Vertebrate Tissues

OMHS Human Anatomy and Physiology Class

Tissues

• Groups of cells that have specialized structural and functional roles.

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

Classification of Tissues• Based upon shapes,

arrangements, and functions:

- Simple – single layer

- Stratified – many layers

- Cuboidal –cube shaped

- Columnar – elongated shape

- Squamous - flattened

A. Epithelial Tissue

• Protects, secretes, absorbs.

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

• Always has a free surface (an exposed surface).

Epithelial Cont.

• Anchored to connective tissue by non-living layer called the basement membrane.

• Lack blood vessels.

• Readily divide (injuries heal rapidly).

• Cells are tightly packed to form a good barrier.

SimpleSquamous Epithelium

•Single layer of thin, flat cells.

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

• Found in alveoli of lungs and 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 moves 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

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.

Glandular Epithelium

• Cells that are specialized to produce and secrete substances.

• Usually found within cuboidal or columnar epithelia.

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.

• 2 types of fibers–Collagenous fibers - thick threads of protein (collagen); flexible; hold things together; white fibers.

–Elastic fibers - made of protein called elastin; weaker than c.f. but stretch easily; vocal cords; yellow fibers.

(continued)

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.

• Chondrocytes occupy small chambers called lacunae.

a. Hyaline Cartilage

• Very fine collagen fibers in matrix looks like glass.

• Found on ends of bones, soft part of nose, rings that support airway, fetal skeleton.

Hyaline Cartilage

lacunae

Chondrocyte

b. Elastic Cartilage

Chondrocyte

Lacunae

• Web-like mesh of elastic fibers.

• Provides flexible, elastic support.

• External ear and parts of larynx.

c. Fibrocartilage

• Very tough, contains many collagen fibers.

• Absorbs shock.

• Found in meniscus of knee, intervertebral discs, etc.

Fibrocartilage

lacunae

chondrocyte

5. Bone

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

•Matrix deposited in layers called lamellae around tubes called Haversian canals.

•Haversian canals contain blood vessels.

Bone (cont.)

• Bone cells are called osteocytes – located in lacunae (chambers) spread out between lamellae.

• Support, attachment for muscles, mineral storage, protection (cranial &thoracic cavities), forms blood cells.

• Found in skeleton.

Bone

Haversian Canal Osteocytes in lacunae

Bone

Haversian canal

Osteocyte

6. Blood

•Transports materials throughout body; helps maintain homeostasis.

•Matrix is fluid (called plasma).

Blood

Leucocytes

Erythrocytes

Thrombocytes

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 the heart.

• Pumps blood through heart chambers and into blood vessels.

Cardiac MuscleIntercalated disc

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 are called neurons.

Nerve TissueCell Body

Axon

Dendrites

Nucleus

How well do you know your body tissue types?

Essay Questions

• What essay questions can you think of that would be a good assessment of your learning for this unit?– How would you………..?– What would result if…..?– Describe how……………– Compare and contrast…– Why do you think………?