Why is the diameter of the afferent arteriole to the glomerulus larger than the efferent ateriole?
Explain one example of a homeostatic mechanism in the body.
Explain why the control of carbon-dioxide in the blood is a negative feed back mechanism.
To understand why the diameter of the afferent arteriole to the glomerulus is larger than the efferent arteriole, we need to consider the structure and function of the nephrons in the kidney.
The glomerulus is a specialized network of capillaries located within the nephron. It plays a crucial role in the filtration of blood to form urine. Blood flows into the glomerulus through the afferent arteriole and exits through the efferent arteriole.
The larger diameter of the afferent arteriole compared to the efferent arteriole is important for maintaining appropriate blood pressure and filtration rates. The higher pressure in the afferent arteriole allows for increased blood flow into the glomerulus, promoting more efficient filtration. This is essential because the glomerulus needs to filter waste products from the blood to produce urine.
On the other hand, the narrower diameter of the efferent arteriole is crucial in generating resistance to blood flow. By maintaining higher pressure in the glomerulus, it helps to create a pressure gradient within the capillary network. This gradient facilitates the filtration of fluid and small molecules through the specialized filtration membrane of the glomerulus, while retaining larger molecules like proteins in the blood.
In summary, the differential diameter of the afferent and efferent arterioles in the glomerulus is designed to optimize filtration and regulate blood pressure in the kidneys.
Now, let's move on to the second question.
An example of a homeostatic mechanism in the body is the regulation of body temperature. The body continuously strives to maintain a stable internal temperature, usually around 98.6°F (37°C), as variations in temperature can have detrimental effects on cellular function.
When the body senses an increase in temperature, such as during exercise or exposure to a hot environment, several homeostatic mechanisms are triggered to prevent overheating. One of these mechanisms is through the activation of sweat glands. When the body temperature rises, the sweat glands release sweat onto the skin's surface, which then evaporates and cools the body down.
Another example is when the body senses a decrease in temperature, such as being exposed to cold conditions. In this case, the body initiates processes to conserve heat and maintain core temperature. These mechanisms can include vasoconstriction (narrowing of blood vessels), shivering (rapid muscle contractions), and increased metabolic activity to generate heat.
Overall, these homeostatic mechanisms work together to regulate body temperature, ensuring that it remains within a narrow range that supports cellular function.
Moving on to the last question.
The control of carbon dioxide (CO2) in the blood is a negative feedback mechanism. Negative feedback occurs when the body detects a change in a physiological parameter and initiates responses to counteract that change, ultimately bringing the parameter back to its normal range.
In the case of carbon dioxide in the blood, the level of CO2 is continually monitored by chemoreceptors primarily located in the brainstem. When these chemoreceptors sense an increase in CO2 concentration, they send signals to the respiratory centers in the brain.
In response to the elevated CO2 levels, the respiratory centers stimulate an increase in the rate and depth of breathing. This leads to enhanced ventilation, facilitating the removal of excess CO2 from the blood through exhalation.
As CO2 levels decrease, the chemoreceptors detect this decrease and send signals to the respiratory centers to reduce the rate and depth of breathing. This ensures that the CO2 levels in the blood remain within the normal range.
This negative feedback mechanism helps to maintain the acid-base balance in the body. Since excessive CO2 can lead to a drop in blood pH, the removal of carbon dioxide restores the blood's acidity to a more optimal level.
In summary, the control of carbon dioxide in the blood is a negative feedback mechanism that involves the respiratory system's regulation of breathing rate and depth to maintain an appropriate balance of CO2 in the body.