Planet Earth and Its Environment A 5000-million year Journey

Biology in Focus, HSC CourseGlenda Childrawi, Margaret Robson and Stephanie Hollis

CommunicationTopic 15: The Mammalian Brain1DOT Point(s) identify those areas of the cerebrum involved in the perception and interpretation of light and soundperform a first-hand investigation to examine an appropriate mammalian brain or model of a human brain to gather information to distinguish the cerebrum, cerebellum and medulla oblongata and locate the regions involved in speech, sight and sound perceptionIntroduction The brains of humans appear to be out of proportion compared with overall body size. This is due to the great entanglement of the cerebrum. The cerebrum splits into two hemispheres, a left and a right. Each hemisphere receives impulses from and exerts control over the opposite side of the body.otroblogpelotudo.blogspot.com

The CerebrumThe hemispheres are divided into four lobes:FrontalOccipitalParietalTemporal

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CerebellumThe CerebrumUnder a tough protective covering (dura matter), the surface of the cerebrum is drawn up into folds called convolutions. This triples the surface area of the brain where important processes occur. www.allposters.com -

The CerebrumMost of the activities of the cerebrum occur on its outer surface, in a layer of grey matter (cerebral cortex) only a few millimetres thick. Those activities fit three general categories:Motor (movement)Sensory (senses)Associative (higher mental activities such as reasoning and logic. This takes up about 95% of the cerebral cortex)

best-diving.org The CerebrumThe greater the surface area of the cerebrum the greater the ability to perform functions.

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LightOptic nerves are the sensory nerves of vision. Fibres arise from the retina of the eye to form the optic nerve. Each optic nerve passes through the skull via an opening in the eye socket. The optic nerves from each eye cross over partly to form the optic chiasma (cross).

medical-dictionary.thefreedictionary.com LightAbout half of the nerves cross to the other side, providing each visual cortex with the same image as viewed by both eyes but each eye received the image at a slightly different angle.

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LightA visual cortex lies within the occipital lobe of each cerebral hemisphere. Impulses reach this lobe from the retina via the optic nerve. Different sites on the visual cortex process information from different positions on the retina.

drugline.orgSoundAuditory nerves arise from the hearing (cochlea) and equilibrium (vestibule) within the inner ear. The two divisions merge to form one nerve now known as the vestibulochochlear nerve. This nerve runs from the organ of Corti to the auditory cortex, in the temporal lobe of the brain.

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SoundAn auditory cortex is found on the temporal lobe of each cerebral hemisphere. Different sites on this cortex receive and interpret different sound frequencies.

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PRAC-Sheep Brain Dissection