BIOL 100 Chapter Notes - Chapter 45: Blood Sugar, Alpha Cell, Adipocyte
Textbook Notes
Chapter 45
Diabetes/Obesity
Concept 1: Blood Glucose Metabolism
Blood Glucose Level
Amount of glucose present in the blood
In mammals it is maintained at a range of between 3.6 and 5.8 mm it is tightly regulated as a part of metabolic
homeostasis
Rise after meals for an hour or two and are usually lowest in the morning before the first meal of the day
Transported via the bloodstream from the intestines of liver to body cells, glucose, which is transported via the
bloodstream from the intestines to the liver to body cells, is the primary source of energy for the cells. Fats and
lipids are primarily used for storage of energy
Blood Glucose Metabolism
The liver is responsible for glucose metabolism
The liver absorbs and produces/stores glucose in the form of glycogen, a macromolecule
Glycogen breaks down when needed and releases glucose into the blood stream slowly between meals
Gluconeogensis - metabolic pathway that results in the generation of glucose from fat, glycogen, and
proteins
The rate of glucose utilization by peripheral tissues must match the rate of glucose production to
maintain homeostasis
The homeostatic mechanism which keeps the blood value of glucose in a remarkably narrow range is composed
of several interacting systems, of which hormone regulation is the most important
Catabolic hormones - glucagon, which increase blood glucose
Anabolic hormones - insulin, which decreases blood glucose
Produced in the pancreas
The beta cells produce insulin and the alpha cells produce glucagon
Insulin - key regulator of blood glucose
Its action is predominant after a meal and the cellular receptors mediate its broad range
Once glucose is released from the liver, it can be delivered to muscle or adipose tissue, or any of the
other organs
Glucose is regulated by insulin discharged from the pancreas
Binds to receptors on target cells throughout the body and only when insulin is bound can glucose get
inside the cells
The binding of insulin to its receptor turns on various signaling cascades. One of these causes glucose-4
transporter (GLUT-4) to translocate to the plasma membrane, leading to an influx of glucose into the cel
Glucagon - hormone produced by the alpha cells in the pancreas
When blood glucose levels drop, insulin production drops and glucagon is produced
Causes the liver to convert stored glycogen into glucose so that it can be released into the blood stream
and raise glucose levels
Concept 2: Diabetes Mellitus
Diabetes Mellitus
Condition in which the body either does not produce enough, or does not properly respond to, insulin, a hormone
produced in the pancreas
Insulin enables cells to absorb glucose which provides energy
Glucose is our source of energy and several body organs are involved in its regulation to maintain homeostasis
If there is a lack of insulin, glucose will accumulate in the blood, often leading to various complications
Can be described as a spectrum that ranges from severe to mild
Type 1 diabetes - insulin dependent diabetes mellitus, beta cells are dead
Type 2 diabetes - insulin independent diabetes mellitus, insulin receptors are non- responsive, affects
both obese and non-obese
Gestational diabetes - reversible, 2-7% of pregnant women
Type 1 vs. Type 2 Diabetes
Type 1 diabetes - chronic progressive autoimmune disease that kills the beta cells resulting in the lack of insulin
production
Most common in children and identification of autoantibodies in the general population can predict DM1
Symptoms:
Polyuria - frequent urination
Thirst - due to loss of fluids
Weight loss - due to rapid breakdown of fat and muscle
Hunger
People affected with DM1 are not able to use glucose efficiently because they make very little to no
insulin to meet their metabolic needs
If glucose builds up in the bloodstream because it cannot get inside the cells, it can damage the heart,
kidneys, eyes, and feet
People affected with DM1 are not able to use glucose efficiently because they make very little to no
insulin to meet their metabolic needs
Type 2 diabetes - a chronic progressive disease with either decreased insulin secretion, or insulin resistance
The risk of type 2 DM and glucose intolerance has been associated with obesity
Research has demonstrated that genetic factors are also associated with DM
Symptoms:
Increased thirst
Increased hunger
Fatigue
Polyuria
Weight loss
Blurred vision
Sores that do not heal
Diabetes causes both macrovascular and microvascular disease
Macrovascular (large vessels) disease leads to strokes, cardiovascular disease, renovascular and peripheral
vascular disease
Microvascular (small blood vessels) system is affected and causes three common complications: reduced
blood supply to the nerves (neuropathy), damage to the retina (retinopathy), and damage to the renal
glomerulus (nephropathy)
After development of diabetes, an untreated individual will suffer from tissue damage that can lead to
the following problems, limb amputation, blindness, and kidney disease
Diabetic neuropathy - a condition in which the peripheral nerves are damaged due to damage of the blood vessels
which supply the nerves
The pain sensory nerve fibers will fire spontaneously sending sensory signals to the brain
Neuropathies do not affect the central nervous system, which includes the brain and spinal column, but do affect
the peripheral nerves, which transmit signals to the brain via the spinal column
Diabetic neuropathy can be either acute or chronic sensory nerve disorder producing asymmetric or
symmetric pain
Symptoms:
Decreased sensitivity to pain
Hypersensitivity to pain
Numbness
Tingling
Shooting, burning or electric pains
Cold feet/ inability to judge temperatures
Food ulcers
Infections
Muscle and bone deformities
Poor wound healing
Diabetic nephropahty - progressive kidney disease caused by damage of capillaries in the kidney glomeruli
The kidney regulates blood volume and pressure, controls levels of electrolytes and metabolites, and it
also regulates blood pH
Kidney failure provoked by resultant these blockages leads to fluid filtration deficits and other disorders
It is important for diabetes patients’ urine to be tested annually for protein since at the beginning of the disease
there might be no symptoms
DM Treatments
The major goal in treating diabetes is to minimize any elevation of blood glucose without causing abnormally
low levels of blood sugar
DM1 is treated with insulin, exercise, and a diabetic diet
DM2 is treated first with weight reduction, a diabetic diet, and exercise
Oral treatment is the preferred method for DM2
Goal is to educe increasing blood glucose and to minimize hyperglycemia
Medications for DM2
Increase the insulin output by the pancreas
Decrease the amount of gluocose released from the liver
Increase the sensitivity of cells to insulin
Decrease the absorption of carbohydrates from the intestine
Slow emptying of the stomach to delay the presentation of carbohydrates for digestion and absorption in
the small intestine
Insulin pen - can be injected usually in three places in the body: the upper arms, the inner/outer thighs, and the
abdomen
Document Summary
In mammals it is maintained at a range of between 3. 6 and 5. 8 mm it is tightly regulated as a part of metabolic homeostasis. Rise after meals for an hour or two and are usually lowest in the morning before the first meal of the day. Transported via the bloodstream from the intestines of liver to body cells, glucose, which is transported via the bloodstream from the intestines to the liver to body cells, is the primary source of energy for the cells. Fats and lipids are primarily used for storage of energy. The liver absorbs and produces/stores glucose in the form of glycogen, a macromolecule. Glycogen breaks down when needed and releases glucose into the blood stream slowly between meals. Gluconeogensis - metabolic pathway that results in the generation of glucose from fat, glycogen, and proteins. The rate of glucose utilization by peripheral tissues must match the rate of glucose production to maintain homeostasis.
