General Anatomy (Introduction To The Circulatory System And Lymphatic System) Flashcards
What does the circulatory system do?
The circulatory system transports fluids throughout the body & thus it
• Provides the oxygen (O2) & nutrients to the organs, muscles & tissues; keeps them healthy and alive.
• Helps the body to get rid of carbon dioxide (CO2) & metabolic waste products.
What are the two types of circulatory system?
Circulatory system consists of cardiovascular (blood circulation) and lymphatic circulation.
• Blood circulation:
– Heart pumps the blood into blood vessels (vascular system).
– Blood vessels (artery, capillary, vein) are the transportation network throughout the
body.
• Lymph circulation:
– Lymphatic vessels
– Lymph nodes
What are the two types of blood circulatory system?
• Closed circulatory system: Blood is circulated through vessels such as arteries, capillaries, veins.
• Open circulatory system: Through the capillary wall blood pass through & fills the body interstitial (intercellular) space, where tissues & cells directly bathe (e.g., in spleen).
What is pulmonary circulation?
- Portion of cardiovascular system
- Pulmonary circulation moves blood between the heart and the lungs.
- It transports deoxygenated blood via the pulmonary artery to the lungs to absorb oxygen and release carbon dioxide.
- The oxygenated blood then flows back to the heart through pulmonary veins.
What is the systemic circulation?
- Portion of cardiovascular system
- Systemic circulation moves blood between the heart and the rest of the body.
- It sends the oxygenated blood out to cells via arteries (Away from the heart to the body).
- Returns deoxygenated blood to the heart by the veins.
What is the coronary and the foetal circulation?
➢ Coronary circulation: for the heart only
➢ Foetal circulation is in embryonic & foetal period.
What are the 3 layers of tunics in the wall of vessels?
- tunica intima (innermost)
- tunica media - thicker in arteries than in vein
- tunica adventitia (outer)
What is the tunica intima?
Endothelium: Simple squamous epithelium
Subendothelium: Loose connective tissue, few smooth muscle
Internal elastic lamina: Elastic fibers
What is a tunica media?
Connective tissue fibers & Smooth muscle
What is the tunica adventitia?
Connective tissue fibers
Connective tissue cells
How does the structure of arteries and vein changes?
• The structural changes in the wall of different types of arteries or veins are gradual.
• No sharp demarcation is there.
What is the process of atherosclerosis (hardening) of arteries?
• Deposition of cholesterol within smooth muscle cells & macrophage (foam cell) in
subendothelium.
• Proliferation of smooth muscle cell & connective tissue elements
• Later the calcium deposit forms an atheromatous plaque (atheroma).
• Well-demarcated, hardened yellow areas or swellings on the intimal surfaces of arteries.
• Focal thickening of intima & narrowing of the lumen of the vessels
• Loss of elasticity of the arterial walls
• Focal thickening of intima→surface irregularity may result in thrombosis & may occlude the artery.
• This thrombus may also be flushed into the bloodstream and block smaller vessels distally as an embolus.
• The consequences of thrombosis & embolus from atherosclerosis include ischemia (reduction of blood supply) and infarction (local death, or necrosis).
• These are particularly significant in the
Heart (ischemic heart disease and myocardial infarction or heart attack), Brain (stroke), and
Distal parts of limbs (gangrene/necrosis).
What are arteries?
- Carry blood from the heart under a relatively high pressure
- The further they are from the heart the less caliber they will have, and therefore the different types of arteries are distinguished from each other depending on their overall size, the amount of muscle in tunica media.
What are the three types of arteries?
- muscular arteries
- elastic arteries
- arterioles
What are the muscular arteries? (Medium arteries)
- Medium muscular arteries, the wall has a circular pattern deposited smooth muscle which enables it to control its diameter.
- Decrease the diameter to regulate the blood distribution to the body.
- Most of them are named arteries, e.g. brachial and femoral arteries.
What are elastic arteries? (Large arteries)
- Large elastic arteries, have many elastic layers in their walls (subendothelial layer, tunica media) they receive the cardiac output, they include:
a) aorta
b) brachiocephalic trunk c) subclavian
d) carotid arteries
e) pulmonary trunk. - Their elasticity enables them to receive the high blood pressure from the ventricle, reduce the pressure and return to their normal size.
- They expand as the pressure increases, and when the ventricles relax they will constrict and return to their normal size; and maintain the blood pressure within the circulation.
What are arterioles? (Small arteries)
- Thick wall in relation to its lumen
- Tunica media entirely made up of smooth muscle
- The pressure within the arterial vascular system is controlled by the arterioles muscle tonus
- The filling of the capillary bed is regulated by the level of contraction of the muscular layer in the arterioles. Hypertension will result if their walls are over constricted.
Arterioles and small arteries are not named.
What are capillaries?
- Microscopic blood vessels in the form of network connecting the arteriole and the venules
- Usually less than 1 mm long. They have selective permeability
- Tunica intima made up of single layer endothelium (no media, no adventitia)
What are the three type of capillaries?
- continuous
- fenestrated
- sinusoids
What is the function of the capillaries?
- Providing nutrients and oxygen to the surrounding tissue
- Absorption of nutrients, waste products and carbon dioxide
- Excretion of waste products from the body
Where are continuous capillaries found?
Muscle and brain
Where are the fenestrated capillaries found?
Pancreas, Thyroid gland, renal glomeruli
Where are the sinusoid capillaries found?
Liver and spleen
What are veins?
- Veins (except for the pulmonary vein) transfer the low-oxygenated blood from the capillary bed to the heart
- Due to its low oxygen content; the blood will be dark in color.
- The veins walls are thinner (specially in the tunica media) than those of the arteries due to the low blood pressure.
- They don’t pulsate.