Unit 3C/DAnswers

1) The cerebral hemispheres function differently:

Left Hemisphere (in most) / Right Hemisphere (in most)
Right hand control (body) / Left hand control (body)
Language / Music & Art
Numeric & Scientific skill / Space & Pattern Perception
Reasoning / Insight
Comparing

2) The White Matter of the Cerebrum containsAssociation fibers found between gyri in the same hemisphere, they do not exist in the cerebral hemisphere, while Commissuralfibers found in the corpus callosumconnect the right and left hemispheres, and finally the Projection fibers connect the cerebrum to the rest of the brain and spinal cord.3C 8

3) The Cerebral Nuclei or Basal Gangliaare composed of gray matter deep inside the cerebrum. Interneurons provide connection of the cerebral cortex with the brainstem, the thalamus and the hypothalamus. Its functions are to influence muscular activity, regulate attention and cognition, also regulate the intensity of slow or stereotyped movements and inhibit antagonistic and unnecessary movements. 3C 8-9

4) The Diencephalon is made up of the Thalamus, Hypothalamus and the Epithalamus. 3C 9

5)The thalamus gland is the relay station for sensory input, except for smell, to the cerebrum. Its role is in mediating sensation, motoractivities,cortical arousal, learning, and memory. It has four groups of nuclei on each side:anterior, ventral, dorsal,and posterior.3C 9

6)The Hypothalamus senses sound, taste, smell,and somatic sensations. It monitors the body providing homeostasis and connects the nervous system to the endocrine system and controls it.

7) The epithalamusregion is located on the roof of the third ventricle. The pineal gland is found here and is part of the endocrine system and it secretes the hormone melatonin. The choriod plexusalso forms CSF from the blood. 3C 9

8) The midbrain contains cerebral peduncles which are located on the ventral side and are composed of white matter. This containsmotor fibers from the cerebral cortex that go to the pons and the spinal cord and also sensory fibers from the spinal cord to the thalamus for sorting.

The tectum is located on the dorsal side and contains reflex centers that receive visual input and cause head and neck movement and receive auditory input that causes head and trunk movement.

9) The midbrain also contains the cell bodiesfor cranial nerves such as Oculomotor III,Trochlear, andAbducens VI nerve. 3C 10

10) The pons connects the medulla oblongata, and the spinal cord to the brain, it is in control of respiration with the medullary respiratory center. Nuclei for cranial nerves within the pons are the Trigeminal V, the Adbucens VI, the Facial VII,theVestibulocochlear VIII. 3C10

11) In the Autonomic Nervous System (ANS) motor neurons innervate the viscera of smooth and cardiac muscle and also glands, as it regulates the viscera to ensure homeostasis during body activities. It is very hard to override the ANS voluntarily as it operates subconsciously.

12) The Autonomic Nervous System (ANS) has two branches, the Sympathetic and the Parasympathetic. The Sympathetic NS which is referred to as the Fight or Flight response called for during exercise, excitement, emergencies, and embarrassment. It works with the Somatic Nervous System (SNS) to provide oxygen and fuel to the skeletal muscles. While the Parasympathetic NS is referred to as the rest and digest, which conserves energy during relaxation, mostly controlling digestion, defecation, and diuresis. 3D1