Circulation Flashcards
What are the two types of circulatory systems?
The open circulatory system and the closed circulatory system.
What is an open circulatory system?
- It consists of a fluid called hemolymph (interstitial fluid)
- Hemolymph is pumped into body cavities known as sinuses.
- Arthropods and most mollusks have this system
What is a closed circulatory system?
- Blood moves in vessels
- Annelids and all vertebrates have a closed circulatory system
- High blood pressures are seen which allow for more effective O2 and nutrient delivery to body cells.
What are the three types of vessels?
- Arteries, veins, and capillaries are the three main types of vessels.
Describe arteries
- They are under high pressure and they are rich in O2. - - They carry blood away from the heart.
- They are strong and elastic with 3 distinct layers with thick walls.
- They get progressively smaller and make way to arterioles. These convey blood to capillaries and also have three layers
Why is resistance the highest in arterioles? Why is this significant?
There is the biggest drop in diameter from arteries to arterioles. The drop in diameter increases the surface area blood must travel against, increasing resistance. Capillaries also have a small diameter, but they are more numerous, therefore there is less resistance overall.
Due to their high resistance, arterioles are the perfect place for the body to control blood flow and blood pressure by vasoconstriction or vasodilation of the arterioles.
What are the three layers of arteries?
- An outer layer (tunica adventitia) of connective tissue with collagen fibers.
- A middle layer (tunica media) of circularly arranged smooth muscle and elastic fibers.
- An inner layer (tunica intima) (endothelium), consisting of a specialized simple squamous epithelium, often called the endothelium, that lines all blood vessels and the endocardium of the heart.
- The basement membrane, a subendothelial layer composed of connective tissue, supports the endothelium and resides between the endothelium and the tunica media
Describe capillaries
- They are distributed throughout all body tissues
- Smallest blood vessels
- Single layer of squamous epithelium
- Speed of blood is the slowest
- The thin walls allow for easy substance exchange (O2 and nutrients) through diffusion mostly.
- Largest cross sectional area of any part of the circulatory system. (There are so many capillaries, that despite their very small size, all of their cross sections added up is larger than any other part of the circulatory system. This is also why the blood speed is so slow, as cross section size is inversely proportional to blood flow speed. )
- Capillaries converge into a venule, which then converge into veins.
Describe Veins
- There is very little blood pressure remaining by the time the blood gets to the veins, due to the slow down of the blood from the capillaries.
- Veins are high in CO2 concentration generally
- They also have three layers, but they are thinner and have less smooth muscle and less elasticity than arteries.
- Many veins have valves
- Due to the low blood pressure, valves are needed to prevent the backflow of blood while muscle contractions push the blood along the veins toward the heart.
Describe how capillaries filter liquid and nutrients out of capillaries and then back in.
When blood first enters the arterial end of the capillary there is a high blood pressure. The blood pressure pushes liquid into the interstitial space through the thin layer of squamous cells lining the lumen of the capillaries. This is called filtration. As the blood moves toward the venous end of the capillaries, the blood pressure moves to essentially nothing. The osmotic pressure of the blood proteins brings liquid back into the blood before it moves into the veins. The osmotic pressure doesn’t bring all of the liquid back into the cell through reabsorption. Any additional liquid not brought back in, is pumped through unidirectional lymphatic vessels with valves to prevent backflow. These lymphatic vessels eventually dump their lymph into the subclavian veins.
How many chambers do each of the following organisms’ hearts contain?
Mammals Birds Reptiles Amphibians Fish
NB: Must know for the DAT
- Mammals: 4
- Birds: 4
- Reptiles: Most have 3. Crocodiles and Alligators have 4 though
- Amphibians: 3
- Fish: 2
Atria
Upper Chamber
Ventricle
Lower Chamber
Superior Vena Cava
Brings blood low in O2 to right atria from upper body.
Cave Venue for RADEO show
RADEO - Right Atrium Deoxygenated
Inferior Vena Cava
Brings blood low in O2 to right atria from lower body
Cave Venue for RADEO show
RADEO - Right Atrium Deoxygenated
Tricuspid valve
Between right atria and right ventricle
Bicuspid valve (Mitral Valve)
Between left atria and right ventricle
What are the semilunar valves?
Pulmonary valve and aortic valve
Aortic valve
Separates the left ventricle and aorta. Keeps blood from flowing backward
Pulmonary Valve
Separates the pulmonary artery from the right ventricle
Describe the flow of blood through the heart
The superior vena cava and the inferior vena cave bring deoxygenated blood from the upper and lower portions of the body and dump it into the Right atria of the heart.
The blood then gets pumped through the tricuspid valve into the Right Ventricle.
The deoxygenated blood in the Right Ventricle gets pumped through the the right and left pulmonary arteries where it travels through the lungs to release waste CO2 and pick up O2.
The oxygenated blood flows into the left atria from the pulmonary veins. (Two from each lung)
The blood in the left atria is pumped through the mitral (bicuspid) valve into the left ventricle.
The blood in the left ventricle is pumped through the aortic valve into the aorta where it flows to the rest of the body.
Describe what happens during the Lub Dub of the heart
The Lub: The AV Valves close and the semilunar valves are open
The Dub: The AV Valves open. The semilunar valves close.
The Dub step club opens its AV club. When night starts to become morning its semilunar, so the AV club closes and everyone lubs their way home.
Papillary muscles
Muscles in the ventricles that help stabilize heart valves
My papi is my stability. He helps me from back sliding by playing me some low tender chords on his guitar
Chordae Tendineae
Fibrous “strings” attached to the cusps on the ventricular side, originating from the papillary muscles.
Systolic Pressure
Arterial blood pressure when ventricles contract.
About 120 mmHg normally
Diastolic Pressure
Arterial blood pressure when ventricles relax
About 80 mmHg normally
Intercalated discs
transverse bands that separate adjacent ends in cardiac muscle fibers; essentially, they hold cardiac adjacent cells together. They have low resistance; hence impulses can move rapidly.
They consist of desomosomes (cell staples of intermediate fibers, fascia adherens (that connect the sarcoplasms of each cell together), and gap junctions that allow the fast transmission of ions.
The intercalated discs essentially provide support and function to allow the heart to both contract simultaneously and not destroy itself.
SA Node
This is the pacemaker of the heart.
It’s found in the right atria of the heart
The cells excite themselves to initiate impulses
Generates electrical impulses analogous to nerve cells
Describe the hearts electrical system
The SA node sends out a signal through the bachmann’s bundle (tract that connects both atria) and both atria contract nearly simultaneously
The signal travels to the AV node with a slight delay to allow for atrial systole. The AV node then sends a signal to the bundle of His and travels along tracts to all the purkinje fibers throughout both ventricles that cause the ventricles to contract nearly simultaneously.
SA Node -> AV Node -> Bundle of His -> Purkinje fibers
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Bachmann’s bundle
Where are arteries carrying deoxygenated blood and veins carrying oxygenated blood?
The pulmonary veins and arteries are the reverse of the rule.
Where does gas exchange occur? How does it occur?
Gas exchange occurs in the tiny sacs of alveoli in the lungs.
Alveoli are the functional units of the respiratory system
O2 diffuses through the alveolar walls and attach to the Hb in the erythrocytes. This occurs through passive diffusion.
What are the risk factors for cardiovascular pathologies?
- High Blood Pressure
- Obesity
- Smoking
- Lack of Excercise
- High Cholesterol
- Genetics
- Age
Artherosclerosis
We lose the elasticity of arteries and they thicken and lipids build up. This can lead to further problems such as heart attack.
Arrhythmias
Irregular or abnormal heart beat rhythms
Bradycardia
decreased heart rate
Tachycardia
increased heart rate
Hypertension
An increased force at which blood is pumped against an arterial wall. This can lead to heart attack or death.
