NURSE112 Nervous System 2 - Brain PDF

TE PŪNAHA IOIO NURSE112 Emily Grout THE NERVOUS SYSTEM [email protected] THE BRAIN KEY POINTS Identification of some key areas of the brain Identification Structure Function Brain segments Lobes Brain stalk Cerebellum Pr...

TE PŪNAHA IOIO NURSE112 Emily Grout THE NERVOUS SYSTEM [email protected] THE BRAIN KEY POINTS Identification of some key areas of the brain Identification Structure Function Brain segments Lobes Brain stalk Cerebellum Protective elements (meninges, CSF, blood brain barrier) Identification of the blood supply to the brain THE BRAIN Located in the cranial cavity Pinkish/grey and soft 1.3-1.4 kg Wrinkly (high surface area) Requires oxygen and glucose! central (supra-) rostral caudal (sub-) Para-/Peri HEMISPHERES a Separates pueres ~> DECUSSATION OF THE BRAIN HEMISPHERES HEMISPHERIC SPECIALISATION The idea that the left or right hemisphere dominates process specific tasks or behaviours For right handed people, the left hemisphere will be finer-tuned for motor control of the hands You also see sided preference for other activities; kicking, throwing, looking through cameras/microscopes, mouth movements Therefore for right handed people with left hemisphere dominance – a left- hemisphere stroke would result in greater impairment of motor control, speech  fine Motor HOMUNCULUS function & VENTRICLES Large fluid filled cavities in the CNS Each cerebral hemisphere contains a lateral ventricle The diencephalon is connected by the ‘third ventricle’ At the base of the cerebellum lies the ‘fourth ventricle’ and continues into the spinal cord VENTRICLES BRAIN DIVISIONS Diencephalon 1. Cerebrum Cerebrum 2. Diencephalon 3. Brain stem 4. Cerebellum Cerebellum Brain Stem CEREBRUM Largest part of the brain Divided into left and right hemispheres Joined in the middle by the corpus callosum Each hemisphere is formed from four lobes; Frontal (front) Parietal (side) Temporal (tempals) Occipital (back) GREY AND WHITE MATTER The cerebrum contains white and grey matter The grey matter is a thin layer (cerebral cortex) around the outside of the cerebrum Made of cell bodies and interneurons Allows us to do high performance mental tasks (learning, reasoning, language, memory) White matter forms the bulk biologie Made of myelinated axons ~ molecu lipids Lipids of the myelin provide the opacity Form connections through the brain and spinal cord SULCUS AND GYRUS Suculus – groove (depression) in the cerebral cortex Gyrus – ridge (raised portion) of the cerebral cortex BRAIN ANATOMY Doesn't develop till later on ↳ later in males  BRAIN ANATOMY Primary Motor Cortex Primary Sensory Cortex Midbrain Brain Stem Pons Medulla Spinal Cord FRONTAL LOBE Largest lobe of the cerebrum Functions in; Motor Personality Behaviour Emotional expression Intellectual functions Memory storage Contains the most dopamine neurons – reward, attention, short-term memory, planning (high level tasks, decision making), motivation BROCA’S AREA Left hemisphere of the frontal cortex Involved in motor speech When damaged (like in stroke) may result in aphasia Underactivity may result in stuttering PARIETAL LOBE Posterior to the central sulcus Involved in the reception of sensory information Primary somatosensory area Takes information from the skin, muscles, temperature, pain, light touch, proprioception, taste, reading, speech ↳ upright where limbs are stay know e ability to TEMPORAL LOBE Inferior to lateral fissure (above the ear) Primary auditory cortex Receives sensory information from the ears, damage to this lobe may cause cortical deafness Receives sensory information from the nose (olfactory area) Receives sensory information from the taste buds for taste WERNICKE’S AREA Involved in the comprehension of language (written and spoken) and the translation of thoughts into words In the temporal lobe (left hemisphere) Damage can cause fluent aphasia Can speak But sentences have no meaning OCCIPITAL LOBE Posterior of the cerebrum Contains the visual cortex Sensory fibres from the optic nerve send information to the occipital lobe where it can be interpreted as sight Damage to the visual cortex causes cortical blindness DIENCEPHALON (THE HIDDEN PART OF THE BRAIN) Area Postrema Hippocampus Amygdala  DIENCEPHALON (THE HIDDEN PART OF THE BRAIN) Regulates temperature, blood pressure, body weight, sexual drive, childbirth (parental drive), thirst, hunger. Pea sized, secretes melatonin for circadian Hormone secretion rhythm stimulatingParsa Area Postrema when body hormones Hippocampus Low in the brain stem, where blood brain know barrier is leaky. Emetic, reacts to osmotic to Memory throw up dysregulation, chemotoxins, sends signals Amygdala to hypothalamus Emotions THALAMUS Relay centre for sensory fibres from the lower brain to the sensory parts of the cerebrum Receives sensory stimuli from the spinal cord and directs it to the correct region Has nerve fibres that project out in different directions to each region of the cerebral cortex HYPOTHALAMUS body temp regulations BP body weight HYPOTHALAMUS Located below the thalamus Regulates many body processes Synthesises neurohormones Involved in temperature, huger, attachment, fatigue, sleep, circadian rhythms Links the nervous system to the endocrine system PITUITARY GLAND Located below the hypothalamus Controls or affects almost all our hormones in the human body Regulates stress, growth, reproduction, lactation, blood pressure, energy, sex organs, thyroid, metabolism, pregnancy, childbirth, fluid and electrolyte balance, and more! PINEAL GLAND Small endocrine gland in the brain Produces melatonin Involved in sleep, and circadian rhythms Has profuse blood supply, not via the blood brain barrier Receives chemical signal from the retinal ganglion AMYGDALA Located in the temporal lobe Left and right Some research shows L and R process different emotions Left develops earlier than Right Right develops more extensively 5 develop faster Involved in processing memories, in female decision making, emotional responses (fear, anxiety, anger) Part of the limbic system HIPPOCAMPUS Located in the temporal lobe Left and right Part of the limbic system Involved in formation of memory (short term and long term) Damage to the hippocampus may cause anterograde amnesia (inability to form new memories) BRAIN STEM Connects the spinal cord to the other brain structures Encompasses the midbrain, pons, and medulla oblongata MID-BRAIN From lower diencephalon to the pons Relay function Sensory Motor signals Sensory centre for reflex centers PONS From the midbrain to the medulla oblongata Functions like a bridge where information can cross to reach the lower CNS to the relative brain structure Important in respiration (pneumotaxic centre) MEDULLA OBLONGATA Connects the spinal cord to the pons Relays sensory and motor information Controls heart rate, blood pressure, and respiration Sensitive to drugs (like opioids) OD can depress medulla oblongata function Why it’s important to check RR before administration of opioids AREA POSTREMA Vascular section in the medulla oblongata Has permeable capillaries and sensory neurons Detects chemical messengers in the blood and sends them to correct area Detects emetic hormones, thirst, hunger, blood pressure DYSFUNCTION IN THE BRAIN: PRADER-WILLI SYNDROME3 video A deletion on chromosome 15 Resulting in decreased function of the hypothalamus And therefore dysregulation of the hypothalamus Causes insatiable hunger Because of dysregulation to the hypothalamus, signals from the area postrema are not received No emetic effect Patients can and will overeat without feeling sick! Axons from the area postrema are sent to the hypothalamus, but there is no where to go – therefore the emetic effect/desire to stop eating is not received! https://www.youtube.com/watch?app=desktop&v=-kNSEn8rNLc  as mitter CEREBELLUM App neuror Final major structure of the brain Protrudes from under the occipital lobe Connects to the brainstem Receives, and innervates information from the brain and spinal cord Involved in coordination of skeletal muscle, maintaining posture Interpreting sensory input Predictive movements PROTECTION OF THE CNS BONE CNS components are encased by bone Cranium Vertebrae-braininal cord hard mineralised structure withs rand can force MENINGES Connective tissue around the brain and spinal cord Dura mater Epidural space Arachnoid space Subarachnoid space Filled with CSF and contains blood vessels Pia mater Protect the CNS CEREBROSPINAL FLUID Third layer of protection to the cranium Colourless fluid in the tissues around the brain and spinal cord Located in the subarachnoid space of the brain and spinal cord Produced by ependymal cells 500 mL generated every day! Functions as shock absorber, cushioning, buffer, mechanical and immunological protection to the brain Chemically similar to blood plasma with nearly no proteins, and higher Cl-  videa The cilia of the ependymal cells circulates the CSF through the ventricular system of the brain Circulating ~125-150 mL CSF FUNCTION 1. Protection From injury when hit (shock absorption) 2. Homeostasis Distribution of substances between areas of the brain maintain inside environment 3. Removal of waste Metabolic waste diffuses effectively into CSF and is then reabsorbed into the blood stream 4. Prevention of ischemia Balancing intracranial pressure 5. Buoyancy The brain is heavy, but suspending the weight of the brain in CSF takes the pressure off, and stops compaction of the brain weight onto the blood supply and neurons of the lower brain  position CEREBROSPINAL FLUID Metal MENINGITIS Bacterial or viral Inflammation to the meninges te Headache, neck stiffness, confusion, gram nausea, vomiting, lessened ability to tolerate light/noise, possible non- blanching rash Lumbar puncture can diagnose/exclude meningitis we cloudy = - milk BLOOD-BRAIN BARRIER Final layer of protection to the brain An arrangement of cells (particularly astrocytes!) that are selectively permeable Tighter junctions that are more selective about what can pass in and out! WHAT IS BLOCKED BY THE BLOOD-BRAIN BARRIER? Water Some gases (hydrophobic) Lipid soluble substances Glucose? Needs transport Alcohol? yes Immune factors? Some Drugs? Some BRAIN BLOOD SUPPLY 80% supplied by the internal carotid Divides into anterior cerebral artery (ACA) Supplying the medial, frontal, and parietal lobes And Middle cerebral arteries (MCA) Supplying frontal, orbital, parietal, and temporal 20% supplied by the vertebral arteries Divides into the posterior inferior cerebellar artery (PICA) Supplying to the cerebellum and posterior spinal arteries  Yo L CIRCLE OF WILLIS Z Supplies blood to the brain and surrounding structures is If a arterie Still can blocks to load getbstructed the lobe Yr2 KEY POINTS Identification of the lobes, stem, diencephalon, and cerebellum Basic overview of the functions of each brain region Identify some key structural differences in the brain (white vs grey matter) Link how disorder or damage to segments of the brain can result in some particular * symptoms Describe the protective features of the brain Describe how the brain receives blood supply and what may be special about blood supply to the CNS