CIrculatory System

arteries (blood vessels)

• carry blood away from the heart

• branch into smaller arterioles

• thicker walled

• narrower diameter

• elastic recoil helps maintain blood pressure even when heart relaxes

capillaries (blood vessels)

• where nutrients and waste exchange occurs with surrounding cells

• very thin walls

• come together to form venules, which come together to form veins

veins (blood vessels)

• return blood to the heart (atrium)

• thinner walled

• wider diameter (blood travels back to heart at a lower velocity anad a lower pressure than found in the arteries)

atrium (chambered heart)

receives blood

ventricles

pump blood out of the heart

Blood flows from the heart in the following order (blood vessels):

ventricles —> arteries —> arterioles —> capillaries —> venules —> veins —> atrium—> ventricles

interstitial fluid

any fluid between blood vessels and cells

pre-capillary sphincters

• ring-like muscles that open and close capillaries

• control blood flow in capillaries

Exchange Across Capillary Walls

• fluid and solutes flow out of capillaries to the tissues due to blood pressure that’s higher than the osmotic pressure

• interstitial fluid flows back into capillaries when the osmotic pressure is greater than the blood pressure

  • plasma proteins are responsible for the high osmotic pressure in the capillaries

lymphatic vessels

• collect interstitial fluid and return it to the circulatory system

• maintains volume and protein concentration of blood

• drains into circulatory system near junction of vena cava and right atrium

lymph

fluid within the lymphatic system

lymph nodes

• identify and fight infections

• contain immune system cells (white blood cells including lymphocytes)

Evolution of Vertebrate Circulatory System

• fish - 2 chamber heart

• amphibian - 3 chamber hear

• reptiles - 3 chamber heart

• birds & mammals - 4 chamber heart

pulmonary circuit

carries oxygen-depleted bloods from the heart to the lungs and oxygen-rich bloods back to the heart

systemic circuit

carries oxygen-rich blood from the heart to the rest of the body and deoxygenated bloods back to the heart

lymphatic vessels

• collect interstitial fluid and return it to the circulatory system

• maintain volume and protein concentration of blood

• drain lymph into circulatory system near junction of vena cava and right atrium

lymph nodes

• identify and fight infections

• contain immune system cells (white blood cells including lymphocytes)

atrioventricular (AV) valves

• between atrium and ventricle

  • ex.tricuspid and biscuspid valves

• keeps blood from flowing back into atria when ventricles contract

semilunar valves

• between ventricle and arteries

  • ex. pulmonary valve and aortic valve

• prevent backflow from arteries into ventricles while they are relaxing

coronary artery

• carries oxygen and nutrients to cardiac cells

• if your heart cells don’t receive enough oxygen, they will die triggering a heart attack

systole blood pressure

• ventricles pump blood out

• heart contracts and pushes blood out into the arteries

• heart squeezes, pressure goes up

diastole blood pressure

• atria refill with blood

• heart relaxes and fills with blood between beats

• heart relaxes, pressure goes down

ductus venosus

carries oxygenated blood from the umbilical vein to the inferior/posterior vena cava

foramen ovale

hole between the atria which allows blood to flow from the right to left atrium

ductus arteriosus

carries oxygenated blood from the pulmonary artery to the aorta

erythrocytes

• red blood cells

• contain hemoglobin which transport oxygen

leukocytes

• white blood

• fight pathogens