NURS 3366 - RRD #1 Intracellular Functions and Disorders

Etiology of cellular-level disruptions

1. Hypoxia.

2. Nutritional problems - decreased glucose and/or vitamin availability for cell use.

3. Changes in balance of electrolytes and other solutes, including acid/base imbalance.

4. Changes in fluid distribution.

Hypoxia

Decrease in oxygen supply to the tissues and cells or the ability to use oxygen appropriately; always at the cellular level.

Acidosis

A state of greater-than-usual concentration of acidic substances in the blood and cells.

Aerobic

O2 is present.

Anaerobic

Low or absent O2.

The byproducts of the body's normal metabolic activities are slightly more _________ than _________.

Acidic; alkaline

pH range of blood

7.35 - 7.45

The pH range of blood is slightly _________.

Alkaline

What are the results of glycolysis?

2 molecules of pyruvate, 2 ATP, 2 NADH

Examples of what can cause Hypoxia:

1. Overworked muscles in extreme exercise (muscles use up immediate available O2).

2. Someone having difficulty breathing so they cannot get enough O2 to the heart and circulated to the tissues.

3. A cut artery in the arm - tissues distal to the trauma aren't able to get O2.

What are the two main sequela from hypoxia?

1. Deficiency of ATP for cellular functions.

2. Altered acid/base balance, especially acidosis.

Hypoxia - the cellular metabolism does what?

Recycles through glycolysis rather than completing the usual aerobic pathway.

Glycolysis is the only step of cellular respiration that _____.

Can operate under aerobic and anaerobic conditions.

Positives of anaerobic glycolysis

It can give 2 ATP per molecule of glucose.

Negatives of anaerobic glycolysis

2 molecules of ATP isn't enough to keep going long term. Plus, every time the cell goes through glycolysis, multiple molecules of pyruvate (pyruvic acid) accumulate, causing acidosis.

Is the resting membrane potential (RMP) normally negative or positive?

Negative

What happens without ATP?

The Na+/K+ pump can't maintain normal electrical cell membrane status - electrical impulses will be disrupted.

Glucose is obtained from ________________ to begin the cellular metabolic pathway.

Carbohydrates

What happens if the intake of food/glucose is greater than immediate cellular needs?

Insulin directs excess glucose to be stored as glycogen in the liver via glycogenesis.

Glycogenesis

The formation of glycogen from glucose.

If the availability of glucose is less than cellular energy needs, what happens?

You go into a state of hypoglycemia, which triggers counterregulatory hormones.

Hyperglycemia

High blood sugar

Hypoglycemia

Low blood sugar

What counterregulatory hormones are triggered by hypoglycemia?

1. Epinephrine

2. Cortisol

3. Growth Hormone (GH)

4. Glucagon

Hypoglycemia triggers, epinephrine, which is released from the...

Adrenal medulla

Hypoglycemia triggers cortisol, which is released from the...

Adrenal cortex

Hypoglycemia triggers growth hormone (GH), which is released from the...

Pituitary gland

Hypoglycemia triggers glucagon, which is released from the...

Pancreas

What is the role of the counterregulatory hormones?

They act as alarms; they bring on sensations of hunger, shakiness, sweating, irritability (being "hangry") to tell you to eat.

Which counterregulatory hormone stimulates the conversion of glycogen to glucose?

Glucagon

What is the first process after hypoglycemia (if you don't eat)?

Glycogenolysis

Glycogenolysis is considered a ________________ until we can take in glucose.

Stop-gap measure.

Glycogenolysis

The process of breaking down glycogen to glucose.

What is one of the breakdown products of fats and proteins?

Ketones

What happens if glucose isn't available and glycogenolysis has already exhausted a person's store of glycogen?

The body breaks down fats and protein through gluconeogenesis.

Gluconeogenesis

The formation of glucose from noncarbohydrate sources (e.g. fats and proteins).

What are the three main ketones?

1. Acetoacetic acid

2. Beta-hydroxybutyric acid

3. Acetone

What are two negative characteristics of ketones?

1. They are acids, which puts you at risk of acidosis over time.

2. Ketoacids can't be used by brain cells (only glucose can be used by brain cells).

If a patient presents with an altered level of consciousness, what's the first things we test?

Blood sugar

Glucosuria

Presence of glucose in the urine.

Example of glycogen storage disease

McArdle's Disease

McArdle's Disease

Autosomal recessive disease in which the normal ability to breakdown muscle glycogen (glycogenolysis) is diminished.

S/S of McArdle's Disease

Muscle weakness and cramps (during exercise due to no energy reserves).

Type I Diabetes Mellitus

Gluconeogenesis taken to the extreme due to the inability to make insulin.

Why is a Type I diabetic usually thin?

The body uses up fat and muscle due to sustained gluconeogenesis.

Sustained gluconeogenesis leads to:

Ketone over-accumulation, resulting in hyperketonemia.

Hyperketonemia

Excess levels of ketones in the blood.

Hyperketonemia is manifested by:

1. Blood test showing high serum ketones.

2. Blood test showing a blood pH of

What type of patient is at a high risk for vitamin deficiencies?

Alcoholics - this is due to a typically poor diet (lack of iron and B vitamins, like thiamine).

What is a sequela of iron deficiency?

Iron-deficiency anemia.

S/S of iron deficiency anemia

Weakness, SOB, fatigue, etc. (due to less iron for cytochromes in the electron transport chain > less ATP).

Vitamin B1 is also known as:

Thiamine

Beriberi

The thiamine-deficiency disease.

What is the sequela of Beriberi?

Neuro problems such as Wenicke-Korsakoff syndrome and paresthesia.

Wernicke-Korsakoff Syndrome

Classically associated with alcoholism and manifested as memory loss, ataxia, and eye movement issues.

Paresthesia

Numbness and tingling, or other unusual sensations; usually in the legs and feels like "pins and needles." Also seen in B12 deficiency.

Ataxia

Inability to perform coordinated movements; staggering, uncoordinated gait.

Solutes

Particles, such as electrolytes and protein molecules, that have been dissolved in a solvent (fluid).

Five electrolytes found in the body

1. Sodium (Na+)

2. Chloride (Cl-)

3. Potassium (K+)

4. Calcium (Ca+)

5. Phosphorus/Phosphate (PO4-)

Electrolytes - Sodium (Na+)

The main cation in extracellular fluids.

Electrolytes - Chloride (Cl-)

Follows Na - may travel together as NaCl (sodium chloride).

Electrolytes - Potassium (K+)

The main cation in intracellular fluids.

Electrolytes - Calcium (Ca+)

Important cation for muscle contraction and clotting.

Electrolytes - Phosphorus/Phosphate (PO4-)

The main intracellular anion; balances Ca+ in that generally when one is high, the other is low.

What is the normal resting membrane potential (RMP) of most cells?

-90 mv

Why is the RMP negative?

There are more anions (negative charges) than cations (positive charges) inside the cell membrane.

What is the normal depolarization point for most cells?

+30 mv

What happens once an electrical signal reaches a resting cell?

It changes the balance of cations and anions - cations flood the cell, increasing the positivity of the cell membrane until it gets to +30mv. This "goal charge" allows the cell to depolarize (contract).

What are the cell's two basic fluid departments?

Intracellular and extracellular

What are the two components of the extracellular compartment?

Interstitial fluid and plasma fluid

The changes in solute and fluid balance occurs first in the ___________ compartment, then spreads to the ____________.

plasma compartment (blood); interstitial fluid and cells (tissue)

Hyperkalemia

Higher-than-normal K+ numbers in the blood.

Hypokalemia

Lower-than-normal K+ numbers in the blood.

Potassium Lab Values

3.5-5.1 mEq/L

Hypernatremia

Higher-than-normal Na+ numbers in the blood.

Hyponatremia

Lower-than-normal Na+ numbers in the blood.

Sodium Lab Values

135-145 mEq/L

Hypercalcemia

Higher-than-normal Ca+ numbers in the blood.

Hypocalcemia

Lower-than-normal Ca+ numbers in the blood.

Calcium Lab Values

8.5-10.5 mg/dL

Solutes typically diffuse from areas of ___________ to areas of __________ concentration.

High; low

"emia"

In the blood.

Hypopolarization

When the resting membrane potential is a more positive number than normal, the polar status is shortened and making cells more sensitive. (e.g. instead of -90mV, it's -60mV).

Hyperpolarization

When the resting membrane potential is a less positive number than normal, the polar status is lengthened and making cells less sensitive. (e.g. instead of -90mV, it's 120mV).

States in which cells become hypopolarized:

Hypocalcemia

Hypernatremia

Hyperkalemia

S/S of hypopolarization

Manifests clinically as muscles that are too sensitive - e.g., hyperactive, "irritable," they contract with smaller-than-normal stimulation, often resulting in muscle tics or spasms (example—positive Chvostek's sign), and tetany if spasms are severe and/or unrelenting.

States in which cells become hyperpolarized:

Hypercalcemia

Hypokalemia

Hyponatremia

S/S of hyperpolarization

Muscles that are less sensitive than usual (hypoactive) and contract more slowly, fatigue, lethargy, mental slowness, and bradycardia.

Bradycardia

Heart rate less than 60 bpm

ABGs

Arterial blood gases.

What is measured in ABGs?

pH, HCO3, PCO2, PO2, SO2

pH Lab Values

7.35-7.45

HCO3 Lab Values

22-26 mEq/L

PCO2 Lab Values

35-45 mmHg

PO2 Lab Values

80-100 mmHg

SaO2 Lab Values

97-100%

Too much CO2 or H+ in the blood causes:

Acidosis

HCO3 is the chemical formula for:

Bicarbonate

S/S of Acidosis

Headache, disorientation, nausea, vomiting, muscle pain, cramps, SOB, low BP, bradycardia, shock, bradypnea, organ failure, death.

What types of acidosis are there?

Metabolic and respiratory