lec 8-Fundamentals of Physiology: Practicals

Vocabulary and key concepts from Fundamentals of Physiology practicals, covering cardiovascular and respiratory modules, measurements, and pathologies.

Mean Arterial Pressure (MAP)

The average pressure in a patient's arteries during one cardiac cycle, calculated as $\text{MAP} = \text{diastolic BP} + (\frac{\text{pulse pressure}}{3})$.

Pulse pressure

The difference between systolic and diastolic blood pressure ($\text{systolic} - \text{diastolic}$).

Total Peripheral Resistance (TPR)

The resistance to blood flow offered by all of the systemic vasculature, excluding the pulmonary vasculature.

Orthostatic hypotension

A condition that would cause dizziness or fainting upon moving from supine to standing if the baroreceptor reflex did not correct for the reduced stroke volume and cardiac output.

Mammalian diving reflex

An oxygen-saving response triggered by facial immersion in cold water characterized by selective vasoconstriction, greatly increased TPR, reduced heart rate, and a net increase in MAP.

Sphygmomanometer

A technique used to calculate MAP by measuring systolic and diastolic blood pressure, typically from the brachial artery.

ECG P wave

The component of the electrocardiogram representing atrial depolarisation.

ECG QRS complex

The component of the electrocardiogram representing ventricular depolarisation.

ECG T wave

The component of the electrocardiogram representing ventricular repolarisation.

R-R interval

The time between heartbeats used to calculate heart rate in beats per minute using the formula $\text{HR (bpm)} = \frac{60}{\text{R-R interval (in secs)}}$.

Central chemoreceptors

Specialised neurons in the medulla that detect changes in $PCO_2$ in arterial blood to determine breathing rate.

Hyper-ventilation

Over-ventilation in proportion to metabolism where $CO_2$ is expired faster than it is produced, leading arterial $PCO_2$ to drop below normal ($< 5.3\text{\text{\text{\text{,}}}kPa}$).

Tidal Volume ($V_T$)

The volume of air inspired and the volume expired during normal regular breathing, approximately $500\text{\text{\text{\text{,}}}ml}$ for males and $400\text{\text{\text{\text{,}}}ml}$ for females.

Inspiratory Reserve Volume (IRV)

The maximum amount that lung volume can be increased above the Tidal Volume ($V_T$).

Expiratory Reserve Volume (ERV)

The maximum extra volume of air that can be expired after expiring the Tidal Volume ($V_T$).

Residual Volume (RV)

The volume of air remaining in the lungs after maximal expiratory effort, meaning the lungs cannot be completely emptied.

Inspiratory Capacity (IC)

The sum of the Inspiratory Reserve Volume and Tidal Volume ($IRV + V_T$).

Vital Capacity (VC)

The sum of the Inspiratory Reserve Volume, Tidal Volume, and Expiratory Reserve Volume ($IRV + V_T + ERV$).

Functional Residual Capacity (FRC)

The sum of the Expiratory Reserve Volume and Residual Volume ($ERV + RV$); cannot be measured directly because it includes RV.

Total Lung Capacity (TLC)

The sum of all four lung volumes ($IRV + V_T + ERV + RV$).

Pneumotachograph spirometer

An instrument used to measure lung volumes and capacities, with volumes recorded at ATPS and converted to BTPS by multiplying by $1.09$.

Minute ventilation

The volume of air breathed every minute, calculated as $\text{breathing rate (breaths per min)} \times \text{tidal volume (vol of each breath)}$.

Vitalograph

An evaluation tool for lung function that records the cumulative volume of air expired over time during a single forced expiration.

Forced Expiratory Volume (FEV1)

The volume of air that can be forcibly expired from the lungs in the first second of a forced expiration.

Forced Vital Capacity (FVC)

The total volume of air that can be forcibly expired from the lungs, typically measured over approximately $6\text{\text{\text{\text{,}}}sec}$.

Forced Expiratory Ratio (FER)

The ratio of $\frac{FEV_1}{FVC}$, which is normally around 75\text{\text{\text{\text{,}}}\text{\text{\text{\text{%}}}}} in healthy lungs.

Obstructive lung disease

A condition (e.g., asthma or emphysema) where airways are narrowed or collapse, making it difficult to breathe out and resulting in a low FER (< 50\text{\text{\text{\text{,}}}\text{\text{\text{\text{%}}}}}).

Restrictive lung disease

A condition (e.g., lung fibrosis) where the lung cannot expand fully, resulting in a reduced Vital Capacity but a high FER (> 90\text{\text{\text{\text{,}}}\text{\text{\text{\text{%}}}}}).

BTPS

Body Temperature and Pressure, Saturated; the standard conditions for reporting lung volumes.