Biomedicine NERVOUS SYSTEM Part II Copyright CNM – College of Naturopathic Medicine 1 Regeneration and repair of Nervous tissue • Plasticity: The ability for the NS to change based on experience – Sprouting new dendrites, changes in synaptic contacts • But… Neurons have limited powers of regeneration • In the PNS - If the Schwann cell and cell body are intact, and scarring doesn’t happen too quickly, regeneration may occur. • In the CNS, cut axons do not regenerate 2 CNS Brain & Spinal cord 3 Protective Covering of the Brain & Spinal cord SPINAL CORD • Protected by the Vertebral Column BRAIN • Protected by the Cranium, • Cranial Meninges • Cerebro-Spinal fluid (CSF) • Blood Brain Barrier 4 MENINGES 3 layers of CT that cover the brain and spinal cord 1. Dura mater (tough mother) - The dura mater in the brain has two layers that create some venous sinuses that allow blood to drain out of the brain into the jugular veins. Subdural Space = Interstitial Fluid 2. Arachnoid mater (similar to spider) - Collagen and elastic fibres Subdural space between arachnoid mater (2) and Dura mater (1) filled with interstitial fluid. Sub-arachnoid Space = Cerbro Spinal Fluid 3. Pia mater (delicate) - Contains blood vessels that supply the spinal cord. Between the Pia mater and Arachnoid mater is the sub- arachnoid space filled with CSF 5 Arrangement of the Meninges/ Membranes covering the Brain & Spinal cord 1. Skull 2. Dura mater Subdural space filled with Interstitial Fluid 3. Arachnoid mater Sub-arachnoid space filled with CSF 4. Pia mater 5. Artery 6. Brain 7. Cerebrospinal fluid 6 Cerebrospinal Fluid - CSF Clear liquid that protects the brain & spinal cord from trauma and chemical injuries. • CSF is made from filtered blood & is mostly water with ions & glucose. • Blood cells are too large to filter through the blood vessels, so CSF is transparent and colourless. • The CSF occupies the Subarachnoid Space & the Ventricles (Irregular shaped cavities) in the Brain, as well as the Central Canal of the Spinal Cord. • CSF is secreted continuously and produced at a rate of 500 ml/day. • Since the brain can only contain about135 - 150 ml, large amounts are gradually absorbed back into the blood after circulating around the brain and spinal cord. 7 http://www.riverarunsthroughit.com/2012/08/from-60-to-16.html CSF • Functions of CSF 1. Supports & Protects the Brain & Spinal Cord = ‘Shock absorber’ 2. Maintains Uniform Pressure round the brain- In case of brain enlargement compensation occurs by reduction of CSF 3. Keeps brain and spinal cord moist 4. Circulates nutrients and waste 8 BLOOD BRAIN BARRIER • Blood flows to the brain from the vertebral and carotid arteries • Brain uses 20% of all oxygen and glucose in the body at rest • Lack of supply for 4 mins will cause injury! • The BBB protects the brain from toxins, harmful substances and bacteria that enter the bloodstream, by maintaining tightness of the capillaries and the junctions between cells. •The BBB is maintained by Astrocytes 9 TRANSPORT across Blood Brain Barrier • Lipid soluble substances cross easily eg. Alcohol, Anaesthetics • Glucose crosses by Active transport • Gasses diffuse easily eg. oxygen, carbon dioxide. • Other ions etc diffuse slowly across • Proteins and some drugs do not pass at all across the barrier 10 THE BRAIN 1. BRAIN STEM: (Continuous with the spinal cord) Midbrain, Pons, Medulla oblongata 2. DIENCEPHALON: Thalamus, Hypothalamus, Epithalamus 3. CEREBELLUM: (Little Brain) 4. CEREBRUM 11 12 BRAIN STEM 1. MEDULLA OBLONGATA: Controls vital body functions, contains Respiratory and Cardiac Centres, controls Reflexes such as Vomiting, Sneezing & Hiccupping. Contains 5 cranial nerves. 2. PONS: Helps to control Breathing, four pairs of cranial nerves 3. MIDBRAIN: Eye reflexes and tracking, Subconscious muscle activities, Auditory Tracts, movement of head and neck Orientation in space 13 DIENCEPHALON 1. THALAMUS - Relay Centre – relays sensory info. to the cerebrum, regulates Autonomic activities & Consciousness 2. HYPOTHALAMUS - Sense of smell, Hormone regulation and Homeostasis, sensory info, control of the ANS, regulation of Emotional and Behavioural patterns, regulation of Eating and Drinking, control of Body Temp, regulation of Circadian Rhythms 3. EPITHALAMUS - Contains the Pineal Gland which secretes melatonin, olfactory sensation 14 CEREBELLUM Functions: 1. Tracks Motor functions 2. Co-ordinates movements 3. Posture and Balance 4. Cognition (the process of thought) 5. Language Processing 6. Processing of Sensory information 15 CEREBRUM Two Hemispheres • Superficial Part: Grey Matter = Cerebral cortex • Multiple foldings or furrows • Deeper Layer: White matter 16 CEREBRUM Functions: • Sensory Perception • Motor Control of Skeletal Muscles (Movement) • Cognition • Speech 17 Why the each side of the Brain co-ordinate the OPPOSITE side of the Body? In the internal capsule: • Motor fibres form pyramidal tracts • Cross over at the Medulla Oblongata (Decussating) • This means the left side of the Brain co- ordinates the right side of the Brain & Right side of brain co-ordinates Left side of the body 18 Functional Areas of the Cerebrum Scientists revealed these different Functional Areas by researching/ Studying The Effects of injuries eg. Broca’s Area and through Electric Stimulation 19 • In the Motor and Sensory areas of the brain, the body is represented according to the importance of the parts Motor representation Sensory representation 20 Blood Supply to the Brain • Constant supply of oxygen and glucose is necessary • Brain receives about 15% of cardiac output (about 750 ml per minute) 21 CRANIAL NERVES • The brain also contains 12 pairs of cranial nerves each responsible for specific functions in the body: i. Olfactory nerve– Sense of Smell ii. Optic nerve – Vision iii. Oculomotor – Eye movements, eyelid opening, proprioception, Pupil size iv. Trochlear – Eye movements, proprioception v. Trigeminal – Facial sensations, chewing vi. Abducens – Eye movements and proprioception 22 CRANIAL NERVES Cont’d vii. Facial – Taste, facial expressions viii. Vestibulocochlear / Auditory– Hearing, balance ix. Glossopharyngeal – Taste, swallowing, tongue sensations x. Vagus – Swallowing, taste, senses from epiglottis, monitoring BP and CO2 and O2, sensations from abdomen and viscera xi. Accessory / Spinal – Neck and shoulder muscles movt, swallowing xii. Hypoglossal – Tongue movement and speech 23 24 Worksheet • Please complete the exercise in your handout using the information in the slides 25 CSF & MENINGEAL PATHOLOGIES http://health-7.com/Atlas%20of%20Pediatric%20Physical%20Diagnosis/Signs%20%26amp%3B%20Symptoms/4 26 Increased Intracranial Pressure ↑ICP Cerebral Oedema or Inflammation Cause: • Haemorrhage • Hypoglycaemia • Hypoxia • Infections, abscesses • Inflammation of the brain or meninges • Infarcts • Tumours • Traumatic injury 27 ICP Signs & Sx: • Pupil fixed +/ dilated, Impaired Eye movement • Impaired Motor Function Abnormal Posture • Changes in Speech • Changes in Vital Signs: ↑ Systolic Blood Pressure ↓Pulse Irregular Respiratory Pattern • Vomiting/Nausea • Headache • Changes in behaviour • Progressively ↓ consciousness • Lethargy • Seizures = Abnormal neuron activity in the brain 28 ICP Rx: • Critical condition !!! • Intensive care • Frequently measured neurological and Vital signs Complication: • Permanent neurological problems • Seizures • Death 29 HYDROCEPHALUS An abnormal accumulation of cerebrospinal fluid (CSF) in the ventricles or other cavities of the brain caused by blocked circulation or absorption of CSF. Causes: • Small Children: Infection often before birth. • Older Children and adults: Tumours, Trauma etc. • Possible in Older People: Circulation problems 30 HYDROCEPHALUS • May lead to ↑ ICP inside the skull and progressive enlargement of the head, convulsion & mental disability. • Hydrocephalus can also cause death!! Rx: • Shunt / Ventricular Catheter/ Tube • Lumbar Puncture 31 MENINGITIS Def: Infection or inflammation of the membranes covering the brain and spinal cord Cause: • Mostly Bacterial Infection (usually Haemophilus influenzae & Streptococcus pneumoniae) • Also viral infection (less severe) eg. Herpes Simplex virus • May also be fungal or parasitic microorganisms 32 MENINGITIS S: • Can be Life threatening when it leads to Increased ICP!!! So the condition is classified as a MEDICAL EMERGENCY!!! • Petechiae: Small purple / red spots on the skin as a result of tiny haemorrhages. The spots are Non-blanching i.e. the redness does not disappear when pressed with a finger or a glass tumbler. • Sudden onset of severe headache, photophobia, stiff neck, vomiting, • Kernig's sign - Resistance to leg extension when lying with the hips flexed, • Brudzinski sign (neck flexion causes flexion of hip and knee) 33 MENINGITIS Diagnosis: • Lumbar Puncture (Withdraw CSF from Spinal Canal, region L4-L5 ) Rx: Antibiotics, Antivirals & Corticosteroids Complication: Brain /Nerve Damage DIAGNOSTIC: Collect CSF for analysis e.g to detect meningitis THERAPEUTIC: To reduce ICP 34 BRAIN PATHOLOGY 35 HEAD INJURIES Symptoms: Vary (Mild to Severe) • Unconsciousness • Amnesia • Headaches • Seizures • Leaking CSF or blood from ear or nose • Fever Rx: • Always 999, A&E !! • Arnica 200C in addition to calling Emergency Services 36 Head Injuries: CONCUSSION • Reversible head injury which usually results from a significant BLOW to the head causing a sudden movement of the Brain & disrupting Neurological Function • Symptoms: Vary (Mild to Severe): –Loss of consciousness –Memory