Animal Tissues and Organ Systems Chapter 33 Animal Tissues and Organ Systems AP Biology Spring 2011

Chapter 33.4 Nervous Tissue

Nervous Tissue Nervous Tissue: composed of neurons and a variety of cells (called neuroglia), that structurally and functionally support them

Nervous Tissue Neurons: kind of excitable cell that makes up the communication lines in most nervous systems

Motor Neuron Neuron: highly excitable in a specific way When stimulated, propagates a message along its plasma membrane, all the way to some outpoint zone, without altering it Message triggers release of signaling molecules called neurotransmitters Signals diffuse to another cell that is almost but not quite touching the neuron that sent them

Neurons Interneurons: neurons in your brain and spinal cord Receive and integrate sensory information, store the bits that hold meaning, and coordinate the body’s short-term and long-term responses to stimuli Motor Neurons: relay commands from brain and spinal cord to muscle cells

Overview of Major Organ Systems Chapter 33.5 Overview of Major Organ Systems

Organ Systems Germ cells give rise to sperm or egg Fertilization  zygote forms Mitotic cell divisions  three primary tissue layers Forerunners of all adult tissues and organs

Three Primary Tissue Layers Ectoderm: the outer layer, is the first to form Gives rise to epidermis and the nervous system Mesoderm: middle layer, start of muscles, bones, and most of circulatory , urinary, and reproductive systems Endoderm: inner primary tissue layer, start of lining of digestible tract and organs derived from it

Division of Labour Division of Labor: organ systems of multicelled body show this compartmentalization of function Help body survive in ways no one tissue can offer

Division of Labor Organ systems divide up tasks of securing, processing, and distributing materials, and expelling wastes, protecting the body, integrating its activities, and reproducing

Organ Systems Integumentary Systems Protects body from injury, dehydration, and some pathogens; controls its temperature; excretes certain wastes, receives some external stimuli

Organ Systems Nervous System: Detects external and internal stimuli; controls and coordinates the response to stimuli; integrates all organ system activities

Organ Systems Muscular System: Moves body and its internal parts; maintains posture; generates heat and increases metabolic activity

Organ Systems Skeletal System: Supports and protects body parts; provides muscle attachment sites; produces red blood cells; stores calcium, phosphorous

Organ Systems Circulatory System: Rapidly transports many materials to and from cells; helps stabilize internal pH and temperature

Organ Systems Endocrine System: Hormonally controls body functioning; works with nervous system to integrate short-term and long-term activities

Organ Systems Lymphatic System: Collects and returns some tissue fluid to the bloodstream; defends the body against infection and tissue damage

Organ Systems Respiratory System: Rapidly delivers oxygen to the tissue fluid that bathes all living cells; removes carbon dioxide wastes of cells; helps regulate pH

Organ Systems Digestive System: Ingests food and water; mechanically, chemically breaks down food and absorbs small molecules into internal environment; eliminates food residues

Organ Systems Urinary System: Maintains the volume and composition of internal environment; excretes excess fluid and blood borne wastes

Organ Systems Reproductive System: Female: produces eggs; after fertilization affords a protected, nutritive environment for the development of a new individual Male: produces and transfers sperm to the female; hormones of both systems also influence other organ systems

Cavities Cranial cavity Spinal cavity Thoracic cavity Abdominal cavity Pelvic cavity

Directional Terms and Planes Direction: dorsal, ventral, posterior, anterior

Directional Terms and Planes Planes: frontal, midsagittal , transverse

Directional Terms and Planes Anterior: at or near front of body Posterior: at or near back of body Superior: of two body parts, the one closest to the head Inferior: of two body parts the one farthest from the head Proximal: closest to trunk or point of origin of a body part Distal: farthest from trunk or from point of origin of a body part

Vertebrate Skin: An Example of an Organ System Chapter 33.6 Vertebrate Skin: An Example of an Organ System

Skin Outer body covering has the largest surface area Two layers: underlying dermis and outer epidermis

Dermis Dense connective tissue with many fibers of stretch resistant elastin and supportive collagen Blood vessels, lymph vessels, sensory receptors thread through it Rest on hypodermis: not part of skin, contains loose connective tissue and adipose tissue

Dermis Dermis contains exocrine glands Sweat glands Oil glands (except on palms and soles)

Epidermis Stratified squamous epithelium with an abundance of adhering junctions and no extracellular matrix Ongoing mitotic cell divisions in the deepest layers push previously formed cells to the surface

Epidermis Wear and tear from surface and pressure from growing mass, flatten and kill cells before they reach the surface Dead one are flaked off Main types: keratinocytes, melanocytes, dendrite cells

Epidermis Keratinocytes: sectret keratin, tough, water resistant protein, makes skin water proof and more durable Dead, flattened keratinocytes make up hair

Epidermis Melanocytes: produce brownish-black pigment melanin (gives up pigments to keratinocytes) Body’s barrier to UV radiation Variations in skin colour result from differences in the distribution and activity of melanocytes

Epidermis Langerhans: migrate through epidermis Engulf bacteria or viruses, communicate with immune system UV radiation damages these cells and skin will be more vulnerable to viral outbreaks

Epidermis Lab-grown epidermis: used to protect tissues and aid wound healing in some patients A new tattoo removal procedure developed by the Wake Forest Institute in North Carolina for Regenerative Skin Treatment was recently used by rapper Pharrell Williams. The procedure involves the patient providing a sample of his/her skin from which is grown in a laboratory  enough new skin to cover the tattooed area. Supposedly the new skin is stitched over the tattoo and does not leave any scars. Once the skin has healed, new tattoos can be done.

Suntans and Shoe-Leather UV light stimulates melanocytes in skin to make melanin and gives skin “tan” look Chronic UV damage causes skin to be less resilient and starts to look like shoe leather UV attacks DNA causing skin cancer

Suntans and Shoe-Leather As we age, epidermal cells divide less often Skin thins, becomes less elastic as collagen and elastin fibers become sparse Glandular secretions dwindle, wrinkles deepen

Vitamin Connection UV stimulates vitamin D production Helps body absorb calcium UV aids breakdown of folate (B vitamin) Variations in skin colour may be adaptations to differences in sunlight xposure