Final exam condensed Flashcards
Simple epithelium
One layer, found in areas like the alveoli that need thin tissue for diffusion
Stratified epithelium
2+ layers, found in areas like the esophagus that need thick tissue to resist mechanical or chemical stress
Where is the body is epithelial tissue found?
Covers/lines organs and body cavities (outer layer of skin, urogenital, digestive, and respiratory systems). Also glandular epithelium that makes up the glands of the body
Basement membrane
The epithelial tissue is attached to the basement membrane, which is made up of fibers rather than cells. This allows nutrients to diffuse to the epithelial tissue, which is avascular.
Connective tissue characteristics (3)
- Cells
- Ground substance
- Fibers
The ground substance and fibers make up the matrix
Covering epithelium is joined by
Tight junctions and desmosomes
Basement membrane layers (2)
- Basal lamina- secreted by the epithelium itself
- Reticular lamina- contains fibers that belong to connective tissue. Bottom layer of the basement membrane, sits closest to connective tissue
Epithelial tissue is the only tissue type that has apical basal polarity. Why is this important?
One free (apical) surface is necessary, as the epithelium covers the body and lines body cavities
Pseudostratified columnar epithelium
“False” stratified cell nuclei lie at different levels- the nuclei are displaced so it looks like there are multiple layers of cells. Only some cells stretch from the apical surface to the basal surface. “Short” cells give rise to “tall” cells (the cells are different sizes). Shorter cells attach to the basement membrane. Located in respiratory tract, male ducts, and ducts of large glands. Responsible for secretion and absorption.
Under a microscope, you see that many cells of an exocrine gland are in metaphase. Is this a merocrine or a holocrine gland?
Holocrine. Holocrine glands release products as a result of cell rupture. Sebaceous glands are an example
Merocrine glands
Product secreted from the acinus via exocytosis, cell remains unchanged. Example- sweat or salivary glands
Apocrine glands
Similar to holocrine, but do not truly rupture. The cells have a small tear in the membrane so the secretion can leave, and the membrane quickly reassembles. Mammary glands could be an example
Functions of connective tissue (5)
- Binding and supporting
- Protecting
- Insulating
- Storing reserve fuel
- Transporting substances within the body
What types of fibers can be found in connective tissue (3)?
- Collagen- resist pulling forces
- Elastic- high density in areas of the body that are subjected to frequent stretching- skin, lungs
- Reticular- high density in areas of the body where connective tissue attaches to another tissue
What type of connective tissue is capable of acting as a fluid reservoir?
Areolar tissue can act as a fluid reservoir because of its web-like nature.
What type of connective tissue is damaged when you lacerate a tendon?
Dense regular connective tissue
When aging cartilage tends to ossify, its cells die. What survival needs are not being met in those cells?
Oxygen and nutrient needs are not being met. The calcified cartilage matrix is too hard to allow for these substances to reach the cell by diffusion.
What type of membrane consists of epithelial and connective tissue, and lines body cavities open to the exterior?
Mucous membranes fit this criteria. It lines any body cavity that leads out of the body and is a wet/moist membrane. Function- absorption/secretion.
What type of membrane lines the thoracic walls and covers the lungs?
The serous membranes (pleurae) line the body cavity and cover the lungs.
What is the difference between the serous and mucus membranes, and the plasma membrane and basement membrane?
Plasma membranes surround cells and are made of phospholipids. The basement membrane is a layer of extracellular material that lies just outside the basal surface of epithelial cells. Serous and mucous membranes are considered organs because they are composed of multiple types of tissues.
The serous membranes are held together by serous fluid, which is mainly water. What property of water makes them stick together?
Water’s high surface tension due to its hydrogen bonds
What are the 3 main steps of tissue repair?
- Inflammation
- Organization
- Permanent repair via regeneration and fibrosis
Why does a deep injury to the skin result in abundant scar tissue?
More severe injuries damage and destroy more tissue, requiring greater replacement with scar tissue.
One patient has brain damage from a stroke, one had a heart attack, and one has a damaged liver (a gland) due to a car accident. Which one will regain full function of the damaged organ through tissue regeneration?
The liver is a gland derived from epithelial tissue. Epithelial tissue regenerates well, but nervous tissue in the brain and cardiac muscle exhibit virtually no functional regeneration.
Types of covering and lining membranes (3)
These are considered simple organs.
- Cutaneous (skin)- composed of keratinized stratified squamous epithelia
- Mucous
- Serous- line closed body cavities
Types of cartilage (3)
- Hyaline- found in trachea, nose, ends of joints
- Elastic- very flexible
- Fibrocartilage- found in areas of the body that need a lot of support/bear a lot of weight
Types of connective tissue
- Connective tissue proper (areolar, adipose, dense regular)
- Cartilage
- Osseous tissue
- Blood
Marfan Syndrome
A genetic disorder that affects the body’s connective tissue. Results from a mutation in the FBN1 gene, which codes the production of fibrillin. This protein contributes to strength and elasticity. Connective tissue loses strength/elasticity. Connective tissue is located throughout the body, so symptoms are widespread- bones, blood vessels, eyes, respiratory system
Simple gland
Unbranched duct- one straight tube into secretory unit
Functions of the skin (6)
- Protection (chemical, physical, biological)
- Temperature regulation
- Sensation- cutaneous receptors
- Metabolic functions (vitamin D absorption and production)
- Reservoir for blood
- Excretory- sweat eliminates waste
Tactile and lamellar corpuscles
Responsible for touch sensations
Hypodermis functions (4)
- Storage- easy to access energy source for the body
- Protection/shock absorption- prevents physical trauma to internal organs
- Insulation- prevents excessive heat loss
- Anchor- holds skin to underlying skeletal muscle tissue- is still flexible
Cellular portion of epidermis (4)
- Keratinocytes- produce keratin (fibrous protein, very tough). Give the epidermis its dry and tough quality.
- Melanocytes
- Dendritic cells
- Tactile cells (Merkel cells)
Keratinocytes are linked by
Linked by desmosomes (with some tight junctions). Tight junctions are important to prevent releasing water to the environment
Where are melanocytes located?
The stratum basale
Dendritic cells (Langerhans cells)
Move to epidermis from bone marrow. Active macrophages- this activates the immune system
Tactile cells (Merkel cells)
Present in epidermal-dermal junction. Associated with nerve endings- sensory receptor function (2 types of touch)- light touch
and vibration
5 layers of the epidermis
- Stratum corneum- dead keratinocytes
- Stratum lucidum- dead cells, relatively transparent, not found in thin skin
- Stratum granulosum- keratinization begins here, has lamellar granules to make the skin waterproof
- Stratum spinosum- contains pre-keratin- thick bundles of filaments that resist tension. Dendritic cells are most abundant here (immune system).
- Stratum basale- single layer of stem cells attached to dermis
All reproduction in the epidermis comes from this layer- melanocytes and keratinocytes are found here.
Papillary dermis
More superficial layer, made of thin areolar connective tissue. Fibers are thin- defensive cells wander freely here. Has projections called dermal papillae. Can have either pain receptors or tactile corpuscles
Increase the surface area of the dermis so the epidermis can be better attached to the dermis. Also, the amount of nutrients and oxygen passed on to the epidermis will increase. Attaches to the epidermis, pulling it in- indents overlying epidermis forms friction ridges (fingerprints)
Reticular dermis
Deep layer, made of dense irregular connective tissue. Forms cleavage lines in the skin. Not visible externally, lines are formed by alternating dense and less dense regions of fibers. This is very important for surgeons. The direction of the cleavage line determines the type of incision. Also forms flexure lines at joints to make the skin more flexible.
3 factors that determine skin color
- Melanin- reddish yellow and brownish black pigment, synthesized by tyrosinase enzyme
- Carotene- yellow orange pigment that can be used for vitamin A synthesis. Accumulates in stratum corneum and adipose tissue
- Hemoglobin- pink/red pigment found in blood cells- influences skin color in fair skinned individuals
Hair functions (2)
- Sensory structures: nerves associated with hair follicle
- Protection- scalp (from the sun), eyes (from dirt/debris), nose (hairs trap dirt and debris and prevent it from entering the lungs)
3 layers of hair
- Medulla- central core composed of large cells and air space. Absent in fine hairs of the body (vellus hairs)
- Cortex- several layers of flattened cells- less air space, cells are tightly packed together
- Cuticle- outermost layer that is most heavily keratinized, cells stacked like roof shingles. Separates individual hairs to prevent mats
3 layers of the hair follicle
- Peripheral sheath- most external layer composed of dermis. Like a follicle wall.
- Glassy membrane- “basement membrane” joining the peripheral sheath to the root sheath
- Root sheath- most internal layer derived from epidermis. Surrounds and protects the growing hair so cells can be added.
Root hair plexus
found at base of hair (hair bulb). Contains nerve endings, detects when the hair bends/moves
Dermal papilla
Provides capillaries to the hair follicle. Need to have blood supply to grow hair
Shape of hair depends on
Hair follicle: round= straight hair, oval= wavy/slightly curly, flattened= very curly
Hair matrix
Composed of rapidly dividing cells from hair bulb- new cells push old cells up and out to become the hair shaft- hair growth. Most growth is cyclical. When hair is in the dormant stage it won’t actually grow/cells won’t divide. The hair could also shed. Not all follicles are in the same stage at the same time
Telogen effluvium
Hair loss for no apparent reason- maybe poor diet or chronic stress
Alopecia universalis
Complete loss of hair on the scalp and the rest of the body. Can take shots that help to stimulate the follicles
Nail root
Underneath the skin, can’t be seen externally, covered by nail matrix- cells divide rapidly
Nail plate
Part that can be seen externally