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.

Transport in animals

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Transport in animals

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Transport in animals Questions