circulatory system - blood vessels, venous return, blood pressure

function of circulation/blood vessels

1. closed system of tubes - transport blood/materials

2. exchange of materials between blood and tissues

3 types of blood vessels

1. arteries

2. veins

3. capillaries

arteries

• thick muscular walls, highly elastic

• carry blood away from heart under high pressure

• normally carry oxygenated blood

veins

• thinner walled

• may contain certain valves to prevent backflow of blood with low pressure

capillaries

microscopic vessels that permit the exchange of nutrients and wastes between blood vessels and tissues

4 divisions of circulatory routes

1. coronary

2. cerebral

3. hepatic portal

4. renal

coronary circulation

blood supply to the muscles of the heart itself

cerebral circulation

blood supply to the brain

hepatic portal circulation

• venous blood from GI organs/spleen feed into hepatic portal vein and liver

• materials are modified/processed by liver before continuing onto general circulation

renal circulation

vessels into/out of kidneys where blood is filtered; nitrogenous wastes removed

aorta

• major artery

• delivers oxygenated blood from the left ventricle to systemic circulation

pulmonary artery

• major artery

• delivers deoxygenated blood to the lungs from the right side of the heart

carotid arteries

• major artery

• deliver oxygenated blood to the brain and face; crucial for thinking, speech, movement, and sense

subclavian arteries

• major artery

• provide oxygen-rich blood to the head, neck, and upper limbs through their many branches

hepatic arteries

• major artery

• supply oxygenated blood to the liver, gallbladder, pylorus of the stomach, pancreas, and duodenum

• crucial for liver, vital for metabolic functions

mesenteric arteries

• major artery

• supply blood to the digestive system including organs like intestines, stomach, and spleen

renal arteries

• major artery

• transport oxygenated blood from the aorta to the kidneys so they can filter waste products

iliac arteries

• major artery

• transport blood from the aorta to the lower part of the body

jugular veins

• major vein

• remove deoxygenated blood from brain, face, and neck and return it to the heart through the superior vena cava

• located in neck

subclavian veins

• major vein

• remove deoxygenated blood from upper extremtiies including arms, neck, and shoulders; located just below collarbones

pulmonary veins

• major vein

• transport oxygenated blood from the lungs to the left atrium of the heart; located in lungs/heart

superior vena cava

• major vein

• returns deoxygenated blood from the head, neck, arms, and chest into the right atrium

inferior vena cava

• major vein

• transports deoxygenated blood from the lower body, abdomen, and pelvis back to the right atrium

hepatic vein

• major vein

• drain deoxygenated blood from the liver and transport to inferior vena cava

hepatic portal vein

• major vein

• transport nutrient-rich blood from GI tract, spleen, pancreas, and gallbladder to the liver to be processed

renal veins

• major vein

• drain blood from the kidneys and return to the heart; located in abdominal cavity

iliac veins

• major vein

• drain deoxygenated blood from lower limbs, pelvis, and gluteal region and return it to the heart

• located in pelvis

venous return

volume of blood flowing back to the heart through systemic veins

3 factors of venous return

• heart

• skeletal pump

• respiration pump

heart impact on venous return

left ventricle pushes blood through the systemic vessels by contracting

skeletal pump

contraction of leg muscles cause blood to be pushed through valves closer to the heart and back against valves further from the heart

respiration pump

• inhalation: thoracic cavity pressure below pressure of abdominal cavity; abdominal vessels are compressed and a greater volume of blood moves into the decompressed thoracic veins/RV

• exhalation: pressure reverses; valves prevent backflow of blood

sphygmomanometer

blood pressure cuff

blood pressure

the pressure of the blood pressing against walls of blood vessels

4 factors affecting blood pressure

1. heart rate/stroke volume

2. blood volume

3. blood viscosity

4. diameter of blood vessels

vasoconstriction

smooth muscles contract narrowing vessels; increases blood pressure

vasodilation

smooth muscles relax and enlarge diameter of blood vessels; decreases blood pressure

systolic blood pressure

force exerted by blood on walls of arteries during periods of ventricular contraction

diastolic blood pressure

force exerted by blood on walls of arteries during periods of ventricular relaxation

normal blood pressure

less than 180 mmHg/80 mmHg

hypertension

chronic high blood pressure

causes of hypertension

• poor diet

• sedentary lifestyle

• family history

• overweight

• age

• stress

effects of hypertension

• damage to blood vessels, heart, brain, and kidneys

• vessels in brain can rupture and cause a stroke due to brain hemmorhage

• ventricles of heart work harder —> long term wearing of heart/heart failure