Unit 5 Anatomy & Homeostasis › cms › lib04 › VA01000023...& Homeostasis Homeostasis 24 The organ systems of the human body contribute to homeostasis The liver and the kidneys

Anatomy & Homeostasis

Unit 5

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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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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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


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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


8 Epithelial Tissue

Example

1.Squamous epithelium is composed of flat cells (e.g., air sac linings of lungs, walls of capillaries).


9 Epithelial Tissue

Example

2.Cuboidal epithelium has cube-shaped cells.


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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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Figure 33.1d


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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.


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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

14 Diagram of Fibrous Connective Tissue


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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


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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


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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


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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.


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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

26 Negative Feedback Mechanisms:

Simple

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Negative Feedback

Mechanism Analogy: a thermostat

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Same diagram, but now featuring Regulation of

Body Temperature

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Positive Feedback 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

Unit 5 Anatomy & Homeostasis › cms › lib04 › VA01000023...& Homeostasis Homeostasis 24 The organ systems of the human body contribute to homeostasis The liver and the kidneys

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