Unit 4: Ammonia

__________ is produced in the deamination of amino acids during protein metabolism.

Ammonia

It is removed from the circulation and converted to urea in the liver.

Ammonia

___________ is toxic; however, ammonia is present in the plasma in _____________

Free ammonia

low concentrations

BIOCHEMISTRY AND PHYSIOLOGY

Ammonia (NH3) is produced in the ____________ and by _________ in the lumen of the intestine.

catabolism of amino acids

bacterial metabolism

BIOCHEMISTRY AND PHYSIOLOGY

Some _____________ results from anaerobic metabolic reactions that occur in skeletal muscle during exercise.

endogenous ammonia

BIOCHEMISTRY AND PHYSIOLOGY

Ammonia is consumed by the _____________ in the production of urea.

parenchymal cells of the liver

BIOCHEMISTRY AND PHYSIOLOGY

At normal physiologic pH, most ammonia in the blood exists as _______________.

ammonium ion (NH4+)

BIOCHEMISTRY AND PHYSIOLOGY

1. The main source of ammonia is _______________ and ________________, where the ammonia is derived from the intestinal bacteria that breakdown proteins.

2. Ammonia is produced in the ________________, ___________, ___________ as the end product of protein metabolism.

• Ammonia is a by-product of ____________.

• The major source of NH3 is the ____________.

• In the hepatic portal vein, NH3 concentration is ________________ than the systemic circulation.

3. Most of the ammonia is made by ___________ acting on protein present in the intestine.

4. This intestinal ammonia enters the blood and reaches the liver; by way of the ______________.

5. The liver converts ______________ which is then excreted by the kidneys

skeletal muscles (urea cycle) and the gut

liver, intestine, and kidneys

• protein catabolism

• gastrointestinal tract

• 5 to 10 times higher

bacteria

portal vein

ammonia into urea,

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Clinical conditions in which blood ammonia concentration provides useful information are ______________, ________________, _______________

hepatic failure, Reye’s syndrome, and inherited deficiencies of urea cycle enzymes

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

HEPATIC FAILURE

____________ is the most common cause of disturbed ammonia metabolism

Severe liver disease

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

HEPATIC FAILURE

______________ is a better indicator of the severity of disease

Arterial ammonia concentration

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Occurring most commonly in children

Reye’s syndrome

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

A serious disease that can be fatal

Reye’s syndrome

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Preceded by a viral infection and the administration of aspirin

Reye’s syndrome

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

An acute metabolic disorder of the liver

Reye’s syndrome

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Autopsy findings show severe fatty infiltration of that organ

Reye’s syndrome

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Blood ammonia concentration can be correlated with both the severity of the disease and prognosis

Reye’s syndrome

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Survival reaches 100% if plasma NH3 concentration remains below five times normal

Reye’s syndrome

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Testing should be considered for any neonate with unexplained nausea, vomiting, or neurological deterioration associated with feeding

Inherited deficiencies of urea cycle enzymes

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Inherited deficiencies of urea cycle enzymes

Assay of blood ammonia can be used to monitor _________________

hyperalimentation therapy

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Inherited deficiencies of urea cycle enzymes

______________ can be used to confirm the ability of the kidneys to produce ammonia

Measurement of urine ammonia

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

In severe liver disease in which there is significant collateral circulation or if parenchymal liver cellfunction is severely impaired, ______________ is not removed from the circulation and blood concentration increases.

ammonia

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

_____________ are neurotoxic and often associated with encephalopathy.

High concentrations of NH3

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

___________ may be partly a result of increased extracellular glutamate concentration and subsequentdepletion of adenosine triphosphate (ATP) in the brain

Toxicity

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

Associated with inherited deficiency of enzymes of the urea cycle

Hyperammonemia

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY]

Measurement of plasma ammonia is important in the diagnosis and monitoring of these inherited metabolic disorders

Hyperammonemia

CLINICAL SIGNIFICANCE AND PATHOPHYSIOLOGY

In congenital urea cycle disorders, detoxification of ammonia is impaired, leading to ____________________.

hyperammonemia