Blood and the vascular system Flashcards
lecture 6 week 4
What are some of the different purposes of the blood
- transport of O2 and CO2 from and to the lungs and other tissues
- ionic maintenance throughout the body
- deliver nutrients from the gut around the body
- transport waste metabolic products to disposal tissue sites
- transport hormones from endocrine glands to target tissue
- protect against invading organisms
What is haematopoiesis (blood cell production)
- all blood cells derive from a MULTIPOTENTIAL HAEMATOPOIETIC STEM CELLS which differentiate into all blood cells circulating in the blood
- stem cell > common myeloid progenitor/ common lymphoid progenitor > into further division
What is the haematopoetic pyramid
haematopoietic stem cell
common progenitors
lineage-restricted progenitors
procursor cells
mature circulating cells
Where does haematopoiesis occur
- in humans haematopoesis starts in the yolk sac before transitioning to the liver and the spleen
- in adults haematopoesis occurs in the pelvis. sternum and vertebral bone
What does circulating blood contain
- erythrocytes (red blood cells)
- leukocytes (white blood cells)
monocytes, granulocytes, lymphocytes - platelets (chunks of megakaryocytes)
What are the two different sub-categories of leukocytes
granulocytes: has granules (high protein)
agranulocytes: no granules
What are the different granulocytes
Neutrophils (40-75% of blood cell count)
- made in bone marrow, act as phagocytes
Eosinophils (1-6%)
- made in bone marrow, accumulates at inflammation sites, very short lived
Basophils (<1%)
- made in bone marrow, implicated in inflammation
What are the different agranulocytes
monocytes
- made in bone marrow, act as phagocytes (become macrocytes)
lymphocytes
- made in bone marrow, lymphoid tissue and spleen. production of antibodies (B-lymphocytes) and involved in cell-mediated immunity (T-lymphocytes)
What are erythrocytes and platelets
platelets: made in bone marrow, aggregate at sites of injury and initiate haemeostasis
erythrocytes: made in bone marrow, transport O2 and CO2, numbers vary in males and females
What is plasma made up of
- plasma makes up 4% of total body weight
- 95% is water, 5% mineral ions, small organic molecules (glucose) and plasma proteins (albumin)
- most components kept in physiological range, but can be disturbed in disease
What are the components of the vascular system
circulation consists of a pump (heart) and a series of interconnected tubes
blood is pumped from the right side of the heart to the lungs and then the left side of the heart to the entire body
three main blood vessels: arteries, veins, microcirculation (arterioles, venules, capillaries)
What is branching and velocity of flow in circulation
branching
- increasing the number of vessels from single aorta to 10-10 capillaries, radius decreases from 1.1cm to 3um
- combined cross-sectional area increases with branching, large surface area for material exchange
velocity of flow
- velocity steeply decreases as resistance is increased slowing movement of blood
- fastest in aorta and slowest in capillaries `
What is the structure of an artery
arteries withstand the highest pressure
- tunica intima: flat endothelial cells touch blood
- tunica media: concentric layers of smooth muscle with elastin and collagen fibres
- tunica externa: collagen and elastin fibres
elastic arteries: close to heart, have elastin for expansion and recall
muscular arteries: further away, less elastin: vasoconstriction
What are the components of veins
- thin walls and large, irregular lumens
- have valves to prevent backflow and pooling of blood
What are the components of arterioles
- small arteries going into capillaries, thinner tunica layers
- primary site of blood pressure and flow regulation which is influenced by neural and chemical controls
