GLUCOSE HOMEOSTASIS AND FUEL METABOLISM Flashcards by Iseoluwa Ojo

Glucose homeostasis

Glucose homeostasis reflects a balance between __________ and ____________

hepatic glucose production

peripheral glucose uptake and utilization.

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Glucose homeostasis

______ is the most important regulator of this metabolic equilibrium, but neural input, metabolic signals, and other hormones (e.g., _______) result in integrated control of glucose supply and utilization.

Insulin

glucagon

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Plasma glucose concentration

Fasting blood glucose:

Random blood glucose:

Post-prandial blood glucose:

70-110mg/dl( 3.9-6.1mmol)

<140mg/dl (<7.8mmol/l)

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Hepatic glycogen stores : sufficient to maintain plasma glucose levels for approximately _______

This time period can be shorter if glucose demand is increased by ———- or if glycogen stores are depleted by______ or ______

8hours

exercise

illness or starvation

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Systemic glucose balance
Maintenance of the normal plasma glucose concentration is accomplished by-

 A network of __________
_________ signals
 _________ effects

that regulate endogenous glucose production and glucose utilization by tissues other than the _____

hormones

Neural

Substrate

brain

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Hormonal regulation of glucose homeostasis

List 6

Insulin
Glucagon
Thyroxine
Epinephrine
ACTH
GH

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Insulin

Insulin is a polypeptide hormone produced by the _____ cells of the ______

Its metabolic effects are ____bolic and favoring ________ of ______,______,_____

β; islets of Langerhans

ana

synthesis of glycogen, triacylglycerols, and protein

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Insulin

Insulin is composed of _____ amino acids arranged in ____ polypeptide chains, designated ____ and ____, which are linked together by __________

51; two

A and B

two disulfide bridges

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_________ and _________ insulin differ from human insulin at _____ and ____ amino acid positions, respectively.

Pig (porcine) and beef (bovine)

one and three

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Pig (porcine) and beef (bovine) insulin

Each can be used in humans for the treatment of ______; however, _________ to these foreign proteins can develop

diabetes

antibodies

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Regulation of insulin secretion

Stimulation of insulin secretion by
Glucose:

•_______________ of _____________ leads to a rise in blood glucose, which is a signal for increased insulin secretion

Amino acids:
_______ of _____ causes a ____ rise in plasma amino acid levels, which, in turn, induces the immediate secretion of insulin.

Gastrointestinal hormones
intestinal peptides ________ and _________ increase insulin secretion in response to _______, and so are referred to as “_____.”

Ingestion of glucose or a carbohydrate-rich meal; insulin

Ingestion of protein; transient

cholecystokinin and gastric-inhibitory polypeptide; oral glucose

incretins

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Inhibition of insulin secretion

The synthesis and release of insulin are decreased when:

-scarcity of _______

-during periods of _____ (for example, _______ or ________).

These effects are mediated primarily by _________

dietary fuels

stress

fever or infection

epinephrine

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__________ is the key regulator of insulin secretion by the pancreatic beta cells

Glucose

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Glucose levels >___ mmol/L (______mg/dL) stimulate insulin synthesis

3.9; 70

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Glucose stimulation of insulin secretion begins with its transport into the ______ by the __________ transporter

beta cell

GLUT2 glucose t

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Insulin promotes _______ glucose uptake and utilization, and inhibits ___________ as well as __________

peripheral

gluconeogenesis as well as glycogenolysis.

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Role of other hormones

Epinephrine:

Secreted by ________ and _____eases blood glucose level

Acts on _____________ to bring _________ by _______________activity

Secreted in response to ____,_______, or __________

adrenal medulla; incr

both muscle and liver

glycogenolysis; increasing phosphorylase

stress, trauma, or extreme exercise.

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Role of other hormones
Epinephrine:

Epinephrine has a direct effect on energy metabolism, causing a rapid mobilization of energy-yielding fuels, including glucose from the ______ (produced by ________ or -_______)

liver

glycogenolysis or gluconeogenesis

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Role of other hormones

Thyroxine:

Hormone of ________
________ blood glucose level by stimulating _______ glycogenolysis and gluconeogenesis

thyroid gland

Elevates

hepatic

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Role of other hormones

Glucocorticoids:
Hormones of _______

Stimulate ______ metabolism and ____ease gluconeogenesis

Inhibits glucose ______ by ________ tissues

____eases blood glucose level

adrenal cortex

protein; incr

utilization; extrahepatic

Incr

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Role of other hormones

Growth Hormone and adrenocorticotropic hormone (ACTH):

Hormones of ____________

causing _____glycemia

Glucose uptake by certain tissues is ____eased by GH

ACTH decreases glucose ______

anterior pituitary gland

hyper; decr

utilization

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In the early fasting state

The peripheral cells switch to __________, such as _________ and ___________

alternative fuels

fatty acids and ketone bodies.

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In the early fasting state

Ketone bodies are synthesized by the _____ but utilized in the _______ cells.

Glycerol and amino acids released form the _________ and _________ respectively are used for glucose production.

________is the main fuel for brain.
TAG ________ is decreased in adipose tissues

liver; peripheral

adipose tissue and muscle

Glucose; synthesis

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Role of insulin in the fasting state

low insulin levels increase glucose _________ by- Promoting hepatic _________ and ________ and Reducing glucose ——- in insulin-sensitive tissues (______ and ______)

production

gluconeogenesis and glycogenolysis

uptake

skeletal muscle and fat

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Role of insulin in the fasting state Low insulin levels promotes mobilization of stored precursors such as ________ and _________ (lipolysis). These effects are mediated by________.

amino acids and free fatty acids Glucagon

Role of glucagon in the fasting state • Glucagon,secreted by pancreatic _____ cells when blood glucose or insulin levels are (low or high?) , (inhibits or stimulates?) – Glycogenolysis,

alpha; low Stimulates

Role of glucagon in the fasting state • Gluconeogenesis by the ______ and _____ and Prevents glucose uptake by the _______

liver and renal medulla peripheral cells

Glucose homeostasis in well fed state In the well fed state, glucose absorbed from gut is supplied to all cells it acts as a signal for the release of ____ from Beta cells of pancreas it is ______ completely to provide energy the surplus is stored as _____ in ———- and _______ _________ obtained from pyruvate, can be used for lipogenesis, the triglycerides are stored in ___________

insulin; oxidized glycogen liver and muscle. Acetyl co A; adipose tissue.

Postprandial glucose homeostasis Postprandially, the glucose load elicits a (rise or fall?) in insulin and (rise or fall?) in glucagon, leading to a reversal of these processes. The major portion of postprandial glucose is utilized by _________, an effect of ______- stimulated glucose ______. Other tissues,most notably the ———, utilize glucose in an insulin-independent fashion.

Rise ; fall skeletal muscle; insulin; uptake brain

Glucose metabolism: Increased ________ of glucose Increased glycogen ______ Increased activity of the ________ pathway Increased __________ Decreased __________

phosphorylation synthesis hexose monophosphate glycolysis gluconeogenesis

In post absorptive phase Glucose utilization is _____eased in the _______,________, and _________ _________________ provides the most glucose (75%) ______________ providing the remainder The glucose-_______ cycle becomes active. ___-____% of glucose is consumed by the brain

decr liver, muscle and adipose tissue Liver glycogenolysis gluconeogenesis alanine 50-60

In the state of starvation _____________ cycle is active. ______ and ______ released from muscle are used in _____ and _____ respectively for glucose production

Glucose alanine Alanine and glutamine liver and kidney

In the state of starvation ________ play a central role in prolonged starvation, replacing _____ as the primary fuel for the brain and signaling a ________ in protein catabolism and alanine output from muscle.

Ketones glucose reduction

Variations in blood glucose levels A) Hypoglycemia- Decrease in blood glucose below the normal (______mg/dl) is called hypoglycemia. A decrease in _____ secretion is the first defense against hypoglycemia.

<45 insulin

Variations in blood glucose levels A) Hypoglycemia- As plasma glucose levels decline just below the physiologic range, glucose counter regulatory (plasma glucose–raising) hormones are released. Among these, pancreatic ___ cell ______, which stimulates ____________, plays a primary role.

α; glucagon hepatic glycogenolysis

_______ is the second defense against hypoglycemia

Glucagon

Variations in blood glucose levels A) Hypoglycemia- Adreno- medullary ________, which stimulates ____________________ (and ——————-), is not normally critical, however, it becomes critical when ________ is deficient.

epinephrine hepatic glycogenolysis and gluconeogenesis renal gluconeogenesis; glucagon

_________ is the third defense against hypoglycemia.

Epinephrine

Variations in blood glucose levels A) Hypoglycemia- When hypoglycemia is prolonged, ______ and ______ hormone also support glucose production and limit glucose utilization.

cortisol and growth

Hypoglycemia is a laboratory ‘diagnosis’ which is usually considered a blood glucose level below _____mg/dL. Symptoms begin at plasma glucose levels in the range of ____ mg/dL and Impairment of brain function at approximately ____ mg/dL.

60 60 50

Types of hypoglycemia Spontaneous hypoglycemia in adults is of two principal types: 1) Fasting hypoglycemia: Observed in patients with ________ and __________ it is often ________ or ________ and usually presents with _________ as its principal manifestation.

pancreatic beta cell tumor and hepatocellular damage sub acute or chronic neuroglycopenia

Types of hypoglycemia • Spontaneous hypoglycemia in adults is of two principal types: Postprandial hypoglycemia: •________ hypoglycemia with ____________ insulin secretion following ______ It is relatively _____ and is often heralded by symptoms of __________________________ (sweating, palpitations, anxiety, and tremulousness).

Reactive; an elevated; a meal acute neurogenic autonomic discharge

Types of hypoglycemia 3)Insulin-induced hypoglycemia: Hypoglycemia occurs frequently in patients with ________ who are receiving insulin treatment

diabetes

Alcohol is metabolized in the liver by _____________ reactions Ethanol is first converted to _______ by _______________. And that is subsequently oxidized to ______ by _________________. In each reaction, electrons are transferred to ______, resulting in a massive increase in the concentration of __________.

two oxidation acetaldehyde; alcohol dehydrogenase acetate; aldehyde dehydrogenase NAD+; cytosolic NADH

Hypoglycemia and alcohol intoxication: Alcohol is metabolized in the liver by two oxidation reactions In each reaction, electrons are transferred to NAD+, resulting in a massive increase in the concentration of cytosolic NADH. The abundance of NADH favors the reduction of __________ to _______ and of _________ to ________ Thus, the ethanol-mediated increase in NADH causes the intermediates of _________ to be diverted into alternate reaction pathways, resulting in the decreased ______________. This can precipitate hypoglycemia, particularly in individuals who have _________________________.

pyruvate to lactate oxaloacetate to malate gluconeogenesis; synthesis of glucose depleted their stores of liver glycogen

Common causes of hypoglycemia Physiological- ________ or ________ Pathological

Pronged fasting or starvation.

Fasting hypoglycemia Drug induced- _____, oral hypoglycemic drugs,_____,__________ etc. Critical illnesses - ______,_______, or _____ failure, and _____. Hormone deficiencies-_____,_______, or both, _______ and _______ (in insulin-deficient diabetes) • Endogenous __________ • Insulinoma

Insulin; alcohol; sulfonamides Hepatic, renal, or cardiac ; sepsis Cortisol, growth hormone Glucagon and epinephrine hyperinsulinism

Fasting hypoglycemia Autoimmune (_______ to ______ or ________) _______ insulin secretion ————— hyperinsulinism and Inherited ___________

autoantibodies insulin or the insulin receptor Ectopic Congenital enzyme deficiencies

Postprandial (reactive) hypoglycemia Causes Alimentary (____________) Hereditary _____________ ______________ Idiopathic.

Post-gastrectomy fructose intolerance Galactosemia

Hyperglycemia Causes of hyperglycemia _________________ Diseases of pancreas ( ________,_______,______,________ ) Infections and ———— __________ _____________

Diabetes mellitus pancreatitis, hemochromatosis, carcinoma head of pancreas, Cystic fibrosis sepsis Anesthesia Asphyxia

Hyperglycemia Causes of hyperglycemia Hormonal tumors- ______ ,_____,_____, and ————- Pharmacologic agents (_______,______,______, and ————- ) Liver disease (______,________) Muscle disorders (______________) Adipose tissue disorders ( ————- and ___________ )

Acromegaly, Cushing'ssyn, Glucagonoma and Pheochromocytoma corticosteroids, sympatho mimetic drugs, thiazide diuretics and niacin cirrhosis, hemochromatosis myotonic dystrophy Lipodystrophy truncal obesity

Clinical implication of disturbed glucose homeostasis- GLYCOSURIA Although normal urine contains virtually ____ sugar but under certain circumstances, glucose or other sugars may be excreted in urine. This condition is called ‘_____’.

no Melituria

The term Glucosuria, Fructosuria , Galactosuria, Lactosuria and Pentosuria are applied specifically for urinary excretion of glucose, fructose, galactose, lactose and pentose respectively. T/F

Glycosuria (Glucosuria) can be classified in to two main groups A)_________ glycosuria B)_____ glycosuria

Hyperglycemic Renal

Hyperglycemia glycosuria ________ Glycosuria _______ Glycosuria

Alimentary Emotional

Hyperglycemia glycosuria Alimentary Glycosuria(Excessive _________________ ) Emotional Glycosuria(Excessive __________)- Stress, anxiety etc.

ingestion ofcarbohydrates catecholamine release

Hyperglycemia glycosuria • Glycosuria due to endocrinal disorders e.g. List 6

 Diabetes Mellitus  Hyperthyroidism  Epinephrine hyper secretion  Hyperactivity of anterior pituitary(Acromegaly)  Hyperactivity of Adrenal cortex (Cushing’s syndrome/disease)  Increased secretion of glucagon

Renal glycosuria • Renal Tubular disease ____________ ________________ disease

Fanconi's Syndrome Toxic renal tubular

Renal glycosuria • Renal Tubular disease •_____ Toxicity • _______ Toxicity • Inflammatory renal disease: ______,______ • Increased ____ without ________ •_______ renal glycosuria (Carrier protein def) • Lowering of ————— (eg in ________)

Lead Mercury acute AGN, nephrosis GFR; tubular damage Hereditary renal threshold ; pregnancy

Diabetes mellitus Diabetes mellitus is a syndrome with disordered metabolism and inappropriate _______glycemia due to either a __________________ or ___________________

hyper deficiency of insulin secretion or to a combination of insulin resistance and inadequate insulin secretion to compensate.

Diabetes mellitus T1DM is due to ____________ predominantly by __________, and these patients are prone to _______

pancreatic islet B cell destruction an autoimmune process ketoacidosis

Diabetes mellitus T2DM is the (more or less?) prevalent form and results from ________ with a defect in ____________

More insulin resistance compensatory insulin secretion

Dawn Phenomenon The dawn phenomenon and the Somogyi effect cause (low or high?) blood sugar levels, especially in the ______________, in people who have ______.

High ; morning before breakfast diabetes

Dawn Phenomenon In the early morning hours, hormones (______,______,_______) cause the ____ to release (small or large?) amounts of sugar into the bloodstream.

growth hormone, cortisol, and catecholamines liver Large

Dawn Phenomenon For most people, the body produces ____ to control the rise in blood sugar. If the body doesn't produce enough insulin, blood sugar levels can rise. This may cause (low or high?) blood sugar in the _________ ((before or after?) eating).

insulin morning Before

Somogyi Effect If the blood sugar level _______ in the _____________,hormones(such as ______,_______, and _______ ) are released. These help ______ the ____ blood sugar level but may lead to blood sugar levels that are (lower or higher?) than normal in the morning.

drops too low early morning hours GH, , cortisol, and catecholamines reverse the low ; higher

Somogyi Effect An example of the Somogyi effect is: A person who takes________, doesn't ________________, and the person's blood ___________ during the night. The person's body responds to the low blood sugar by releasing hormones that raise the blood sugar level. This may cause a high blood sugar level in the early morning.

insulin eat a regular bedtime snack sugar level drops

Somogyi Effect If the blood sugar level drops too low in the early morning hours,hormones(such as GH, cortisol, and catecholamines) are released. These help reverse the low blood sugar level but may lead to blood sugar levels that are higher than normal in the morning. An example of the Somogyi effect is: A person who takes insulin doesn't eat a regular bedtime snack, and the person's blood sugar level drops during the night. The person's body responds to the low blood sugar by releasing hormones that raise the blood sugar level. This may cause a high blood sugar • • • level in the early morning.

GLUCOSE HOMEOSTASIS AND FUEL METABOLISM Flashcards

(68 cards)