circulatory system Flashcards
Describe the position of the heart within the mediastinum.
Obliquely in the mediastinum, medial to two lungs and superior to the diaphragm
Superior chambers
collecting, atria, top of the heart and collect blood from the lungs
Inferior chambers
discharging, ventricles, bottom of the heart and eject blood from the heart
Left atrium
receive oxygenated blood returning from lungs through four openings
Four pulmonary veins 2 from each lung
Left ventricle
received oxygenated blood from left atrium
Opens to aorta
Thickest walled chamber in the heart
Right atrium
receives deoxygenated blood returning from the body
Right ventricle
receives deoxygenated blood from right atrium
Opens to pulmonary trunk
valves in the heart
Atrioventricular valves x 2 (tricuspid and bicuspid)
Semilunar valves x2 (pulmonary and aortic)
Atrioventricular valves
valve between atria and ventricles
Have cusps attached to papillary muscles by tendons = chordae tentineae
Right side has three cusps
Left side has two cusps
When the valve is open blood flows from the atrium to ventricle
Semilunar valves
valves at the exit of ventricles
Pulmonary semilunar valve = at base of pulmonary trunk
Aortic semilunar valve = at the base of the aorta
function of valves in the heart
prevent back flow of blood
Chordae tendineae
strings connecting valve cusps to papillary muscles preventing the valves from bulging into aorta
Papillary muscles
muscles in ventricles preventing prolapsed of AV valves
Fibrous pericardium
tough fibrous outer layer, prevents over distention (over filling), acts as an anchor
Serous pericardium and its two layers
thin, transparent, inner layer
1. parietal pericardium
2. visceral pericardium
the two layers are continuous and have a pericardial cavity between them filled with pericardial fluid
parietal pericardium
lines the fibrous outer layer
Visceral pericardium
covers the hearts surface
three layers of heart wall
Epicardium - single squamous epithelium over areolar tissue
Myocardium - middle layer, thickest, composed of cardiac muscle cells for contractibility allowing the heart to create pressure
Endocardium - smooth inner surface of heart chamber covers valve surface and continuous with epithelium
pathway of blood through the heart
- Superior and inferior vena cavae.
- Right atrium.
- Tricuspid/atrioventricular valve.
- Attached via chordae tendineae To the papillary muscles.
- Right ventricle.
- Pulmonary/semi-lunar valve.
- Where it becomes the pulmonary circulation.
- Pulmonary trunk/artery.
- Lungs.
- Where blood becomes oxygenated.
- Right and left pulmonary veins.
- Left atrium.
- Where it becomes systemic circulation.
- Bicuspid/mitral/atrioventricular valve.
- Left ventricle.
- Which has a much thicker muscular wall than the right side of the heart.
- Aortic/semi-lunar valve.
- Aorta.
- To the rest of the body and organs.
describe how a heartbeat is generated.
through the cardiac cycle
Repetitive contraction (systole) and relaxation (diastole) of heart chambers, moves blood throughout the body
pulmonary circulation
deoxygenated blood is transported to lungs for oxygenation and then returned to the heart
Systemic circulation
oxygenated blood is transported to body tissues then returned to the heart
Coronary circulation
part of systemic circulation that supplies heart only
Describe the effects of exercise on cardiac output.
cardiac output increases during exercise
To supply cells which are working with the extra oxygen and nutrients they need and to remove waste
Cardiac output = heart rate x stroke volume
amount of blood ejected from the heart at every contraction
List the components of blood.
Plasma
Proteins, water, ions, nutrients, waste products, gases
formed elements
Platelets, white blood cells, red blood cells
Platelets = assist with blood clotting and sealing holes in blood vessels
Describe the transport of carbon dioxide and oxygen in the blood.
Erythrocytes
red blood cells
Carries oxygen from lungs to tissues, dissolved in plasma or attached to haemoglobin
Carries carbon dioxide from tissues to lungs in plasma and attached to haemoglobin
Red blood cells have no nucleus and a biconcave shape to increase surface area and increase their oxygen carrying capacity
arteries
= away
take blood away from the heart to tissues
Located deep in tissue
Thick walls
No valves
Contain blood under pressure
All are oxygenated except for the pulmonary artery
veins
take blood to the heart
Blood not under pressure
Located closer to surface of body
Thinner walls then arteries
Contain valves
Capillaries
site of exchange between tissues
three types
1. Continuous = no gaps between endothelial cells, less permeable to large molecules
2. Fenestrated = have pores in endothelial cells called fenestrae, highly permeable
3. Sinusoidal = larger diameter, irregular incomplete wall of endothelial cells
Why is the wall in the left ventricle much thicker then the right ventricle
right ventricle only has to push blood to the lungs which is closer whereas the left ventricle has to push blood to the whole body so needs more power in the contraction
- Name the two major arteries that leave the heart and the chamber they exist from
pulmonary trunk = right ventricle
Aorta = left ventricle
pulmonary trunk
becomes the two pulmonary arteries (one for each lung)
- What are the names of the major veins entering the heart
superior and inferior vena cave into the right atrium
Pulmonary veins into the left atrium
