Paramedic Science: Session 1 - Nervous System & Disability Conditions PDF

Paramedic Science Health & Human Development 2 The Nervous System Your nervous system is your body’s command centre. Originating from your brain, it controls your movements, thoughts and automatic responses to the world around you. It also controls other body systems and processes, suc...

Paramedic Science Health & Human Development 2 The Nervous System Your nervous system is your body’s command centre. Originating from your brain, it controls your movements, thoughts and automatic responses to the world around you. It also controls other body systems and processes, such as digestion, breathing and sexual development (puberty).  The Nervous System The Central Nervous System The Peripheral Nervous System Sensory Function The Brain & Spinal Cord Motor Function (Afferent Nerves) (Efferent Nerves) Somatic Nervous System Autonomic Nervous System Parasympathetic- Response Sympathetic Response The Central Nervous System The meninges are three membranous layers that surround the structures of the central nervous system. They include the dura mater, the arachnoid mater, and the pia mater. Together they cushion the brain and spinal cord with cerebrospinal fluid and support the associated vascular structures. The Central Nervous System Cerebrospinal fluid (CSF) is a clear, colourless, watery fluid that flows in and around your brain and spinal cord. Your brain and spinal cord make up your central nervous system. Cerebrospinal fluid acts like a cushion that helps protect your brain and spinal cord from sudden impact or injury. The fluid also removes waste products from the brain and helps your central nervous system work properly.  The Central Nervous System The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. The Central Nervous System  The Central Nervous System Three Sections of the Brain Cerebrum Cerebellum Brain Stem  The Central Nervous System The Frontal Lobes The frontal lobes are located directly behind the forehead. The frontal lobes are the largest lobes in the human brain and they are also the most common region of injury in traumatic brain injury. The frontal lobes are important for voluntary movement, expressive language and for managing higher level executive functions. Executive functions refer to a collection of cognitive skills including the capacity to plan, organise, initiate, self-monitor and control one’s responses in order to achieve a goal. The frontal lobes are considered our behaviour and emotional control centre and home to our personality. There is no other part of the brain where lesions can cause such a wide variety of symptoms.  The Central Nervous System The Parietal Lobes The parietal lobe is vital for sensory perception and integration, including the management of taste, hearing, sight, touch, and smell. It is home to the brain's primary sensory area, a region where the brain interprets input from other areas of the body. Research suggests that the more sensory input a region of the body provides, the more surface area of the parietal lobe is dedicated to that area. For example, the fingers and hands are a primary site for sensory data, so much of the parietal lobe is dedicated to receiving and processing their input.  The Central Nervous System The Temporal Lobes The temporal lobes sit behind the ears and are the second largest lobe. They are most commonly associated with processing auditory information and with the encoding of memory. The temporal lobes are also believed to play an important role in processing affect/emotions, language, and certain aspects of visual perception. The dominant temporal lobe, which is the left side in most people, is involved in understanding language and learning and remembering verbal information. The non- dominant lobe, which is typically the right temporal lobe, is involved in learning and remembering non-verbal information (e.g. visuo-spatial material and music).  The Central Nervous System The Insular Lobe (Cortex) The insular lobe is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal and frontal lobes). The insulae are believed to be involved in consciousness and play a role in diverse functions usually linked to emotion or the regulation of the body's homeostasis. These functions include compassion, empathy, tast e, perception, motor control, self- awareness, cognitive functioning, interperso nal experience, and awareness of homeostatic emotions such as hunger, pain and fatigue.  The Central Nervous System The Occipital Lobe (Cortex) The occipital lobe is the seat of most of the brain's visual cortex, allowing you to see and process stimuli from the external world and to assign meaning to and remember visual perceptions. Mapping the visual world, which helps with both spatial reasoning and visual memory. Determining colour properties of the items in the visual field. Assessing distance, size, and depth. Identifying visual stimuli, particularly familiar faces and objects. Transmitting visual information to other brain regions so that those brain lobes can encode memories, assign meaning, craft appropriate motor and linguistic responses, and continually respond to information from the surrounding world. Receiving raw visual data from perceptual sensors in the eyes' retina.  The Central Nervous System The Cerebellum The cerebellum is a structure that is located at the back of the brain, underlying the occipital and temporal lobes of the cerebral cortex. Although the cerebellum accounts for approximately 10% of the brain’s volume, it contains over 50% of the total number of neurons in the brain. It is responsible for:  The Central Nervous System The Cerebellum Maintenance of balance and posture. The cerebellum is important for making postural adjustments in order to maintain balance. Through its input from vestibular receptors and proprioceptors, it modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles. Patients with cerebellar damage suffer from balance disorders, and they often develop stereotyped postural strategies to compensate for this problem (e.g., a wide- based stance).  The Central Nervous System The Cerebellum Coordination of voluntary movements. Most movements are composed of a number of different muscle groups acting together in a temporally coordinated fashion. One major function of the cerebellum is to coordinate the timing and force of these different muscle groups to produce fluid limb or body movements.  The Central Nervous System The Cerebellum Motor learning. The cerebellum is important for motor learning. The cerebellum plays a major role in adapting and fine-tuning motor programs to make accurate movements through a trial-and- error process (e.g., learning to hit a baseball).  The Central Nervous System The Cerebellum Cognitive functions. Although the cerebellum is most understood in terms of its contributions to motor control, it is also involved in certain cognitive functions, such as language. Thus, like the basal ganglia, the cerebellum is historically considered as part of the motor system, but its functions extend beyond motor control in ways that are not yet well understood. The Central Nervous System The Brainstem The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum. It is composed of three sections in descending order: the midbrain, pons, and medulla oblongata. It is responsible for many vital functions of life, such as breathing, consciousness, blood pressure, heart rate, and sleep. The Central Nervous System The Midbrain Midbrain, also called mesencephalon, region of the developing vertebrate brain that is composed of the tectum and tegmentum. The midbrain serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing. The Central Nervous System The Pons Your pons is a part of your brainstem, a structure that links your brain to your spinal cord. It handles unconscious processes and jobs, such as your sleep-wake cycle and breathing. It also contains several junction points for nerves that control muscles and carry information from senses in your head and face. The Central Nervous System The Medulla Medulla Oblongata, also called Medulla, the lowest part of the brain and the lowest portion of the brainstem. The medulla oblongata is connected by the pons to the midbrain and is continuous posteriorly with the spinal cord, with which it merges at the opening (foramen magnum) at the base of the skull. The medulla oblongata plays a critical role in transmitting signals between the spinal cord and the higher parts of the brain and in controlling autonomic activities, such as heartbeat and respiration. The Central Nervous System PYRAMIDAL DECUSSATION The point at the junction of the medulla and spinal cord where the motor fibres from the medullary pyramids cross the midline. The fibres then continue into the spinal cord primarily as the corticospinal tract. The Central Nervous System The Cranial Nerves The cranial nerves are a set of 12 paired nerves in the back of your brain. Cranial nerves send electrical signals between your brain, face, neck and torso. Your cranial nerves help you taste, smell, hear and feel sensations. They also help you make facial expressions, blink your eyes and move your tongue.  The Central Nervous System The Cranial Nerves 1.Olfactory nerve: Sense of smell. 2.Optic nerve: Ability to see. 3.Oculomotor nerve: Ability to move and blink your eyes. 4.Trochlear nerve: Ability to move your eyes up and down or back and forth. 5.Trigeminal nerve: Sensations in your face and cheeks, taste and jaw movements. 6.Abducens nerve: Ability to move your eyes. 7.Facial nerve: Facial expressions and sense of taste. 8.Auditory/vestibular nerve: Sense of hearing and balance. 9.Glossopharyngeal nerve: Ability to taste and swallow. 10.Vagus nerve: Digestion and heart rate. 11.Accessory nerve (or spinal accessory nerve): Shoulder and neck muscle movement. 12.Hypoglossal nerve: Ability to move your tongue. The Central Nervous System Spinal Cord The spinal cord is an extension of the central nervous system (CNS), which consists of the brain and spinal cord. The spinal cord begins at the bottom of the brain stem (at the area called the medulla oblongata) and ends in the lower back, as it tapers to form a cone called the conus medullaris. The Central Nervous System The Central Nervous System The Peripheral Nervous System  The Peripheral Nervous System Our body is composed of millions to billions of nerve cells. Some nerve cells can be comparatively smaller by 0.1 millimetres or can be longer by 1 meter. The size of nerve cells is usually based on their functions i.e. how long electrical impulse is transmitted within our body. They are found in the brain, spinal cord and peripheral nerves. For instance, the nerve cell, which transmits the electrical impulse from our brain to the end of the toe finger may be the largest nerve cell. The size of the nerve cell even varies with the type of organism.  The Peripheral Nervous System Functions of a Nerve Cell The nerve cell or neuron acts as the mediator and is the basic signalling unit of the nervous system. The human nervous system is a complex network of neurons specialized to carry messages. The main functions of the nerve cell are: 1.To respond to stimuli 2.To control the metabolic actions 3.Regulation of physiological functions 4.To carry messages from other neurons to the cell body 5.To receive stimuli and send signals to the brain and spinal cord  The Peripheral Nervous System A nerve cell is also known as a neuron. It is mainly involved in receiving and transmitting information to different parts of the body. Nerve cell or Neuron is called the main structural and functional units of the nervous system. The shape and size of the Neuron generally vary, depending upon the location and functions. A group of neurons forms a nerve and the nervous system.  The Peripheral Nervous System Dendrites A branch-like structure that functions by receiving messages from other neurons and allows the transmission of messages to the cell body.  The Peripheral Nervous System Axon It is a tube-like structure, which functions by carrying an electrical impulse from the cell body to the axon terminals and by transmitting the impulse to another neuron.  The Peripheral Nervous System Myelin Sheath It is present in the exterior region of the nerve cell. In neurons, as per the name, the myelin sheath functions as a protective layer of the nerve cell by surrounding the nerve fibres.  The Peripheral Nervous System Nucleus Each neuron or a nerve cell has a cell body with a nucleus and other cell organelles including, the endoplasmic reticulum, Golgi apparatus, mitochondria and other components.  The Peripheral Nervous System Synapse It is also called the nerve ending or nerve junction, which is mainly involved in permitting the entry of a neuron to move electrical signals from one neuron to another neuron.  The Peripheral Nervous System Sensory neurons Neurons, which carry sensory impulses from sensory organs to the central nervous system (CNS) are called sensory neurons. There are about 9 to 10 million sensory nerves in the human body and are found in sense organs – eyes, ears, nose, tongue and skin.  The Peripheral Nervous System Motor neurons Neurons, which carry motor impulses from the central nervous system (CNS) to specific effectors, are called motor neurons. There are about 50 to 60 thousand motor neurons in the human body and are found in glands and muscles.  The Peripheral Nervous System Interneurons Interneurons are the intermediate neurons or the connector neurons of neural circuits. It is an intermediary between the two neurons and functions by passing signals and enabling communication between sensory neurons to the central nervous system and motor neurons to the central nervous system. These neurons are present all over the body, including the spinal cord and brain and are exclusively found in the central nervous system (CNS).  The Sodium Potassium Pump The sodium-potassium pump maintains the resting potential of a neuron. This pump keeps the concentration of sodium outside the cell greater than the concentration inside the cell while keeping the concentration of potassium inside the cell greater than the concentration of potassium outside the cell.  The Nervous System The Central Nervous System The Peripheral Nervous System Sensory Function The Brain & Spinal Cord Motor Function (Afferent Nerves) (Efferent Nerves) Somatic Nervous System Autonomic Nervous System Parasympathetic- Response Sympathetic Response  Afferent Nerves (Sensory) The word ‘afferent’ means “steering or conducting something towards a destination”. The afferent nerves are the messenger neurons that bring the information from different parts of the body to the central nervous system (CNS). In biology, the afferent nerves are defined as the projections of axons that carry the stimulus from the peripheral organs to the central nervous system. The information of the stimulus received by afferent nerves is known as ‘sensory data’. Efferent Nerves (Motor) Efferent neurons, also called motor neurons, are the nerve fibres responsible for carrying signals from the brain to the peripheral nervous system in order to initiate an action.  Reflex ARC A reflex arc is a neural pathway that controls a reflex. In vertebrates, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This allows for faster reflex actions to occur by activating spinal motor neurons without the delay of routing signals through the brain.  Somatic Nervous System The somatic nervous system (SNS), or voluntary nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles. The somatic nervous system consists of sensory nerves carrying afferent nerve fibres, which relay sensation from the body to the central nervous system (CNS), and motor nerves carrying efferent nerve fibres, which relay motor commands from the CNS to stimulate muscle contraction.  Autonomic Nervous System The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is the primary mechanism in control of the fight-or-flight response.  Parasympathetic Nervous System Your parasympathetic nervous system is part of your autonomic nervous system. It could be called your “automatic” nervous system, as it’s responsible for many functions that you don’t have to think about to control. This can include control of your heart rate, blood pressure, digestion, urination and sweating, among other functions. The parasympathetic part of your autonomic nervous system balances your sympathetic nervous system. While your sympathetic nervous system controls your body’s “fight or flight” response, your parasympathetic nervous system helps to control your body’s response during times of rest.  Sympathetic Nervous System Your sympathetic nervous system is part of your autonomic nervous system. It could be called your “automatic” nervous system, as it is responsible for many functions that you don’t have to think about to control. This can include control of your heart rate, blood pressure, digestion, urination and sweating, among other functions. Your sympathetic nervous system is best known for its role in responding to dangerous or stressful situations. In these situations, your sympathetic nervous system activates to speed up your heart rate, deliver more blood to areas of your body that need more oxygen or other responses to help your get out of danger.  Pathophysiology Stroke What is a stroke? A stroke is an emergency condition in which there is a disruption of blood supply to part of the brain, leading to brain injury.  Pathophysiology Stroke Ischemic Stroke Ischaemic strokes are the most common type of stroke. They happen when a blood clot blocks the flow of blood and oxygen to the brain. These blood clots typically form in areas where the arteries have been narrowed or blocked over time by fatty deposits known as plaques. Haemorrhagic Stroke They're caused by a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue. The two types of haemorrhagic strokes are intracerebral (within the brain) haemorrhage or subarachnoid haemorrhage. Pathophysiology  Pathophysiology Stoke or Transient Ischemic Attack What is the difference?  Pathophysiology Transient Ischemic Attacks (TIA) A transient ischaemic attack (TIA) or "mini stroke" is caused by a temporary disruption in the blood supply to part of the brain. The disruption in blood supply results in a lack of oxygen to the brain. This can cause sudden symptoms similar to a stroke, such as speech and visual disturbance, and numbness or weakness in the face, arms and legs. But a TIA does not last as long as a stroke. The effects last a few minutes to a few hours and fully resolve within 24 hours.  Pathophysiology Signs & Symptoms F = Face Drooping – Does one side of the face droop or is it numb? Ask the person to smile. Is the person's smile uneven? A = Arm Weakness – Is one arm weak or numb? Ask the person to raise both arms. Does one arm drift downward? S = Speech Difficulty – Is speech slurred? T = Time to call 999 Numbness or weakness of face, arm, or leg, especially on one side of the body Confusion, trouble speaking or understanding speech Trouble seeing in one or both eyes Trouble walking, dizziness, loss of balance or coordination Severe Headache with no known cause Pathophysiology  Pathophysiology Treatment Follow JRCALC Stroke /Transient Ischaemic Attack Guideline.  Pathophysiology Addison's Disease Addison's disease, also known as primary adrenal insufficiency or hypoadrenalism, is a rare disorder of the adrenal glands. The adrenal glands are 2 small glands that sit on top of the kidneys. They produce 2 essential hormones: cortisol and aldosterone. The adrenal gland is damaged in Addison's disease, so it does not produce enough cortisol or aldosterone. About 9,000 people in the UK have Addison's disease, with over 300 new cases diagnosed each year. It can affect people of any age, although it's most common between the ages of 30 and 50. It's also more common in women than men.  Pathophysiology Signs & Symptoms Early-stage symptoms of Addison's disease are similar to other more common health conditions, such as clinical depression or flu, lack of energy or motivation (fatigue), muscle weakness, low mood, loss of appetite and unintentional weight loss, increased thirst, dizziness, fainting, cramps and exhaustion. Patients may also develop small areas of darkened skin, or darkened lips or gums.  Pathophysiology Adrenal Crisis Adrenal crisis, also termed acute adrenal insufficiency, is a life- threatening endocrine emergency due to a lack of production of the adrenal hormone cortisol. Adrenal crisis can also occur if existing cortisol replacement does not meet the body’s increased need for cortisol due to illness such as fever, persistent vomiting or diarrhoea, or trauma. Equally, sudden cessation of corticosteroid medication for conditions listed above, will risk adrenal crisis in those with adrenal insufficiency.  Pathophysiology Treatment Follow JRCALC Steroid-dependent Patients Guideline  Pathophysiology Diabetes Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high. Blood glucose is your main source of energy and comes from the food you eat. Insulin, a hormone made by the pancreas, helps glucose from food get into your cells to be used for energy. Sometimes your body doesn’t make enough, or any insulin, or doesn’t use insulin well. Glucose then stays in your blood and doesn’t reach your cells.  Pathophysiology Type 1 Diabetes Type 1 diabetes is a serious condition where your blood glucose (sugar) level is too high because your body can’t make a hormone called insulin. This happens because your body attacks the cells in your pancreas that make the insulin, meaning you can’t produce any at all. We all need insulin to live. It does an essential job. It allows the glucose in our blood to enter our cells and fuel our bodies. When you have type 1 diabetes, your body still breaks down the carbohydrate from food and drink and turns it into glucose. But when the glucose enters your bloodstream, there’s no insulin to allow it into your body’s cells. More and more glucose then builds up in your bloodstream, leading to high blood sugar levels.  Pathophysiology Type 2 Diabetes We all need insulin to live. It does an essential job. It allows the glucose in our blood to enter our cells and fuel our bodies. When you have type 2 diabetes, your body still breaks down carbohydrate from your food and drink and turns it into glucose. The pancreas then responds to this by releasing insulin. But because this insulin can’t work properly, your blood sugar levels keep rising. This means more insulin is released. For some people with type 2 diabetes this can eventually tire the pancreas out, meaning their body makes less and less insulin. This can lead to even higher blood sugar levels and mean you are at risk of hyperglycaemia.  Pathophysiology Gestational Diabetes Gestational diabetes is diabetes that can develop during pregnancy. It affects women who haven't been affected by diabetes before. It means the patient will have high blood sugar and will need to take extra care of themselves and the baby. This will include eating well and keeping active. It usually goes away again after giving birth. It is usually diagnosed from a blood test 24 to 28 weeks into pregnancy.  Pathophysiology Diabetic Ketocidosis (DKA) Diabetic ketoacidosis (DKA) is a serious complication of diabetes that can be life-threatening. DKA is most common among people with type 1 diabetes. People with type 2 diabetes can also develop DKA. DKA develops when your body doesn’t have enough insulin to allow blood sugar into your cells for use as energy. Instead, your liver breaks down fat for fuel, a process that produces acids called ketones. When too many ketones are produced too fast, they can build up to dangerous levels in your body.  Pathophysiology Hyperosmolar Hyperglycaemia Hyperosmolar hyperglycaemic state is a metabolic complication of diabetes mellitus characterized by severe hyperglycaemia, extreme dehydration, hyperosmolar plasma, and altered consciousness. It most often occurs in type 2 diabetes, often in the setting of physiologic stress. Hyperosmolar hyperglycaemic state is diagnosed by severe hyperglycaemia and plasma hyperosmolality and absence of significant ketosis. Treatment is IV saline solution and insulin. Complications include coma, seizures, and death.  Pathophysiology Hyperglycaemia Hyperglycaemia is the term used to describe high blood glucose levels. Symptoms include unusual thirst (polydipsia), urinary frequency (polyuria) and tiredness. They are usually of slower onset in comparison to those of hypoglycaemia but can develop relatively quickly (days to weeks) in those with newly presenting Type 1 diabetes. If patients have typical osmotic symptoms such as excessive thirst, polyuria, tiredness, weight loss, thrush or recurrent infections, with capillary glucose >=11.1 mmol/l, that is diagnostic of diabetes.  Pathophysiology Hyperglycaemia Treatment Follow JRCALC Glycaemic Emergencies in Adults and Children  Pathophysiology Hypoglycaemia In the patient with diabetes, the definition of hypoglycaemia is a blood glucose of