What is the function and structure of the Autonomic Nervous system (ANS)and what are its two divisions?Function | Regulated by | Impulses to | Division |
|---|
| | | | maintains body’s internal enviro. | | | | groups of nerve cells in the medulla oblongata, hypothalamus and erebral cortex | to the heart and invol. muscles/glanda. | sypm. /parasymp. These have differing effects | |
What are the characteristics of the autonomic division and what are their functions?Characteristic | Specified |
|---|
effectors | heart muscle, involuntary muscles, glands | general function | adjustment of the internal environment (homoestasis) | efferent pathway | two nerve fibresfrom the CNS to the effector with a synapse in a ganglion | neurotransmitter at effector control | Acetylcholine or noradrenaline | nerves to target organ | | effect on target organ | |
Parasympathetic Division?What it does. | Ganglia | Neurons | Neurotransmitter |
|---|
Produces responses that maintain the body during relatively quiet conditions - “Rest & Digest” | lie near/within the viscera of the peripheral organs that they innervate | Preganglionic neuron is long and postganglionic neuron is short | | ACETYLCHOLINE | | | |
Sympathetic Division?What it does. | Ganglia | Neurons | Neurotransmitter |
|---|
responses preparing body for strenuous physical activity - ‘fight or flight’. | located close to spinal cord | pregang. is short, postgang. is long | |
| NORADRENALINE | Summarise the Effects of the Autonomic Nervous System?Structure | Effect of Sympathetic Stimulation | Effect of Parasympathetic Stimulation |
|---|
Heart | Increase rate and strength of contraction | decreases rate/strength of contraction, constrict bronchioles | Lungs | dilates bronchioles (fine air passages in the lungs) | Constricts bronchioles | Stomach, intestines | decrease movements | increased movement | Liver | increases breakdon of glycogen and release of glucose | Increases uptake of glucose and synthesis of glycogen | Iris of eyes | dilates pupil | constricts pupils | Sweat glands | incr. sweat secretion | no effect | Salivary glands | Decreases secretion of saliva | incr. secretion of saliva | Blood vessels of: | | |
skin skeletal muscles internal organs | Constricts vessel (expect in heart and lungs, dilates vessels, constricts vessels (except heart/lung) | little effect, no effect, litttle effect | | Adrenal medulla | stims. hormone secretion | No effect | | urinary bladder | relaxes muscles of wall | constricts muscles of wall |
In threatening situations, what happens in the fight or flight response?How does the body prepare for movement and an increased demand for oxygen and glucose?rate/force of contraction of the heart increases blood vessels to skeletal muscles, heart and liver dilate blood glucose levels increase blood vessels constrict to organs not involved (e.g. stomach)
At the beginning of the experiment, the heart rate of the participants decreased. This could be due to the dive reflex or mammalian diving response, a physiological response triggered by cold water immersion, especially on the face or hands. This reflex involves slowing down the heart rate, reducing blood flow to the limbs, and conserving energy, which could explain the initial drop in BPM. As the exposure to cold continues (15-second increments), the body starts to experience more painful stimulation and stress due to prolonged cold exposure. The body responds by initiating the fight-or-flight response, mediated by the sympathetic nervous system, releasing stress hormones like adrenaline (epinephrine). This results in increased heart rate. As the body gets used to the cold, there might be a decreased vasoconstriction (narrowing of blood vessels), leading to a higher heart rate to compensate for the initial cold-induced constriction. If there were slight changes in the temperature of the water over time or differences in how the ice was added, this could also have affected the results Additionally: When your hand was first submerged in cold water, your body likely experienced a cold shock response. This often involves a brief decrease in heart rate as the parasympathetic nervous system (controlled by the vagus nerve) kicks in. This is part of the body's attempt to conserve energy and protect vital organs. This vagal response is typically brief, and after the initial discomfort or shock of the cold wears off, the heart rate may start to increase as the body responds to the discomfort and pain more actively. After the initial parasympathetic response, your sympathetic nervous system (which governs the "fight or flight" response) would likely activate. When the body senses cold stress, it activates the sympathetic nervous system to prepare for increased physical demands, leading to a increase in heart rate. This is an example of thermoregulatory adaptation: initially, the body tries to limit energy expenditure (slower heart rate), but as the body needs to keep circulating blood to the extremities and core, the heart rate increases to help with this. And all the other stuff like the water wasn’t cold enough and we weren’t stressed enough lol |
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