The cardiovascular system

How blood gets around the body

Types of blood vessels

• Arteries– Carry blood away from the heart– Get progressively smaller– Arteries (large elastic, medium muscular);

arterioles; capillaries– Can constrict or dilate

• Veins– Carry blood back to the heart– Venules, veins

Comparison of arteries and veins

Functions of different types of arteries

• Elastic arteries– Largest diameter– Move blood to muscular arteries– Aorta, brachiocephalic, common carotid, subclavian, vertebral,

pulmonary and iliac • Muscular arteries

– More susceptible to dilation and constriction• Arterioles

– Deliver blood to capillaries– Resistance to blood flow

• Capillaries- molecular exchange– Absent from surface epithelia, cornea nad lens and cartilage

Different types of capillaries• Continuous

– Skeletal and smooth muscle, connective tissue and lungs

• Fenestrated (holes)– Kidneys, villi of small

intestine, endocrine glands

• Sinusoid (big holes)– Red marrow, liver,

spleen

Venules converge into veins• Designed to bring

blood back to the heart

• Can serve as a reservoir of blood (can hold up to 64% of blood at rest)

• Valves are critical to keep blood moving in the right direction

Circulatory routes of blood; pulmonary and systemic most prominent

Studying the circulatory routes

• Exhibits give an overview of the vessels themselves and how they are organized

• Origins of names of the blood vessels• Note that there are superficial and deep

vessels (arteries are mostly deep)• Regions supplied (arterial) or drained

(venous)• Illustrations- you have seen some of the

major vessels in cats already!

Aorta and its branches (all systemic arteries)

Example: branching of the abdominal aorta

Three systemic veins return blood to the heart

• Superior vena cava- head, neck, chest, upper limbs

• Inferior vena cava-abdomen, pelvic, lower limbs

• Coronary sinus-myocardium• Venous networks are more irregular• Tend to be more superficial (good for

injections or blood draws)

Principal veins

The hepatic portal system• Portal carries blood

from one network to another without going through the heart

• Sends blood from GI tract and spleen to liver before going to the heart

• Blood is “processed” in the liver

Blood flow to, from and through hepatic portal system

Pulmonary circulation

Fetal circulation• Gas exchange occurs

with maternal blood (within placenta)

• Fetal lungs, kidneys and GI organs don’t function until birth

• Umbilical vein delivers oxygen to fetus

• Umbilical artery returns blood to placenta

Fetal circulation changes significantly after birth

Disorders of the circulatory system

• Hypertension• Atherosclerosis• Risk factors:

– Excess weight– Sedentary lifestyle– Dietary– Smoking– Genetic– Aging