PBS Study Guide 2.1

Hormone:

A product of living cells that circulates in blood and produces a specific, often stimulatory, effect on the activities of cells that are often far from the source of the hormone.

Glucagon:

A protein hormone secreted by pancreatic endocrine cells that raises blood glucose levels; an antagonistic hormone to insulin.

Insulin:

A protein hormone secreted by the pancreas that is essential for the metabolism of carbohydrates and the regulation of glucose levels in the blood.

Positive Feedback -

Feedback that tends to magnify a process or increase its output. Create a larger and larger response until something major occurs to stop the process (represented by single loop).

Effects Diabetes has on Blood:

The sugar thickens the blood, causing less flow. That stresses the cardiovascular system & causes high blood pressure, blood clots, poor circulation (often resulting in blindness and/or need for amputation of toes or even limbs).

What is diabetes?

A disorder characterized by high blood glucose levels and caused by insufficient insulin or the inability of the insulin to function properly.

What does feedback refer to in the human body?

A feedback mechanism is just when one thing happens in response to another thing - sort of like a chain reaction. The human body uses feedback mechanisms to maintain homeostasis.

Negative Feedback -

A primarily mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation. Maintain homeostasis (keep things same) - trigger results in a "correction" in order to keep BALANCE.

How does the body regulate the level of blood glucose?

Blood glucose levels are regulated by the feedback action of the hormones insulin and glucagon. High blood glucose promotes the release of insulin--> the pancreas releases insulin which (1) stimulates glucose uptake from the blood into tissue cells (2) stimulates the formation of glycogen from glucose in the liver--> lowers blood glucose. Low blood glucose promotes the release of glucagon--> the pancreas secretes glucagon which stimulates the breakdown or glycogen to glucose in the liver--> glucose is released into the blood stream--> raises blood glucose

How is glucose tolerance testing used to diagnose diabetes?

Diabetes is diagnosed and characterized as Type 1 or Type 2 by measuring glucose and insulin levels in the blood or urine. Glucose Tolerance Testing: A test of the body's ability to metabolize glucose that involves the administration of a measured dose of glucose to the fasting stomach and the determination of blood glucose levels in the blood or urine at intervals thereafter and that is used especially to detect diabetes.

What is the relationship between insulin and glucose? How does insulin assist with the movement of glucose into body cells?

Insulin is a hormone (particular kind of protein) produced by the pancreas. Its job is to regulate the transfer of glucose into body cells. In a non-diabetic, insulin maintains homeostasis of blood sugar levels, but in a diabetic, homeostasis is not maintained, causing lots of problems. Cells are all "locked" in a way and only let certain materials in. Insulin acts like a key, "unlocking" cells to let in glucose whenever levels in the blood get high. It works via a negative feedback loop.

Type 2 Diabetes:

Not typically treated with insulin--usually treated with lifestyle changes (exercise, limiting carbohydrates, etc.) & oral medication.

Type 1 Diabetes:

Only treatment is insulin--without it there is certain death. Patients have option of injections or an insulin pump.

What is homeostasis?

The maintenance of relatively stable internal physiological conditions (such as body temperature, blood composition, energy, sleep, etc.) in higher animals under fluctuating environmental conditions.

Effects Diabetes has on Cells:

Too much sugar in blood means not enough is reaching the cells. Cells use sugar (glucose) to make energy (ATP). If the sugar can't get in, the person lacks energy and will experience fatigue. For homeostasis, the solutions that make up blood and cells should be isotonic (same concentration in the solutions). In a diabetic, a concentration gradient develops because the blood becomes hypertonic (greater concentration of solute) & osmosis draws the solvent (water) out of cells and into the bloodstream, dehydrating cells :(. That leads to constant hunger & thirst that isn't properly satiated with food/water intake.

How does the development of Type 1 and Type 2 diabetes relate to how the body produces and uses insulin?

Type 1 Diabetes: Usually occurs in children (used to be called "Juvenile Diabetes"). An autoimmune disorder, in which the immune system attacks the insulin-producing cells of the pancreas. Creates severe insulin deficiency. Sugar can't get into the cells because the pancreas has stopped producing insulin. Type 2 Diabetes: Usually occurs in adults (used to be called "Adult Onset"), especially those who are overweight. An endocrine disorder--caused by a person's lifestyle habits making cells reject insulin. Sugar can't get into cells because they've become "insulin resistant" & no longer recognize it as the "key". Reversible IF lifestyle changes are made. Similarities: Sugar cannot get into the cells. Results in hyperglycemia (high blood sugar) & dehydration of cells. Can lead to cardiovascular problems (high blood pressure, heart attacks). Can lead to blindness. Can cause need for amputation of toes or even limbs, due to poor circulation.