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Nervous System and Sense Organs
- functions in obtaining information from the environment & coordinating body
- information is transferred byelectrical signals, and is rapid and specific.activities
- the basic units are neurons, whichinclude three types: sensory (receptor),motor (effector) and interneurons
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The vertebrate nervous system has two major components
- central nervous system (info. processing)
- peripheral nervous system (cranial and spinal nerves), including motor (ventral) and sensory nerves (dorsal)
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The peripheral nervous system in turn includes two parts:
- a) the somatic system (bodywall & appendages)
- b) the visceral or autonomic system, including two parts
- i) the sympathetic system (“fightor flight”)
- ii) the parasympatheticsystem
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The brain includes five basic sections
- (i) telencephalon
- (ii) diencephalon
- (iii) mesencephalon
- (iv) metencephalon
- (v) myelencephalon
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(i) telencephalon
- olfactory lobes
- bulbs (olfaction)
- cerebrum (voluntary movement)
- corpus striatum (instinctive behaviour)
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(ii) diencephalon
- thalamus (sensory relay)
- hypothalamus (visceral integration)
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(iii) mesencephalon
optic lobes or tectum(vision and visual reflexes)
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(iv) metencephalon
- cerebellum(hearing/balance/orientation and motor coordination)
- pons (co-ordination of cerebrum and cerebellum)
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(v) myelencephalon
medulla oblongata(reflex centers for basic functions)
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receptors
The nervous systems alsoincludes receptors for taste, smell, touch, etc
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multicellular sense organs
- photoreception, including colour and UV
- vision from the beginning, included: cornea, lens, iris, and retina
- detection of orientation, motion and infrasound vibrations (inner ear semi circular canals, utricle, saccule)
- via hair cells - cells with special cilia that detect motion in the extracellular fluid
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The Endocrine System
- functions in communication and coordination
- information transfer is slow & general, through chemicalsignals (hormones [internal] and pheromones [external]
- includes endocrine (no ducts) and exocrine glands (ducts)
- originally included only the pituitary ("master gland"),pineal (coordinates daily and seasonal rhythms) and thyroid (controls metabolism and homeostasis), plus scattered specialized cells
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