B3 The Circulatory System Review Flashcards
What are the main functions of the circulatory system?
- Transport gases, nutrients, wastes and hormones (O2, CO2)
- Regulates internal temperature
- Protects against microbes (pathogens) and toxic substances
What are the 3 main components of the circulatory system?
- Heart
- Blood vessels
- Blood
What are the 3 blood vessels?
- Arteries
- Veins
- Capillaries
Describe an Artery
-Carry blood from the heart to the body/lungs
-has highly elastic walls to allow the artery to expand
-thin to arterioles [mini arteries]
What is pulse?
-It’s a measure of the rhythmic expansion and contraction of an artery as blood moves through it
Describe a vein
-Veins carry blood from the body/lungs to the heart
-thinner walls then arteries and a larger inner circumference
-not elastic
-move blood to the heart by one way valves and skeletal muscle contractions
-venules expand to veins
Describe a capillary
-Where gases and other materials are transferred from blood to tissues and vice versa
-smallest blood vessels
-diameter is a single cell layer
-spread through the body in a network
What is a pulmonary pathway?
-Transport oxygen poor blood to the lungs
Describe the heart
-4 chambered
-made of cardiac muscle
-contractions are rhythmic and involuntary
Describe the right side of the heart
-Right side of the heart receives blood from the body (deoxygenated) through the vena cava and pumps it to the lungs via the pulmonary artery
What are pulmonary arteries?
-Only arteries which contain oxygen poor blood (all other arteries are oxygenated)
Describe the left side of the heart
-Left side of the heart receives blood from the lungs via the pulmonary veins and pumps it to the body through the aorta
What are pulmonary veins?
-Only veins which contain oxygen rich blood (all other veins are deoxygenated)
What is the sinoatrial node?
-Stimulates the muscle cells to contract and relax rhythmically (pace maker)
-in the wall of the right atrium
How does the heart contract?
- An electrical signal from the SA node spreads over the 2 atria and make them contract simultaneously
- As the atria contract, the signal reaches the atrioventricular node
- Electrical signal then proceeds through the bundle of his
- Fibers relay the signal through the 2 branches called purkinje fibers
- Stimulates contractions of the ventricles
What is an ECG (electrocardiogram)?
-Change in voltage produced by the electrical signal
-electrical system
-“lub”: closing of AV valves during ventricular contraction
-“dub”: closing of semilunar valves during ventricular relaxation
-heart murmur caused by valves not closing properly
What is blood pressure?
-The pressure exerted against the vessel (arteries) walls by blood
-measured using a sphygmomanometer (blood pressure cuff)
-average is 120/80
-high blood pressure is also called hypertension
What is systolic pressure?
-Maximum pressure during ventricular contraction
-top of the fraction representing blood pressure
What is diastolic pressure?
-Lowest pressure during ventricular relaxation
-bottom of the fraction representing blood pressure
What are baroreceptors?
-Blood pressure receptors
-in the walls of the Aorta and carotid arteries
-monitor blood pressure and signal heart to beat with more or less force
What is cardiac output?
-Amount of blood pumped by the heart per minute (mL/min)
-indicates the level of oxygen delivered to the body
-~4900 mL/min for the average person
What is heart rate?
-Number of heart beats per minute
-low resting heart rate is considered an indicator of cardiovascular fitness (if heart rate is low then stroke volume must be high)
What is stroke volume?
-Amount of blood forced out of the heart with each heart beat (mL per beat)
-average is ~70 mL per beat
