Your Thirst Center Tells You That You Are Dehydrated – Assignment Example
Answer: Part one: Our nervous and muscular systems activates as we lift the glass of water to drink. Neurons carry messages from the brain to the muscles and generate electrical nerve impulses. Each nerve impulse begins in the dendrites of a neuron and reaches the axon tip. Neuron sends impulses through an action potential (AP) and passes its AP impulse to the next neuron at a synapse. These neurons have neurotransmitters that change the membrane potential by starting the whole action potential in receiving neuron. Acetylcholine is a neurotransmitter released at the neuromuscular junction. It triggers a muscle action potential, which leads to muscle contraction. The sliding filament theory explains the actual muscle fiber contraction and voluntary movements of muscle. Actin and myosin filaments are actual moving parts that results in contraction. They can hook and pull, which shorten the myofibril and causes muscle to contract. The action potential travels down the inward projecting T tubules that reach deep into the muscle fiber, and actual muscular contraction begins. Muscles use the bones as levers and cause movement. They supply the force that moves the ones. Skeletal (striated) muscles and arm bones are involved in lifting a glass of water. Humerus, radius and ulna are arm bones. Wrist bones include scaphoid, lunate, trapezoid and hamate. Metacarpal and phalanges are also involved.
Answer: Part two: When we drink water, it enters our buccal cavity that leads to pharynx and travels down the oesophagus and fall into our stomach. Stomach opens into the small intestine. Here, duodenum, the first part of small intestine absorbs the water into the blood. The water travels around the body in the blood, first to the liver, then to the lungs, heart and through the aorta down to the kidneys. Kidneys filters it and water in the form of urine travels down from ureters into the urinary bag called urethra.
Robert K, Clark. (2005). Anatomy and Physiology. London UK: Jones and Bartlett Publishers.