25 - blood Flashcards
(35 cards)
what does blood transport?
red blood cells supply oxygen to cells (via haemoglobin).
removes metabolic waste (CO2, lactic acid, etc…)
nutrients such as glucose, amino acids and fatty acids (dissolved in blood or bound to plasma proteins)
transport of hormones and signalling of tissue damage.
how does blood support defence?
activation of the coagulation cascade of restrict fluid losses at injury sites.
white blood cells defend against toxins and pathogens.
how does blood support temperature regulation?
stabilisation of core body temperature.
thermoregulation - increased/decreased blood flow to skin surface causing increased/decreased heat loss.
blood is considered to be specialised form of _____ _____ that supports, connects or separates different types of tissue.
connective tissue
what is blood made up of?
this connective tissue is made up of cells and a matrix:
- plasma
- formed elements
what is plasma made up from?
plasma (46 to 63%)
- water (92%)
- plasma proteins (they transport lipids, minerals and vitamins to the circulatory system) (7%)
- other solutes (glucose, carbon dioxide, hormones) (1%)
what are the formed elements of blood?
formed elements (37 to 54%):
- red blood cells, RBCs (95%) - 4.2 to 6.2 million per microlitre
- white blood cells, WBCs (~1%) - 4000 to 11,000 per microlitre
- platelets (~4%) - 200,000 to 500,000 per microlitre.
what are red blood cells known as?
RBCs make up the majority of cellular components of the blood and are known as erythrocytes.
how many red blood cells do adult humans have?
roughly 20-30 trillion.
roughly one quarter of the total number of cells in the human body!!
what is the life span of a RBC
about 120 days - each cell travels about 700 miles.
what makes RBCs unique cells?
they lack classical cellular constituents such as nucleus, organelles and ribosomes.
what are RBCs a package of?
it is mainly a package of haemoglobin molecules and iron.
iron atoms bind to O2 molecules temporarily in lungs & release them throughout the body.
what shape are RBCs
its flat, biconcave, disc shape is well-suited to carry out its main function:
- large surface area to maximise oxygen-carrying capacity.
the plasma membrane of the RBC is flexible allowing it to slide through narrow capillaries (which averages 7 µm)
what is the function of Haemoglobin?
haemoglobin is the primary transport of oxygen. about 98% of oxygen in arterial blood is attached to haemoglobin (2% dissolved in plasma)
what does the haem group carry?
iron
each polypeptide carries a haem group.
what does oxygen bind to?
oxygen binds to iron. this forms oxyhemoglobin.
why can red blood cells not reproduce?
since they lack a nucleus, they cannot reproduce.
what is the production of new red blood cells called?
erythropoiesis.
explain how more red blood cells are produced
feedback loop:
- kidneys detect low oxygen levels
- kidneys release erythropoietin
- this stimulates production of erythrocytes in bone marrow
- macrophages consume old blood cells - a type of white blood cells that engulfs and digests cellular debris.
what is the role of white blood cells?
they defend against the invasion of pathogens – bacteria & viruses capable of identifying cancer cells.
they remove the body’s waste by phagocytosis.
WBCs surround pathogens and digest with enzymes and peroxides.
to do this they leave the circulation and go to the sites of invasion/tissue damage through a process known as extravasation.
what are the five types of white blood cells?
- neutrophils
- eosinophils
- basophils
- monocytes
- lymphocytes
what are neutrophils?
formed from stem cells and bone marrow, first responder phagocyte during inflammation (bacteria and fungi)
what are eosinophils?
formed in bone marrow, fight parasites and certain infections, modulates inflammatory responses.
what are basophils?
respond to specific types of inflammatory reactions, typically those that cause allergic symptoms, contains heparin and histamine.
