CCEA A-Level Life and Health Sciences 0008
Experimental Techniques
Human Body Systems
Physical Chemistry in Industrial Processes
Brain ScienceDouble Award
Material ScienceDouble Award
Medicine, Drugs and Clinical TrialsDouble Award
Scientific Method, Investigation, Analysis and Evaluation
Organic Chemistry
Medical PhysicsA2 option
Sound and LightA2 option
Genetics, Stem Cell Research and CloningA2 option
MicrobiologyDouble Award
Oral Health and DentistryDouble Award
Histology and PathologyDouble Award
Analytical Chemistry TechniquesDouble Award
Enabling TechnologyDouble Award
Human Body Systems
Sodium, blood pH and oxygen saturation
- 3 things to know
- AS 2
Overview
Sodium balance and imbalance, the normal range of blood pH, buffering by blood, lungs and kidneys, acidosis and alkalosis, oxygen saturation and how a pulse oximeter works.
What you need to know
Answer each one before you reveal it.
Why are sodium and chloride ions important for health?
What happens if blood sodium is too high or too low?
Questions from this subtopic
Each one with the model answer underneath.
- 1
How is sodium balance regulated in the body?
Model answer
The kidneys adjust how much sodium is reabsorbed or excreted in urine. Aldosterone from the adrenal glands increases sodium reabsorption.
- 2
Why are sodium and chloride ions important for health?
Model answer
Sodium and chloride ions control the balance of water between body fluids. Sodium ions are also essential for nerve impulses and muscle contraction.
- 3
What happens if blood sodium is too high or too low?
Model answer
High sodium draws water from cells and is linked to high blood pressure. Low sodium can cause confusion, cramps and, in severe cases, seizures.
- 4
What is the normal range of blood pH?
Model answer
Normal blood pH is between 7.35 and 7.45. The narrow range is needed for enzymes and proteins to work properly.
- 5
How is blood buffered to keep its pH stable?
Model answer
The hydrogencarbonate buffer system mops up excess hydrogen ions or releases them as needed. Plasma proteins and haemoglobin also act as buffers.
- 6
How do the lungs and kidneys help control blood pH?
Model answer
The lungs remove carbon dioxide, which forms acid in the blood. The kidneys excrete hydrogen ions and retain hydrogencarbonate.
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