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Chapter 19

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Western University
Biology 1225
Michael Butler

Chapter 19 Animal Tissues and Organs pg. 379 19.2 Animal Structure and Function pg. 379 1. All animals are multi celled. Most have cells organized as tissues, organs and organ systems. 2. Tissues, organs and organ systems interact in homeostasis – the process that keep conditions in the internal environment within the limits that cells tolerate (keeping body parameters within limits) 3. Anatomical and physiological traits can evolve by natural selection. Existing structures become modified over generations to better adapt their bearers to their environment 4. Evolutionary remodeling of existing structures for new purposes often results in body plan that are less than optimal. Example the lungs evolved from outpouchings of the gut not from fish gills – the human throat opens to both the digestive tract and respiratory tract – as a result food sometimes goes where air should and a person could choke. 1 Animal bodies are structurally and functionally organized on several levels: a. A tissue – is a group of ***one or more specific cell types that assemble and interact to perform a common task or a specific function. - Tissues make up organs. b. Organs – is a number of different ***tissues (2 or more) assembled together to perform a specific function – organs interact as organ systems Examples are hearts, lungs, liver, skin c. Organ systems – consist of ***2 or more organs organized to perform a specific function. Examples are the integumentary (skin) and the circulatory system Tissues consist of ***one or more cell types- and often an extracellular matrix- that collectively perform a specific task or tasks. Four types of tissue occur in all vertebrate bodies: 1. Epithelial tissue – cover body surfaces and line internal cavities 2. Connective tissues - hold body parts together and provide structural support 3. Muscle tissues - move the body and its parts 4. Nervous tissue - detect stimuli and relay information 2 19.3 Types of Animal Tissues pg. 380 1.Epithelial tissue 2. Connective tissue 3.Muscle tissue 4.Nervous tissue 1. Epithelial tissue – ***Sheet like animal tissue that covers outer body surfaces and lines internal tubes and cavities a. ***Epithelium (continuously dies and replaces itself) has one free surface and one surface glued to an underlying tissue by its secretions. b. ***Endocrine gland – ***ductless gland that secretes ***hormones into a body fluid c. ***Exocrine gland – gland that secretes ***milk, sweat, saliva, mucus, but not hormones or some other substance through a duct d. ***Tight junctions connect its cells, which have no matrix between them ***Adhering and gap junctions are found in the plasma membrane e. ***Examples of epithelial cells are skin, nails, lining of the small intestine, lining of the veins, but not Bone. 3 2. Connective tissue – Animal tissue with an extensive extracellular matrix; provides structural (holds body parts together) and functional support a. Fibroblast – main cell type in soft connective tissue; secretes collagen and other components of extracellular matrix b. ***adipose tissue – connective tissue with fat storing cells 1.) energy storage 2.)cushioning 3.)insulation 4.) protection c. ***bone tissue – connective tissue with cells surrounded by a mineral-hardened matrix of their own secretions (Calcium hardened connective tissue) d. cartilage – connective tissue with cells surrounded by a rubbery matrix o their own secretions e. ***blood f. dense connective tissue – connective tissue with many fibroblasts and fibers in a random or regular arrangement g. loose connective tissue – connective tissue with relatively few fibroblasts and fibers scattered in its matrix ***Connective tissue – are the body’s most abundant tissues. ***Bones attach to muscle by ***connective tissue 3. Muscle tissue - move the body and its parts - contract (shorten) when stimulated a. cardiac muscle tissue – striated, involuntary muscle of the heart wall b. skeletal muscle tissue – striated, ***voluntary muscle that interacts with bone to move body parts c. smooth muscle tissue – not striated, involuntary muscle that lines blood vessels and hollow organs 4. Nervous Tissue – Animal tissue composed of neurons and supporting cells; detects stimuli and controls responses to them. Neurons serve as communication lines in nervous tissue. They relay electrical signals along their plasma membrane and send and receive chemical signals. Cells called neuroglia support the neurons.
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