Animal Tissues and Organ Systems

Chapter 20

Stem Cells

• Undifferentiated cells with potential to develop into many cell types– Embryonic stem cells, more

versatile– Adult stem cells, less

versatile

Body Organization

• Tissue– Group of cells performing same task

• Organ– Two or more tissues performing same task

• Organ system– Two or more organs performing same task

Tissues

• Groups of cells and intercellular substances

that interact in one or more tasks

• Example: muscle tissue

Organs

• Group of tissues organized to perform a task or tasks

• Example: Heart is an organ that pumps blood through body

• Heart consists of muscle tissue, nervous tissue, connective tissue, and epithelial tissue

Organ Systems

• Groups of organs that interact physically and/or chemically to perform a common task

• Example: Circulatory system includes heart, arteries, and other vessels that transport blood through the body

Homeostasis

• Stable operating conditions in the internal environment

• Brought about by coordinated activities of cells, tissues, organs, and organ systems

4 Types of Tissues

• Epithelial tissues

• Connective tissues

• Muscle tissues

• Nervous tissues

Epithelial Tissues

• Line body surfaces, cavities, ducts, and

tubes

• One free surface faces a body fluid or the

environmentsimplesquamousepithelium

basementmembrane

connective tissue

simple epithelium

basement membrane

connective tissue

free surface of epithelium

Epithelium

Glands

• Secretory organs derived from epithelium

• Exocrine glands have ducts or tubes• Endocrine glands are ductless

Cell Junctions• Tight junctions

prevent leaks • Gap junctions

connect abutting cytoplasms

• Adhering junctions cement cells together

Tight junctions

Adhering junction

Gap junctions

Connective Tissues

• Most abundant tissues in the body• Fibroblasts secrete – polysaccharide “ground substance” that

surrounds and supports cells– fibers of collagen and/or elastin

Soft Connective Tissues• Loose connective tissue• Dense, irregular connective tissue• Dense, regular connective tissue

Specialized Connective Tissues• Cartilage• Bone tissue• Adipose tissue• Blood

red blood cell

white blood cell

platelet

Fig. 20-3g, p.342

cells and platelets of blood

Muscle Tissue

• Cells contract when stimulated• Moves body and specific body parts• 3 types– Skeletal– Cardiac– Smooth

Skeletal Muscle

• Attaches to and moves bones

• Long, cylindrical cells• Striated cells • Voluntary control

nucleus

Smooth Muscle• Located in soft internal

organs and blood vessels • Cells taper at ends• Cells not striated• Not under voluntary control

where abutting cells meet

Cardiac Muscle

• Present only in heart• Cells are branching– ends of cells joined by communication

junctions

• Cells striated• Not under voluntary control

cell nucleus

Nervous Tissue• Detects stimuli, integrates information,

and relays commands for response• Consists of excitable neurons and

supporting neuroglial cells

Functional zones of a motor neuron

Neurons

Neurons

• Excitable cells• Stimulus sends electrical impulse along

plasma membrane• Transmits information to other neurons,

muscles or glands

Neuroglia

• Neuroglial cells make up more than half of nervous tissue

• Protect and support neurons

11 Major Organ Systems• Integumentary • Nervous• Muscular• Skeletal• Circulatory• Endocrine• Lymphatic

• Respiratory

• Digestive

• Urinary

• Reproductive

Nervous System

Muscular System Skeletal System

Circulatory System

Endocrine System

Fig. 20-6, p.344a1

Integumentary System

11 Major Organ Systems

Lymphatic System

Respiratory System

Digestive System

Urinary System

Reproductive System

Fig. 20-6a2, p.344

11 Major Organ Systems

midsagittal plane

transverse planefrontal plane

dorsal surface

ventral surface

anteriorposterior

Fig. 20-6b, p.345

Position References:Animals

Position References: Humans

frontal plane(aqua)

transverse plane(yellow)

midsagittal plane (green)

Major Body Cavities

• Cranial cavity

• Spinal cavity

• Thoracic cavity

• Abdominal cavity

• Pelvic cavity

cranial cavity

spinal cavity

thoracic cavity

abdominal cavity

pelvic cavity

Fig. 20-6d, p.345

Primary Tissues

• Three primary tissues in vertebrate embryos give rise to all adult tissues:

EctodermMesodermEndoderm

Skin: An Organ System

• Epidermis: Stratified epithelium

• Dermis: Dense connective tissues

• Hypodermis: Loose connective tissue and adipose tissue

hair

epidermis

dermis

hypodermis(below skin, not part of it)

oil gland

hair follicle

blood vessels

smooth muscle

sweat gland

sensoryneuron

Fig. 20-7a, p.346

outermostepidermallayer (alldead cells)

keratinizedcells beingflattened

rapidlydividingcells ofepidermis

dermis

Fig. 20-7b, p.346

Functions of Human Skin

• Protects body from injury, dehydration, UV radiation, and some pathogens

• Helps control temperature• Receives external stimuli• Involved in vitamin D production

Sun Damages Skin• UV light stimulates melanin production– tans skin

• Tan protects inner layers against UV damage

• UV exposure causes– elastin fibers to clump– skin to age prematurely– skin cancer

Langerhans Cells

• White blood cells in skin• Attack viruses and bacteria• Stimulate immune system• Are damaged by UV exposure

Epithelial Tissues