Vertebrate Tissues

Dr. Strong’s Zoology ClassOMHS

Tissues

• Groups of cells that have specialized structural and functional roles

• 4 basic types of tissues: epithelial, connective, muscle, and nervous

A. Epithelial Tissue

• Protects, secretes, absorbs

• Cover body surfaces, cover and line internal organs, compose glands

• Always has a free surface (an exposed surface)

Classification of Tissues• Based upon shapes,

arrangements, and functions

- Simple – single layer

- Stratified – many layers

- Squamous - flattened

- Cuboidal –cube shaped

- Columnar – elongated shape

SimpleSquamous Epithelium

•single layer of thin, flat cells

•Allows for rapid diffusion of substances; also filtration, osmosis

• Found in alveoli of lungs, lines inside of blood vessels

•Thin and delicate – easily damaged

SimpleSquamous Epithelium

SimpleCuboidal Epithelium

• single layer of cube-shaped cells

• Absorption & secretion

• lines kidney tubules, etc.

SimpleCuboidal Epithelium

SimpleColumnar Epithelium

•Single layer of tall, narrow cells

• lines most organs of digestive tract

•Secretes digestive fluids & absorbs nutrients from food

SimpleColumnar Epithelium

Often have microvilli and secrete mucous

Pseudostratified Ciliated Columnar Epithelium

•Single row of cells- not all reach the free surface, but each cell borders the basement membrane

•Protects, secretes, & moves mucous

• lines respiratory system, mucous traps dust, etc; cilia move mucous out

Pseudostratified Ciliated Columnar Epithelium

Cilia

Goblet Cells- secrete mucus

Basement Membrane

Stratified Squamous Epithelium

•many layers of cells; cells divide in deeper layers and push older cells outward

•Layering = protection (prevents water loss and entry of chemicals, micro-organisms, etc.)

•forms epidermis; lines throat & mouth

Stratified Squamous Epithelium

Basement Membrane

Stratified Squamous

● Keratinized – extra, tougher layers of dead skin cells to add protection. Thickest on the palms of hands and soles of feet.

● Nonkeratinized – layers of living cells found in areas where friction occurs such as in the mouth and throat where food is chewed and swallowed.

Transitional epithelium

• Changes in response to tension (can stretch)

• Inner lining of bladder

• Protects – prevents contents of urinary tract from diffusing back into internal environment

4 Basic Tissue Types

B.Connective Tissue– Supports, binds together, protects

– Most widely distributed tissue in body

– Usually well-vascularized

– Has a matrix - material between cells

• Consists of fibers and a ground substance

1. Loose connective tissue (Areolar Tissue)

• Cells are mainly fibroblasts (cells that produce fibers in the matrix)

• Matrix = gel-like ground substance and many collagen and elastin fibers

• Binds skin to organs & fills space between muscles

• Has many blood vessels that nourish nearby epithelial cells

Loose Connective Tissue

2. Adipose Tissue (fat)

• Made up of cells that store fat

• Beneath skin; between muscles; around kidneys; surface of heart; around joints

• Cushions joints and organs

• Insulates

• Stores energy

Adipose Tissue

• Large, empty-looking cells with thin margins; nucleus pressed against cell membrane

3. Dense Connective Tissue

• Densely packed, parallel collagen fibers (white) with only a few fibroblasts

• Very strong; makes up tendons and ligaments

• Low blood supply injuries slow to heal

Dense Connective Tissue

fibroblasts

4. Cartilage• Cartilage cells = chondrocytes

3 types of cartilage found in the body:

a. Hyaline Cartilage• Very fine collagen fibers in matrixlooks like glass.• Found on ends of bones, soft part of nose, rings that

support airway, fetal skeleton.

b. Elastic Cartilage● Very flexible. Found in ear.

c. Fibrocartilage• Can act as a shock absorber in knee.

5. Bone

•Hardness due to mineral salts and many collagen fibers in matrix.

Bone cells are called osteocytes.

Function - support, attachment for muscles, mineral storage, protection (cranial & thoracic cavities), forms blood cells

Found in skeleton.

Bone

Haversian Canal Osteocytes in lacunae

6. Blood

•Transports materials (nutrients and oxygen) throughout body; helps maintain homeostasis

•Matrix is fluid (called plasma)

Blood

Leucocytes

Erythrocytes

Thrombocytes

Six types of connective tissue

C. Muscle Tissue• Made up of elongated cells

(muscle fibers) that can contract• Functions in movement of body

parts• 3 types

–Skeletal Muscle–Smooth Muscle–Cardiac Muscle

Skeletal Muscle

•multi-nucleated; striated – light and dark bands

• Voluntary – can be controlled by conscious effort

• Found: attached to bones

Skeletal Muscle

striations

Smooth Muscle• one nucleus; unstriated

• Found: walls of hollow internal organs- such as esophagus, intestines, stomach, blood vessels, etc.

• Involuntary

• Move food through digestive tract, blood through blood vessels, etc.

Smooth Muscle

Nuclei

Cardiac Muscle

• Striated, one nucleus, branched

• Has intercalated disks (where cells are connected)

• involuntary

• Found: only in heart

• Pumps blood through heart chambers and into blood vessels

Cardiac MuscleIntercalated disc

3 Types of Muscle Tissue

D. Nerve Tissue

• Sensory reception and conduction of nerve impulses; allows for communication and coordination of body functions

• Found in brain, spinal cord, nerves

• Cells called neurons

Nerve TissueCell Body

Axon

Dendrites

Nucleus

Tissues form OrgansMost organs are made of several types of tissues.