Unit 5 Anatomy & Homeostasis Animal Organization & Homeostasis 2 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? Animal Organization & Homeostasis 3 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. Animal Organization & Homeostasis 4 Animal Organization & Homeostasis 5 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 6 Types of Tissues& Homeostasis

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) Animal Organization 7 Epithelial Tissue& Homeostasis 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 8 Epithelial Tissue & Homeostasis Example 1.Squamous epithelium is composed of flat cells (e.g., air sac linings of lungs, walls of capillaries).

Animal Organization Epithelial Tissue & Homeostasis 9 Example 2.Cuboidal epithelium has cube- shaped cells.

Animal Organization 10 Epithelial Tissue & Homeostasis Example Columnar epithelium has elongated cells that resemble pillars or columns (e.g., small intestine). Used for absorption Animal Organization & Homeostasis 11 Figure 33.1d Animal Organization 12 Special Epithelial& TissuesHomeostasis

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 13 Connective Tissue& Homeostasis • 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 Diagram of Fibrous Connective Tissue14 Animal Organization & Homeostasis 15 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 Figure 33.4 17 Blood - Actually a connective tissue in which cells are embedded in a liquid matrix (plasma) Red blood cells - erythrocytes White blood cells - leukocytes

Transports nutrients and oxygen to cells Removes carbon dioxide and other wastes Animal Organization 18 Muscular Tissue& Homeostasis 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 20 Nervous Tissue& Homeostasis 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 21 Nervous Tissue& Homeostasis

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 22 Neurons and Neuroglia Long axons and dendrites form neuron fibers; bound by connective tissue, they form nerves. Animal Organization 23 Homeostasis & 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 Animal Organization 24 Homeostasis & 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 Animal Organization 25 Negative Feedback& Homeostasis

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 Negative Feedback 26 Mechanisms: Simple 27

Negative Feedback Mechanism Analogy: a thermostat 28

Same diagram, but now featuring Regulation of Body Temperature 29 Animal Organization 30 Positive Feedback& Homeostasis During positive feedback, an event increases the likelihood of another event (change is good here) Childbirth Process Urge to urinate Positive Feedback Does not result in equilibrium Does not occur as often as negative feedback