The 2000-Meter Row: A Case in Homeostasis
Adapted from the National Center for Case Study Teaching in Science* by Nathan Strong
At the start
1. Recall that Jim's heart and respiratory rate are increased, he was sweating and that his mouth was dry before the raise began. Explain what is happening to his autonomic nervous system (including which division is the most active) and specify exactly how those ANS responses are creating the symptoms noted. What changes do you think are occurring in the digestive and urinary systems at this time? (8 points)
In his autonomic nervous system, the sympathetic division was the most active before and during the race because it is what prepares your body for extra somatic activity. It activated as he was preparing for the race because he was becoming more stressed and nervous. It started in the sympathetic center located in his hypothalamus, and from there led multiple places causing his symptoms. His increased heart rate started when the cardioacceleratory center in the Medulla oblongata sent impulses down the spinal cord to the preganglia and ganglionic neurons of the Cervical and T1-T3 spinal cord segments, then the cardiac and pulmonary plexuses, which then leads to the heart and increases the rate at which it pumps. At the same time, his respiratory rate increased similarly. Impulses sent down his spinal cord through the preganglia and ganglionic neurons of the Cervical and T1-T3 spinal cord segments, to his cardiac and pulmonary plexuses, which then led to a higher breathing rate. The sweating is another response to the activation of his fight or flight mode, the sympathetic division. His body perceived his nervousness as a sign that there is a threat and he may begin to exert more energy and in turn become hot, so it prepares for that by sweating in an effort to cool his body. His postganglionic fibers began to innervate his sweat glands by releasing acetylcholine and activating his muscarinic receptors. The cause of his dry mouth was his preganglionic fibers which ascend to his superior cervical sympathetic ganglia and inhibited his salivary glands. Finally, during a time where the sympathetic division of the ANS has been activated, the blood flow to the digestive system will be restricted and temporarily restricts digestive activities. Then, in the urinary system, kidney functioning is reduced, the detrusor urinae muscle of the bladder wall relaxes as the internal urethral sphincter contracts, which overall suspends the urinary system.
One minute in
2. Consider the power stroke of rowing from the perspective of the actions at the shoulder and elbow joints. Create a table that shows what muscles, under control of what nerves, pull on what bones to cause each action. Be sure to include the action of fixating the shoulder blade and pulling it back. The first column for your table must be the action. This column should describe what is occurring in both English and anatomical terminology (see chapter 9). But only include those actions needed to row the boat. Points will be deducted for unneeded actions. See example below*. (15 points)
Maintain Handle Height:Angular motion of the humerus at the shoulder
| Clavicle, spine and acromion of scapula
| Deltoid tuberosity of humerus
| Axillary Nerve
| Pulls Together The Shoulder Blades:Adducts and rotates scapula downward
| Rhomboidmajor and minor
| Spinous processes of C7 and T1-T5
| Medial border of scapula
| Dorsal Scapular Nerve
| Pulling The Handle Toward Your Body:Flexes the forearm at the hinge joint of the elbow
| Biceps brachii
| Long head at supraglenoid tubercle of the scapula through the intertubercular groove, short head at coracoid process of scapula
| Radial tuberosity
| Musculocutaneous Nerve
| Pushing The Handle Away From Body:Extend the forearm at the hinge joint of the elbow
| Triceps brachii
| Lateral head at posterior side of humerus,...
Cited: “Breathing Rate And Heart Rates After Exercise.” LiveStrong. Demand Media, Inc., 14 Jul. 2011.
“Chapter 6 – Visual Perception.” Oup. n.p., n.d. Web. 1 Dec. 2012. PDF file.
“Homeostasis.” BiologyMad. IHW, Mar. 2006. Web. 1 Dec. 2012.
“Keeping Your Autonomic Nervous System Healthy.” DrWilson. The Center For Development. June 2011. Web. 27 Nov. 2012.
“Muscles Used In A Rowing Machine.” LiveStrong. Demand Media, Inc., 3 May, 2011. Web. 28
“The Brachial Plexus.” UpState. Health Science Center, n.d. Web. 28 Nov. 2012.
Demand Media, Inc., 28 Apr. 2011. Web. 1 Dec. 2012.
“Why Do You Sweat When You’re Nervous?” WiseGeek. Conjecture Corporation, 15 Nov. 2012.
Web. 27 Nov. 2012.
“Why You Should Load Up On Good Carbs The Night Before A Big Game.” FitDay
Brands, Inc., n.d. Web. 30 Nov. 2012.
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