Ch. 11 -15 Exam 3

Embryonic tissues appear when

cells from a zygote divide enough so that they can begin to organize into layers

What are the 3 layers in humans :

Ectoderm, Mesoderm, Endoderm

Ectoderm is responsible for

the epidermis and nervous system

Mesoderm becomes ____ which ____

the mesenchyme

gives rise to all connective tissues and cardiac muscle

Endoderm become part of

the digestive and respiratory tracts

The 4 primary classes into which all adult tissues are classified

are epithelial, connective, muscle, and nervous tissues.

based on structure and function

What is a tissue?

A group of similar cells with similar embryological origin → specialized for a specific function

Tissues make up

organs

epithelial tissue covers and lines ?

Covers body surfaces, lines hollow organs, body cavities, and ducts, and forms glands

epithelial tissue functions to

allow interaction with internal and external environments

connective tissue does what

protects and supports body and organs

connective tissue functions to

connect epithelial tissue to supportive structures underneath

binds organs together, store energy as fat, and provide pathogenic immunity

support, protection, tissue repair, energy storage, blood cells production

has fibroblasts

All connective tissue has

Cells and Extracellular Matrix

Fruit with Jello → cells suspended in matrix

Widely spaced out, abundant ECM

Connective tissues differ from each other and other tissues via

the relative abundance of both cells and ECM

Connective tissue is highly

vascularized, and has a nerve supply

• except tendons and cartilage

Immature cells that end in _____ are responsible for

-blast

generating the ECM

fibroblast, chondroblast

Mature cells end in

-cyte

osteocyte, chondrocyte

live and persist in ECM

classification of connective tissues :

embryonic and mature

Embryonic CT classifications :

mesenchyme and mucus

Mature CT classifications

Loose

Dense

Adipose

Cartilage

Bone

Blood

Fibrous connective tissue types

Loose and Dense

Supportive CT :

cartilage and bone

Liquid CT :

blood

Embryonic CT is present in

embryo and fetus

Mesenchyme is found exclusively in the

embryo

Mesenchyme is the origin tissue for

all connective tissues

“the precursor” → all start as mesenchyme before developing into differentiated tissues

Mucous CT is found in

the umbilical cord of the fetus

Mature CT are present at

birth, and persist through life

3 types of mature CT

Fibrous CT

Supporting CT

Liquid CT

Fibrous CT is what and contains what

flexible and contains viscous ground substance and many fibers (reticular, dense regular, irregular, areolar)

Supporting CT does what

protects and supports soft tissues of the body (cartilage and bone)

Liquid connective tissue is

blood (liquid ECM)

Fibrous CT contains what cells?

Fibroblasts

Macrophages

Leukocytes

Plasma Cells

Mast Cells

Adipocytes

Fibroblasts are cells that produce

the ECM of fibrous connective tissues

build and produce the different fibers

Macrophages function in

immunity

Leukocytes are

white blood cells that function in immunity

Plasma cells are

B cells, produce plasma

Mast cells release

Heparin

Adipocytes

Fat cells that store energy

Fibrous CT can be

Loose or dense

Loose means

fibers are arranged loosely between cells (areolar and reticular)

Dense means

fibers are thicker, more closely packed with fewer cells (dense irregular and dense regular)

Supportive CT are

Cartilage and Bone

Chondroblasts are

immature cells that actively divide to form ECM of cartilage

Chondrocytes

Mature cells that dont divide anymore, trapped in lacunae (within ECM)

Osteoblasts

immature cells that actively divide to form ECM of bone

Osteocytes

Mature bone cells trapped in lacunae

Liquid CT is composed of what formed elements

Fluid ECM = plasma

Formed elements = cellular components of blood:

• erythrocytes (red blood cells)

• leukocytes (white blood cells)

• platelets (thrombocytes)

Extracellular matrix is found in

the spaces between cells

Extracellular matrix is composed of

protein fibers and ground substance consisting of non-fibrous protein, fluid, etc.

Ground substance is

a fluid/gel like component of ECM

• can also be called extracellular fluid

contains water with gases, minerals, wastes, hormones, and other chemicals

ECM fibers are

elastic, collagen, and reticular fibers

ECM fibers are secreted by

fibroblasts

What is the most abundant cell type in Fibrous CT

fibroblasts → star shaped, large, secrete proteins that form extracellular matrix components, including collagen and elastin.

Ground substance ranges from ____

Why?

gelatinous and rubber consistency due to 3 classes of large molecules (Glucosaminoglycans, proteoglycans, and adhesive glycoproteins).

Glucosaminoglycan (GAG) is

what charge?

attracts what?

regulates what?

a long polysaccharide with unusual composition

• negatively charged (weird)

• attracts positively charged sodium and potassium ions (making GAG absorb and retain water) → waters follow ion!

• regulates water and electrolyte balance

Proteoglycans are

attach to?

for?

do what?

a giant bottle brush shaped molecule with central core protein and GAG bristles

• attach to hyaluronic acid to make enormous complex

• form thick colloids like gravy, gelatin, or glue → makes ECM thick

• slows the spread of pathogens and can help hold tissues together

Adhesive glycoproteins are

bind what?

mark?

protein/carb complexes (together)

• bind plasma membrane proteins to extracellular collagen and proteoglycans → cells can stick to ECM

• bind components of tissue together

• mark paths to guide migrating embryonic cells to their destination tissue (where they are going)

Collagen fibers are composed of

the protein collagen

What proteins are tough and resistant to stretching, allow some flexibility in tissue, and are present in bone, cartilage, tendons, and ligaments

Collagen fibers

Where are collagen fibers present in

bone, cartilage, tendons, and ligaments.

Elastic fibers are composed of

the protein elastin, surrounded by the glycoprotein fibrillin

What fiber provides strength and stretching capacity, and present in skin, blood vessels, and lungs?

elastic fibers

reticular fibers are composed of

support what?

thin collagen fibers and glycoproteins

support in the walls of blood vessels, spleen, and lymph nodes

lymphatic system

form networks that support tissues

what fibers are a supporting network around fat cells, nerve fibers, and skeletal and smooth muscle fibers

reticular fibers

Loose Fibrous CT : Areolar appearance

Loosely organized arrangement of collagen and elastic fibers

Abundant ground substance and blood vessels

Loose Fibrous CT : Areolar Locations

underlies nearly all epithelial tissue (deep to)

surrounds blood vessels, nerves, esophagus, and trachea

fills fascia (space) between muscles

in membranes around organs → mesenteries, visceral layers of pericardium and pleura (heart and lungs)

Loose Fibrous CT : Areolar functions

loosely binds epithelia to deeper tissues (binds skin to underlying organs)

allows passage of nerves and blood vessels through other tissues

provides location for immune defense

Loose Fibrous CT : Reticular appearance

loose network of reticular fibers and cells

abundant white blood cells, especially lymphocytes

short, branched

Loose Fibrous CT : Reticular locations

lymph nodes

spleen

thymus

bone marrow

Loose Fibrous CT : Reticular functions

forms supportive framework (stroma) for lymphoid organs

Dense Fibrous CT : Dense regular appearance

densely packed, parallel, wavy collagen fibers

skinny/slender fibroblast nuclei between collagen bundles

minimal ground substance

little to no blood vessels

Dense Fibrous CT : Dense regular locations

tendons and ligaments

Dense Fibrous CT : Dense regular functions

ligaments tightly bind bones together (bone to bone) and resist mechanical stress

tendons attach muscles to bones and transfer muscle tension to bones (give the stress)

Dense Fibrous CT : Dense Irregular appearance

densely packed collagen fibers running in random directions

few visible cells

minimal ground substance

little to no blood vessels

Dense Fibrous CT : Dense Irregular Locations

deepest portion of dermis

forms capsules around organs and fibrous sheaths around bones

Dense Fibrous CT : Dense Irregular functions

withstands stress applied in unpredictable directions

makes tissues more durable, can let our skin get twisted, pulled, pushed, stretched.

Adipose CT appearance

dominated by adipocytes

nuclei pressed against plasma membrane

minimal cytoplasm when stained

blood vessels present

Adipose CT locations

subcutaneous fat

breasts

heart surface surrounding other organs like kidneys and eyes (behind eyes, around kidneys and heart)

under skin

Adipose CT functions

energy storage (extra calories)

thermal insulation and protective cushion (shock absorption)

heat production (brown fat → babies)

Supporting CT : hyaline cartilage appearance

clear, glassy matrix

chondrocytes enclosed in lacuna in clusters called cell nests

usually covered by perichondrium

most common

Supporting CT : hyaline cartilage locations

articular cartilage between bones and costal cartilage of ribs

rings and plates around trachea and bronchi

most of fetal skeleton

Supporting CT : hyaline cartilage functions

ease joint movement

hold open airway when breathing and moves vocal cords for speech

precursor to bone in fetus and location of growth zones in long bones of children

Supporting CT : elastic cartilage appearance

elastic fibers form weblike mesh near lacunae

always covered by a perichondrium

Supporting CT : elastic cartilage locations

external ear

epiglottis

Supporting CT : elastic cartilage functions

provides flexible, elastic support

Supporting CT : fibrocartilage appearance

parallel collagen fibers similar to tendons (thick)

rows of chondrocytes in lacunae between fibers (densely packed)

never has a perichondrium (no outer covering)

Supporting CT : fibrocartilage locations

pubic symphysis

intervertebral discs

shock-absorbing cartilage pads in knee

point where tendons attach bones near articular hyaline cartilage

Supporting CT : fibrocartilage functions

resists compression and absorbs shock

transitional tissue between dense CT and hyaline cartilage

cushions bones in knees and pelvic girdle

Supporting CT : bone (osseous tissue) appearance

spongy = delicate slivers and plates with visible spaces

compact = dense with no spaces

calcified matrix arranged in concentric lamellae around the central canals

osteocytes in lacunae between lamellae

lacunae connected via canaliculi (little river)

Hardness of bone comes from

mineral salts, which form blood vessels in bone marrow

bone contains what

osteocytes, concentric lamellae, central canals, and lacunae

what are canaliculi

minute tubes in the compact bone matrix that allow passage of cytoplasmic processes of bone cells

what is an osteon?

arrangement of osteocytes in concentric circles around the central canal (cylinder)

bone rely on a network of

blood vessels

provide pathways for immune cells to travel between the marrow and the rest of the body.

Supporting CT : bone (osseous tissue) locations

skeleton

Supporting CT : bone (osseous tissue) functions

physical support and protection of body

leverage for muscle action

reservoir for calcium and phosphorus

liquid CT : blood appearance

dominated by erythrocytes - resemble pale discs with no nuclei

lymphocytes - larger, have nuclei, violet stain

platelets - cell fragments with no nuclei

liquid CT : blood locations

contained in heart and blood vessels

liquid CT : blood functions

gas, nutrient, waste, chemical signals, and heat transport throughout the body

provides defensive leukocytes

contains clotting agents to minimize bleeding

platelets secrete growth factors that promote tissue maintenance and repair