight.
basal cell carcinoma: most common, least malignant. stratum basal cells proliferate uncontrollably and invade dermis and subcutaneous tissue. slow growing, rarely metastasizes. surgical excision is used.
squamous cell carcinoma: second most common, impacts keratinocytes of stratum spinosum. grows rapidly and can metastasize is not removed. early radiation or surgical removal is best.
melanoma: typically associated with irregularly shaped mole, affects melanocytes and highly metastatic. also resistant to most types of chemotherapy, but chemo is still coupled with immunotherapy and excision and gene therapy. accounts for 2-3% of skin cancers, but incidence is rising. Melanoma ABCs Asymmetry Border irregular Color: several Diameter: > 6mm Evolving
Discuss the functions of the skeletal system
Could be considered a structure, a tissue (osseous tissue; type of CT) and an entire organ (because it has many different tissues).
acts as a reservoir for a number of minerals, especially calcium, and phosphorus. minerals can be released back into the bloodstream to maintain levels needed to support physiological processes. Calcium ions are essential for muscle contractions and transmission of nerve impulses.
bone marrow: Yellow bone marrow contains adipose tissue, and the triglycerides stored in the adipocytes of this tissue can be released to serve as a source of energy for other tissues of the body. Red bone marrow is where the production of blood cells (hematopoiesis) takes place. Red blood cells, white blood cells, and platelets are all produced in the red bone marrow
axial: support, framework, carry
appendicular: locomotion/movement
could be classified as short, flat, irregular, or long bones.
short bones are cube shaped to carry out function of shock absorption
flat bones: provide points of attachment for muscles, tendons, ligaments, and provide a large surface area to protect underlying structures.
irregular bones: fulfill very specific functions such as the vertebrae protecting the spinal cord. vertebral column has varying ridges and to help it resist mechanical forces.
long bones: functions as the framework for the appendicular skeleton, example is femur. function for locomotion or movement.
List the features and structures of a long bone.
long bones will have 2 membranes has epiphyses and a long axis called diaphysis. collar of compact bone and a thin layer of compact bone and a layer of spongy bone lining interval surface. also has central medullary cavity could be filled with yellow or red marrow.
contains cortical and trabecular bone and bone marrow.
epiphyses has a compact bone lining and spongy bone center. covered by a thin layer if articular (hyaline cartilage and allows for smooth movements on bone ends) on joint surfaces. epiphyseal line is remnant of epiphyseal line (growth plate).
Describe the microscopic anatomy of compact bone. How is compact bone different from spongy bone?
inorganic material: 2/3 of bone. composed of mostly minerals and then water (10% of bone).
minerals crystalize and form calcium phosphate crystals or hydroxyapetites. surround collagen fibers and ability to resist compression. gives bone stiffness and harndness.
calcium phosphate structures are very strong and resist compressive forces extremely well.
organic material:1/3 of bone. composed of osteoid (organic extracellular matrix such as collagen) and cells.
osteoid is made by osteoblasts, made of mostly collagen and some glycoproteins and proteoglycans (sugar protein complexes)
collagen is important for allowing bone to resist tension. it also gives bone slight flexibility.
osseous tissue is composed of resident cells imbedded in a cellular matrix with collagen and minerals are the ground substances.
Differentiate between osteoblasts, osteocytes, and osteoclasts as to function.
osteoblasts are bone forming or building cells and synthesizing osteoid.
osteocytes: mature osteoblasts that sense in order to maintain the matrix. have dendrites that extend to be able to sense the status of bone in a large area.
osteoclasts: cut or resorb bone matrix. they have microvilli on one surface to increase surface area for digestive enzymes. they can suction off a region they want to remodel by only having the microvilli on one side.
osteogenic cells/osteoprogenetor cells: stem cells that can become other types of bone cells.
bone lining cells: line the surface of bone where no activity is occurring.
Describe the composition of bone matrix. What is meant by osteoid? What are hydroxyapatite crystals?
Osteoid, which makes up approximately one-third of the matrix, includes ground substance and collagen fibers, both secreted by osteoblasts. Collagen contributes both to a bone’s structure and to the flexibility and tensile strength. inorganic matter (calcium phosphate, mostly hydroxyapatite crystals)
The hydroxyapatite crystals give bones their hardness and strength, while the collagen fibers give them flexibility so that they are not brittle. synthesize and secrete the collagen matrix and calcium salts.
Describe the sequence of events in the development of intramembranous bone. Where can intramembranous bone be found?
forms bones from fibrous CT membrane.
6-8 week old embryo
starts with mesenchyme model of bone with stem cells called mesenchymal stem cells which differentiate into osteoblasts (now known as ossification centers).
osteoblasts then start secreting osteoid (organic) and producing extracellular matrix.
matrix then becomes mineralized.
all primary ossification centers join in forming immature spongy bone. once formed, mesenchyme is going to condense to form the periosteum (outer bone membrane).
periosteum has outer fibrous layer and inner cellular layer. cellular layer contains osteoblasts start producing (compact bone starts to be formed) matrix on outside face of bone.
ex. skull, clavicle and mandible is now formed- compact outside with spongy inside.
Describe the sequence of events in the development of endochondral bone. Where can it be found?
forms bone from hyaline cartilage models around weeks 6-8 and ossify until birth.
begin with hyaline cartilage structure with perichondrium on outside. has mesanchymal that differentiate into osteoblasts. converts perichondrium into periosteum. cartilage to bone membrane.
osteoblasts in the newly formed periosteum starts building matrix forming an ossification center.
cells in the center start to age and enlarge- now called hypertrophic cartilage cells and start depositing calcium phosphate crystals and calcify surrounding matrix so they die. The center of the hyaline cartilage models of bone (diaphysis) starts to deteriorate and forms the beginnings of medullary cavity.
periosteum continues to lay down more and more bone and extending the bone collar. around month 3 or 12 weeks, the periostial bud invades cavity.
bud contains blood vessels, red marrow and stem cells.
elongation is continuing and osteoblasts fill cavity with osteoid and generate spongy bone.
osteoclasts degrade spongy bone that was just laid down to create the final medullary cavity that is now hollow. reason spongy bone needs to fill in the first place is so there is a thin layer of spongy bone still left over after degradation.
four steps continue from week 9 until birth.
above is development of diaphysis.
secondary ossification forms, difference is periostial bud lays down spongy bone, and it is not deteriorated because epiphyses have no cavities.
most models of bone have ossified at birth. hyaline cartilage still occurs in epiphyseal plates to separate diaphysis from epiphysis. allows bones to continue to grow in length throughout puberty. also persists in articular cartilage.
continues throughout infancy and childhood (postnatal bone growth). bone grows in length (interstitial growth) and grows in thickness (appositional growth) where more bone is added by the periosteum to the external surface.
Differentiate between primary ossification sites and secondary ossification sites in endochondral ossification.
Primary ossification center forms in the diaphyseal region of the periosteum called the periosteal collar. Secondary ossification centers develop in the epiphyseal region after birth.
How does a bone grow in length? Describe what happens in each “zone”. How does a bone grow in width?
depends on epiphyseal plate, so when it closes and it is all bone, the bone is not able to grow in length anymore.
growth occurs as hyaline cartilage up and is replaced by bone at the bottom. bone is chasing cartilage bone.
proliferation zone: growth via mitosis
hypertrophic zone: older hypertrophic cells are aging and want to die so they calcify their matrix
calcification zone: cells cut themselves off from nutrient by calcifying their surroundings
ossification zone: cartilage has been converted into spongy bone
later: osteoclasts from below will degrade spongy bone to expand the medullary cavity.
What is bone remodeling? How is bone remodeling affected by mechanical forces and gravity? Give examples.
bones continue to remodel even after the epiphiseal plate closes.
each week, 5-7% of bone mass is remodeled.
bone remodeling is a balance between osteoblast and osteoclast activity to renew bone but have the same mass. equal amounts are best
- bone resorption
function of osteoclasts that break down or degrade bone matrix by secreting an acid that break down inorganic constituents of bone ca and P. lysosomal enzymes are also released to break down the organic contituents (collagen). osteoclasts have degraded section, they undergo apoptosis. - deposition
osteoblasts follow osteoclasts and lay down new organic extracellular matrix (collagen and osteoid) - calcification
mineralizes ECM and lays down inorganic matrix. collagen is going to bind collegen because it is attracted to it, causing the ca levels in bone to rise, triggering release of alkaline phosphate from osteoblasts. calcium follows collagen
alkaline phosphitatse breaks off groups of surrounding molecules. high concentrationof collagen bound to calcium and phosphate. ca and p crystalize forming hydroxyapatites that are now deposited in bone.
Why are specialized junctions important in epithelium?
Desmosomes and tight junctions are very prominent in epithelium. Both help create a boundary between two environments.
Desmosomes (anchoring junctions) help epithelial cells be held together to resist mechanical stress or stretching.
Tight junctions form a continuous seal around cells that prevent molecules from passing through intercellular spaces, thus promoting the epithelium’s function as a boundary.
What is the significance of apical-basal polarity in epithelium?
Apical-basal polarity is essential for epithelial cell form and function, as it determines the localization of the adhesion molecules that hold the cells together laterally and the occluding junctions that act as barriers to diffusion.
polarization allows epithelial cells to transport molecules across the surface in a directional manner.
Why is the basement membrane significant?
Underlying connective tissue composed of reticular fibers (fine collagen fibers). Reticular fibers are produced by the connective tissue cells.
It provides structural support to epithelia and forms a mechanical connection between epithelia and underlying connective tissue. The basement membrane also regulates the metabolism, proliferation, survival and differentiation of epithelial cells. The basement membrane functions as filter and because epithelia lack their own blood supply, all small molecules and gases derived from the blood must diffuse across the basement membrane. The basement membrane also prevents epithelial cells from invading into connective tissue.
Basal lamina
Non-cellular region of the basal surface that consists of glycoproteins and fibrous proteins. Functions as supporting tissue and a selective filter to help decide what molecules can enter into the epithelium and connective tissue and vice versa.
Glycoproteins that may exist in the basal lamina
entactin, perlecan, and laminin (adhension molecules)
Basal lamina
Non-cellular region of the basal surface that consists of glycoproteins and fibrous proteins (collagen). Functions as supporting tissue underneath the epithelium and a selective filter to help decide what molecules can enter into the epithelium and connective tissue and vice versa. Produced by the epithelium.
