Question 19 – Exchange and transport - Questions

The table below compares the hydrostatic and oncotic pressures of a blood capillary with those of the surrounding tissue fluid in a specific skeletal muscle bed:

Pressure type	Capillary	Tissue fluid
Hydrostatic pressure	$kPa4.2\text{ kPa}$	$kPa0.35\text{ kPa}$
Oncotic pressure	$kPa3.6\text{ kPa}$	$kPa0.15\text{ kPa}$

The net rate of fluid movement ( $J_v$ ) across the capillary wall can be modeled by Starling's equation:

J_v = (P_c - P_i) - \sigma(\pi_c - \pi_i)

Where:

$P_c$ = capillary hydrostatic pressure
$P_i$ = tissue fluid hydrostatic pressure
$πc\pi_c$ = capillary oncotic pressure
$πi\pi_i$ = tissue fluid oncotic pressure
$σ\sigma$ = reflectance factor (a measure of the capillary wall's impermeability to plasma proteins, ranging from $0$ for fully permeable to $1$ for fully impermeable)

In this muscle bed, the capillary wall has a reflectance factor ( $σ\sigma$ ) of $0.75$ . Calculate the net driving force, $J_v$ , and state the direction of net fluid movement.

During a systemic inflammatory response, histamines are released that increase the permeability of the capillary walls to plasma proteins, causing the reflectance factor ( $σ\sigma$ ) to decrease. Explain the effect of this change on the net driving force ( $J_v$ ) and the volume of tissue fluid formed.

The table below compares the hydrostatic and oncotic pressures of a blood capillary with those of the surrounding tissue fluid in a specific skeletal muscle bed:

Pressure type	Capillary	Tissue fluid
Hydrostatic pressure	$kPa4.2\text{ kPa}$	$kPa0.35\text{ kPa}$
Oncotic pressure	$kPa3.6\text{ kPa}$	$kPa0.15\text{ kPa}$

The net rate of fluid movement ( $J_v$ ) across the capillary wall can be modeled by Starling's equation:

J_v = (P_c - P_i) - \sigma(\pi_c - \pi_i)

Where:

$P_c$ = capillary hydrostatic pressure
$P_i$ = tissue fluid hydrostatic pressure
$πc\pi_c$ = capillary oncotic pressure
$πi\pi_i$ = tissue fluid oncotic pressure
$σ\sigma$ = reflectance factor (a measure of the capillary wall's impermeability to plasma proteins, ranging from $0$ for fully permeable to $1$ for fully impermeable)

In this muscle bed, the capillary wall has a reflectance factor ( $σ\sigma$ ) of $0.75$ . Calculate the net driving force, $J_v$ , and state the direction of net fluid movement.

Exchange and transport

Question 13

Exchange and transport

Question 13

Exchange and transport

Question 13

Exchange and transport Questions

Exchange and transport

Question 13

Exchange and transport Questions