Transport in Mammals Flashcards
What is the mammalian circulatory system?
the closed, double circulation system by which blood is transported around the mammalian body, consisting of a heart, blood, and blood vessels
What are the structural features of arteries?
tunica intima (very smooth, squamous epithelium cells), tunica media (smooth muscle, collagen, elastic fibres), tunica externa (elastic and collagen fibres)
What are the functional features of arteries?
strength, elasticity, thick walls, fast transportation of blood, even out blood flow
What are the structural features of veins?
tunica intima, media, and externa, but media has far fewer elastic and muscle fibres, semilunar valves
What are the functional features of veins?
to return blood to the heart, do not have to withstand high pressure, blood is squeezed up by the tensing of muscles, and kept from running back down by semilunar valves
What are the structural features of capillaries?
very small, form a network throughout tissues called capillary beds, thin walls with a single layer of endothelial cells with gaps between them
What are the functional features of capillaries?
carry blood to and from cells, connect arteries and veins
What are red blood cells?
formed in bone marrow, fragile, biconcave disc, very small, very flexible, no nucleus, mitochondria, or endoplasmic reticulum, carriers of haemoglobin
What are lymphocytes?
a type of white blood cell with a large nucleus and small amount of cytoplasm, which destroys microorganisms in different ways, one being the secretion of antibodies
What is blood?
made of blood plasma, red and white blood cells, and platelets
What is tissue fluid?
leaked plasma from the gaps in cells in capillary walls which seep into the gaps between tissue cells, with far fewer proteins, no red blood cells, and some white blood cells
What is lymph?
the fluid inside lymphatics
What is blood plasma?
the pale yellow liquid in blood, composed of mostly water, solutes such as glucose and urea, and plasma proteins
What is the role of haemoglobin in the blood?
to transport oxygen from the alveoli in the lungs all over the body inside red blood cells
What is carbonic anhydrase?
the enzyme in red blood cells that catalyses the reaction: CO2 + H2O > H2CO3
What is haemoglobinic acid, HHb?
the compound which forms when haemoglobin combines with the hydrogen ions formed in the dissociation of carbonic acid
What is carbaminohaemoglobin?
the compound formed when carbon dioxide in the red blood cells combine with the amine groups of haemoglobin, ten percent of carbon dioxide in the blood is carried this way, this reaction reverses in the alveoli to free haemoglobin so that it can combine with oxygen once again
What is the Bohr effect?
higher partial pressure of carbon dioxide causes haemoglobin to release oxygen more readily, plotted on a graph this shifts the curve below and to the right of the normal curve
What is the significance of the Bohr effect?
maintains ph of blood by mopping up hydrogen ions from the dissociation of carbon dioxide, causes haemoglobin to release oxygen more readily
How does high altitude affect the cardiovascular system?
less oxygen partial pressure at higher altitudes means less oxygen carried in the blood, which can cause altitude sickness, adaptations include higher red blood cell counts, broad chests with larger lung capacity, larger right side of heart, and more haemoglobin
What is the internal structure of the mammalian heart?
the left and right atria and left and right ventricles, the left and right side of the heart is separated by the septum, the atria and ventricles are separated by the atrioventricular valves, bicuspid on the left, and tricuspid on the right
What is the external structure of the mammalian heart?
the aorta, pulmonary arteries, venae cavae, pulmonary veins, and coronary arteries can be seen on the surface of the heart
What are the wall thicknesses of the heart chambers?
walls of the ventricles are much thicker than atria as they need to develop more force, the right ventricle wall is less thick than the left as less pressure is needed to send blood to the lungs
What is the cardiac cycle?
the sequence of events in one heartbeat, atrial systole, ventricular systole, ventricular diastole
What is atrial systole?
both atria contract, blood flows into the ventricles, backflow is prevented by semilunar valves in the veins, pressure is not that great
What is ventricular systole?
ventricles contract, atrioventricular valves are pushed shut by pressurised blood, semilunar valves in aorta and pulmonary artery are pushed open, blood flows from ventricles into arteries
How is heart action initiated?
SAN muscle cells contract, producing an excitation wave which makes the muscles in the atrial walls contract simultaneously
How is heart action controlled?
a band of fibres between the atria and the ventricles do not conduct the excitation wave, the only way from the atria to the ventricle walls is through the AVN, which passes the wave to the Purkyne tissue after 0.1 seconds, it passes down the septum and causes ventricles to contract from bottom up
What is the atrioventricular node?
a patch of conducting fibres in the septum, also known as AVN
What is Purkyne tissue?
a bunch of conducting fibres which run down the septum between the ventricles
What is an arteriole?
a smaller vessel that an artery branches into, containing a larger proportion of smooth muscle, which can contract to control blood flow into tissues
What is a venule?
a smaller vessel that branches into a vein
What is a semilunar valve?
a half-moon shaped valve formed from the endothelium of veins, which allow blood to move towards the heart, but not away from it
What is oedema?
an excess of fluid which accumulates in the tissues due to too high blood pressure
What are lymphatics?
the vessels which collect the ten percent of fluid which does not seep back into the capillaries, and return it to the blood system
What are the structural features of lymphatics?
blind-ending vessels containing tiny valves wide enough to allow protein molecules to pass through, and to allow tissue fluid in, but not out, join to form lymph vessels
Where is lymph transported?
the subclavian veins
What are lymph nodes?
present along the lymph vessels, some white blood cells in the nodes remove bacteria, while others secrete antibodies
What are phagocytes?
a type of white blood cell which destroy microorganisms by phagocytosis, neutrophils and monocytes are types of phagocytes
What are white blood cells?
made in the bone marrow, have a nucleus, most are larger than red blood cells (excepts lymphocytes), spherical or irregular in shape
What is the haemoglobin dissociation curve?
the percentage saturation of a sample of haemoglobin with oxygen plotted against the partial pressure of oxygen, where the partial pressure of oxygen is higher, the percentage saturation of haemoglobin will be higher
Why is the haemoglobin dissociation curve S-shaped?
each time an oxygen molecule combines with a haem group, the shape of the molecule distorts, making it easier for successive molecules to bind, causing the curve to rise very steeply
What is ventricular diastole?
atria and ventricles relax, semilunar valves in aorta and pulmonary artery are pushed shut, blood flows from veins through atria
What is the sinoatrial node?
a myogenic patch of muscle in the right atrial wall, also known as SAN or pacemaker, the natural rhythm of contraction of SAN muscle cells is slightly faster than other cardiac muscle cells
