Question

What are the biological interactions that occur during the "fight or flight" reflex. In general, how do neurotransmitters and neurohormones play a role in communication between the CNS and the ENS? How do the endocrine and nervous systems work together in times of an emergency. Explain the biological changes and signs that occur during Walter Cannon's arousal reflex (the fight or flight reflex) and Selye's General Adaptation Syndrome – including the concept of reactivity.

Answer 1

• When our senses perceive an environmental stress such as danger or a threat, cells in the nervous and endocrine systems work closely together to prepare the body for action. Often referred to as the fight or flight or stress response, this remarkable example of cell communication elicits instantaneous and simultaneous responses throughout the body.
• Sensory nerve cells pass the perception of a threat, or stress, from the environment to the hypothalamus in the brain. Neurosecretory cells in the hypothalamus transmit a signal to the pituitary gland inciting cells there to release a chemical messenger into the bloodstream.
• Simultaneously, the hypothalamus transmits a nerve signal down the spinal cord. Both the chemical messenger and nerve impulse will travel to the same destination, the adrenal gland.
• When a threat is perceived, the sympathetic nerve fibres of the autonomic nervous system are activated. This leads to the release of certain hormones from the endocrine system.
• The fight-or-flight response is characterized by an increased heart rate (tachycardia), anxiety, increased perspiration, tremour, and increased blood glucose concentrations (due to glycogenolysis, or breakdown of liver glycogen). These actions occur in concert with other neural or hormonal responses to stress, such as increases in corticotropin and cortisol secretion, and they are observed in some humans and animals affected by chronic stress, which causes long-term stimulation of the fight-or-flight response.
• The central nervous system (CNS) communicates with the intestine through what is known as the brain-gut axis, comprising of the hypothalamic-pituitary-adrenal (HPA) axis and, in a gut context, the autonomic enteric nervous system (ENS) within the intestinal wall. Both vagal and spinal sensory neurons terminate at various points within the gut wall including the muscularis and the mucosal epithelium and play an important role in the transfer of information from the CNS to the ENS, and vice versa.
• Important components of the ENS are the supportive enteric glial cells (EGCs), which form a large and widespread network at all levels of the gastrointestinal tract and serve as intermediaries in the enteric neurotransmission and information processing.
• Stress is the simple name for what happens when the body’s emergency response is activated; a stressful event is one that activates the sympathetic (fight-or-flight) nervous system. Because it elevates arousal, heart rate, and breathing, stress is useful for helping animals and humans escape dangerous situations; however, it can damage the body to be under stressful conditions for too long.
• Both the nervous and endocrine systems send messages everywhere inside the human body. These messages allow your heart to beat, your lungs to breathe in air, and your mind to make decisions. In the nervous system, signals travel very quickly, leading to instantaneous responses. However, within the endocrine system, signals move slowly but last longer.
• In a fight or flight response, there is a coordination of both the nervous and endocrine systems. The nervous system detects stimuli, either inside or out, for example, danger like an oncoming car about to run someone over, and that in turn sends an impulse to the endocrine system where a response is carried out.
• The last part can be asked as another question.due to time constraints it can be answered in another question