Answer:
C) Release of von Willebrand factor (vWF) from the endothelium, not the epithelium.
Explanation:
Hemostasis is the physiological process of reparation and maintenance of a blood vessel to stop excess loss of blood in case of vascular injury. This process occurs in four stages:
- Vascular Injury i.e. a breach in the endothelial barrier. This results in the dislodge of endothelial cells, exposing the collagen fibers underneath.
- Vascular constriction or vasoconstriction is the constriction of the blood vessels to prevent excessive blood loss.
- Platelet plug formation involves the aggregation and adhesion of platelets to the endothelium.
- Coagulation
Platelet plug formation occurs by the adhesion of circulating platelets to the collagen fibers that have been exposed by dislodging of the endothelial cells. The endothelium, as well as the platelets release a ligand known as the von Willebrand factor (vWF). This molecule acts as a relay or bridge between the integrin receptors on the platelets and the exposed collagen fibers.
Platelets also release chemicals to attract more platelets to the wound site, resulting in more vWF release. This results in more and more platelets adhering to the endothelium, leading to platelet plug formation.
Yes we have to maintain homeostasis so our bodies have to adapt to Mother Nature
<h2>Cannon -Bard theory</h2>
Explanation:
- Alone in the woods, Pedro hears a noise. He thinks he sees a bear coming toward him. His heart starts pounding and then, a moment later, he realizes how frightened he is. This sequence of events is BEST explained by the <u>Cannon-Bard t</u>heory of emotion.
According to Cannon-Bard theory, all the emotional expressions occur due to the stimulation of hypothalamic structures present in brain. This theory also states that feeling and physiological effects of an emotional stimuli occurs simultaneously.
Here, James thinks that a bear is coming, this is a stimulus. His heart starts pounding that is the physiological effect of the stimulus and the next moment he feels frightened which is a feeling.
So we conclude that in this case, the physiological effect and feeling of emotion occurred simultaneously. So these sequence of events is best explained by Cannon-Bard's theory.
