more unit two stuff

heart secondary function

helps maintain homeostasis of blood pressure and acts as an endocrine organ

Frank-Starling law

According to this law, increased ventricular muscle cells stretch, leads to more forceful contraction

Frank-Starling law

Stretching causes a more optimal overlap of actin and myosin
filaments in muscle cells; enables a stronger contraction and a higher stroke volume

Frank-Starling law

Ensures that volume of blood discharged from heart is equal to volume that enters it

vascular anastomoses

locations where vessels connect via pathways called collateral
vessels

Arterial anastomoses

heart brain and around joints. formed when blood flow through artery insufficient to meet tissue needs

venus anastomoses

most common. Small collateral connect neighboring veins. some veins so small, make weblike pattern

Diffusion and osmosis through gaps and pores

fenestrated capillaries. Some capillaries have small pores within their endothelial cells, called fenestrations Water, as well as small substances that are dissolved in water, are able
to move freely through these pores when a gradient exists

Diffusion through membranes of endothelial cells

Lipid-soluble substances such as oxygen, carbon dioxide, and certain lipids can generally enter and exit capillary by diffusing across membrane of one side of endothelial cell and out membrane on other side
Substances then enter either interstitial fluid or blood

Transcytosis

Used for larger molecules. Molecules are taken into cell by endocytosis and then are moved out other side of cell by exocytosis

myogenic mechanism

slows flow by increasing arteriolar pressure and vice versa

platelets

smallest of formed elements. Don’t have nucelli or organelles. some cytoskeleton elements

erythropoietin

causes a negative feedback loop that keeps hemocrit at normal range and regulates erythropoiese