Tissues

Chapter 4

What Are Tissues?

• Groups of cells with the same structure and general function.

• Four types of tissues:

1. Epithelial 2. Connective3. Muscle4. Nervous

• All are surrounded by non-living, intercellular material: MATRIX

Tissue TypesType Description Location

Nervous Excitable cells specialized for rapid communication with other cells

Brain, spinal cord, nerves

Muscular Elongated, excitable cells specialized for contraction

Skeletal, cardiac, and smooth

Connective Lots of matrix, supports, protects and binds together

Tendons, ligaments, blood, cartilage, bone and lymph

Epithelial Little matrix, closely packed, covers surfaces or lines cavities

Epidermis, lining digestive tract, liver and all glands

Epithelial Tissue

• Functions: Covers and protects body surfaces internal and external; secretion, absorption, and excretion.

• Physical Characteristics:- tightly packed, readily divide- anchored by a non-living Basement Membrane to the adjoining tissue layer.

• Lacks blood vessels so nutrients diffuse from adjacent connective tissue

Locations where found:- skin (epidermis)

- Lining of digestive, urinary, reproductive, respiratory tracts.

- Lining body cavities

- Lining fluid filled cavities in brain

- Lining of blood vessels and heart

- Covering organs

“Apical region”

“Basal region”

Classification of Epithelial Tissues

• Number of cell layers:1. simple means a single layer of cells.2. stratified means several cell layers.

• Shape of the cells:1. squamous – flat, tile-like 2. cuboidal – cube shape3. columnar – tall and cylindrical4. transitional – change shape when

under tension

Filtration, osmosis, diffusion

Lung alveoli, capillary walls, lines body cavities

Nuclei are central and round

Secretion and absorption

Kidney tubules, thyroid, and smaller exocrine glands

Absorption, secretion, protection,

Lines digestive tract and uterus

Protection, secretion, mucus movement, Lines respiratory passages

Can be ciliated or have microvilli!

Ciliated!

Protection, secretion, excretion

Skin, oral cavity, throat, anal canal, and vagina.

Lines larger exocrine glands: mammary, sweat, salivary

Protection, secretion, excretion

Distensibility, protection, lines bladder and urethra

Urethra, vas deferens, pharynx

Protection and secretion

Glandular Epithelium

• Most glands are exocrine

• Secrete to internal or external surface

• Exocrine glands have ducts and are lined with simple cuboidal cells.

• Endocrine are ductless and they secrete directly into lymph fluid or bloodstream.

Comparing Endocrine and Exocrine

Type of Exocrine Glands

Connective Tissues

Section 5.3

General Characteristics

• Most abundant tissue in body• Rich blood supply (except for cartilage)• Nerve supply (except for cartilage)• Never exposed to the environment!• 2 Basic Components:

1. Specialized cells

2. Matrix (intercellular material)

a. Ground substance (liquid to solid)

b. Fibers

General Functions

1. Support and protection

2. Binds tissues/organ

3. Transport of materials

4. Store energy

5. Insulation

6. Defense

7. Damage repair

Specialized Cells

• Fibroblasts – most common, secrete fibers and G.S. into matrix. Fiber types:

1. Collagenous (parallel bundles, strength)

2. Elastic (elastin, stretchy, branching)3. Reticular (thin, branching, Basement

Mem.)

• Macrophages – wandering monocytes, phagocytes• Plasma cells – produces antibodies, B-lymphocytes• Adipocytes – cells that store triglycerides (fat molecules)

• Mast cells – large, release Heparin and Histamine substances.

• Melanocytes – production of melanin pigment

Group #1: Connective Tissue

Proper

Areolar (Loose)

Locations: multiple locations including under epithelial tissue of skin, mesentaries

Functions: provides nutrients and support to other tissue types; immune functions; protection

Key Features: loose, scattered fiber appearance, multiple fiber and cell types

Adipose

Locations: subcutaneous region, bone marrow, around viscera and joints, behind eyeball in socket

Functions: lipid storage; thermoregulation; protection (padding)

Key Features: cells with nuclei "pushed to the side"; minimal matrix; white and brown types

Dense or Collagenous

Locations: tendons, ligaments, aponeuroses, sclera (white of eye)

Function: strong support

Key Features: matrix is shiny and white, one fiber type in parallel arrangement; thin fibroblasts; minimal ground substance

Dense (Irregular)Locations: dermis of skin; periosteum, fascia, pericardium, perichondrium and organ capsules.

Function: strong support, resists pulling from all directions

Key Features: thick bundles of fibers with no pattern, minimal ground substance

Group #2: Specialized

Connective Tissues

• Cartilage – Chondrocytes; collagenous fibers, lacunae, and avascular

Types:

1. Hyaline – fine fibers, most common

2. Elastic – thicker with most flexiblity

3. Fibrocartilage – thick collagen fibers

• Bone – osteocytes; mineral deposits and collagen fibers

• Blood – plasma (clear matrix) with formed elements (RBC, WBC, platelets)

Hyaline CartilageLocations: fetal skeleton; covering of bones at joints; ends of ribs, nose, tracheal rings, part of larynx

Function: flexible support, smooth movements at joints

Key Features: bluish/white, glassy appearance; chondrocytes in lacunae

Elastic CartilageLocations: outer ear; epiglottis; eustachian tube, part of larynx

Function: flexible support, strength, maintains shape

Key Features: single chondrocytes in lacunae; random elastic fibers look hairy

FibrocartilageLocations: intervertebral discs, pubis symphysis, meniscus

Function: very firm support, shock absorption

Key Features: collagen fiber bundles, small chondrocytes, no perichondrium

Bone

Locations: all bones, spongy and compact

Function: support, blood cell production, energy storage, protection, levers for muscles

Key Features: rings of bone (Osteons), solid G.S. with minerals, collagen for flexibility

BloodLocations: within blood vessels (arteries, veins, and capillaries), bone marrow, and heart chambers

Functions: transportation of O2 and CO2, immunity, clotting

Key Features: liquid G.S., RBC’s with doughnut appearance, WBC’s have nuclei, platelets tiny fragments