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Animal Organization & Homeostasis
Main Ideas – discuss with a buddy
What is Homeostasis?
How is homeostasis different in single-celled organisms vs. multicellular organisms?
What unique challenges to maintaining homeostasis do multicellular organisms have to address?
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Animal Organization & Homeostasis
Main Ideas – answers
What is Homeostasis?
-maintaining a constant internal balance
How is homeostasis different in single-celled organisms vs. multicellular organisms?
-Single-celled organisms perform all homeostatic needs (waste removal, energy input, respiration, etc.) within one, single cell. Multicellular organisms must coordinate efforts with cell “teams” called organs/organ systems specialized for certain jobs.
What unique challenges to maintaining homeostasis do multicellular organisms have to address?
-Cells in multicellular organsims must differentiate and specialize to cover one homeostatic mechanism for the whole body. Cells must be able to coordinate and communicate to time homeostatic mechanisms properly.
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Animal Organization & Homeostasis
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Review: Levels of Organization
•Tissue - Group of similar cells performing a similar function
•Organ - Group of tissues performing a specialized function
•Organ System - Collection of several organs functioning together
•Organism - A collection of organ systems
Animal Organization & Homeostasis
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Types of Tissues
Four Major Types of Tissue
1. Epithelial tissue covers body surfaces and lines body cavities. (skin)
2. Connective tissue binds and supports body parts. (tendons)
3. Muscular tissue causes motion in body parts. (biceps)
4. Nervous tissue responds to stimuli and transmits impulses for communication/control. (brain)
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Epithelial Tissue Epithelial tissue: Forms a continuous layer over body surfaces Lines inner cavities Forms glands
-Exocrine glands - Secrete products into ducts or cavities
-Endocrine glands - Secrete products directly into the bloodstream
Covers abdominal organs
Animal Organization & Homeostasis
8 Epithelial Tissue
Example
1.Squamous epithelium is composed of flat cells (e.g., air sac linings of lungs, walls of capillaries).
Animal Organization & Homeostasis
9 Epithelial Tissue
Example
2.Cuboidal epithelium has cube-shaped cells.
Animal Organization & Homeostasis
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Columnar epithelium has elongated cells that resemble pillars or columns (e.g., small intestine). Used for absorption
Epithelial Tissue
Example
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Special Epithelial Tissues
1. Ciliated Epithelia - cells are covered with cilia (e.g., lining of human respiratory tract).
Cilia can bend and move material over the surface of the epithelium.
2. Glandular Epithelia - can be unicellular or have multicellular glands.
Glands are a single cell or a group of cells that secrete a chemical signal into the body; two types:
- Exocrine glands secrete their products into ducts or directly into a tube or cavity.
- Endocrine glands secrete their product directly into the bloodstream.
Animal Organization & Homeostasis
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Connective Tissue • Connective tissues consist of:
1. Fibroblast cells
2. A matrix containing collagen and elastic fibers
• Loose fibrous connective tissue
Allows organs to expand
• Dense fibrous connective tissue
Strong connective tissue
- Tendons
- Ligaments
Animal Organization & Homeostasis
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Special Connective Tissue
Adipose Tissue Fat cells; stores energy, insulates the body, and provides padding
Cartilage Classified according to type of collagen and elastic fibers found in the matrix
Cartilage cells (chondrocytes), lie in small chambers (lacunae) in the matrix
17 Figure 33.4
Transports
nutrients and
oxygen to cells
Removes carbon
dioxide and other
wastes
Blood - Actually a connective tissue in which cells are embedded in a liquid matrix (plasma)
Red blood cells - erythrocytes
White blood cells - leukocytes
Animal Organization & Homeostasis
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Muscular Tissue Contractile cells containing actin and myosin
filaments (cytoskeleton fibers made to contract and release)
Cells are called muscle fibers
Skeletal Muscle
- Voluntary - Long, striated fibers
Smooth Muscle
- Involuntary - No striations
Cardiac Muscle
- Striated, but mostly involuntary
- Bound by intercalated disks
Animal Organization & Homeostasis
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Nervous Tissue Nervous Tissue contains neurons
Made up of dendrites, a cell body, and an axon and used for quick communication
-Long axons covered by insulating myelin
-Outside the brain and spinal cord, fibers form nerves
Neuroglia support and nourish neurons
Animal Organization & Homeostasis
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Nervous Tissue Nervous system has three functions
1. Sensory input – receive stimulus
- Sensory receptors detect changes
- Transmit info to the spinal cord
2. Data integration – make a decision
- Spinal cord and brain integrate
- Decision is made regarding appropriate response
3. Motor output – respond to stimulus
- Response is transmitted to effector (gland or muscle)
- Effector initiates actual response
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Neurons and Neuroglia
Long axons and dendrites form neuron fibers; bound by connective tissue, they form nerves.
Animal Organization & Homeostasis
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Homeostasis
The organ systems of the human body contribute to homeostasis
The digestive system
-Takes in and digests food
-Provides nutrient molecules that re-place used nutrients
The respiratory system
-Adds oxygen to the blood
-Removes carbon dioxide
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Homeostasis The organ systems of the human body contribute to homeostasis
The liver and the kidneys
-Store excess glucose as glycogen
-Later, glycogen is broken down to replace the glucose used
-The hormone insulin regulates glycogen storage
The kidneys
-Under hormonal control as they excrete wastes and salts
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Negative Feedback
Homeostatic Control
Partially controlled by hormones (and)
Ultimately controlled by the nervous system
Negative Feedback is the primary homeostatic mechanism that keeps a variable close to a set value (e.g. constant temperature)
Sensor detects change in environment
Regulatory Center activates an effector
Effector reverses the change