Histology

Hyaline

Forms fetal skeleton, lines articular surface of synovial joints, and support respiratory airways.

Most common, template for endochondral bone formation type 2 collagen. Perichondrium present

found in nose larynx

template for endochondral bone

ECM and cellular composition

Different types of cartlialge are due to properties of

Chondrocytes

Chondroblast begin secreting cartilage matrix. Once cells are trapped in lacunae they become

chondrocytes

10-30 micrometers, large nucleus, eleborate RER, and we developed Golgi

diffuse through matrix

Cartilage is avascular so nutrients

perchondrium

with chondrocytes which are responsible for generating cartilage

Elastic Cartilage

type 2 collagen, larger and abundant chondrocytes, found in the pinna of the ear, and walls of the auditory canal. does not calcify

Fibrocartilage

mix of hyaline and elastic and dense fibrous connective tissue. Type 1 collagen, lack perichondrium. found n intervertebral disc, menisci of the knee

Chondrocytes

round nuclei

Osteoblast

From mesenchymal origin, differentiate into osteocytes

Osteoclast

from mono-macrophage progenitor cells in bone marrow

Bone Characteristics

1. Vascular connective tissue

2. Functions in support, protect and hemopoiesis

3. Cartilage at the articular ends

Compact bone

Dense, reduced spaces, lamellar organization laid down in sheets

Cancellous

Large open marrow spaces, spicules, trabeculae

Osteoproenitor cells

population of renewable cells, reposnsible to molecular stimuli, that transform into the bone forming cells (Osteoblast).

CBFA-1

triggers transcription

Osteoblast

synthesize oranic matrix of bone and have receptors for parathyroid hormone, communicate via gap junctions. Produce osteocalcin for bone mineralization

Osteocytes

Mature bone cells derived from osteoblast, housed in the lacunae. Secrete substances necessary for bone maintenance

Osteoclast

responsible for resorbing bone, up to 150 micrometers with 50 nuclei

Calcium

needed for nerve system to sed signals and for blood clotting and muscle contractions

Primary Bone (Immature)

first bone to form during fetal development, abundant osteocytes, will turn into secondary bone

Secondary Bone (Mature)

Compact, spongy

Bone Structure

Outer portion is solid compact bone and inner structures are spongy bone

Periosteum

shealth of sense fibrous connective tissue that contains osteoprogenitor, found all over except where bone articulate with other bones

Sharpey’s fibers

collagen fibers that extend into bone tissue, connect periostem to the bone

Articular surface cartilage

surface of joint is covered with hyaline cartilage, hyaline cartilage is remnant of the fetal skeleton that persist through life

Endosteum (Endosteal Cells)

A layer of connective tissue cells that contains osteoprogentitor cells.

Red Bone Marrow

consist of developing blood cells and reticular cells and fibers that are supporting frame work. does not increase as individual grows. it resides in the spaces of spongy bone.

yellow bone marrow

during aging process, fat cells replace the blood forming tissues

bone mineralization

Separates bone from the other connective tissues, traps cells that produced the matrix. serves as a storage site for body Ca and PO4

Bone makeup

2 epiphyses 1 diaphysis and metaphyses

articular surface of epiphyses

covered in hyaline cartilage. my made up of mostly spongy bone

diaphysis

articular surface covered with periosteum, and is made up mostly compact bone

intramembranous ossification

Flat bones, have trabecular network, multiple ossification centers, skull, vascular connective tissue is turned into bone marrow.

endochondral ossification

cartilage template but bone replaces eventually, one ossification center, long and short bones

epiphyseal plates

growth plates

Intramembranous formation (compact and spongy bone)

1. mesenchymal cells form network and aggreate

2. Mesenchymal cells differentiate into osteoblast and form blastema and a synctium.

3. form bone matrix which calcifies, osteoblast mature into osteocytes

4. Multiple ossification centers

Epiphyseal plate remains

as long as mitotic activity equals the rate of resorption

Osteoprogenitor cells of periosteum

growth in width of bone

Endochondral bone formation

type x collagen

1. Osteoprogenitor cells set up periosteal bone collar and primary ossification center.

2. chondrocytes proliferate and the hypertrophy into the primary center

3. chondrocytes secrete vascular endothelial growth factor to induce blood vessel sprouting from perichondrium.

4. later secondary ossification cetner established near epiphysial plate

Chondrocyte

1. construct transient growth plate tissue

2. contribute to bone elongation proliferation, ECM secretion and hypertrophy

3. controlled by circulating molecules such as hormones such as autocrine and paracrine

Defective collagen

Osteogenesis imperfecta (Brittle Bones)

Defective endochondral Ossification

Achondroplasia-limb dwarfism

Inadequate calcification

Osteomalacia (soft bones in adults

mesoderm

All muscle comes from here

Striated Muscle

regular arranged contractile units, skeletal muscle and cardiac muscle

Skeletal muscle

peripherally placed nucleus, quick and vigorous under voluntary control. used for locomotion, mastication and phonation.

surrounded by epimysium,

a bundle of muscle fiber that stretch the entire length of skeletal muscle

surrounded by 3 layers of connective tissue

Cardiac muscle

single centrally placed nucleus and intercalated disc, involuntary vigorous and rhythmic

Smooth muscle

irregularly arranged, involuntary slow and long lasting contraction centrally placed nucleus, blood vessels, GI tracts dermis of skin

collagen 1,3,4 are present

contraction is triggered by mechanical pressure hormones

Satellite cells

located in shallow depressions on the external surface of muscle cells

Glial cells

surround neuron cell bodies within ganglia of periphreal nervous system

Supply nutrients and provide strucural support to neuron cell body

Myofibrils

proteins of the cell

sarcolemma

storage of ca2+

Muscle contration

metabolism of ATP induces movements

myofibril

scan stretch tice there resting length with damage

fascia

dense connective tissue that attaches muscle to bone

epimysium

dense irreular connective tissue

perimysium

sourrounds the bundles of muscle cells

Endomysium

reticular fibers, basal lamina and surround each muscle

electric excitation

trans-membrane electric potential can be converted to action potential and passed to other cells

Contractile

ion movements initiated by action potential cause muscle cells to shorten

Extensible

stretched without damage

Cadiac muscle

derived from myoepicardial mantle

Tryglycerides

energy source for muscle

intercalated disk

The end to end connections between cardiac myocytes are specialized junctions

Astrocytes

20-50% of brain volume, induce/maintain tight junctions forming blood brain barrier, 2nd hardest barrier to get across, after urothelium

Large oval nucleus

Surround neurons and neuronal processes in areas devoid of myelin and form the structural matrix of the CNS

oligodendrocytes

Wraps the axons and make insulatory pieces,

synthesize myelin

permit rapid impulse conduction

Microglia

Mediators of immune response; derived from monocytes

Macrophages, keep the inflammation down in nervous system

figure out what they need to engulf or destroy

derived from mesoderm

phagocytose dead cells-clear debree from the CNS

Ependymal cells

Line the ventricles and secrete cerebral spinal fluid

Fibrous astrocytes

found in white matter and long thin processes with few branches

Protoplasmic astrocytes

in grey matter and have short branches

Astrocytes in the central nervous system

Connected by gap junctions forming a synctium that allows ions and small molecules to diffuse across brain parenchyma

take part in angiogenesis or making of blood vessels which is important in the development and repair of CNS

Cilia

facilitate circulation of cerebral spinal fluid.

3rd ventricle

used to direct drugs into the brain

Similarities of Schwan and Oligodencytes

Both wrap around the axon nerve cells,

Both glial cells

Differences of Schwan and Oilgodencyte

Schwan wraps around the peripreal nervous system

Oli wraps around central nervous system

Oli suppresses repair

Schwan promotes repair

oli can insulate 50 neurons at once

schwan on insulate 1

color of skin

could indicate pathology

Black skin

darkness of skin is determined by the amount of melanin secreted, not melanin cells

integument system

Protection

Water barrier

Regulate body temp

excrete salts

synthesis of vitamin D

Sexual signaling

3 skin layers

Epidermis, dermis, hypodermis

Keratinocytes

produce keratin

Melanocytes

produce melanin

Langerhans cells

immune function-white blood cells

from bone marrow

sit in mid-spinous layer, not visible by light microscopy

merkel cells

deepest layer from touch receptors with SNC

not visible by light microscopy. located in stratum basale

desquamatization

Layers of epidermis represent vertical maturation from undifferentiated basal cells to fully differentiated cornified cells

epidermal layers (top to bottom)

Coneum

Lucidium (only thick skin)

Granulosum (water proof barriers)

Spinosum (Thickest)

Basale (cuboidal)

Thin skin

5 layers of stratum corneum with no lucidum

thick skin

5 layers thick stratum corneum with increased granular layer.

more sensory receptors

lacks sebaceous glands but increase eccrine glands

Papillary Layer

directly beneath epidermis.

Loose connective tissue with type 3 collagen

houses pacinian and ruffini corpuscles

Hemidesmosome

connects basal keratinocytes to basement membrane

Sweat glands

prevents overheating secretes cerumen and milk

Apocrine sweat gland

found in axillary and anogenital areas

Open into hair follicels

seceration is odorless and hormonally influence

released by shedding part of cytoplasm

larger than eccrine

Eccrine sweat glands

found in palms, soles of feet, and forehead

Ceruminous glads

modified apocrine glands in external ear canal that secrete cerumen

sebaceous Glands

simple alveolar glands all over the body

soften skin when stimulated by hormones

Secretion an oily substance called sebum

Hair

filamentous keratinized structures

types

vellus-soft fine short pale-eyelids

terminal-long coarse (scalp and eyebrows)

Lanugo-fetus only

arrector pili muscles

smooth muscle

depress skin and elevate hair

Reticular layer

houses sweat glands and hair follicles sebaceous glands

dense irregular CT with type 1 collagen fibers