Nervous System Part 3 PDF

Nervous System Part 3 Central Nervous System & Peripheral Nervous System Tutor Debbie Hemington Module BMS GDC Learning outcomes As for parts 1 & 2 Intended learning outcomes At the end of the session, you will be able to: Describe the 2 parts of the nervous system List the ke...

Nervous System Part 3 Central Nervous System & Peripheral Nervous System Tutor Debbie Hemington Module BMS GDC Learning outcomes As for parts 1 & 2 Intended learning outcomes At the end of the session, you will be able to: Describe the 2 parts of the nervous system List the key features of the human brain and spinal cord Describe the main areas of the brain and their function List the functions of cerebrospinal fluid List the groups of spinal nerves Assessment Formative Summative Short answers End of module exams MCQ The central nervous system Brain Weighs around 1.4kg Lies in cranial cavity Comprises of: Cerebrum Thalamus Hypothalamus Mid brain Pons Medulla oblongata Cerebellum Cerebrum Largest part of the brain 3 main functional areas associated with; Mental Activities-memory, intelligence, problem solving, reflection, judgement, thinking, reasoning, initiative, inhibition, moral sense of responsibility and learning Sensory perception-perception of pain, temperature and touch Initiation and control of voluntary muscle contraction The Cerebrum The cerebral cortex is highly wrinkled, which makes the brain more efficient, because it can increase the surface area of the brain and the amount of neurons within it. A deep furrow divides the cerebrum into two halves, known as the left and right hemispheres. The corpus callosum is a bundle of axons which connects these two hemispheres. Thalamus Small structure Sensory receptors in skin & viscera send info about touch, pain & temperature Input from the special sense organs travels here too where there is perception but only in basic form Thought to be involved in arousal and the processing of some emotions and complex reflexes Hypothalamus Situated within the cerebrum Attached to the pituitary gland Controls the output of hormones Controls effectors of the autonomic nervous system: Emotional reactions Hunger and thirst Body temperature Biological clocks Mid brain Consists of nuclei and nerve fibres which connect the cerebrum with the lower parts of the brain and spinal cord. Nuclei act as relay stations for the ascending and descending nerve fibres and have important roles in auditory and visual reflexes. Pons Contains nerve fibres, which form a bridge between the two hemispheres of the cerebrum Processes info from several of the cranial nerves Medulla Oblongata Is continuous with the spinal cord Controls effectors: cardiovascular centre respiratory centre reflex centres: coughing, vomiting, sneezing, swallowing Spinal Cord Nerves conveying impulses from the brain to various organs and tissues descend through it. Starts in the medulla oblongata and descends through the spinal column. Spinal cord Elongated, almost cylindrical part of the CNS. Suspended in the vertebral canal Surrounded by meninges & cerebro-spinal fluid Approx the thickness of a little finger Approx 45cms long Cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear colourless fluid that: occupies the subarachnoid space in the brain acts as a "cushion" or buffer for the cortex is renewed 4 times daily contains proteins, glucose and lymphocytes Functions of Cerebrospinal Fluid Protection Buoyancy Excretion of waste products Endocrine medium for the brain. Protection The CSF protects the brain by ‘buffering’ the brain. This lessens the impact when there is a blow to the head. Image sourced April 2021 Dreamstime.com Buoyancy Because the brain is immersed in fluid, the net weight of the brain is reduced from about 1400g to about 50g, thus reducing the pressure at the base of the brain. Image sourced April 2021 Q Files Excretion of waste products The one-way flow from the CSF to the blood takes potentially harmful metabolites, drugs and other substances away from the brain Image sourced April 2021 Depositphotos Endocrine medium for the brain The CSF serves to transport hormones to certain areas of the brain. Hormones released into the CSF can be carried to remote sites of the brain where they may act. Image sourced April 2021 SubPNG The Peripheral Nervous System Peripheral Nervous System Image sourced April 2021 Biology Libre Texts. Autonomic Nervous System The sympathetic nervous system activates the “fight or flight” response during a threat or perceived danger Needed for short term survival The parasympathetic nervous system restores the body to a state of calm, the “rest and digest” phase Needed for long term survival. Cranial Nerves Spinal Nerves Intervertebral Foramina Peripheral Nerves Useful links Autonomic Nervous System: Sympathetic vs Parasympathetic, Animation – YouTube 2-Minute Neuroscience: Divisions of the Nervous System – YouTube Thank you