Blood, Vessels, Homeostasis, Haemodynamics Flashcards
What are the functions of blood?
Transportation -> O2, CO2, nutrients, waste products, hormones
Regulation -> homeostasis of fluids, pH, temp, osmosis
Protection -> blood clotting, white blood cells, antibodies
What is the density of blood in relation to water?
Blood is denser than water
What is the pH of blood?
7.35 - 7.45
What is the temperature of blood?
38°C
Approximately how much blood does a person have in their body?
5 litres circulating at any one time
What are the two main components of blood?
Plasma (55%) and Formed elements (cells) (45%)
What are the components of blood plasma?
Proteins
Water
Other solutes
What are the components of formed elements in the blood?
Platelets
White blood cells
Red blood cells
What is the role of Albumin proteins in the blood plasma?
Maintain colloid osmotic pressure
What is the role of Globulin proteins in the blood plasma?
Immunoglobins fight disease
What is the role of Fibrinogen proteins in the blood plasma?
Involved in blood clotting
What is the scientific name for red blood cells?
Erthrocyte(s)
Describe the shape of erthrocytes:
Biconcave discs No nucleus 7-8μm diameter 4 polypeptide chains each with an attached haem group Centre of each haem group is Fe2+
What is the scientific name for white blood cells?
Leukocyte(s)
Describe the shape of leucytes:
Larger than RBC
Have a nucleus
Various different shapes
What are the different types of leucyte?
Neutrophils Eosinophils Basophils Lymphocytes Monocytes
What are the two main types of leucytes?
Granular (-phils)
Agranular (-cytes)
What are the functions of neutrophils?
Phagocytosis
What are the functions of eosinophils?
Allergic reaction response and Parasitic infections
What are the functions of basophils?
Release histamine
Develop into mast cells
What are the functions of lymphocytes?
Mediate immune response
What are the functions of monocytes?
Phagocytosis
Develop into macrophages
What are the functions of platelets?
Cell fragments involved in blood clotting
What is the structure of platelets?
2-4μm in diameter
Disc shaped
No nucleus
Explain the process of blood clotting:
Collagen exposed at site
Vascular spasm, constriction of vessels to reduce blood loss
Platelet plug, bind to collagen and make a temporary seal
Clotting factors (enzymes)
Why may clotting occur in an unbroken vessel (usually a vein)?
Roughened endothelial surfaces as a result of atherosclerosis, trauma or infection
What is a thrombus?
A blood clot in an unbroken vessel
What is a embolus?
A thrombus which remains intact and becomes disloged
Why is an embolus in an artery dangerous?
It may reduce the blood supply to an organ
What is a pulmonary embolism?
When an embolus lodges into the lungs
Define homeostasis:
The maintenance of internal conditions by living systems for optimal organism function
What regulator mechanisms are involved in homeostasis?
Receptor
Control centre
Effector
What are haemodynamics?
Factors affecting blood flow
What is blood flow?
The volume of blood that flows through a given tissue at a given time (mL/min)
What is the relationship between the velocity of blood flow and the cross sectional area of a given tissue?
Velocity of blood flow is inversely proportional to the cross sectional area, flow is slow when extensive branching
What is the equation for total blood flow?
Total blood flow = Cardiac output (CO) - vol. blood circulating systemic blood vessels per minute
What is the equation for cardiac output (CO)?
CO = Heart rate (HR) x Stroke volume (SV)
Cardiac output (CO) is dependent on 2 factors, what are these?
Pressure difference that drives blood through the vessel
Resistance to blood flow
What is the stroke volume (SV)?
The volume of blood leaving the ventricle in one contraction
What is the relationship between size of lumen in a blood vessel and blood flow?
Increased size -> increased blood flow
Increased lumen size means less resistance, meaning more blood flow
What is the relationship between blood viscosity and blood flow?
Increased viscosity -> decreased blood flow
Increased blood viscosity means more resistance, meaning less blood flow
What is the relationship between total blood vessel length and blood flow?
Longer vessel -> decreased blood flow
Longer length means more resistance, meaning less blood flow
Where is blood pressure highest?
In the Aorta
What is mean arterial pressure (MAP)?
The average pressure flowing through the arteries
What is the function of Baroreceptors?
Stretch in the vessel walls
Where are Baroreceptors located?
In the Aorta arch and Carotid sinus
Where is the cardiovascular centre (CVC) located?
Medulla Oblongarta in the brain
What controls vasoconstriction and vasodilation autonomically?
The Vasomotor centre (VC), located in the Medulla Oblongarta in the brain
What system acts as a control of blood pressure?
Renin-angiotensin aldosterone system
Explain how Baroreceptors control blood pressure?
Decreased blood pressure means decreased stretch on blood vessel walls, this means decreased signals sent via the glossopharyngeal and vagus nerves to the CVC, less inhibitory signals sent through PNS to SA node, leads to increased HR
What is pulmonary circulation?
Blood circulated to the lungs
What is systemic circulation?
Blood circulated to the rest of the body (not lungs)
What are the 3 layers of a blood vessel wall?
Tunica intima (interna) Tunica media (middle) Tunica externa (adventitia)
Which layer of the blood vessel is an endothelium cell?
Tunica intima (interna)
Describe the structure of the Tunica intima:
Thin flattened cells
A basement membrane
Internal elastic lamina
Smooth
What are the functions of the Tunica intima:
Reduced friction
Secrete locally acting chemical mediators
Describe the structure of the Tunica media:
Elastin
Muscle arranged circularly to regulate diameter of blood cells
What are the functions of Tunica media:
Circular muscle fibres contract and relax to control the diameter, controlled by the SNS
Describe the structure of the Tunica externa:
Elastic and collagen fibres
Nerves
Anchors in larger vessels
Describe the structure of Arteries:
Tunica intima
Tunica media
Tunica externa
What are the functions of Arteries?
Distribute blood to major organs
Describe the structure of Arterioles:
Tunica intima
Tunica media
What are the functions of Arterioles?
Regulate blood flow to tissues and affect blood pressure
Describe the structure of Capillaries:
Tunica intima
What are the functions of Capillaries?
Permit exchange of nutrients and waste between blood and tissues
Describe the structure of Venules:
Tunica intima
Tunica media
What are the functions of Venules?
Exchange of nutrients and waste
Describe the structure of Veins:
Tunica intima
Tunica media
Tunica externa
Pocket valves
What are the functions of Veins?
Blood reservoir bringing blood back to the heart
Explain the venous return system of valves:
Open to push blood up to the heart and close to prevent backlog of blood due to gravity
Explain the venous return system of skeletal muscle pump:
Skeletal muscle contraction assists with pumping blood back to the heart
Explain the venous return system of respiratory muscle pump:
Diaphragm moves down, reduces pressure in thorax increasing pressure in abdominal cavity, compressing veins, moving blood towards the heart
