Animal Tissues

and Organ Systems

Chapter 32

Impacts, Issues

Open or Close the Stem Cell Factories?

Only embryonic stem cells can differentiate into

any specialized cell in the body; engineered

stem cells are not yet safe for humans

Homeostasis in Animals

Body parts must interact to perform many tasks

• Coordinate and control individual parts

• Acquire and distribute raw materials to cells and

dispose of wastes

• Protect tissues against injury or attack

• Reproduce, nourish and protect offspring through

early growth and development

• Maintain the internal environment (homeostasis)

32.1 Organization of Animal Bodies

Tissue

• Interacting cells and extracellular substances that carry out one or more specialized tasks

Organ

• Structural unit of two or more tissues organized in a specific way to carry out specific tasks

Organ systems

• Two or more organs and other components interacting in a common task

Animal Cells are United by Cell Junctions

Tight junctions

• Prevent fluid from seeping between epithelial

cells; fluid must pass through cells

Adhering junctions

• Hold cells together at distinct spots

Gap junctions

• Permit ions and small molecules to pass from

cytoplasm of one cell to another

32.1 Key Concepts

Animal Organization

All animals are multicelled, with cells joined by

cell junctions

Typically, cells are organized in four tissue

types: epithelial tissue, connective tissue,

muscle tissue, and nervous tissue

Organs, which consist of a combination of

tissues, interact in organ systems

32.2 Epithelial Tissue

Epithelium (epithelial tissue)

• A sheet of cells that covers the body’s outer

surface and lines its internal ducts and cavities

Basement membrane

• A secreted extracellular matrix that attaches the

epithelium to the underlying tissue

Microvilli

• Fingerlike projections of absorptive epithelia

General Structure of Simple Epithelium

Describing Epithelial Tissues

Thickness

• Simple epithelium: One cell thick

• Stratified epithelium: More than one cell thick

Cell shape

• Squamous: Flattened

• Cuboidal: Cube-shaped

• Columnar: Tall

Types of Epithelial Tissues

Fig. 32-4b, p. 541

Fig. 32-4c, p. 541

Glandular Epithelium

Glands

• Organs that release substances onto the skin, or

into a body cavity or interstitial fluid

Exocrine glands (glands with ducts)

• Deliver secretions to an external or internal

surface (saliva, milk, earwax, digestive enzymes)

Endocrine glands (no ducts)

• Secrete hormones which are carried in blood

32.3 Connective Tissues

Connective tissues consist of cells and the

extracellular matrix they secrete

Connective tissues connect body parts and

provide structural and functional support to other

body tissues

Soft Connective Tissues

Loose connective tissue

• Fibroblasts secrete a matrix of complex

carbohydrates with fibers dispersed widely

through the matrix

Dense connective tissue (dense collagen fibers)

• Dense irregular: Supports skin, internal organs

• Dense regular: Ligaments and tendons

Specialized Connective Tissues

Cartilage: Rubbery extracellular matrix,

supports and cushions bones

Adipose tissue: Fat filled cells, stores energy,

cushions and protect organs

Bone: Rigid support, muscle attachment,

protection, mineral storage, blood production

Connective Tissues

Connective Tissues

Cartilage and Bone Tissue

A Fluid Connective Tissue

Blood: Plasma, blood cells and platelets

32.4 Muscle Tissues

Muscle tissue is made up of cells that contract

when stimulated, requires ATP energy

Three Types of Muscle Tissues

Skeletal muscle tissue

• Moves the skeleton (voluntary)

• Long, striated cells with many nuclei

Cardiac muscle tissue

• Heart muscle (involuntary)

• Striated cells with single nuclei

Smooth muscle tissue

• In walls of hollow organs (involuntary)

• No striations, single nuclei

32.5 Nervous Tissue

Nervous tissue

• Consists of specialized signaling cells (neurons)

and cells that support them (neuroglial cells)

Nervous tissue detects internal and external

stimuli, and coordinates responses to stimuli

Neurons

Neurons

• Excitable cells with long cytoplasmic extensions

• Send and receive electrochemical signals

Three types of neurons

• Sensory neurons are excited by specific stimuli

• Interneurons integrate sensory information

• Motor neurons relay commands from brain and

spinal cord to muscles and glands

A Motor Neuron

Coordination of Nervous Tissue

and Skeletal Muscle

32.2-32.5 Key Concepts

Types of Animal Tissues

Epithelial tissue covers the body’s surface and

lines its internal tubes

Connective tissue provides support and

connects body parts

Muscle tissue moves the body and its parts

Nervous tissue detects internal and external

stimuli and coordinates responses

32.6 Overview of Major Organ Systems

In vertebrates, organs arise from three

embryonic germ layers

• Ectoderm (outermost layer) forms nervous tissue

and epithelium of skin

• Mesoderm (middle layer) forms muscle,

connective tissue, and lining of body cavities

• Endoderm (innermost layer) forms epithelium of

gut and lungs

Body Cavities and Directional Terms

Body Cavities and Directional Terms

Body Cavities and Directional Terms

Eleven Vertebrate Organ Systems

Eleven Vertebrate Organ Systems

32.6 Key Concepts

Organ Systems

Vertebrate organ systems compartmentalize the

tasks of survival and reproduction for the body

as a whole

Different systems arise from ectoderm,

mesoderm, and endoderm, the primary tissue

layers that form in the early embryo

32.7 Vertebrate Skin—

Example of an Organ System

Skin is the body’s interface with the environment

• Sensory receptors, barrier against pathogens,

internal temperature control, water conservation

Vertebrate skin is made up of all four tissue

types arranged in two layers:

• Outer epidermis contain keratinocytes

• Deeper dermis contains nerves, blood and lymph

vessels, hair follicles and glands

Skin Structure

Skin Structure

Skin Structure

Frog Skin

Amphibians may have glands that secrete

mucus, distasteful chemicals, or poisons

• Pigmented cells in dermis warn predators

Sunlight and Human Skin

Melanocytes in skin make a brown pigment

(melanin) which affects skin color and tanning

Melanin protects against UV radiation

• A little UV promotes vitamin D production

• A lot of UV damages DNA and promotes cancer

32.8 Farming Skin

Commercially grown skin substitutes are already

in use for treatment of chronic wounds

Skin may be a source of stem cells that could be

used to grow other organs

32.7-32.8 Key Concepts

A Closer Look at Skin

Skin is an example of an organ system

It includes epithelial layers, connective tissue,

adipose tissue, glands, blood vessels, and

sensory receptors

It helps protect the body, conserve water, control

temperature, excrete wastes, and detect

external stimuli