vce biology regulatory mechanisms in animals
TRANSCRIPT
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VCE BIOLOGY
www.drlakshmisharma.comDr Lakshmi Sharma
NO LIMITS TO LEARNING! BELIEVE & YOU CAN ACHIEVE!
Regulatory Mechanisms in Animals
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Regulatory Mechanisms in Animals
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What do we mean by Regulatory Mechanisms in
Animals ???
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Hormone released from glands, neurotransmitters released from nerve endings
Mammals well developed – maintain a stable internal environment with changing conditions HOMEOSTASIS involves –ve feedback.
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Maintaining Equilibrium
Communication within an animal requires mechanisms: Hormonal Nervous
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Negative Feedback
Nervous & Hormonal system
promoting stability of internal environment
Stimulus Response Mechanism
the response reduces original stimulus
(–ve effect on stimulus)
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Negative Feedback
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Hormones -Slower than nervous responses
Synthesised from fatty acids
Small & lipid-soluble, easily pass thro membranes – nucleus-act on genes
Steroid hormones – testosterone & oestrogenAmino Acid Hor Fatty Acid Hor
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Hormones -Slower than nervous responses
Synthesised from amino acids
Water soluble, cannot pass through membranes – bind to receptors plasma membrane, responses in cell. Adrenaline & growth hormonesAmino Acid Hor Fatty
Acid Hor
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Endocrine glands release hormones directly into the circulatory system
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Pituitary Gland
Central role in overall endocrine regulation
Growth, lactation, reproductive state, skin pigmentation, fat tissue, kidney function & activity of thyroid and adrenal glands
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Pituitary Gland
Hypothalamus -collects info the body’s state (water, food, pain, emotions), releases releasing hormones to pituitary
Pituitary- receives info, releases hormones regulate body’s response
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Thyroxin Hormone
Stimulates metabolic rate of cells
Involved in physical development
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Anterior Pituitary Gland
Thyroid Stimulating Hormone
Thyroid Gland
Thyroxine
Target Cells (most cells in the body)
via blood vessels
Thyroid stimulating hormone releasing hormone
Hypothalamus
via blood vesselsreleases
releases
via blood vessels
Sequence of hormones in release of thyroxine from the thyroid gland
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Hormones Video
Endocrine System
Please go to dnatube.com - excellent video resource
Endocrine - Mr Anderson
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Nervous Systems
More direct pathway of communication
Extremely rapid responses are possible
Functional unit is the neuron Neurons communicate between
Sensory cells that detect a disturbance Effector cells that produce the response
Specific receptors bring about highly precise responses
Requires a lot of energy to run
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Nervous Systems – Evolution
Note development of a bundle of nerves at the front of the animal
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The Reflex Response
A reflex is a rapid, unconscious response hand on a stove Stand on a pin
Brain registers the ‘pain’ but doesn’t facilitate the response (spinal cord does)
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Knee-Jerk Response
Stretch Receptor
Effector Muscle
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Receptors in Skin
Withdrawal Reflex
Spinal cord
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Nervous Response
Environmental Disturbance
(eg. hot plate)
Sensory Cells (skin)
Effector Cells
(muscles)
Neurons sensory, interneuro
ne & motor
Response
(pull hand away)
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Interneurons
Neurons that transmit information from one neuron to another (97% of human neurons are interneuron)
Allow more co-ordination & integration
Tread on nail, can’t withdraw your foot interneurons instruct muscles of opposite leg to bear weight
Try balancing on one foot.
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Reflexes in Homeostasis Baroreceptor-heart rate reflex maintains blood
pressure
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Neurons
Signals travel quickly along neurons as electrical
impulses
The signals that travel between neurons, across the
synapse are chemical
Nerve Bundle - many neurons group together
forming a single nerve
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Types of Neurons
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THE STRUCTURE OF NEURONS
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Synapse
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Nerve Bundle
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Action Potentials
Nerve impulse or action potential is a wave of electrical change along the
axon membrane stimulation
At the dendrite it stimulates the release of a chemical transmitter, which
diffuses across a synapse
The transmitter binds to receptor sites on the postsynaptic cell membrane
to stimulate the generation of another impulse
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The Nervous System
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Mammalian Nervous Systems
Central nervous system (CNS) – ‘co-ordinating centre’ BrainSpinal cord
Peripheral Nervous System – ‘sensing and responding’
Motor (muscular) neuronsSensory neurons
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The Central Nervous System
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Human Nervous System
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Major Sense OrgansTypes of Receptors
Photoreceptors
Visible light, infrared radiation
Chemoreceptors
Taste, smell, communication
Oxygen, CO2, pH, water, salts etc
Mechanoreceptors
Hearing, balance, pressure, touch
Thermoreceptors
Heat and cold
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VisionPhotoreceptor cells contain
Light sensitive pigments
Light with the pigment creates
an electrical signal
in a sensory nerve
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Colour Blindness Inherited & affects more boys than girlsLack one or more of the cone cells.
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The Nervous System Video
The nervous system
The nervous system short video
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Mind Maps of the Nervous System
The following are nervous system mind maps to help you – read through the ppt & devise your own mindmap
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HOPE YOU ENJOYED THE LESSON !
ANY QUESTIONS ???!