-gives rise to endoderm, mesoderm, ectoderm

-starts from tail to head

-comes in through midline

Gastrulation (3.5)

3 Germ Layers

-movement of cells out of primitive streak to form germ layers

-endoderm, mesoderm, ectoderm

1.) Epidermis: skin

2.) Neural Tube: central nervous system

3.) Neural Crest (individual cells): sensory & autonomic neurons (PNS), melanocytes, muscle of face

1.) Notochord (below neural tube)

2.) Somites: break into 3 parts

3.) Intermediate mesoderm: kidneys and gonads

4.) Lateral plates: somatic and splanchinic layer

1.) Dermatome: dermis of dorsal skin

2.) Myotome: muscle of body walls and limbs

3.) Sclerotome: bone of vertebrae and ribs

1.) Walls of digestive and respiratory tubes

2.) Visceral serosa layer: outer lining of organs, part of coelom

3.) Heart & Blood vessels

1.) Dermis of ventral skin

2.) Parietal serosa: other part of coelom lining

3.) Connective tissue of bones and limbs

-somatic and splanchnic layers

-becomes the coelom: peritoneal, pericardial, and pleural cavities

-becomes the epithelial lining: of digestive tubes, respiratory tubes, urinary bladder, secretory cells of liver and pancreas

-innermost layer of cells of the digestive tract

1.) Epithelium

2.) Connective

3.) Muscle

4.) Nervous

1.)cellularity

2.)specialized junction between cells

3.)cell polarity

4.)supported by connective tissue

5.)avascular by innervated

6.)regenerates by cell division

7.)undergoes cell division (skin & digestive tract): to replace lost cells

Simple epithelium

-4 types

-only 1 cell layer thick

1.) Simple squamous

2.) Simple cuboidal

3.) Simple columnar

4.) Pseudostratified columnar

-very flat cells

-functions in filtration and diffusion

-equally high and wide (like a cube)

-functions in secretion and absorption

-tall

-also functions in secretion and absorption

-tall but irregular shape so it appears to have multiple

-has multiple layers

-main function is protection of underlying tissues

-also subdivided in squamous, cubodial, and columnar based on shape in apical layer (next to lumen)

-has multiple layers

-apical layer cells flatten as tissue is stretched

-functions in protection as well as allowing stretching (urinary structure fill)

-few cells, surrounded by ECM (ground substance and protein fibers)

-contains collagen fibers, reticular fibers, and elastic fibers

-water is held by complex carbohydrates (glycosaminoglycans) by themselves

-water can also be attached to proteins (proteoglycans) which are hydrophilic

-contained in connective tissue

-resist pulling

1.) Connective Tissue Proper

-resist tension (pulling) due to collagen fiber

2.) Cartilage

-resist compression (pushing)

3.) Bone

-resist both tension and compression

4.) Blood

-contained in ECM along with protein fibers of connective tissue

-frequently holds fluid but usually not tighthly allowing for fluid movement and diffusion of disolved molecules

-contained in connnective tissue

-forms a network that allows some stretching

-resist tension (pulling) due to collagen fibers

-divided in to 2 subclass

1.) Loose: proteins fibers well seperated by ground substance

2.) Dense: fibers are closely packed

-connective tissue proper

-basic tissue within organs

-3 types of protein fibers in gel-like ground substance that holds extracellular fluid (interstitial fluid)

-includes fibroblast (make the ECM), immune cells, adipose cells

-type of connective tissue

-like areolar tissue, but almost all cells are adipose cells (fat)

-contains all 3 fibesrs

-all fibers are reticular proteins to form network with spaces

-found in bone marrow, spleen, and lymph nodes

-no collagen or elastic

-lots of collagen fibers to really resist pulling

-fibers arranged irregularly

-located in dermis and fibrous capsules around joint

-collagen fibers are arranged parallel

-located in ligaments, tendons, aponeuroses (flat tendon-like membrane)

-also called fibrous connective tissue

-have a lot of elastic fibers to provide recoil

-located in arterial walls, bronchial tubes, and certain ligaments between vertebrae

-no collagen fibers

Cartilage

3 different types

-cells are chondrocytes

-resist compression (pushing)

-type of connective tissue

1.) Hyaline

2.) Elastic

3.) Fibrocartilage

-cells are osteocytes

-type of connective tissue

-resist pulling and pushing equally well

-red blood cells involved in oxygen transport, white blood cells (immune system), and platelets (involved in blood clotting)

-its extracellular matrix is liquid plasma (no protein fibers)

1.) Skeletal

2.) Cardiac

3.) Smooth