Cardiovascular System Flashcards
What is blood?
- Fluid connective tissue
- Cellular elements: RBCs, WBCs and platelets
- Extracellular matrix = plasma
Describe the anatomy of erythrocytes
Function: transport oxygen from lungs to other tissues, and CO2 from tissues to lungs
Diameter: 7-8 um
No nucleus
Cytoplasm colour: diffusely reddish-pink
Biconcave shape
No mitochondria
Describe neutrophils
Function: Leave the bloodstream and enter loose connective tissue. Become active phagocytes and ingest bacteria
Size: 9-15um
Shape of nucleus: 2-4 lobes connected by fine chromatin
Cytoplasmic granules: fine, evenly distributed, purple granules
Describe lymphocytes
Function: Produce antibodies or directly kill cells
Size: 7-10um
Shape of nucleus: round/oval
Cytoplasm: rim of intensely basophils cytoplasm around nucleus
Describe monocytes
Function: Traverse capillary walls and enter adjacent connective tissue and become phagocytise macrophages
Size: 15-20um
Shape of nucleus: indented/kidney shaped
Cytoplasm colour: translucent grey-blue
Describe platelets
- Membrane-bound fragments of cytoplasm from megakaryocytes (located in bone marrow)
- Function: blood clotting
- Often in small clusters
- Diameter: 1-3um
Where is the heart located?
In the mediastinum of thoracic region
(Median region of thorax between the lungs)
What are the chambers of the heart
Left and right atrium (receives blood) and ventricle (pumps blood)
What is the pericardium?
- double layered membrane that surrounds the heart
- Heart is contained within the pericardial cavity
Pericardial sac: Outer wall of pericardial cavity. Attaches to sternum and central tendon of thoracic diaphragm
What are the great vessels of the heart
- Superior vena cava
- Inferior vena cava
- Pulmonary veins
- Pulmonary trunk
- Aorta
What are the 2 circuits?
Pulmonary circuit: blood goes to lungs to be reoxygenated then flows back to the heart
Systematic circuit: blood flows to tissues of the body and back to the heart.
Describe the superior vena cava
One of the systematic veins
Drains blood from the head, neck, and upper limbs to empty into superior region of RA
No valves
Describe inferior vena cava
One of systematic veins
Drains blood from the abdomen, pelvis, and lower limbs to empty into the inferior region of RA
Pulmonary veins
- 4
- Carry blood from lungs to drain into LA
- No valves
- Only veins to carry oxygenated blood
Describe pulmonary trunk
- Terminally divides into R and L pulmonary arteries
- Carries deoxygenated blood from RV to lungs
- Only arteries that carry deoxy. Blood
- Has pulmonary semilunar valve
Describe aorta
Carries blood from LV to most parts of the body
Why is left ventricle thicker?
LV wall and interventricular septum have thicker myocardium because more pressure is needed to pump blood around the long systematic circuit, compared to pulmonary circuit
What is the myocardium?
Middle coat of the heart, and the thickest
General features of the RA
Thin-walled chamber that lies superior to RV.
Receives blood from systematic circuit
Orifice of superior/inferior vena cava
Site where SVC/IVC empty
Located superiorly/inferiorly respectively in RA
Coronary sinus opening
- Location: Internally in the wall of RA. In between orifice of IVC and right atrioventricular valve opening
- Receives all blood draining from the heart itself
Fossa Ovalis
Thinnest part of interatrial septum, oval shape
Site of closure of the foremen ovale
Auricle of RA
Ear-shaped extension of RA; projects to the left from root of SVC
Pectinate muscles
Parallel muscular ridges on internal wall of majority of RA and R auricle
Right ventricle Function
Receives blood from RA via right atrioventricular orifice
Trabeculae carnae
Cross-crossing muscular ridges on internal walls of ventricle
Right atrioventricular valve
AKA tricuspid valve
3 triangular-shaped flaps (called cusps)
Papillary muscles of right ventricle
- 3
- internal cone shaped projections
- attaches to seperate cusp of tricuspid valve via chordae tendinae
Chordae Tendinae of RV
- connective tissue fibrous cords
- attach cusps of of tricuspid valve to papillary muscles
- Function: maintain closed state of right AV
Pulmonary semilunar valve
- Location: base of pulmonary trunk
- 3 cusps
- Function: prevent backflow of blood from pulmonary trunk into RV
Left atrium general features
- Location: to the left and slightly posterior to RA
- Function: Receives oxygenated blood from pulmonary blood circuit via pulmonary veins
Pulmonary veins
- 4
- Drain into LA
- Carry oxygenated blood
Auricle of LA
- Similar to auricle of RA
- Only part of LA that has pectinate muscles
General features of LV
- Thickest walls
- Need more pressure to pump blood through the whole body
- Recieves blood from LA
- Drained by aorta
- Trabeculae carnae line internal walls
Bicuspid Valve
- 2 cusps
- Function: prevent backflow into LA
Papillary muscles of LV
- 2
- attaches to cusp of bicuspid valve via chordae tendinae
Aorta and aortic semilunar valve
- Drains LV → systemic circuit though aortic semilunar valve
-
********Aortic semilunar valve********
- similar to pulmonary
- 3 cusps
- Function: prevents backflow from aorta
Blood supply and drainage of heart
-
L and R coronary arteries
- only collateral branches of ascending aorta
- encircle the base of the ventricles
- Function: supply oxygenated blood to the heart
-
Coronary sinus
- Large dilated vein
- Location: posterior aspect of the heart
- Venous blood from myocardium returns into coronary sinus via coronary veins
- Empties in RA to be reoxygenated
What are the layers of a blood vessel wall?
- Tunica intima
- Tunica media
- Tunica externa/adventitia
Parts of Tunica intima
- Endothelium: specialised squamous epithelium
- Basement membrane: connective tissue
- Outer layer: areolar connective tissue
- Arteries: internal elastic membrane
- Veins: contain valves
Describe tunica media
- Layers of smooth muscle tissue supported by connective tissue
- elastic fibres predominate in arteries (arranged in circular sheets)
- collagenous fibres predominate in veins
-
Function: vasoconstriction and vasodilation
- Regulated in part by sympathetic vascular nerves in walls of blood vessels
External elastic membrane of tunica media
- Loose connective tissue
- Seperates tunica media from tunica externa in larger arteries
- Appears wavy in slides
Describe tunica externa
- Sheath of connective tissue composed mainly of collagenous fibres
- Some elastic fibres
- External layers blend with surrounding connective tissue outside the vessel to hold it in relative position
- Prevents disruption of blood flow
What are the types of arteries?
-
Elastic artery
- Close to the heart
- Thickest walls
- High % of elastic fibres
- allows them to expand, and recoil after surge of blood has passed
- Diameter: 10mm
-
******Muscular artery******
- Further from the heart
- Elastic fibre amount in tunica intima decreases, smooth muscle in tunica media increases
- Thick tunica media allows better vasoconstriction
- Diameter: 0.1-10mm
Describe veins
- Conducts blood → heart
- Multiple **venules** join to form veins
- Thin walls
- Large and irregular lumina
- Valves (bc. low pressure)
-
**Venae comitantes:** paired deep veins run adjacent to an artery
- found in distal regions of upper and lower limbs
- Communicating vein: communicating section between paired veins
Describe capillaries
- Simple, endothelial tubes that form networks of narrow canals between arterioles and venules
- Function: allows exchange of gases and other substances between blood and tissue
- Diameter: Around 8um (diameter of erythrocyte)
- Capillary Wall
- Single layer of flattened endothelial cells, resting on a basement membrane. Supporting thin layer of connective tissue forms outermost layer
- Leaky walls, allowing substances to pass through
