Circulation of Blood Flashcards
Learning outcomes
• To recognise the basic anatomy and the function of the major components of the CVS, including the heart (including valves), arteries, veins and microcirculation.
• To identify which body systems the CVS integrates with, and how secondary nervous and hormonal elements control the function of the CVS.
• To describe the normal distribution and flow of blood through the pulmonary and systemic circulations.
• To compare the features of myocardial muscle with skeletal muscle.
What are 5 functions of the cardiovascular system?
• Functions of the CV system:
1) Bulk flow of materials e.g gas, nutrients, hormones, waste
2) Temperature regulation
3) Homeostasis
4) Host defence
5) Reproduction
What function does the CNS have in relation to the CVS system?
What function does the sympathetic and parasympathetic nervous system have on the CVS system?
- The CNS integrates overall activity of the CVS with the activity and functions of the respiratory and renal systems
The CNS control the autonomic ns and hormones, both of which have an effect on blood volume, blood vessels and heart
Why is the wall of the left ventricle thicker than the right ventricle?
Describe the route of blood through the pulmonary and systemic circulation (in picture).
- The wall of the left ventricle is thicker than the right wall because the left side pumps to the whole body, while the right side only pumps to the lungs
How are blood vessels arranged in parallel?
What are 3 reasons why parallel arrangement of blood vessels important?
- Blood vessels are arranged in parallel through having capillary beds that branch at different organs
- Parallel arrangement of blood vessels is important because:
1) Can have more or less blood flow to a particular organ
2) If an organ gets blocked, it doesn’t compromise the entire blood flow
3) Allows adaptations to the metabolic demands of tissues e.x sweating or exercise may need to increase volume and rate of blood flow
Why do both sides of the heart need to contract at the same time?
- Both sides of the heart contract at the same time to prevent a build-up of blood in the blood vessels, which can lead to heart failure
what vessels are involved in the microcirculation of the heart?
- arterioles
- precapillary sphincters
- capillaries
- venules
what does the parallel arrangement of the cardiovascular system allow?
- it allows independent regulation of blood flow to different organs
- adapts to metabolic demands of the tissues.
What are 3 major differences between arteries and veins?
- The lumen of veins is significantly larger than arteries because veins carry a greater volume of blood than arteries
- Arteries (particularly muscular arteries) contain significantly more smooth muscle and veins contain more collagen and elastic fibres.
- This is due to arteries (especially muscular arteries) handling blood at higher pressure than veins, and veins carrying a greater volume of blood
What are all blood vessels lined by?
What are the 4 functions of these cells?
- All blood vessels are lined by endothelial cells
- 4 functions of endothelial cells:
1) Filtration of fluids
2) Blood vessel size regulation
3) Haemostasis – process to prevent and stop bleeding
4) Transport of substances throughout the body
what do blood vessels vary in?
1) Number
2) Diameter
3) Wall thickness
4) Smooth muscle
5) Elastic tissue
6) Fibrous tissue
describe arterioles as a feature of the microcirculation?
arterioles = the smallest diameter muscular walled arteries
describe precapilarry sphincters as a feature of the microcirculation?
2) Precapillary sphincters
* Rings of smooth muscle which control entry of blood from arterioles into each capillary
* No capillary is constantly filled, otherwise all the blood in the body would be in the capillaries
* Precapillary sphincters prevent this
describe capillaries as a feature of the microcirculation?
3) Capillaries
* Smallest diameter blood vessel
* Simple tube, one cell thick, of flattened endothelial cells
* Allows for diffusion of nutrients, waste etc in and out of tissues
* About 10 billion capillaries
describe venules as a feature of microcirculation?
4) Venules
* Small diameter vessels which drain blood back to the larger true veins
Label these heart structures
What are the 2 semi-lunar valves?
How strong are these valves compared to atrioventricular valves?
How do these valves close?
- 2 semi-lunar valves:
1) Aortic valve (3 semi-lunar cusps)= Between left ventricle and aorta
2) Pulmonary valve (3 semi-lunar cusps)= Between the right ventricle and pulmonary trunk
- These valves are heavy duty then the atrioventricular valves
- The tri-cuspid valves have smaller openings, higher pressure, therefore have more stress and physical abrasion
What is an echocardiogram?
• An echocardiogram (or echo) is a scan used to look at the heart and nearby vessels
• It is an ultrasound of the heart
What is the structure of cardiac cells?
How are they connected together?
What do these intercalated disks contain?
- Cardiac muscle cells branch into a network
- Cardiac cells are connected together by desmosomes at the junction between cells, which gives strong cell to cell adhesion and forms intercalated disks
- These intercalated disks also contain gap junctions that directly connect the cytoplasm and permit and easy transfer of ions between cells.
What are features of the cardiac muscle?
• Features of the cardiac muscle:
• Striated muscle similar to skeletal muscle
• Composed of thick and thin filaments of myosin and actin
• Cardiac muscle contains smaller fibres with individual nuclei
