Nervous System - Stress and Limbic PDF

TE PŪNAHA IOIO NURSE112 Emily Grout [email protected] THE NERVOUS SYSTEM KEY POINTS Understanding of the somatic vs autonomic nervous system Understand, describe, and differentiate the sympathetic nervous system and parasympatheti...

TE PŪNAHA IOIO NURSE112 Emily Grout [email protected] THE NERVOUS SYSTEM KEY POINTS Understanding of the somatic vs autonomic nervous system Understand, describe, and differentiate the sympathetic nervous system and parasympathetic nervous system Identify and describe the roles of common neurotransmitters; acetylcholine and noradrenaline Identify and describe the function of adrenergic and choleric fibres and receptors Identify key structures and processes involved with perceived stressors, and the stress response Contavoura , as WHAT IS THE SOMATIC NS? Part of the PNS Involved in voluntary control via skeletal muscle Contains sensory nerves Afferent nerve fibres to brain > - Motor nerves finger Efferent nerve fibres ↳ brain to finger  No control WHAT IS THE AUTONOMIC NS? - ↳ automatic Part of the PNS Involved nervous supply to the smooth muscles, glands, and internal organs Unconsciously regulates survival processes; heart rate, digestion, respiration Responsible for control over the fight-or-flight response or rest-and- digest response VISCERAL REFLEX Activation of receptor, transmission of sensory information, travels to the CNS for processing, CNS sends motor reflex for response Baroreceptors in the blood vessels A drop on blood pressure activates baroreceptors, sending a message to the medulla oblongata, medulla oblongata sends motor signals to the heart and blood vessels (visceral effector organs) which elevate blood pressure Continuously unconscious ↳ never thought any pupil dialation eg - DIVISIONS OF THE ANS Divided into; Sympathetic nervous system (SNS) Fight-or-flight division Parasympathetic nervous system (PNS) Rest and digest/repair division An organ will receive nerve fibres from both the SNS and PNS (dual innervation) But they may have opposing effects SNS stimulation of the heart results in increased heart rate PNS stimulation of the heart results in decreased heart rate SYMPATHETIC NERVOUS SYSTEM Activated during stress or threat Helps you to be prepared for confrontation (fight) Or to leave a threatening situation (flight) WHAT PHYSIOLOGICAL CHANGES HAVE YOU EXPERIENCED DURING A PERIOD OF FRIGHT? Increased heart rate and intensity adrenaline Heart pounding! * HR SOB , rush Increased pupil dilation , pounding) Cheartrate and depth of respiration mouth (hands) dry Increased respiration Increased perspiration to the palm , Sweating Decreased salivary output dialation 4 pupil Shaky , 4RR , SNS RESPONSES ARE SHORT-LIVED Normally the SNS responses are short- lived However if you maintain a constant state of stress your SNS may stay in high alert Resulting in stress-induced illnesses PARASYMPATHETIC NERVOUS SYSTEM Activated during quiet, non-stressful times Calming effects on the body Important in digestive and reproductive functions Rest and digest Rest and repair Feed and breed  Don't mem SNS & PNS INNERVATION IN THE BODY Organ SNS PNS Heart Increase rate/strength of contraction Decreases rate Bronchi Dilates Constricts Iris Dilates Constricts Blood vessels Constricts - Sweat glands Stimulates - Intestines Inhibit motility and secretion Stimulates motility and secretion Uterus Relaxes muscle - Adrenal medulla Stimulates secretion of nor/adrenaline - Salivary glands Stimulates thick secretions Stimulates watery secretions Urinary system – bladder wall Relaxes muscle Contracts muscle Urinary system – internal sphincter Closes sphincter Opens sphincter PARADOXICAL FEAR When a situation is too intense for a SNS reaction you may have a massive PNS response What might paradoxical fear look like? bradycardia yourself Loss of control over urinary and digestive/defecation function Piss Severe decrease in heart rate Bradycardia Fainting freezing dyingolight fainting , Dying of fright Severed HR ARRANGEMENT OF THE ANS Neuron to neuron with an intermediatory ganglion Ganglion are clusters of neuron cell bodies The first neuron (pre-ganglionic) will be present in the CNS, extending to the ganglion which forms the bulk and length, synapsing to the second neuron (post- ganglionic) which innervates the organ These post-ganglionic fibres secrete neurotransmitters that affect the organs/systems NEURONS OF THE SNS Leave the CNS at T1 – L2 = Vertebrae Short pre-ganglionic nerve fibre Long distance to innervating target organ Generalised more systemic response Key neurontransmitter; noradrenaline NEURONS OF THE PNS Leave the CNS at the brain or sacrum (S2 - S4) Long pre-ganglionic nerve fibre Short post-ganglionic fibres running to the smooth muscle/organ eing innervated More localised response due to proximity finaon Uses four cranial nerves ~ muscle Key neurotransmitter; acetylcholine and nitric oxide Crest) (stress) in Not test - NEURONS OF THE PNS – OCULOMOTOR (CN III) CN III innervates the eye mucles that move the eyeball (Voluntary, skeletal, Somatic) Also carries PNS fibres to two dialate intrinsic eye muscles Driving pupillary constriction and changing the shape of the eye lense Constrict NEURONS OF THE PNS – FACIAL (CN VII) Carries PNS fibres to the tear glands, salivary glands, and nasal glands Vasodilate and increases sensation to the lacrimal and salivary gland NEURONS OF THE PNS – GLOSSOPHARYNGEAL (CN IX) Carries PNS fibres to the salivary glands Vasodilate and increases sensation to salivary gland NEURONS OF THE PNS – VAGUS (CN X) Carries ~80% of PNS fibres From the brainstem to organs in massive the thoracic/abdominal cavities Innervates a lot NEUROTRANSMITTERS OF THE AUTONOMIC NS Primarily driven by acetylcholine and noradrenaline Neurotransmitter can be seen in the name of some of the nerve fibres Adrenergic fibre will secrete noradrenaline Cholinergic fibre will secrete acetylcholine All pre-ganglionic fibres are cholinergic Post-ganglionic SNS fibres are adrenergic TERMINATION OF NEUROTRANSMITTERS If neurotransmitters are being synthesised and secreted constantly, what stops it circulating and stimulating a number of receptors? Acetylcholinesterase (AChE) is located at the synapse Quickly degrades ACh - Noradrenaline is secreted by adrenergic fibres Noradrenaline is reabsorbed at the adrenergic nerve terminals (re-uptake) and reused usedintreat is in - Noradrenaline persists longer, so the SNS effects are prolonged Noradrenaline can be degraded by Monoamine oxidase (MOA) at the terminal Some may be degraded by catechol-O-methyl-transferase (COMT) if it diffuses away from the 3 synapse RECEPTORS OF THE AUTONOMIC NS Acetylcholine and noradrenaline bind to receptors in a number of cells; cardiac, skeletal muscle, smooth muscle, glands Called; Cholinergic receptors needspeci f e i ar binding If they bind and are activated by acetylcholine Muscarinic and nicotinic ↳ locks key Adrenergic receptors If they bind and are activated by noradrenaline Some systems will have receptors for both MUSCARINIC RECEPTORS Activated by acetylcholine Muscarinic (M) receptors Located on effectors/targets of parasympathetic nerves Activation of PNS releases acetylcholine, stimulating muscarinic receptors Affects; pupil constriction, activation of the SA node, contraction of bladder muscle and release of bladder sphincter NICOTINIC RECEPTORS Activated by acetylcholine Nicotinic neural (NN) receptors are in the ganglia of the ANS, in the sympathetic and parasympathetic NS Nicotinic muscle (NM) receptors are located outside the ANS and are part of the somatic NS, involved in skeletal muscle ALPHA-ADRENERGIC & BETA-ADRENERGIC RECEPTORS Located on target organs of the sympathetic nervous system Stimulated by noradrenaline and other catecholamine Four types; α1 α2 β1 β2 appear α1 receptors are involved with dilation of the blockers pupils, and constriction of blood vessels Beta β1 receptors increase heart rate and strength of heart contractions β2 receptors dilate the bronchi, and relax the uterus  Don't mem WHY IS UNDERSTANDING RECEPTORS IMPORTANT? Provides better pharmacological understanding β2 agonist → mimics catecholamine in the receptor → preventing smooth muscle contraction & on work > heart when fast , hard contractions Ventolin  Joy fear sadness disgust anger Sarah Pippa Kera ! THE LIMBIC SYSTEM WHAT IS THE LIMBIC SYSTEM? brain mid in deep Brain structures around the thalamus Shaped like a wishbone/horseshoe Functions in emotional states and behaviour Boarders the cerebral cortex and diencephalon STRUCTURES OF THE LIMBIC SYSTEM Amygdala Fornix Fear/anxious Hippocampus Memory Parahippocampal gyrus Memory Cingulate cortex Emotion and memory Septal nuclei Pleasure, reward, reinforcement Fornix Carries messages from the hippocampus to the thalamus Hypothalamus Hormone release via pituitary (widespread changes) WHAT DOES IT DO? Determines and elicits emotional states Group Photo fear Joy disgust A CLOSER LOOK AT STRESS RESPONSE WHAT IS STRESS? Physiological response that mediates stressors and target organs Disturbed homeostasis WHAT IS A STRESSOR? Psychosocial stressors Non direct Real or imagined events that elicit a stress response Cannot directly cause the stress response, but can trigger the stress response through cognitive integration Biogenic stressors direct trigger Actually elicit a stress response Do not require cognitive input, can directly trigger the nuclei Ginseng, Ginko, Amphetamines, Caffeine, Nicotine, Heat/cold/pain, Gurana PERCEPTIONS OF STRESSORS ARE INDIVIDUAL Stressors are particularly individual Affected by; Biological predisposition Personality Learning history Coping mechanisms random events  - tears * Cockroach D Ocean - * heights holes * fear of A spiders * snakes WHAT MAY A STRESS RESPONSE LOOK LIKE? What does stress look like in terms of physiology? - Rapid breathing Increased arousal/alertness sweating - - shaking Increased cognition, vigilance, focus - avert appatite - Supressed No feeding/reproductive behaviour - stress tummy - Inhibition to GI motility  WHAT MAY A STRESS RESPONSE LOOK LIKE AT A CELLULAR LEVEL? What does stress look like at a cellular level? to vital organs of oxygen - redirection - HR - ↑RR Redirection of energy - Create more glucose - ↓ Redirection growth redirection energy of oxygen and nutrients to the CNS of - - ↑ Redirection of oxygen and nutrients to the area of stress BP Increased blood pressure, heart rate, respiratory rate Increased gluconeogenesis and lipolysis Inhibited reproductive/growth axes HOW DOES A STRESSOR ELICIT STRESS? (Assuming the stressor is not a non-sympathetic stimulus) The stressor needs to be received by PNS receptors Stimuli message travels from the PNS to the CNS Passes through the limbic system (emotional control system) deep in brain Messages project into the neocortex Stimulating visceral and neuromuscular activity Cognitive stressors turn into physiological stress response  advenaline FIGHT-OR-FLIGHT P ~roduce Driven by the adrenal medulla, fight-or-flight is involved with mobilising the body in response to a perceived threat Can be activated by psychological stimuli Stimulation drives the adrenal medulla to produce catecholamine Catecholamine are released, and travel through the systemic circulation WHAT MIGHT WE SEE IN FIGHT-OR- FLIGHT?  stress ed CHRONIC STRESS - Prolong resp once stress continuous onse prolonged - Driven by the endocrine system Longer and slower acting resp if Can be activated by psychological and psychosocial stimulus Hypothalamic-pituitary-adrenal cortical system (HPAC) - warmful Somatotrophic axis Thyroid axis Posterior pituitary axis GENERAL ADAPTATION SYNDROME Alarm SNS arousal Adrenal medullary stimulation ACTH release Cortisol release GH release Increased thyroid activity Gonadotrophic activity increased Anxiety GENERAL ADAPTATION SYNDROME Resistance stage Reduction to adrenal cortical activity Reduction in SNS activity Homeostatic mechanisms engaged GENERAL ADAPTATION SYNDROME Exhaustion stage Enlargement of lymphatic structures at target organ Increased vulnerability to opportunistic disease Psychological and physiological exhaustion immune system egt  Really deep breathing VAGUS NERVE STIMULATION OR holding breath Treatment through the longest cranial nerve! & Heavily involved in involuntary sensory and motor functions Can help switch from SNS to PNS mode under stressful conditions Through deep slow breathing Cold water face immersion ↳