This document discusses regulatory mechanisms in animals, including hormonal and nervous systems. It explains that hormones and neurotransmitters help maintain homeostasis by providing negative feedback responses. The hormonal system involves endocrine glands that release hormones into the bloodstream to target cells and regulate processes like metabolism and development. The nervous system involves neurons that transmit rapid sensory and motor signals via electrical and chemical signals. This allows for reflex responses and complex coordination between sensory and effector cells. Both systems work to promote stability within the internal environment.

1. VCE BIOLOGY
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Regulatory Mechanisms in Animals

2. Regulatory Mechanisms in Animals

3. What do we mean by Regulatory
Mechanisms in Animals ???

4. Hormone released from glands,
neurotransmitters released from nerve endings
Mammals well developed – maintain a stable
internal environment with changing conditions
HOMEOSTASIS involves –ve feedback.

5. Maintaining Equilibrium
Communication within an animal
requires mechanisms:
Hormonal
Nervous

6. Negative Feedback
 Nervous & Hormonal system
promoting stability of internal environment
 Stimulus Response Mechanism
the response reduces original stimulus
(–ve effect on stimulus)

7. Negative Feedback

8. Hormones -Slower than nervous responses
Synthesised from fatty acids
Small & lipid-soluble, easily pass thro membranes – nucleus-
act on genes
Steroid hormones – testosterone & oestrogen
Amino Acid Hor Fatty Acid Hor

9. 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 hormones
Amino Acid Hor Fatty Acid Hor

10. Endocrine glands release hormones directly
into the circulatory system

11. Pituitary Gland
Central role in overall endocrine regulation
Growth, lactation, reproductive state, skin
pigmentation, fat tissue, kidney function & activity of
thyroid and adrenal glands

12. 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

14. Thyroxin Hormone
Stimulates metabolic rate of cells
Involved in physical development

15. 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

16. Hormones Video
Endocrine System
Please go to dnatube.com - excellent video resource
Endocrine - Mr Anderson

17. 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

18. Nervous Systems – Evolution
Note development of a bundle of nerves at the
front of the animal

19. 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)

20. Knee-Jerk Response
Stretch Receptor
Effector Muscle

21. Receptors in Skin
Withdrawal Reflex
Spinal cord

22. Nervous Response
Environmental
Disturbance
(eg. hot plate)
Sensory Cells
(skin)
Effector Cells
(muscles)
Neurons
sensory,
interneurone
& motor
Response
(pull hand away)

24. Interneuron
s
 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.

25. Reflexes in Homeostasis
 Baroreceptor-heart rate reflex maintains blood pressure

26. 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

27. Types of Neurons

28. THE STRUCTURE OF NEURONS

29. Synapse

30. Nerve Bundle

31. 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

32. The Nervous System

33. Mammalian Nervous Systems
Central nervous system (CNS) – ‘co-ordinating centre’
Brain
Spinal cord
Peripheral Nervous System – ‘sensing and responding’
Motor (muscular) neurons
Sensory neurons

34. The Central Nervous System

35. Human Nervous System

36. Major Sense Organs
Types 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

37. VisionPhotoreceptor cells contain
Light sensitive pigments
Light with the pigment creates
an electrical signal
in a sensory nerve

38. Colour Blindness Inherited & affects more boys than girls
Lack one or more of the cone cells.

39. The Nervous System Video
The nervous system
The nervous system short video

40. Mind Maps of the Nervous System
The following are nervous system mind maps to help
you – read through the ppt & devise your own mindmap

43. HOPE YOU ENJOYED THE LESSON !
ANY QUESTIONS ???!