[PCOL-SEMIS-01-PT3] AUTACOIDS: HISTAMINE RECEPTOR

THIS FLASHCARDS IS ABOUT [PCOL] AUTACOIDS.

G-protein coupled receptors (GPCRs)

One thing to take note about these histamine receptors is that they are?

H1 to H4 receptors

These four types of histaminergic receptors are coupled with G-protein.

Gq linked receptor

What type of linkage does the H1 receptor have?

1. Extravascular smooth muscles of the bronchioles

2. Alveoli

H1 receptors are found in the (1)___________, specifically in the (2)_____.

Bronchoconstriction

(Occurs during anaphylaxis symptoms; difficulty in breathing)

What is the effect of H1 receptor once activated?

Contraction of Respiratory Airways

(AKA Shortness of Breath)

When the number of histamine is high and it binds to H1 receptor, it will activate the activation of H1 receptor in the extravascular smooth muscle. The ultimate result is?

1. Endothelial Cells

2. Blood Vessels

H1 receptors are also found in (1) cells, specifically in the (2) lining of __________.

Lining of Blood Vessels

These lining are important in the regulation of exchange of fluids or nutrients between the bloodstream and outside the tissues.

1. Capillary

2. 100% Epithelial Cells

(1) This is an example of lining of blood vessels that is made up of (2) 100% _______________.

1. Epithelial Cells

2. Contraction

Once H1 receptor is activated in the (1)____ cells there will be a (2)____.

1. Separation/Gaps of Endothelial Cells

2. Vascular Leakage

The epithelial cells are evenly lined up, once H1 receptors is activated there is contraction, causing the (1)________ of endothelial cells leading to (2)__________.

Transudation

Vascular Leakage is also known as?

Local Tissues

Due to vascular leakage, there will be accumulation of fluid in?

Local Edema

(Because of the excessive capillary permeability)

What is the ultimate effect if H1 receptors are activated in the endothelial cells?

Vascular Smooth Muscles

(Particularly in the Blood Vessels)

Aside from the endothelial cells, H1 receptors are also found in?

Vasodilation

If H1 receptor is activated in the blood vessels, what is the ultimate effect?

1. Nitric oxide

2. Prostaglandins

If histamine binds to H1 receptors in the vascular smooth muscles (blood vessels), it will release what (1)______ from the endothelial cells and the (2)________.

1. Nitric oxide

2. Prostaglandins

These are endogenous vasodilators.

1. Vasodilation

2. Hypotension

If we have the endogenous vasodilators like nitric oxide and prostaglandin, the effect is (1)______, with the ultimate effect (2)________.

Baroreceptor Reflex

(A negative feedback mechanism to maintain balance in our body)

If there is hypotension, our body has compensatory mechanism called?

Supplemental Info Only

Once our brain detected that we have hypotension (low blood pressure) it will send stimulus that would somehow increase the blood pressure.

Fever

IDENTIFY THE COMPENSATORY MECHANISM:

When our body is cold, our make heats our body up.

Coughing

IDENTIFY THE COMPENSATORY MECHANISM:

If there is obstruction, this mechanism expels it.

Supplemental Info Only

Because of the binding of histamine with H1 receptor, there is:

1. Vasodilation; if there is vasodilation

2. The blood pressure will decrease; leading to hypotension

3. The compensatory mechanism of our body is sending a signal to our brain to increase the blood pressure

4. Since the blood pressure increase, we will experience reflex tachycardia or vasoconstriction due to the baroreceptor reflex

1. Reflex Tachycardia

2. Baroreceptor Reflex

The elevation of blood pressure, we will experience (1)________ or vasoconstriction due to the (2)__________.

• Vasodilation

• Vasoconstriction

Once H1 receptors are activated in the vascular smooth muscles, both of these occur.

Heart

Aside from blood vessels, H1 receptors are also found in the?; accompanied by the response caused by vasodilation.

1. Frequent heartbeats or

2. Tachycardia

Since there is vasodilation, the result in the heart is?

Sensory Nerve Endings

Aside from the heart, H1 receptors are also found in the?

• Paint

• Itchiness

(Connected to allergy reactions

Once H1 receptors are activated in the sensory nerve endings, it will cause?

CNS (Brain)

Aside from sensory nerve ending, H1 receptors are also found in the?

Neurotransmitters

H1 receptors in the CNS (Brain), occurs as?

1. Stimulation of the Brain

2. Wakefulness

Once H1 receptors are activated in the CNS (Brain), there is a (1)________ leading to (2)________.

Drowsiness

When there is antihistamine in our CNS, we will experience weakness, because the common effect of antihistamines is?

1. Extravascular smooth muscles of the bronchioles (specifically in the Alveoli)

2. Endothelial Cells (specifically in the Lining of Blood Vessels)

3. Vascular Smooth Muscles (specifically in the Blood Vessels)

4. Heart

5. Sensory Nerve Endings

6. CNS (Brain)

What are the (6) Locations where H1 Receptors are found?

Hint: EEV-HSC