Obesity is a major risk factor for the development of type 2 diabetes. What is the mechanism for this?

Choice A reason: A catheter is a flexible tube inserted into the body to allow the passage of fluids or other substances. While catheters can be used for hemodialysis, they are typically considered temporary access points and are not created by surgically attaching an artery to a vein.

Choice B reason: A peripheral intravenous line (PIV) is a catheter placed into a small peripheral vein. PIVs are commonly used for short-term access to administer medications or fluids but are not suitable for the high flow rates needed for hemodialysis and are not surgically created by joining an artery and a vein.

Choice C reason: An arteriovenous graft (AVG) involves using a synthetic tube to connect an artery and a vein. AVGs are used for patients who cannot have an AVF due to small or weak veins. While AVGs are a viable option for hemodialysis, they are not the preferred method due to higher rates of complications like infections and clotting compared to AVFs.

Choice D reason: An arteriovenous fistula (AVF) is the preferred method of vascular access for long-term hemodialysis. It is created by surgically connecting an artery to a vein, usually in the arm. This connection allows for increased blood flow through the vein, which enlarges and strengthens it, making it suitable for repeated needle insertions during dialysis sessions. AVFs are preferred because they have lower rates of complications and provide better long-term access compared to other methods.

Choice A reason: Positive feedback mechanisms amplify changes or deviations in the body. They are less common in physiological processes and typically drive processes to completion, such as childbirth and blood clotting. The regulation of blood glucose levels does not operate on a positive feedback mechanism.

Choice B reason: Releasing hormones are typically involved in the hypothalamic-pituitary axis and the regulation of hormone secretion from other endocrine glands. Examples include thyrotropin-releasing hormone (TRH) and gonadotropin-releasing hormone (GnRH). Insulin secretion in response to blood glucose levels is not directly controlled by releasing hormones.

Choice C reason: Negative feedback is the primary mechanism by which homeostasis is maintained in the body. When blood glucose levels rise, the pancreas secretes insulin to lower blood glucose levels, restoring them to normal. This is an example of negative feedback, as the increase in glucose levels triggers a response (insulin secretion) that counteracts the initial change, bringing blood glucose back to its set point.

Choice D reason: Ectopic hormones are hormones produced by tissues that normally do not produce hormones, often in cases of tumors or certain disease conditions. The regulation of insulin in response to blood glucose levels does not involve ectopic hormone production.