Block1: Foundations Of Medicine Flashcards
Primary function of cardiovascular system and its organs
To transport nutrients, oxygen and waste products to and from the cells of the body
Organs- heart and blood vessels
What is the pulmonary circuit
A short loop in which blood is first pumped to the lungs to be oxygenated before flowing back to the heart
What is The systemic circuit
A much larger loop in which freshly oxygenated blood is pumped around the entire body and back again via a vast interconnected network of arteries, capillaries and veins.
What do the arteries do
Carry blood away from the heart and towards capillaries
The pressure is high due to their relative proximity to the heart
What do the capillaries do
Connect the smallest arteries (arterioles) with the smallest veins (venules) and are involved in the exchange of gases and fluids between tissues and the blood
Capillary walls consist of a semi permeable simple squamous epithelium and a thin basement membrane
What do the veins do
Carry blood away from capillaries and towards the heart
Subdivision of arteries and eg
- Large elastic arteries like the aorta
- Medium muscular arteries eg femoral artery
- Small arteries and arterioles
What are large elastic arteries
Like an aorta are found nearest to the heart
Their walls contain layers of elastic fibres- a feature which helps maintain a steady flow of blood throughout the body
What are medium muscular arteries
Lie distal to elastic arteries and are the main distributors of blood to organs and organ systems. Contraction of smooth muscle fibres in their walls help regulate blood flow according to the demands of the organs
What are small arteries and arterioles
Have narrow linen but thick walls also containing smooth muscle
The dilation and contraction of arterioles help regulate systemic blood pressure
The 3 layers of arteries and veins
Known as tunicae
1. Tunica intima
2. Tunica media
3. Tunica external/adventitia
What is Tunica intima
Tunica intima - think of this innermost layer as being in intimate’ contact with the blood in the lumen. Lined with simple squamous epithelium.
What is Tunica media
Tunica media - this middle layer consists primarily of concentric bands of smooth muscle.
Contraction of the smooth muscle cells decreases the diameter of the vessel, a process known as vasoconstriction.
What is Tunica externa/adventitia
Tunica externa/adventitia - this outermost layer strengthens the vessel and helps anchor it to surrounding structures. In larger vessels, the tunica adventitia contains vasa vasorum (‘vessels of the vessels’) which supply blood to the outer parts of the vessel wall.
What are the 3 categories of veins
- Large
- Medium
- Venules
What are large veins
Large veins have a well-developed tunica adventitia (connective tissue surrounding blood vessels, see Station 2) and are large, such as the inferior vena cava.
What are medium veins
Medium veins frequently accompany medium arteries and have venous valves where needed to stop backflow of blood.
What are venules
Venules drain capillary beds and are only visible with magnification.
Description of the large intestine/colon
Distinctively shaped organ whose ascending. transverse and descending parts frame the small intestine. Functions primarily to absorb water from digested matter, resulting in semisolid waste.
Description of pharynx
A muscular passageway that is found posterior to the oral and nasal cavities, and proximal to the oesophagus and larynx.
Description of oral cavity
This multi-purpose cavity represents the start of the Gl tract. Contains the structures needed to grind, compress, lubricate, and taste foods prior to swallowing.
Description of stomach
An expandable J-shaped organ.
Smooth muscle contractions help churn and squeeze its contents into chyme (an acidic fluid containing partially digested food).
Description of oesophagus
A tube of smooth muscle. Its peristaltic (wave-like) contractions help conduct swallowed food from the pharynx to the stomach.
Description of small intestines
Measuring approximately 6m, this is the longest and most convoluted part of the Gl tract. Most enzymatic digestion and nutrient absorption occurs here.
