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Organization and Homeostasis

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Levels of biological organization

ChemicalCellularTissueOrgansSystem LevelOrganismic Level

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Levels of Structural Organization

� Chemical Level - atomic and molecular level

� Cellular level - smallest living unit of the body

� Tissue level

Group of cells and the materials surrounding them that work together on one task

4 basic tissue types: epithelium, muscle, connective tissue, and nerve

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Epithelial tissue

SECRETION

SELECTIVE ABSORPTION

PROTECTION

Functions of the epithelium

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Epithelial cells are connected to each other by tightjunctions, adhesion junctions and gap junctions.

Epithelium lies on a basement membrane, which actsas a scaffolding and anchors the epithelial tissue to theunderlying connective tissue.

Epithelial tissue

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Cells of the epithelium

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Cells of the epithelium

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Cells of the epithelium

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Cells of the epithelium

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Connective tissue connects, protects and supportsother tissues.

The most abundant tissue in vertebrates-

Connective cells are separated by a collagen-rich fluid called matrix which varies from solid (in bones) to semifluid (in cartilage) to fluid (in blood).

Connective tissue

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Types of Connective Tissue

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Types of Connective Tissue

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Blood is different from the other connective tissues

Blood has different functions as:

•Transport of oxygen•Transport of nutrients•Body heat regulation•pH regulation•Protection

Plasma

RBC

WBC

Platelets

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Muscular tissue

Muscular cells contains contractile filaments, actin andmyosin, that move past each other and change the size of the cell.

Major functions: •Locomotion of the organism;•Movement of internal organs.

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Muscular tissue

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Nervous tissue

Major functions:

•Sensory input•Sensory output•Communication within organs•Control of muscles and glands•Homeostasis

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axon

dendrite

cell body

Neurons transmit impulses

Neuron cells are composed of:

•A cell body (contain nucleus) •Dendrites (for input signals)•An axon (for output signals)

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microglia

oligodendrocyte

astrocyte

Neuroglia cells

Neuroglia cells assistpropagation of the impulse and provide nutrients to the neuron.

Neuroglia cells includemicroglia (destroy bacteria and remove dead cells), astrocytes (supply nutrients) and oligodendrocytes (insulate neurons).

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Read the description of the following tutorial, watch the animation and answer the quiz:http://www.hartnell.edu/tutorials/biology/tissues.html

Watch the following animation and write the names of the animal tissues, organs and organ systems presented:http://www.tutorvista.com/content/biology/diversity-in-living-world/level-of-organization-hierarchy.php

Watch the following animation about the epithelial tissues:http://www.tutorvista.com/content/biology/tissues/animal-tissue.phpAre there some tissues that you do not know?

Animations and activities

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Organs and organ systems

� Organ level - consists of two or more types of primary tissues that function together to perform a particular function or functionsExample: Stomach

Inside of stomach lined with epithelial tissueWall of stomach contains smooth muscleNervous tissue in stomach controls muscle contraction and gland secretion

Connective tissue binds all the above tissues together

� Organ system - collection of related organs with a common function, sometimes an organ is part of more than one system

� Organismic level - one living individual.

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� Groups of organs that perform related functions and interact to accomplish a common activity essential to survival of the whole body.

� Do not act in isolation from one another.

� Human body has 11 organ systems.

Organ systems

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The skin covers and protectsIn humans the skin is divided into two strata: the epidermis(stratified epithelium) and the dermis (dense fibrous connective tissue).

A subcutaneous layer, the hypodermis (connective tissue) connects the dermis with underlying structures.

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Watch the following videos:

1) http://www.youtube.com/watch?v=yKAzVC0WcmI (about skin)

2) http://www.youtube.com/watch?v=9nV_RY2HD7Q(about skin, with subtitles)

3) http://www.youtube.com/watch?v=cAQpchyTXYo(a review of cell, transport and tissues)

Read the descriptions on pages 1, 2, and 3, answer the questions on pages 2 and 3, and solve the quiz on page 5 at:http://www.abpischools.org.uk/page/modules/skin/.cfm?coSiteNavigation_allTopic=1

Videos and activities

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Organ systems work in homeostasisSeveral organs of a system work together to carry out a complex function as:

•Control

•Sensory input and motor output

•Transport

•Maintenance

•Reproduction

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ControlNervous system coordinates the body actions and transmits signals between different locations.Endocrine system regulates the hormones secretion.

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Sensory input and motor outputIntegumentary system is the attachment site for sensory receptors and provides environmental information.Skeletal andmuscular systems are responsible for locomotion in response to nervous system instructions.

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TransportCardiovascular system transports nutrients, gases, hormones and other substances through the body.Lymphatic system is a network of conduits carrying the lymph which returns protein and lipids in excess to the circulation.

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MaintenanceDigestive, Respiratory and Urinary systems are responsible for maintaining the body efficient and constant through the transformation of nutrients or gases and purifying the organism.

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ReproductionOrgans of the reproductive system include the genitalia (penis and vulva) and a number of internal organs as the gamete producing gonads (testicles and ovaries).

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� Defined as maintenance of a relatively stable internal environment� Does not mean that composition,

temperature, and other characteristics are absolutely unchanging

� Homeostasis is essential for survival and function of all cells

� Each cell contributes to maintenance of a relatively stable internal environment

Homeostasis

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HomeostasisHomeostasis is the maintenance of stable, constant conditions of the body’s internal environment which consists of blood and intestitial fluid (tissue fluid).Homeostasis involves dynamic mechanisms that detect and respond to deviations in physiological variables from their “set point” values by initiating effector responses that restore the variables to the optimal physiological range.

EQUILIBRIUM

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Homeostasis

All organ systems contribute to maintain within normal limits the internal conditions as bodytemperature, water content, pH, Glucose and CO2concentrations.

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Homeostatic Control Systems

� In order to maintain homeostasis, control system must be able to

� Detect deviations from normal in the internal environment that need to be held within narrow limits

� Integrate this information with other relevant information

� Make appropriate adjustments in order to restore factor to its desired value

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effect

effect

Control centerControl center

Sensor

Sensor

Negative feedbackThe negative feedback mechanisms is the principal mechanism in homeostasis and is composed of a sensor and a reaction center (i.e. blood glucose levels).

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Read the description on pages 4, 5, 6, and 7, see the animation on page 4 and answer the questions on pages 5, 6, and 7 of the document at:http://www.abpischools.org.uk/page/modules/homeostasis_sugar/.cfm?coSiteNavigation_allTopic=1

Read the description on pages 1 and 2 of the document at:http://www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/homeostasis/removal_waste_water_control/revision/1/

Read the description, watch the video and the animation that can be found at:

http://www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/homeostasis/temperature_control/revision/1/

Animations and activities