Biom3200 unit 3.docx

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Nervous System:
Ø Central Nervous system
- Brain and spinal cord.
Ø Peripheral nervous system
- Cranial nerves that arise from the brain.
- Spinal nerves that arise from the spinal cord.
- Connects to the whole body.
Central Nervous system:
- Brain: composed of neurons and support cells.
- Sensory peripheral nervesà Response (Motor neurons response, or brain: emotions, memory, learning and perceptions).
- Axonial Nerve fibres: Connect the brain with the spinal cord.
- Ascending tract: Sensory info from Peripheral to brain
- Descending tract: Motor nerve impulse to the spinal cord.
Brain Development:
· From the embryonic ectodermal neural tube.
· Rostral to Caudal swelling of neural tube: Telencephalon, diecephalon, mesencephalon, metancephalon and myelencephalon.
- Cerebral Spinal Fluid filled chambers.
- CSF made by choroid plexuses (Specialized tissue)
- Lateral ventricles are deep in the cerebral hemispheres and midline to third ventricle at the level of diecephalon.
- Midbrain: ventricle narrows into the Aqueduct (Fouth ventricle communication level of pons, cerebellum and medulla).
- CSF escapes by Foramen into the subarachnoid space.
- Encase the brain and spinal cord by 3 layers
o Dura mater: tough connective tissue
o Arachnoid mater: Delicate membrane.
o Pia mater: Delicate membrane associated with the surface of the brain.
- Subarachnoid space: between arachnoid and pia with CSF.
o Buoyant layer that protects the brain.
- Arachnoid villi: drain the CSF into the venous circulation.
- Large mushroom shaped wrinkled structure found cranially and partially covering the rest of the brain.
- Sulci: Grooves
- Gyri: Elevated folds
- Surface is grey matter with cell bodies
- White matter: myelinated axons that connect the grey matter to areas of the brain.
- Longitudinal Fissure: Deep groove divided into anatomically left and right hemisphere.
- Divided into sections based on the underlying bones.
- Central sulcus: Divides into anterior and posterior parts. Marks the division of the frontal lobe
- Lateral sulcus is a large groove on each side of the brain and delineates the temporal lobe from the frontal and parietal lobes.
- Precentral gyrus- part of the frontal lobe adjacent to the central sulcus. Involved in voluntary muscle movements.
- Postcentral gyrus is involved in somatic sensation
- Temporal lobe contains neurons for senses,
- Occipital lobe is for the visual stimuli.
Basal Nuclei
- Collections of cell bodies in white matter of the cerebrum, needed for proper body movements.
- Upper moto neurons- of the precentral motor cortex send a signal synapse on basal, impulse transferred to different areas of the nuclei, relayed to the thalamus and
cerebellum, to the motor cortex forming a accessory motor system.
o Important in determining rapid movements will occur and how large the movement will be.
Limbic System:
- Located in both the telencephalon and diencephalon including hippocampus, amygdala, septal nuclei and hypothalamus.
- FUNCTION: Processes olfactory sensory information. Critical for emotional drives and forms complex connections with the thalamus and
The Diencephalon: (Thalamus/ hypothalamus)
- Thalamus and Cortex: motor and sensory pathways.
o Thalamus relays sensory information on previous experience.
- Hypothalamus: Master control of lower autonomic functions or bodily functions that are involuntary. Autonomic nervous system and endocrine system.
o Regulation of body temp.
§ Shivering, constriction of blood vessels, sweating.
o Thirst and hunger.
o Emotional and behavior.
- Connects the pons and cerebellum with diencephalon.
- FUNCTION: Visual reflexes, Red nucleus and substantia nigra- motor function.
- Also called the hindbrain.
- Composed of metencephalon superiorly (Pons and cerebellum) and mylencephalon inferiorly (Medulla oblongata).
- Pons is the anterior to the cerebellum.
o Connects the descending pathways from the cerebral cortex to the cerebellar cortex and medulla, and ascending pathways traveling through
the medulla to the thalamus.
- Cerebellum is located posterior: outer cellular cortex layer and white matter.
o Involved in the motor activities. Efferent signals to coordinate movements. Afferent information from voluntary movements from the cerebral
cortex muscles and joints.
o Balance sensory information.
o Coordinating learned complex movements
- Medulla oblongata: conducts for ascending and descending nerve fiber tracts that connect the spinal cord to the rest of the brain.
o Vital center: Autonomic control of the heart and peripheral blood vessels and respiratory rate.
o Reticular formation: Diffuse neuronal network system.
§ Connects various areas of the brain together and processes a great deal of neuronal information.
§ Reticular activity system: ascending tract of the reticular formation determines consciousness. Triggers consciousness when
asleep or alertness when drowsy.
The Spinal Cord:
- Continuation of the medulla caudally as it leaves the skull through a large opening (magnum foramen).
- Protected by Bony vertebral column, the meninges and cerebrospinal fluid.
- Vertebral column: Composed of seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, the sacrum and the coccyx..
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