Chapter Four A & P I

What are the four types of tissues in the body?

1. Epithelial

2. Connective

3. Muscle

4. Nervous

epithelial tissue

lines exterior surfaces of body, lines internal cavities, and forms certain glands

Connective tissue

Binds the cells and organs together, protects, supports and integrates all parts of the body

Muscle tissue

Excitable, contracts to provide movement

Nervous tissue

excitable, propagates electrochemical signals (nerve impulses) to communicate between different regions of the body.

What are the functions of epithelial tissue ?

• Protection - skin: barrier to keep out bacteria and chemicals

• absorption- digestive system: absorption of nutrients.

• Filtration- kidneys: absorption and filtration of water and nutrients

• Secretion- sweat glands: secrete sweat

epithelial tissue characteristics

• asymmetrical

• Connected by junctions

• Attached to basement membrane and then to connective tissue.

• High rate of regeneration and turnover

Apical side of epithelial tissue?

Cavity, intestinal lumen, stomach lumen, inside of esophagus, inside of tracheae, nasal cavity, mouth cavity.

Basal side of epithelial tissue?

basement membrane (attached to connective tissue)

What are the three types of cell junctions that hold epithelial cells together?

1. Tight junctions: no transport between cells

2. Anchoring junctions: help stabilize epithelial tissues

3. Gap junctions: forms pores between cells, continuous cytoplasm

what are some examples of tight junctions

Intestines

What are some examples of anchoring junctions?

Desmosomes-connects cells to each other

Adherens junctions- connect cells to each other

Hemidesmosomes- connects cells to base

gap junctions examples?

mymetrium of uterus

How is epithelial tissue classified?

Shape and layers

how is glandular epithelial tissue classified?

• gland type

• Secretion method

• Secretion content

classifications of epithelial tissues according to shape

Squamous: thin, scale-like

Cuboidal: cube-like wide

Columnar: more long than wide

what is this?

Stratified squamous epithelium

What is this?

stratified cuboidal epithelium

What is this?

stratified columnar epithelium

What are the classification of epithelial tissues according to layers?

Simple-single layer

Stratified- several layers

Pseudostratified- single layer of irregular cells

Classification of glandular epithelial tissues according to gland type

1. Endocrine: secretions directly into surrounding tissues and fluids. Example: hormones

2. Exocrine: secretions leave through a duct that opens to the external environment. Examples: mucus, sweat, saliva, and breast milk

What are exocrine glands cell type?

classified as either unicellular or multicellular

What cell is this?

goblet cell

What are goblet cells?

• mucous-secreting single gland cells of the small intestine

• mucous is a watery-viscous secretion that contains the glycoprotein mucin

classification of exocrine glandular epithelial tissue according to secretion method?

merocrine: exocytosis of vesicles in apical surface- saliva, eccrine sweat glands

Apocrine: a portion of the cell pinches off- apocrine sweat glands in auxiliary and genital areas, oily

Holocene: whole cell is shed- sebaceous glands in skin, hair

What are sebaceous glands?

• aka Holocene glands secrete oils that lubricate and protect the skin

• Destroyed after releasing their contents and new cells form

connective tissue functions?

• connects tissues and organs (tendons)

• Supports (skeleton)

• Protects soft tissue (fibrous capsules and bones)

• Defense against invading organisms (blood cells)

• Transport of fluid, nutrients, waste, chemical messengers(lymph, blood)

• Store energy and thermal insulation (adipose tissue)

what are the three comments connective tissue is made up of?

1. Cells

2. Protein fibers

3. Ground substance

what is secreted by connective tissue cells?

The matrix

what is the matrix?

protein fibers + ground substance

what are some connective tissue cells?

1. Fibroblasts- most common, secrete matrix

2. Fibrocytes: second most common, less active to divide

3. Adipocytes: store triglycerides for energy, cushion, thermal regulation, white and brown

4. Mesenchymal cell: multi potent stem cell, can differentiate into any connective cell, important for repair

5. Macrophage: phagocytic blood cell, engulf invaders

6. Mast cells: immune cells, release histamine and heparin during injury

connective tissue fibers?

1. Collagen fibers: tensile strength, fibrous (long) protein units

2. Elastic fibers: stretch, elastin and other proteins

3. Reticular fibers: anchoring and support, branched collagen fibers in a network. Support cells of liver, spleen

connective tissue ground substances?

composed of polysaccharides and proteins

What do fibroblasts do?

secrete protein fibers and ground substances

where are protein fibers embedded?

ground substance

Connective tissue proper

dense and loose connective tissue

• fibroblasts produce this fibrous tissue

• Includes fixed cells, fibrocytes, adipocytes, and mesenchymal cells

Supportive connection tissue?

bone and cartilage

Fluid connective tissue ?

lymph and blood

What are the three types of cells in loose connective tissue?

1. Adipocytes

2. Areolar tissue

3. Reticular tissue

Adipocytes

fat storage, insulation from cold temperature, and mechanical injuries. Store fat for energy. White and brown fat.

Areolar tissue

filles space between muscle fibers, surrounds blood vessels and lymph vessels, connective tissue support for most epithelial membranes. provides a supportive framework for soft organs.

Reticular tissue

mesh-like network for lymphatic tissue, spleen and liver

Dense connective tissue?

contain more collagen fibers than loose connective tissue

What are the two types of dense connective tissue?

• dense regular: connective tissue fibers are parallel to each other. Ligaments and tendons

• Dense irregular tissue: the direction of fibers is random. Arterial walls, skin, joint capsules. Mesh-like network.

What are the two major forms of supportive connection tissue?

1) cartilage

2) bone

supportive connective tissue function?

allow body to maintain its posture and protect internal organs

Cartilage

-chondrocytes (cartilage cells) embedded with collagenous fibers (protein fiber) in a firm matrix of chondrites sulfates (polysaccharides)

• avascular, nutrients need to diffuse through the matrix so slow healing

Where does cartilage occupy?

lacunae.

What are the three types of cartilage?

• hyaline

• Fibrocartilage

• Elastic cartilage

hyaline cartilage

provides support with some flexibility- ex is embryonic skeleton before bone formation

Fibrocartilage

provides compressibility and can absorb pressure- ex is intervertebral discs

Elastic cartilage

provides firm but elastic support - ex is the external ear

Bones

the hardest connective tissue

Function of bone?

protection to internal organs and supports the body

• highly vascularized tissue, can recover from injuries fast

what is the extracellular matrix of bones?

Collagen fibers embedded in hydroxyapatite (a form of calcium phosphate)

What are the cells of the bone?

osteocytes are located within lacunae

Fluid connective tissue?

blood- contains erythrocytes and various types of leukocytes

Lymph- a liquid matrix + white blood cells

• both circulate in a liquid extracellular matrix

Where are all blood cells derived from?

hematopoietic stem cells of bone marrow

Erythrocytes

red blood cells that transport oxygen and some carbon dioxide

Leukocytes

white blood cells, defend against invading organisms

Platelets

cell fragments involved in blood clotting

Charcteristics of muscle tissue?

• allows movement

• Excitable (responds to a stimulus)

• Some muscle movement is voluntary and other movements are involuntary

What are the three types of muscle tissue?

1. Skeletal (voluntary) - attached to bones around entrance points to body

• striated and multi-nucleated

1. Cardiac (involuntary) - located in heart

• striated and mostly a single nucleus

1. Smooth (involuntary)- located in walls of major organs and passageways

• a single nucleus and no striations

Nervous tissue characteristics

• excitable

• Two types: 10% neurons, 90% glial cells(cells that support neurons)

• The synapse is between neuron-neuron or neuron-target cell

• Neurotransmitters

The neuron

• the cell body is called the soma

• The dendrites on the soma receives incoming signals

• The axon starts and carries the action potential to another excitable cell

nervous tissue

• made up of neurons and neuroglia

• Send and receive impulses

tissue healing

Collagen fibers are laid down randomly by fibroblasts and white blood cells are attracted by release of inflammatory chemicals and seep into injured area

Epithelial cells multiply a fill over the granulation tissue and the restored epithelium thickens. The area matured and contracts and there becomes an underlying area of scar tissue