homeostasis · 2013. 12. 9. · homeostasis • the relatively constant internal conditions that...
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Homeostasis
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Cell Transport
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Cell Membrane
• Functions:• Provides protection and support• Provides protection and support.
• Regulates what enters gand leaves the cell.• Takes in food and water.
Eli i t t• Eliminates waste.• Allows the cell to maintain
homeostasis.
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The cell membrane is .
S b h h i • Some substances can pass through it, while others cannot.
• Most biological membranes are .
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Parts of the Cell Membrane: the core
of the membrane; forms of the membrane; forms a strong barrier between the cell and the outside
: form pumps to move material p pthrough membrane
: identif : identify the cell; on the outside
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ConcentrationConcentration
• How many molecules are in a given volume (How • How many molecules are in a given volume. (How crowded the molecules are.)
• Concentration = Amount of solute• Concentration = Amount of soluteVolume of Solution
E ll i d d b li id d h li id • Every cell is surrounded by liquid and has a liquid interior (cytoplasm) that are solutions of many different substances.
High Concentration Low Concentration
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: movement from an area of high concentration to areas of lower concentration (getting less crowded)
: molecules th t t l t th h that are too large to pass through the cell membrane go through protein channelsprotein channels
: the diffusion of water: the diffusion of water
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: movement from an area of low concentration to areas of higher concentration (getting more crowded)(g g )
: when a vesicle fuses with the cell membrane to take material out
: brings material into h ll h k i h the cell when a pocket in the
membrane breaks off, forming a vesiclevesicle1.) : large particles taken
in2 ) ll ti l t k 2.) : small particles taken
in
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Homeostasis & Cells
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Cell Specializationp
Cells in multicellular organisms are • Cells in multicellular organisms are interdependent.
• Cells in multicellular organisms are to perform particular functions in the organism.p p g
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Cells – Tissues- Organs- Organ Cells Tissues Organs Organ Systems- Organism
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Cell• The basic unit of life.
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Tissue• A group of cells that perform a particular
functionfunction.• Four types:▫ ConnectiveConnective▫ Epithelial▫ Muscle▫ Nervous
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Organsg• A group of tissues working together to perform a
particular functionparticular function.• Examples:▫ HeartHeart▫ Stomach▫ Lungsg
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Organ Systemg y• A group of organs working together.
Examples:• Examples:▫ Nervous system▫ Circulatory systemCirculatory system▫ Digestive system
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Organismg• Any living thing.
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Cell Communication• Cells in a large organism use chemical
i l t i t signals to communicate. ▫Ex: heart muscle contraction
ifi i h ▫Receptor: a specific protein where the chemical signal can bindOn the cell membrane or in the cytoplasm
Fight or Flight
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Homeostasis• The relatively constant internal conditions that
organisms maintain despite change in their organisms maintain despite change in their internal and external environments.
• Homeostasis and organ systems:▫ The nervous system sends messages over a system
of neurons in fractions of a second of neurons in fractions of a second. ▫ The endocrine system sends messages using
chemicals (hormones) which takes much longer, b t l t l ll ( i t d )but last longer as well. (minutes-days)
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Feedback Systemsy
• When the brain receives messages from th b d b t i t l h it k t the body about internal chance, it works to restore the system to equilibrium
• Two types of feedback loops▫ Negative ▫ Positive
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Negative Feedback LoopsNegative Feedback Loops• Ex: maintaining body temperature
rise in temp. -> brain “thermostat” -> message to sweat glands to sweat -> body temp. drops
OR
drop in temp. -> brain “thermostat”-> sends message s to shiver -> body temp. rises
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Positive Feedback LoopsPositive Feedback Loops• Ex: childbirth (labor)
pressure from baby’s head -> uterine contractions-> more pressure -> more contractions
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Nervous System
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The Nervous Systemy
• Collects information about the body’s internal and external environment processes and and external environment, processes and responds to it.
• Two Parts:Two Parts:▫ Peripheral Nervous System▫ Central Nervous Systemy
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Peripheral Nervous Systemp y• Consists of nerves and supporting cells.
• Collects information about the body’s external and internal environment and internal environment.
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Central Nervous System
i f h b i d i l d• Consists of the brain and spinal cord.
P i f ti f P i h l N • Processes information from Peripheral Nervous System and creates a response, which is sent back out through the PNS back out through the PNS.
PNS C i PNS: Gathers info. & sends it
to CNS
CNS: Processes info. & forms a response
PNS: Carries response to glands & muscles
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N C ll i h Neurons: Cells in the nervous system that transmit impulses.
• Cell body: contains nucleus & cytoplasm
• Dendrites: receive impulses from other neurons
• Axon: carries impulses away from the cell body
• Myelin sheath: insulating membrane found on some neurons
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Nerve Impulsesp
• An impulse begins when one neuron is stimulated by another neuron or the stimulated by another neuron or the environment.
• Impulses are transferred by the movement of action potential (created by ions), much like p ( y ),electric current through a wire.
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Threshold• the minimum level of a stimulus required to
cause an impulse in a neuroncause an impulse in a neuron▫ All stimulus above the threshold trigger the same
impulse, but the frequency of impulses detected by p , q y p ythe brain can change with the sensation. Ex: touching something warm vs. burning yourself
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Synapsey p• Point where a neuron transfers an impulse to
another cellanother cell.
• Neurotransmitters: the chemicals that • Neurotransmitters: the chemicals that transmit the impulse across a synapse to another neuron
Video
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The nervous system helps maintain homeostasis in the bodyhomeostasis in the body.
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Endocrine System
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HormonesHormones• Chemicals released by glands to deliver
messages throughout the body messages throughout the body. • Hormones bind to specific receptors on the cell
membrane or within cells.
• target cells: cells with receptors for a particular g p phormone
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Glands: organs that produce and Glands: organs that produce and release a substance (secretion)
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Hormones help the body maintain Hormones help the body maintain homeostasis.