diff --git a/2016-10-03-lecture04.md b/2016-10-03-lecture04.md
index 858b67a..c205af5 100644
--- a/2016-10-03-lecture04.md
+++ b/2016-10-03-lecture04.md
@@ -517,7 +517,7 @@ red indicates imaged expression of voltage gated Na channels. green indicates a
 
 ## Speed of action potential conduction in unmyelinated versus myelinated axons
 
-<div><img src="figs/Neuroscience5e-Fig-03.12-0_214d611.png" height="500px"><figcaption></figcaption></div>
+<div><img src="figs/Neuroscience5e-Fig-03.12-0_214d611.png" height="500px"><figcaption>Neuroscience 5e Fig. 3.12</figcaption></div>
 
 
 Note:
@@ -556,11 +556,9 @@ Note:
 * Blocks action potentials in sensory axons
 * Pain signals do not reach the brain
 
-<div><img src="figs/neuron_model-sensory_7bb4f48.png" height="100px"><figcaption></figcaption></div>
-
-<div><figcaption class="big">voltage-gated sodium channel</figcaption><img src="figs/Neurochem-Fig6-6_4995928.png" height="300px"><figcaption>Basic Neurochemistry 6e Fig. 6.6</figcaption></div>
-
+<div><img src="figs/neuron_model-sensory_b716495.png" height="100px"><figcaption></figcaption></div>
 
+<div><figcaption class="big">voltage-gated sodium channel and drug binding sites</figcaption><img src="figs/voltage-gated-sodium-channel-structure_03f168c.png" height="300px"><figcaption>Adapted from Basic Neurochemistry 6e Fig. 6.6</figcaption></div>
 
 
 Note: