Gross Anatomy TBL 7

Question 1

Define simple squamous epithelium and what it lines (2) as?

Answer 1

• SINGLE LAYER of squamous (flat) epithelial cells
• lines body cavities and covers organs as MESOTHELIUM.
• lines heart and blood vessels as ENDOTHELIUM.

Question 2

Describe the properties of tight junctions and function.

Answer 2

• Tight Junctions are focal aggregates of intercellular adhesion proteins in cell membrane (PLASMALEMMA)
• Fxn to LINK contiguous squamous cells of endothelium and mesothelium.

Question 3

Where do endocrine and exocrine glands secrete into?

Answer 3

• Endocrine secrete into bloodstream.
• Exocrine secrete into a duct system

Note- endo think endothelium (lining of blood vessels)

Question 4

Define simple cuboidal epithelium, its function, and what it lines.

Answer 4

• SINGLE LAYER of cube-shaped cells.
• simple cuboidal epithelium forms the circular secretory acini in endocrine and exocrine glands.
• simple cuboidal epithelium LINES the DUCTS of the EXOcrine glands.

Note: acini refers to a cluster of cells that resmeble a many-lobed berry, like a raspberry.

Question 5

Define the properties of simple columnar epithelium, where it projects, it’s advantage for absorption and secretion, and where is it found (4)

Answer 5

• Simple columnar epithelium is a SINGLE LAYER of column-shaped cells (e.g. microvilli)
• The surface area created by the short cellular projections along the apical “free” surface of epithelium.
• Found in the stomach, intestines, uterine tubes, and uterus.

Question 6

What are the epithelial cells that are firmly linked by tight junctions?

Answer 6

Squamous, cuboidal, and columnar epithelial cells.

Question 7

Define properties of cilia and function. Also define the properties of goblet cells and function.

Answer 7

• Cilia are mobile apical surface specializations of COLUMNAR cells.
• Goblet cells are COLUMNAR cells filled with mucus.

Question 8

Define property of psuedostratified epithelium. What does it line?

Answer 8

• Psuedostratified epithelium is a mixed layer of CUBOIDAL and COLUMNAR epithelial cells.
• Lines the pulmonary airways as respiratory epithelium.

Question 9

Define the functions of goblet cells and cilia in respiratory epithelium.

Answer 9

• Goblet cell secreted mucus covers the apical surface of respiratory epithelium to entrap inspired particulates and pathogens.
• Cilia have a rhythmic beating of the cilia which mvoes the debris-laden mucus (thanks to the goblet cells) toward the oral cavity for expectoration or swallowing.

Note: expectoration means to eject from mouth “spit”

Question 10

Define nonkeratinized stratified squamous epithelium , its function, and where its found.

Answer 10

• Nonkeratinized stratified squamous epithelium is MULTIPLE LAYERS of contiguous CUBOIDAL cells covered by SEVERAL layers of SQUAMOUS cells.
• Provides protective lining in organs like esophagus and vagina.

Question 11

Define properties of keratinized stratified squamous epithelium and what layer of skin is it

Answer 11

• Keratinized stratified squamous epithelium contains several apical layers of anucleate squamous cells filled with keratin (protein)
• It is the epidermis of the skin.

Question 12

All epithelia rests on what? Discuss the (3) functions of of what all epithelia rests on.

Answer 12

• All epithelia rest on a basement membrane
• Basement membrane supports the epithelium, creates a selective filtration barrier, and controls epithelial differentiation during growth and tissue repair.

Question 13

Discuss the relation of basement membranes to the metastasis of tumor cells.

Answer 13

• Cancers arising from epithelia BREACH BASEMENT MEMBRANE before infiltration of surrounding tissues to gain access to circulation (metastasize- spread of malignant cells from primary tumor to distant areas).

Question 14

Describe the Matastatic cascade.

Note: Understanding the metastatic cascade of a particular lends way for Novel Tx.

Answer 14

1. Tumor cells detach from each other by alteration of intercellular adhesion molecules e.g. CADHERINS
2. INVADOPODIA (finger-like protrusions) develop from the tumor cells to DEGRADE BASEMENT MEMBRANE by releasing proteolytic enzymes.
3. AMBEOID MOVEMENT allows for tumor cell migration via CELL RECEPTORS e.g. INTEGRINS, and signaling proteins that interact with a cytoskeleton (actin and intermediate filaments).

Question 15

Dermis underlies what (2)? Does the dermis consist of loose or dense connective tissue?

Answer 15

basement membrane and epidermis. Loose connective tissue.

Question 16

Fibroblast derived collagen and elastic fibers provide what to the dermis?

Answer 16

Provides tensile strength and allows for passive recoil (after skin was stretched or distended), respectively.

Question 17

Which layer of skin can endothelial lined capillaries be found and what occupies much of the loose connective tissue?

Answer 17

The dermis and the capillary filtrates produce the interstitial fluid which occupies much of the loose connective tissue found in the dermis.

Question 18

How do mast cells contribute to the formation of edema in loose connective tissue that occurs during the inflammatory response to injury?

Answer 18

Mast cells release histamine, heparin, chemotactic factors (important regulators of eosinophil and neutrophil), cytokines, and metabolites of arachidonic acid that act on vasculature, smooth muscle, connective tissue, mucous glands, and inflammatory cells.

Histamine is a potent vasodilator and proteolytic enzyme, can destroy tissue or cleave complement components. Histamine release from cells increases permeability of capillaries and venules and results in local edema and emigration of leukocytes and monocytes from circulation. They stimulate local cell proliferation, which leads to production of connective tissue elements involved in repair of damaged tissues.

Question 19

Compared to loose connective tissue how is dense connective tissue (e.g. tendon and bone) different (3)?

Answer 19

Greater proportion of collagen fibers, fewer cells, and less interstitial fluid than loose connective tissue.

Question 20

The eight cell stage of a zygote can differentiate into all cell types in the Placenta and Embryo. The term used for aforementioned is…

Answer 20

The cells are totipotent.

Question 21

How many days after fertilization and at what cell stage is the zygote at the junction of the uterine tube and uterus?

Answer 21

Three days after fertilization and 12-16 cell stage.

Question 22

What occurs to the the zygote once it enters the uterus?

Answer 22

Fluid secretions from the uterine wall infilatrate the zygote to create a blastocyst cavity, an inner cell mass and an outer cell mass.

Question 23

Inner cell mass and outer cell mass become what after the infiltration of uterine fluid once the zygote has migrated to the uterus?

Answer 23

• becomes the embryoblast (cells are pluripotent)
• becomes the trophoblast (forms the wall for the blastocyst)

Pluripotent - have the ability to become any cell type except placenta.

Question 24

Why do cells of the inner cell mass have clinical potential?

Answer 24

The pluripotent cells may be used for transplatational therapeutics to induce a specific cell type for tissue regeneration.

Question 25

At what week does the trophoblast initiate implantation and into what epithelia?

Answer 25

At week 1 the trophoblast which has formed the wall of the blastocyst cavity has initiated implantation of the into the simple columnar epithelium of uterus.

Question 26

In week 2 what does the trophoblast do?

Answer 26

In WEEK 2 the trophoblast expands into the loose connective tissue of the uterus where local edema was produced due to the engorgement of capillaries.

The trophoblast releases enzymes to erode the endothelium of the engorged uterine capillaries and now the maternal blood enters the trophoblastic lacunae.

Note the trophoblastic lacunae is formed when edamatous fluid penetrates the trophoblast.

Question 27

Penetration of edamatous fluid into the trophoblast creates what?

Answer 27

It creates small fluid-filled lacunae (tiny spots) among the trophoblastic cells.

Question 28

Upon implantation of the blastocyst to the uterine wall the embryoblast (der. inner cell mass) is divided into? Also discuss further development of those two divisions.

Answer 28

The embryoblast differentiates into a BILAMINAR GERM DISK with an Epiblast and Hypoblast.

The amniotic cavity in the epiblast is filled with edamatous fluid from the uterine CONNECTIVE TISSUE.

Proliferation of the Hypoblast forms a lining of the blastocyst which becomes the yolk sac. Also cells from the hypoblast form extraembryonic mesoderm and edamatous fluid infiltrates the mesoderm to form fluid filled lacunae

Question 29

After formation of the extraembryonic mesoderm and fluid filled lacunae from the hypoblast what cavity is found when the lacunae continue to join?

Answer 29

The chorionic cavity (Large extraembryonic cavity) is formed which surrounds the yolk sac and amniotic cavity except where the germ disk connects to the trophoblast via the connecting stalk (der. of extraembryonic mesoderm)

Question 30

At week 2 what is the linear groove that is formed and provide details of its orientation and future development.

Answer 30

The primitive streak forms on the surface of the epiblast facing the amniotic cavity. The primitive streak forms in the caudal region of the germ disc which is closer to the future limbs. The opposite end of the germ disc (caudal) is the region where the future head will be.

Question 31

Gastrulation occurs in what week of the embryonic period? Explain the occurrence of gastrulation.

Answer 31

In WEEK 3 the cells of the epiblast proliferate and migrate through the primitive streak in a process called gastrulation and become the mesodermal (MESYNCHYMAL) cells between the epiblast and hypoblast.

Some of the mesynchymal cells continue to migrate and REPLACE the hypoblast cells of the yolk sac to form endodermal cells.

Question 32

When does the primitive streak disappear?

Answer 32

During gastrulation the cells remaining in the epiblast form the ectodermal cells. Thus the ectoderm, mesoderm, and endoderm make up the trilaminar germ disc.

Formation of the trilaminar germ disc is when the primitive streak disappears.

Question 33

What do the stem cells that compromise the three germ layers differentiate into?

Answer 33

The stem cells of the three germ layers differentiate into the EMBRYONIC TISSUES and ORGANS.

Question 34

How is the primitive streak related to the formation of teratomas and why does it contain a mixture of tissue types?

Answer 34

Sometimes the primitive streak persist in the saccrococcygeal region. The clusters of pluripotent cells proliferate and form teratomas and also the reason for finding a mixture of tissue types.

Question 35

Neural tube, simple columnar epithelium lining the gut tube, and epidermis of skin come from which layer of the trilaminar germ disc?

Answer 35

Neural tube and epidermis of skin –> ectoderm

Simple columnar epithelium lining gut tube –> endoderm

Question 36

Describe how we get from mesenchymal cells to somites and parietal and visceral mesoderm.

Answer 36

The mesenchymal cells form a bilateral longitudinal columns (PARAXIAL MESODERM) that parallel the long axis of the germ disk. The paraxial mesoderm forms block-like SOMITES adjacent to the neural tube which will form the vertebral column enclosing the neural-tube derived spinal cord.

Lateral to the paraxial mesoderm the THIN mesoderm plate splits into the PARIETAL and VISCERAL MESODERM.

Question 37

The parietal mesoderm will form what tissues (3)?

Answer 37

Dermis of the skin, skeletal muscles, and bones of the body wall and extremities.

Question 38

The visceral mesoderm will form what tissues (3)?

Answer 38

Connective tissue, smooth muscle of gut, and smooth muscle of the guts’ derivatives.

Question 39

What week and where does the cardiovascular system begin to form?

Answer 39

Week 3 and the cranial portion of the trilaminar germ disk.

Remember tilaminar germ disk is the product of gastrulation; ectoderm, mesoderm, endoderm.

Question 40

The gut tube consists of what (3)?

Answer 40

The CRANIAL foregut, midgut, and CAUDALhindgut make up the gut tube.

Question 41

The primitive hear tube is adjacent to what structure?

How is the midgut joined to the yolk sac?

Answer 41

• The primitive heart tube forms adjacent to the cranial foregut.
• Yolk sac - VITELLINE DUCT - midgut

Question 42

Explain how the developing venous system receives its nutrients beginning from the developing aorta.

Answer 42

The vitelline arteries transport blood from the developing aorta to the vitelline capillaries (which are in the yolk sac). While in the yolk sac the lumen of the yolk sac has nutrients that will be diffused into the vitelline capillaries. The now nutrient rich blood continue through the vitelline vein to nourish the developing venous system.

Question 43

The yolk sac, vitelline duct, and vitelline vessels reside in what structure?

Throughout embryonic growth what progressively compresses the yolk sac and what is the result of this compression?

Answer 43

• In the CONNECTING STALK.
• The chorionic cavity compresses the yolk sac. As a result of the yolk sac compression embryonic development and subsequent fetal growth is dependent on the umbilical circulation.

Question 44

During Week 3 what occurs to the trophoblast?

Answer 44

The trophoblastic lacunae coalesce into blood filled spaces called INTERVILLOUS SPACES. As a result of the blood filling into the lacunae the trophoblast is reshaped into tufts of trophoblastic cells called VILLI.

Question 45

Branches of the uterine artery empty into the intervillous spaces which into where?

Answer 45

Drains into tributaries of the uterine vein for return to the maternal circulation. (WEEK 3)

Question 46

During Week 4 we have umbilical capillaries where? Describe the spatial arrangement of embyonic blood and maternal blood and the intervening space. Elicit the signifance of the spacing.

Answer 46

EMBRYONIC Umbilical capillaries are found in the villi which connect the umbilical vein and artery.

In the MATERNAL blood filled trophoblastic intervillous spaces there is a separation of a few layers of trophoblast cells.

The very thin space of layers of trophoblastic cells allow for diffusion of O2 and nutrients from maternal blood to be exchanged with waste products from embryonic blood.

Question 47

When does the embryonic period begin and end? When does the fetal period begin?

Answer 47

Week 3 (Gastrulation)  and Week 8 (Embryonic period ends)
Week 9 (Onset of Fetal period)

Question 48

What forms the fetal and maternal portion of the placenta and in what week?

Answer 48

WEEK 9

The trophoblastic villi and intervillous spaces form the fetal portion of the placenta.

The decidua basilis (compact layer of decidual cells filled with lipid and glycogen). Decidual cells come from the functional portion of the endometrium and is shed during parturition (Childbirth)

Question 49

What type of blood does the umbilical arteries and veins carry and where do they bring their blood to and from?

Answer 49

Umbilical arteries transport deoxygenated blood from the fetal aorta to the umbilical capiliaries where the exchange occurs into the trophoblastic intervillous where maternal blood is found.

Umbilical veins transport oxygenated blood from the umbilical capillaries to the fetal circulation

Question 50

Early, middle, or late fetal period fusion of what form a large amniotic cavity?

Answer 50

Early in the fetal period fusion of the amniotic cavity and chorionic cavities creates a single, large amniotic cavity.

Question 51

What cushions the fetus and allows for fetal movement?

Answer 51

Filtrates from maternal blood fill the “now” large amniotic cavity which cushions the fetus and allows fetal movement.

Question 52

What establishes fetal swallowing reflex and maintains amniotic fluid volume?

Answer 52

The fetus swallows the amniotic fluid and the fetus urinates to maintain amniotic fluid volume.

Note urine is mostly water because the PLACENTA REMOVES metabolic waste.

Question 53

Why does malformation of the esophagus and absence of kidney formation cause polyhydramnios and oligohydramnios, respectively?

Answer 53

Polyhydramnios is have too much amniotic fluid volume and can be caused by esophageal malformation because swallowing of amniotic fluid is not accomplished.

Oligohydramnios is having too little amniotic fluid volume and can be caused by absence of kidney formation because urine is what maintains the amniotic fluid volume.

Question 54

Throughout the fetal period how does the fetus remain connected to the placenta?

Answer 54

The fetus remains connected by the umbilical cord.

Question 55

During the entire period of gestation when is the development most susceptible to teratogens, like a few teratogens (2), and when does embryonic organ/tissue growth and maturation end?

Answer 55

Weeks 3 - 8 (embyonic period) with alcohol and smoking. Embryonic organ/tissue growth and maturation of that during fetal period ends at birth or 38 weeks post fertilization.