Tissues Flashcards
Identify the stages of pre-embryonic development, beginning at fertilization and ending
at gastrulation. Describe the main event(s) of each stage.
Chinwe Blames Ife’s Grandma
Cleavage (Days 1-3) - this period of rapid biotic cell division 24 hours after fertilization forms blastomeres then morulas until day 4
Blastocyst - (Day 4 - 7)
When the morula hollows out and creates a cavity with a cluster on one side (contains 32 cells exactly called the embryoblast) and outlined with the trophoblast
Implantation - Trophoblast cells secrete enzymes which breaks down its covering (zone pellucida) and the blastocyst hatches. (forms 2 layers and becomes the embryonic disc)
- By day 7-8 it embeds to the uterine wall. hCG and luteinizing hormone help maintain the uterine lining.
- The bilaminar embryonic disc develops into the embryo and the separation between the epiblast and hypoblast fills with amniotic fluid.
Gastrulation - Formation of primary tissues.
- Embryonic disc forms primitive streak which forms dorsal of fetus and marks the tail.
- bilaminar embryonic disk forms three layers.
What is a blastomere?
identical cells formed by cleavage divisions
Describe the histological differences between a morula and a blastocyst.
The morula doesnt have the blastocyst cavity and trophoblast outlining it. It is a solid mans.
What are the two distinct cellular components of a blastocyst?
Trophoblast - the singular layer of large flattened cells with the blastocyst
Embryoblast- cluster of 20-30 cells within the blastocyst. (above the blastocyst cavity)
What is the function of the trophoblast?
Help invade uterine wall
Secrete enzymes that break down the zone pellucida (the covering around the blastocyst that was there since the egg was fertilized.)
secretes hCG
forms the cellular trophoblast (inner layer, looks like a membrane.) and syncytial trophoblast (outer layer that forms a slime looking thing.)
What role does human chorionic gonadotropin (hCG) play in sustaining pregnancy?
How has knowledge of this hormone become clinically and commercially useful?
Prevents the mothers immune system from rejecting the implanted embryo. It helps maintain the uterine lining to support the development of the embryo.
All pregnancy tests used today are antibody tests that detect hCG in a woman’s blood or urine.
From what embryonic structure does the bilaminar embryonic disk originate?
embryoblast ; the epiblast and hypoblast
Identify the three primary germ layers and describe which tissues ultimately derive from
each.
(Outer layer) Ectoderm -
Skin cells, neurons, pigment cells
Systems: Nervous system and skin epidermis
(Middle layer) Mesoderm -
Cardiac muscle cells, skeletal muscle cells, tubule cells of the kidney, red blood cells, smooth muscle cells
Systems: Mainly connective tissue cells and created organs of the urogenital systems
(Inner layer) Endoderm -
Lung cells, thyroid cells, digestive cells (pancreatic cell)
Systems: Epithelial linings of digestive tract, respiratory and urogenital and glands
Identify the four extraembryonic membranes and describe the function of each.
the amnion- develops sac that surrounds the amniotic cavity (which is filled with amniotic fluid.)
the yolk sac - main source of nutrition for the embryo, forms part of the gut, earliest source off blood cells, where germ cells migrate to form sperm and ova
allantois- structural base for the umbilical cord that links the embryo to the placenta and eventually becomes the bladder.
chorion - helps form the placenta and as the outermost membrane, encodes the embryonic body and all other membranes
What is a tissue?
groups of similar cells that are specialized to perform a particular function
Identify and describe the general function of each of the four basic tissue types.
Eric Makes Cassandra Nervous
Epithelial- Forms boundaries between different environments, protects, secretes and absorbs.
Muscular - Contracts to cause movement
Connective- Supports, protects, binds, other tissues together
Nervous- Internal Communication
What three general features tend to anchor cells together and stabilize tissues?
BCG
Basement membrane
Cell junctions
Glycoproteins
Describe the structure and function of each of the five common types of cellular
junctions.
TAG @ DH
Tight junctions- Adjacent (side by side cells) fused by transmembrane proteins.
*Prevent leakage, are in epithelium cells (respiratory tract)
Adherens- Has an adhesion belt made of plaque and tied together by cadherins. Attached to membrane proteins and microfilaments of the cytoskeleton.
*Adhesion belt prevents separation of epithelial surfaces (allows epithelium to form a covering)
Gap junctions- Connected by connexions but theres gaps between the cells.
- Allows the passage of chemical substances. Helps ions like sugar pass (distributes nutrients to fetuses before the circulatory system is created.)
- Important in smooth muscle, heart, epithelial.
Desesomes- Is like Adherens but the plaque is circular and they have intermediate filaments sticking out
- Helps distribute tension among skin, cardiac muscles, smooth muscle, neck region of the uterus
- Provides strength and stress points
Hemidesmosomes- Looks like Desesomes but is only half of it. Has interns that attach tho the basement membrane. NOT INTERCELLULAR (doesnt bind to another cell)
Identify the two major categories of epithelial tissue.
Glands
Covering and Lining Epithelium
What 5 special characteristics of epithelial tissue distinguish it from other tissue types?
- High degree of cellularity (can multiple fast)
- Specialized cellular contacts
(cellular junctions) - Polarity
(It has an apical side and a lumen side that faces the cavity of the internal organ) - Avascular
(no blood vessels, but has nerve supply) - Has a basement membrane
(Basal lamina - thin layer, is a filter between the blood and ET but allows nutrients to pass through.)
(Reticular lamina- Deeper layer of fibroblast/collagen fibers CT)
What type(s) of specialized lateral contacts are common in epithelium?
tight junctions and desmosomes
What are the 4 general functions of covering and lining epithelium?
- Protection
- Controls permeability
* Absorption & secretion
- Filtration & excretion
3. Surface transport (cilia)
4. Sensory Function
What are the primary functions of simple epithelium? of stratified epithelium?
absorption and filtration processes ; protection
What is a gland?
One or more specialized ET to produce and secrete secretion
Distinguish between endocrine and exocrine glands.
Endocrine - secretes HORMONES into the interstitial fluid (fluid around cells) around secreting cells
Exocrine- secretes PRODUCT into a duct that carries their produce to the surface (skin)
Multicellular - secretes product into a duct that open on an epithelia surface (liver produces bile, salivary glands, pancreas)
Unicellular-(goblet cells and mucous cells) secretes mucins that mixes with water to create mucus ; secrete on epithelia surfaces.
Identify, locate, and describe the function of the human body’s only unicellular
exocrine gland.
Goblet cells, in the epithelial linings of the intestinal and respiratory tracts , secretes mucin which makes mucous
What are the two basic structural components of multicellular exocrine glands?
A duct and a secretory unit (consisting of secretory cells)
What is the difference between simple and compound exocrine glands?
Simple - have an unbranched duct
Compound - Have a branched duct
What is the difference between the tubular, alveolar, and tubuloalveolar secretory
portions of multicellular exocrine glands?
Tubular - secretory cells form tubes
Alveolar- Secretory cells form small hollow cavities
Tubloalveolar - both
Name the three functional types of exocrine gland and describe the secretory process of each.
MAH
Merocine gland - Most common, secrete by exocytosis, cell is not damaged bt it
Apocrine gland - Accumulate secretory product near the apical surface and end up pinching that apical region off
Holocrine gland - explodes when it builds up with secretory product
Which of the above gland types (#30) is most common in the body?
Meocrine
What is the most abundant tissue in the human body?
Connective Tissue
Identify the four major classes of adult connective tissue.
- Connective Tissue Proper
- Blood
- Bones
- Cartilage
What is the common embryologic origin of all classes of connective tissue?
Mesenchyme which originates from the mesoderm tissue layer
What are the two basic components of all connective tissue?
ECM + cells
Describe the composition of ground substance.
Fluid + polysaccharides and proteoglycans (which differentiate the ground substances) + cell adhesion proteins (allows connective tissue to there to the ECM)
What is the most abundant structural protein in the body?
collagen
Identify the three fiber types found in the matrix of connective tissue.
REC
Recticular fibers
Elastic fibers
Collagen
Which of the three fibers found in the ECM are most resistant to tension forces?
collagen
Which of the three fibers in the ECM are found in the basement membrane of the epithelium?
Recticular fiber
What cells are found in connective tissue?
-blast (immature cells) and -cyte
Be able to identify the –blast and –cyte cell type associated with each class of connective tissue.
Connective Tissue Proper - Fibroblast
Cartilage- Chondroblast
Blood- Hemocytoblast
Bones- Osteoblast
Identify and describe the major types of connective tissue proper.
Loose CT
Loosely packed fibers, Has an abundance of ground substance. Few fibers and cells mainly fibroblasts.
*Absorbs shock and binds tissues together
Dense CT
Tightly packed fiber, Has large robust collagen fibers
*Provides strength to the tissue
Which type of the loose CT serves as a reservoir for water and salts, and
accumulates excess fluids, resulting in edema?
Areolar Tissue
What are the 3 examples of loose CT?
- Areolar CT - Most widely distributed CT, binds body parts together while allowing them to move freely
- Adipose CT - Sparse matric and closely packed fat droplets.
* Provides food fuel, insulates against heat loss and supports+ protects organs. - Reticular CT - Loose network of reticular fibers.
* Forms a storm that supports other cell types like white blood cells, mast cells and macrophages.
What are the 3 examples of dense CT?
- Dense Regular CT - Tightly packed college fibers run-in gin the same direction
*Resists tension in a single direction
Ex: Tendons, ligaments , Aponeuroses - Dense Irregular CT - same as regular but the collagen fibers are ranged irregularly.
* Resists tension in different directions - Elastic CT- a type of dense regular connective tissue, in arteries
What type of connective tissue proper is associated with epithelial membranes?
Areolar CT
Which type of connective tissue proper is found primarily in lymphoid organs?
Recticular CT
What is the most widely distributed connective tissue in the body?
Areolar
Which of the above (#51) is found in tendons and ligaments? in the dermis and in joint
capsules?
Tendons and Ligaments - dense
Dermis and joint capsules - Irregular
Describe the matrix of cartilage.
- Avascular
- Chondrocytes
- interstitial fluid
- fibers : elastic and collagen
Identify the location and function of the peri-chon-drium.
A sheet of dense irregular CT membrane which has blood vessels. (Carries the O2 and nutrients that diffuse into the cartilage) surrounds cartilage
Distinguish between the three types of cartilage based on their appearance, fiber
composition, and function.
Hyaline - glossy, bluish-white appearance , fine collagen fibers
- provides firm support with some flexibility (tip of nose)
- MOST ABUNDANT CARTILAGE IN BODY
Fibrocartilage - little ground substance lot of collagenfibers
- resists compression and tension wall
- STRONGEST CARTILAGE
Elastic- Similar to hyaline cartilage but more elastic fibers
*forms skeleton of the external ear and epiglottis (in respiratory system)
Describe the matrix of bone.
(vascular, osteocytes, inorganic calcium salts)
Identify and describe the basic parts of an osteon.
bony rings of bony matrix surrounding central canals
contains: blood + nerves for bone
made of compact bone
Name and identify the basic structural difference between the two types of bone tissue.
1.) Compact - external layer
Made of osteons
hard
2.) Spongey - internal layer
Made of trabeculae (pours bone tissue)
soft/sponget
What is the matrix of blood?
Cells + plasma
Compare and contrast the three types of fascia.
- Superficial - first layer under the skin (has areolar and adipose)
* shock absorber - Deep - middle layers
(made of dense connective tissue)
*strength - Subserous - last layer (areolar)
Identify the three types of muscle tissue.
- Skeletal
- Cardiac
- Smooth
What is fascia?
The CT layers that surround and support body organs and structures
Classify the three types of muscle cells with respect to location, appearance, and
nervous system control.
- Skeletal - Attaches to and moves bony skeleton
- Cardiac - Where heart contracts to pump blood
- Smooth - found in walls of internal organs, vessels , respiratory passages
Everything’s striated BUT: smooth muscle
Everything’s involuntary BUT: skeletal
What are the two main cell types of the nervous system?
neurons + neurological cells
What is a membrane?
A thin layer of tissue which is used to cover a surface, line a cavity, or divides a space or organ
Where are the synovial membranes located? Of what tissue are synovial membranes
composed?
lines joint cavities ; Composed of CT only
Why are epithelial membranes considered simple organs?
Because they only have two layers.
epithelium + CT
What are the three types of epithelial membranes?
- Mucous membrane
- Serous membrane
- Cutaneous membrane- the skin
Describe the location and characteristics of serous membranes.
- made of simple squamous ET
- 2 layers: partial organ lines outside of body cavity , identical copy called visceral lines inside. serous fluid in between them.
reduces friction between internal cavity and cavity wall
What is the function of serous fluid?
Reduces friction between internal cavity and cavity wall
Describe the location and characteristics of mucous membranes.
- Lines cavities that open to the outside of the body (respiratory and digestive tracts)
- Made of Epithelium over a thick, loose layer of CT
What type of epithelial membrane lines body cavities which open directly to the outside
of the body? which do not open to the body exterior?
Mucous ; Serous
The skin is considered to be what type of membrane?
cutaneous
Explain the difference between tissue regeneration and fibrosis.
Regeneration - identical replacement of damaged
Fibrosis- scar tissue
Name and describe the four steps involved in the regeneration of tissue after injury.
Immigrant Moms Protect Me
- Inflammation - chemical announcement of injury, blood clot forms
- Migratory and Organization phase - migration of cells into the area to form a new epidermis (fibroblasts come) , blood clot replaced with granulation tissue
- Proliferate phase - tissue and blood vessels regenerate, scab detaches and epithelium thickens
- Maturation phase
Epithelium is fully regenerated
Fibroblasts decrease in number
What does the basement membrane do?
Anchors and supports the ET
