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What is the primary function of the amygdala in the limbic system?
How does the hypothalamus influence the body's stress response?
Which structure in the limbic system is responsible for carrying messages from the hippocampus to the thalamus?
What is a common outcome when the limbic system determines an emotional state?
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Which of the following best describes the main function of the cingulate cortex?
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What is the primary function of the somatic nervous system?
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Which of the following describes the role of the sympathetic nervous system (SNS)?
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What neurotransmitter is primarily associated with the sympathetic nervous system?
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How do the sympathetic and parasympathetic nervous systems interact?
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Which of these statements correctly differentiates between the sympathetic and parasympathetic nervous systems?
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What is the main role of adrenergic fibres in the nervous system?
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What physiological effect results from the activation of the parasympathetic nervous system?
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Which of the following correctly identifies a characteristic of the autonomic nervous system?
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What is the primary neurotransmitter secreted by post-ganglionic sympathetic fibres?
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Which cranial nerve primarily innervates the muscles that control eye movements?
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Where do the neurons of the sympathetic nervous system primarily originate?
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Which of the following is a characteristic of the nervous system's sympathetic division?
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What is the role of ganglia in the autonomic nervous system?
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Which of the following structures carries the majority of parasympathetic fibres?
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What neurotransmitters are primarily responsible for the functioning of the autonomic nervous system?
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What physiological reaction occurs when individuals experience a decreased heart rate?
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What type of stressors are characterized as being able to directly trigger a stress response without cognitive input?
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Which physiological response is NOT typically associated with stress?
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How does individual perception of stressors vary among people?
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What mechanism allows psychosocial stressors to elicit a stress response?
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Which of the following effects is typically seen at the cellular level during a stress response?
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Which of the following would NOT be a physiological symptom of stress?
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Stress responses can lead to inhibition of which of the following axes?
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Which of the following is an example of a biogenic stressor?
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What is primarily responsible for mobilizing the body in response to a perceived threat?
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Which system is activated during chronic stress responses?
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During the resistance stage of the General Adaptation Syndrome, what happens to adrenal cortical activity?
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What does the fight-or-flight response primarily release into the bloodstream?
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What contributes to the physiological stress response from cognitive stressors?
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What symptom is NOT associated with the alarm stage of the General Adaptation Syndrome?
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What happens to the lymphatic structures during the exhaustion stage of General Adaptation Syndrome?
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Which nerve is involved in vagus nerve stimulation as a treatment method?
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What type of stimulus can activate the fight-or-flight response?
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Which axis is NOT part of the chronic stress response system?
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Study Notes
The Nervous System
- The somatic nervous system (SNS) is involved in voluntary control of skeletal muscle via sensory nerves, afferent nerve fibres, and motor nerves, efferent nerve fibres.
- The autonomic nervous system (ANS) is responsible for unconscious regulation of survival processes like heart rate, digestion, and respiration by controlling smooth muscle, glands, and internal organs.
- Visceral reflexes are continuous unconscious responses to internal stimuli, such as baroreceptors in blood vessels sensing blood pressure drops and triggering a reflex response to elevate blood pressure.
- The ANS is divided into the sympathetic nervous system (SNS), responsible for the fight-or-flight response, and the parasympathetic nervous system (PNS), responsible for the rest-and-digest response.
- Dual innervation means that organs receive nerve fibres from both SNS and PNS, with opposing effects. For example, SNS stimulation increases heart rate, while PNS stimulation decreases heart rate.
- The SNS activates during stress or threat, preparing the body for confrontation (fight) or escaping a threatening situation (flight).
- Physical changes associated with intense fear include loss of control of urinary and digestive functions, severe decrease in heart rate (bradycardia), and even fainting.
- Sympathetic neurons originate in the CNS (T1 - L2 vertebrae) and have a short pre-ganglionic fibre and a long post-ganglionic fibre, leading to a generalised, systemic response.
- Key neurotransmitter for the SNS is noradrenaline.
- Parasympathetic neurons originate in the CNS (brain or sacrum S2 - S4) with a long pre-ganglionic fibre and a short post-ganglionic fibre, leading to a localized response.
- PNS uses four cranial nerves and primarily uses acetylcholine and nitric oxide as neurotransmitters.
- Cranial nerve III (Oculomotor) carries PNS fibres to two intrinsic eye muscles, controlling pupillary constriction and lens shape changes.
- Cranial nerve VII (Facial) carries PNS fibres to tear glands, salivary glands, and nasal glands, contributing to vasodilation and increased sensation.
- Cranial nerve IX (Glossopharyngeal) carries PNS fibres to the salivary glands, facilitating vasodilation and increased sensation.
- Cranial nerve X (Vagus) carries approximately 80% of PNS fibres, innervating a large number of organs in the thoracic and abdominal cavities.
- Neurotransmitters in the ANS are primarily acetylcholine and noradrenaline.
- Adrenergic fibres secrete noradrenaline, while cholinergic fibres secrete acetylcholine.
- All pre-ganglionic fibres are cholinergic.
- Post-ganglionic SNS fibres are adrenergic.
- Neurotransmitter termination mechanisms are crucial for preventing constant stimulation of receptors, allowing for better pharmacological understanding and control. For example, β2 agonists mimic catecholamine in the receptor to prevent smooth muscle contraction, like Ventolin for asthma.
- The limbic system is located deep within the brain and plays a crucial role in emotional states and behaviour, bordering the cerebral cortex and diencephalon.
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Key structures of the limbic system include:
- Amygdala: Fear and anxiety
- 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 the pituitary, influencing widespread changes
- The limbic system determines and elicits emotional states, influencing reactions to stimuli like fear, joy, sadness, and disgust.
- Stress is a physiological response that mediates stressors and target organs, resulting in disturbed homeostasis.
- Stressors are events that trigger the stress response, either psychologically (real or imagined) or biologically, requiring cognitive integration or direct action.
- Perceptions of stressors are individual, impacted by biological predisposition, personality, learning history, and coping mechanisms.
- Stress responses can manifest physically as rapid breathing, increased arousal/alertness, sweating, shaking, increased cognition/vigilance, suppressing appetite, and inhibition of gastrointestinal motility.
- Cellular level stress responses involve redirection of energy and oxygen to vital organs and the area of stress, leading to increased blood pressure, heart rate, respiratory rate, gluconeogenesis, lipolysis, and inhibited reproductive/growth axes.
- Stressors elicit the stress response by being received by PNS receptors, transmitting information through the CNS, passing through the limbic system, and then projecting into the neocortex to stimulate visceral and neuromuscular activity, ultimately creating a physiological stress response.
- The fight-or-flight response, driven by the adrenal medulla, involves mobilizing the body in response to a perceived threat, activated by both psychological and biological stimuli.
- The fight-or-flight response triggers the adrenal medulla to produce catecholamine, which is released into the systemic circulation.
- Signs of fight-or-flight include increased heart rate, breathing rate, blood pressure, sweating, and muscle tension to prepare for action.
- Chronic stress, driven by the endocrine system, results in longer and slower-acting stress responses.
- Chronic stress is activated by both psychological and psychosocial stimuli and involves the hypothalamic-pituitary-adrenal cortical system (HPAC), somatotrophic axis, thyroid axis, and posterior pituitary axis.
- The general adaptation syndrome is a physiological model of stress response with three stages:
- Alarm stage: Initial SNS arousal, ACTH, cortisol, and GH release, increased thyroid and gonadotrophic activity, and feelings of anxiety.
- Resistance stage: A reduction in adrenal cortical and SNS activity, engaging homeostatic mechanisms to cope with prolonged stress.
- Exhaustion stage: Enlarged lymphatic structures, increased vulnerability to disease, and psychological and physiological exhaustion.
- Vagus nerve stimulation is a treatment option for stress and stress-related disorders, using the longest cranial nerve to influence the autonomic nervous system, contributing to relaxation, reduced heart rate, and improved mood.
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Description
This quiz delves into the complexities of the nervous system, including the somatic and autonomic divisions. Explore how voluntary and involuntary functions are controlled, as well as the roles of visceral reflexes. Test your understanding of the sympathetic and parasympathetic nervous systems and their impacts on bodily functions.
