Ischaemia and Hypoxia Overview

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Questions and Answers

Which reactive species is NOT typically considered a reactive oxygen species (ROS)?

Superoxide

Nitric Oxide (correct)

Hydroxyl Radical

Hydrogen Peroxide

What condition is defined as the injury caused by reintroducing blood flow after ischaemia?

Cellular Hypoxia

Ischaemia-Reperfusion Injury (correct)

Oxidative Stress

Acute Inflammation

How much of the total body water is made up of intracellular fluid (ICF)?

Two thirds (correct)

Three quarters

One quarter

One half

Which statement is true regarding the production of ROS?

They are byproducts of normal homeostatic processes. Signup and view all the answers

What can excess ROS lead to following reperfusion after ischaemia?

Further cellular damage Signup and view all the answers

Which type of fluid makes up the extracellular fluid (ECF)?

Interstitial fluid Signup and view all the answers

What is a potential complication following cardiac reperfusion in patients with myocardial ischaemia?

Ventricular dysrhythmias Signup and view all the answers

Why is hydration considered vital for the body's functions?

It makes up more than 50% of body weight and is involved in biochemical reactions. Signup and view all the answers

What does the phrase 'time is tissue' emphasize in the context of ischemic events?

The urgency of restoring blood flow to prevent cell death Signup and view all the answers

Which of the following can cause ischemia?

Obstructed blood flow Signup and view all the answers

What is the relationship between hypoxia and cell death?

Hypoxia and ischemia lead to cell death Signup and view all the answers

Why is early recognition of ischemic tissue critical?

It may result in the provision of reperfusion therapy Signup and view all the answers

What is a common misconception about hypoxia?

Hypoxia leads to immediate tissue death Signup and view all the answers

What clinical action can help reduce hypoxic cell injury?

Correctly assessing the patient and managing airway Signup and view all the answers

When is ischemia considered a time-critical condition?

In cases of strokes and heart attacks Signup and view all the answers

What does the reduced availability of oxygen in the atmosphere indicate?

It can contribute to hypoxia under certain conditions Signup and view all the answers

What is the primary process through which water moves in and out of cells?

Osmosis Signup and view all the answers

Which process predominantly contributes to the loss of water under normal conditions?

Urination Signup and view all the answers

What role do aquaporins play in cells?

They facilitate the movement of water Signup and view all the answers

Where is hydrostatic pressure the highest in the circulatory system?

In arteries Signup and view all the answers

What is the primary function of oncotic pressure?

To withdraw fluid back into the vessel Signup and view all the answers

What happens to any fluid that is not drawn back into the bloodstream by oncotic pressure?

It is collected by the lymphatic system Signup and view all the answers

Which statement about hydrostatic and oncotic pressure is true?

Hydrostatic pressure is responsible for pushing water out of blood vessels. Signup and view all the answers

Which process is primarily responsible for fluid movement in the presence of higher solute concentration inside the vessel?

Oncotic pressure Signup and view all the answers

What condition is characterized by the accumulation of fluid in the interstitial space?

Edema Signup and view all the answers

What primarily drives the osmotic movement of fluid back into a blood vessel?

Oncotic pressure Signup and view all the answers

Which of the following is a common complication of fluid therapy?

Pulmonary edema Signup and view all the answers

In the capillaries, which factor contributes to fluid reabsorption?

Oncotic pressure gradient Signup and view all the answers

What effect does increased hydrostatic pressure have on fluid movement?

Causes fluid to leak into interstitial spaces Signup and view all the answers

Which of the following statements about edema is true?

Edema can be a sign of deteriorating health Signup and view all the answers

Which vessels primarily have the highest hydrostatic pressure?

Arteries Signup and view all the answers

What is the primary factor that can lead to increased hydrostatic pressure?

Heart failure Signup and view all the answers

What symptoms did Phyllis exhibit that led to paramedics being called?

Significant pitting oedema Signup and view all the answers

How does sodium influence water movement in the body?

Through osmotic gradients to regulate water balance Signup and view all the answers

What is the normal concentration range for sodium in the extracellular fluid?

135 - 145 mEq/L Signup and view all the answers

Which of the following best describes the relationship between sodium and chloride?

Chloride balances the charge of sodium to maintain neutrality. Signup and view all the answers

What could be a potential cause for Phyllis' leg swelling and reluctance to walk?

Fluid retention due to pitting oedema Signup and view all the answers

What roles do the kidneys play regarding sodium levels in the body?

They are involved in maintaining sodium concentration through regulation. Signup and view all the answers

Which electrolytes are considered the main positive electrolytes in the body?

Sodium, potassium, calcium, and magnesium Signup and view all the answers

What type of transport does chloride utilize in relation to sodium?

Passive transport proportionate to sodium movement Signup and view all the answers

Study Notes

Time is Tissue

Prolonged tissue deprivation of oxygenated blood increases the risk of cell death and permanent damage.
Early intervention is crucial to minimize tissue loss and improve patient outcomes.

Ischaemia

Reduced oxygen in the atmosphere does not automatically result in ischaemia.
Ischaemia is caused by obstructed blood flow, reduced blood volume, low oxygen levels, or external pressure on blood vessels.

Hypoxia and Ischaemia

Hypoxia and ischaemia are the most common causes of cell death.
Some cells can regenerate, but others are permanently lost upon death.
Proper assessment and airway management/oxygenation can reduce or avoid hypoxic cell injury/death.
Ischaemia is time-critical in situations such as strokes and heart attacks.

Reperfusion Injury

Restoring blood flow to a cell can lead to further injury known as ischaemia-reperfusion injury.
This occurs because oxygen molecules interact with reactive oxygen species (ROS) during reperfusion, causing ROS to multiply and damage cells.

Paramedic Considerations

Some paramedic treatments resolve ischaemia, potentially leading to ischaemia-reperfusion injury.
Reperfusion in myocardial ischaemia may cause temporary cardiac dysrhythmias like ventricular fibrillation or tachycardia.

Total Body Water

Total body water is divided into intracellular fluid (ICF) and extracellular fluid (ECF).
ICF comprises two-thirds of total body water.
ECF comprises the remaining third and is further divided into interstitial fluid and intravascular fluid.

Water Loss

Under normal conditions, most water loss occurs through urine, breathing, sweat, and faeces.
The majority of water loss is through urine.

Osmosis

Osmosis is the movement of water through a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration.
In cells, water moves across the lipid bilayer through aquaporins, which are protein water channels.

Hydrostatic Pressure

Hydrostatic pressure is the pressure inside of vessels.
Fluid under pressure is pushed out of vessels, primarily water.
Hydrostatic pressure is highest in arteries due to higher pressure in the arterial system.

Oncotic Pressure

Oncotic pressure, also called osmotic pressure, is the pull of fluid back into vessels due to osmosis.
This pull is caused by the higher concentration of proteins like albumin inside the vessel.
Under homeostatic conditions, any fluid not drawn back in by oncotic pressure is collected by the lymphatic system.
Oncotic pressure is highest in the veins because of lower pressure in the venous system and less hydrostatic pressure.

Fluid Pressure

Fluid pressure is highest in arteries.

Osmotic Movement

The osmotic movement of fluid back into a blood vessel is due to oncotic pressure.

Oedema

Oedema is the accumulation of fluid in the interstitial space.
The four main causes of oedema are:
- Increased hydrostatic pressure
- Reduced oncotic pressure
- Increased capillary permeability
- Lymphatic obstruction

Case Study - Phyllis

Phyllis presents with significant pitting oedema in her right foot and leg, swollen up to the thigh.
This suggests increased hydrostatic pressure in the lower extremity, potentially due to venous insufficiency or heart failure.

Electrolytes

Electrolytes are molecules with either a positive or negative charge.
The main positive electrolytes in the body are sodium, potassium, calcium, and magnesium.
The main negative electrolytes are chloride, bicarbonate, phosphate, and sulfate.

Sodium

Sodium (Na+) is the main extracellular cation, responsible for regulating water balance and extracellular volume.
Its concentration is maintained by the kidneys, neural, and hormonal processes.

Chloride

Chloride (Cl-) is the main extracellular anion and balances the charge of sodium.
Its transport is passive and is proportionately related to sodium movement.

Sodium Concentration

The normal sodium concentration is 135-145 mEq/L.

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Description

Explore the critical concepts of ischaemia and hypoxia and their effects on tissue health. Understand the factors causing tissue deprivation and the importance of timely intervention in medical emergencies such as heart attacks and strokes. This quiz will help deepen your understanding of how these conditions lead to cell death and the significance of reperfusion injury.