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 Organ Organ system 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 Muscle tissues Nervous 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 environment simple squamous epithelium basement membrane connective tissue

free surface of epithelium simple epithelium basement membrane connective tissue

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

cells and platelets of blood white blood cell platelet red blood cell cells and platelets of blood Fig. 20-3g, p.342

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 Functional zones of a motor neuron

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

11 Major Organ Systems Integumentary System Nervous System Muscular System Skeletal System Circulatory System Endocrine System Fig. 20-6, p.344a1

11 Major Organ Systems Lymphatic System Respiratory System Digestive System Urinary System Reproductive System Fig. 20-6a2, p.344

Position References: Animals dorsal surface midsagittal plane anterior posterior transverse plane frontal plane ventral surface Fig. 20-6b, p.345

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: Ectoderm Mesoderm Endoderm

Skin: An Organ System Epidermis: Stratified epithelium Dermis: Dense connective tissues Hypodermis: Loose connective tissue and adipose tissue

hair epidermis dermis sensory neuron hypodermis (below skin, not part of it) sweat gland oil gland hair follicle smooth muscle blood vessels Fig. 20-7a, p.346

outermost epidermal layer (all dead cells) keratinized cells being flattened rapidly dividing cells of epidermis 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