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Chapter 4: Body Organization & Homeostasis

BIO 105

Organization of the body

Tissues

A tissue is composed of a group of similarly

specialized cells that work together to perform some common function.

Four tissue types:

Epithelial, Connective, Muscle, Nervous

Epithelial Tissue Characteristics

• Organized into sheets of cells

• Covering & lining

• Glands

• Apical & basal surfaces

• Basement membrane

• Functions?

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epithelial tissueSIMPLE EPITHELIUM

Simple squamous

• One layer of flattened cells• Located in air sacs of lungs, heart and blood

vessel linings• Allows exchange of nutrients, gases, and wastes

epithelial tissueSIMPLE EPITHELIUM

Simple cuboidal• One layer of cube-shaped cells

• Located in linings of kidney tubules and glands

• Functions in absorption and secretion

epithelial tissue

SIMPLE EPITHELIUM

Simple columnar• One layer of tall, slender cells

• Located in lining of gut

• Functions in absorption and secretion

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epithelial tissueSTRATIFIED EPITHELIUM

Stratified squamous• Several layers of flattened cells• Located on surface of skin, lining of mouth, esophagus,

anus, and vagina• Provides protection against abrasion, infection, and drying out

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Glands

A gland consists of one or more cells that

secrete the cell product into a duct, onto a

surface, or into the blood.

• Endocrine vs. exocrine glands

Characteristics of Connective Tissue

• Most abundant and widespread

• Binds, supports, anchors

• Cells & extracellular matrix (ECM)

• Consistency of ECM ground substance varies

connective tissueCONNECTIVE TISSUE PROPER

Areolar connective tissue• Widely distributed; found under skin,

around organs, between muscles• Wraps and cushions organs

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connective tissueCONNECTIVE TISSUE PROPER

Adipose (fat) tissue• Found under skin, around kidneys

and heart• Functions in energy storage and insulation;

cushioning for organs

connective tissueCONNECTIVE TISSUE PROPER

Dense connective tissue• Found in tendons and ligaments• Forms strong bands that attach bone to muscle or bone to bone

connective tissueSPECIALIZED CONNECTIVE TISSUE

Cartilage• Found in rings of respiratory air tubes,external ear, tip of nose

• Provides flexible support; cushions

connective tissueSPECIALIZED CONNECTIVE TISSUE

Bone

• Found in the skeleton

• Functions in support, protection(by enclosing organs), and movement

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connective tissueSPECIALIZED CONNECTIVE TISSUE

Blood• Found within blood vessels• Transports nutrients, gases, hormones, wastes;

fights infections

Muscle Tissue

• Muscle tissue can contract and shorten

• There are three types of muscle tissue:Skeletal muscle• Long cylindrical striated

cells with many nuclei

• Voluntary contraction

• Most are found attached

to the skeleton

• Responsible for

voluntary movement

Nucleus

Width of one

muscle cell

Striation

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Cardiac muscle• Branching striated cells,

one nucleus

• Involuntary contraction

• Found in wall of heart

• Pumps blood through

the body

Specialized

junction

Nucleus Striation

Smooth muscle• Cells tapered at each end,

one nucleus

• Involuntary contraction

• Found in walls of hollow

internal organs, such as

the intestines, and tubes,

such as blood vessels

• Contractions in digestive

system move food along

• When arranged in circle,

controls diameter of tube

Nucleus Smooth

muscle cell

Nervous Tissue

• Nervous tissue functions to conduct

messages throughout the body.

• Two types of nervous tissues cells

– Neurons

– Neuroglial (glial) cells

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Neurons and neuroglia

Dendrite

Cell body

Axon

Neuron

Neuroglia

Cellular junctions

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Organs & organ systems

• Organs are made up of two or more

different tissues functioning together towards a common purpose

• Organs that perform related functions are

grouped into organ systems.

• See page 73

Body cavities

The internal organs are suspended in body

cavities that protect the organs and allow organs to slide past one another as they

function and as the body moves.

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Epithelial Membranes

1. Cutaneous membrane

2. Mucous membranes

3. Serous membranes

Connective Tissue Membranes

1. Synovial membranes

2. Meninges

Homeostasis

Definition:

Examples:

Homeostasis

• Homeostatic mechanisms do not maintain

absolute internal constancy, but they do dampen fluctuations around the variable’s

set point.

• The ability to maintain these variables within narrow limits is due to regulatory

control mechanisms.

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Negative Feedback Loops

• Whenever a change occurs in a system,

the change activates a corrective mechanism which corrects the original

change.

• Receptor (sensor)

• Control center (integrator)

• Effector(s)

Homeostatic Control Systems

Positive feedback loops (parturition)

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Integumentary System

Components of the Integumentary System

• Skin

• Nails

• Hair

• Sensory receptors

• Exocrine glands

Functions of the Integumentary System

1. Protection

2. Prevents excessive water loss

3. Temperature regulation

4. Vitamin formation

5. Keeps us informed about the outside

environment

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Skin Layers

Epidermis – thin outer layer of keratinized stratified squamous epithelial cells

Epidermis

Skin Color

Skin color is based on the production of a

pigment called melanin by cells called melanocytes.

• Eumelanin

• Pheomelanin

Skin Color

1. Melanin

2. Hemoglobin

3. Carotene

3. Melanin

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Functions of melanin

1. Skin & hair color

Albinism

2. Absorption of UV light

Dermis

Stretch marks (Striae)

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Hypodermis Wrinkles

Wrinkles & Botox Accessory Structures - Hair

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Accessory structures – Sensory receptors Accessory structures - Nails

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Accessory structures - Skin Glands

• Sudoriferous Glands

• Sebaceous Glands

First degree burns

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Second degree burns Third degree burns

Basal cell carcinoma Squamous cell carcinoma

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Melanoma

“A” – asymmetry

“B” – border

“C” – color

“D” – diameter

“E” – evolving