Describe the neural mechanisms responsible for controlling blood pressure.
How are nutrients, wastes, and respiratory gases transported to and from the blood and tissue spaces?
Part B:
Compare the structure and functions of a lymph node to those of the spleen.
A friend tells you that she has tender, swollen “glands” along the left side of the front of her neck. You notice that she has a bandage on her left cheek that is not fully hiding a large infected cut there. Exactly what are her swollen “glands,” and how did they become swollen?
500 words in txt citations and references
Full Answer Section
Neural Mechanisms for Blood Pressure Control
Blood pressure regulation is a complex process involving the nervous system, hormones, and the cardiovascular system. The baroreceptors, specialized sensory receptors located in the walls of the carotid arteries and aortic arch, play a crucial role.
Here's how it works:
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Baroreceptors sense pressure changes: These receptors detect changes in blood pressure and send signals to the medulla oblongata, the brainstem region responsible for autonomic functions.
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Medulla oblongata processes signals: Based on the baroreceptor input, the medulla oblongata activates the sympathetic or parasympathetic nervous system.
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Sympathetic Nervous System Response: When blood pressure drops, the sympathetic nervous system is activated. This leads to:
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Increased heart rate: The sympathetic nerves stimulate the heart to beat faster, increasing cardiac output.
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Vasoconstriction: The sympathetic nerves constrict blood vessels, increasing peripheral resistance and pushing blood pressure up.
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Parasympathetic Nervous System Response: When blood pressure rises, the parasympathetic nervous system is activated. This leads to:
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Decreased heart rate: The parasympathetic nerves slow down the heart rate, reducing cardiac output.
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Vasodilation: The parasympathetic nerves dilate blood vessels, decreasing peripheral resistance and lowering blood pressure.
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Hormonal Involvement: Hormones like epinephrine (adrenaline) and norepinephrine (noradrenaline) released by the adrenal glands also contribute to blood pressure regulation, primarily by enhancing the effects of the sympathetic nervous system.
Transport of Nutrients, Wastes, and Respiratory Gases
The circulatory system acts as the transport system of the body, delivering vital substances to cells and removing waste products. This occurs through the exchange of materials between the blood and interstitial fluid, the fluid that surrounds cells.
Here's how it happens:
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Capillary Exchange: The smallest blood vessels, capillaries, are responsible for this exchange. Their thin walls allow for easy diffusion of substances.
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Nutrients and Oxygen Delivery: Nutrients like glucose, amino acids, and lipids, as well as oxygen, move from the blood into the interstitial fluid and then into cells. This occurs due to concentration gradients, with higher concentrations in the blood than in the interstitial fluid.
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Waste Product Removal: Carbon dioxide, a waste product of cellular respiration, moves from cells to the interstitial fluid and then into the blood. Other metabolic waste products like urea and creatinine are also transported from the interstitial fluid to the blood.
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Lymphatic System: The lymphatic system plays a vital role in maintaining fluid balance and removing waste. It collects excess interstitial fluid, known as lymph, and returns it to the blood.
Part B: Lymph Nodes vs. Spleen
Lymph Nodes:
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Structure: Small, bean-shaped organs located throughout the body, primarily along lymph vessels. They contain lymphocytes (white blood cells) and macrophages.
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Function: Filter lymph fluid, removing debris, pathogens, and foreign substances. They also house immune cells that can mount an immune response against infection.
Spleen:
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Structure: A large, oval-shaped organ located in the upper left abdomen. It contains red pulp (rich in red blood cells) and white pulp (containing lymphocytes).
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Function: Filters blood, removing old and damaged red blood cells, storing platelets, and mounting an immune response to blood-borne pathogens.
Swollen "Glands"
Your friend's swollen "glands" are actually lymph nodes. The infection in her cheek has triggered an immune response, leading to inflammation and swelling of nearby lymph nodes. This is a common occurrence, as lymph nodes are strategically placed to trap and filter pathogens that enter the body. The inflammation is a sign that the immune system is working to fight the infection.
References:
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Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy & physiology (15th ed.). Wiley.
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Marieb, E. N., & Hoehn, K. (2019). Human anatomy & physiology (11th ed.). Pearson Education.