Transportation Flashcards
Single vs double circulation
Single – one ventricle pumps deoxygenated blood to gills where it gets oxygenated and still has enough pressure to flow directly to another organ od the body where it gets deoxygenated
Double circulation – two ventricles, right pumps deoxygenated blood to lungs, it gets oxygenated and returns to the heart into the left ventricle which pumps it to the body, where it’s again deoxygenated so it returns to the heart, into the right ventricle
Systemic vs pulmonary circulation
Systemic circulation: oxygenated blood goes from the heart’s LV into the aorta and from there into head and the body via carotid arteries – in body tissue, blood loses O2 and gains CO2 – deoxygenated blood goes back into the heart via superior (head) and inferior vena cava (body) and into RA
Pulmonary circulation: deoxygenated blood goes from the heart’s RV into lungs via pulmonary artery – in the lungs, blood loses CO2 and gains O2 – oxygenated blood goes from lungs into the heart by the pulmonary vein and into the LA
Heart anatomy
Atria – collecting chambers with thin myocardium, gradually fill with blood, pump blood intro ventricles
Ventricles – pumping chambers with thick myocardium (especially left V), pump blood into arteries
Septum – separating the two halves to prevent blood from mixing (would cause constant lack of oxygen in the body)
Valves – atrioventricular and semilunar, ensure that blood circulates by preventing backflow
Cardiac muscle (myocardium) – special property of contracting on its own without being stimulated by a nerve (myogenic contraction)
Coronary vessels – the many capillaries in the muscular wall of the heart supply O2 and glucose for aerobic CR and remove waste products, blood running through them is supplied by coronary arteries and removed by coronary veins
Pacemaker (sinoatrial node) – region of specialized cardiac muscle cells in the wall of the right atrium that initiates each contraction
Arteries anatomy and adaptations to function
- carry blood away from the heart
- high blood pressure (at its max at the heart exit and at its min at heart entrance)
- branch into arterioles and then into capillaries
- tunica externa – tough outer coat with collagen fibers (produced by fibroblasts) that make the vessel firm but elastic to prevent aneurysms (bulging outwards) or bursting due to high blood p
- tunica media – thick layer of circular smooth muscle and elastic fibers (elastin) to help pump blood – makes the arteries pulsatile, can accommodate large and variable V of blood
- arteries further down in the body have to be more pulsatile because of the lower p there ((the further away from the heart the lower the p)
- smooth muscles cause vasoconstriction and vasodilation
- tunica intima – inner surface is corrugated (smooth endothelium to reduce resistance of blood flow) and there is an additional layer of elastic fibers in some arteries
- narrow (round-shaped) lumen to withstand high blood pressure which maintains a sufficiently fast blood flow
- No valves
Veins anatomy and adaptations to function
- carry blood to the heart
- contain 60% of all blood in the body at any moment
- branch into venules and they into veins
- tunica externa – thin and tough – no danger of bursting but prevents leaks
- tunica media – thin layer of muscles and some elastin/fibrinogen (not pulsatile but compressible) – surrounding muscles exert a pushing force to push blood up (varicose veins developed because of weak leg muscles) (vein flattens, flexible)
- tunica intima – smooth endothelium to reduce resistance of blood flow
- lumen – wider (slow blood flow) and cross-section is elongated because muscles flatten the vein
- one-way valves prevent blood flowing against gravity from going back – backflowing blood will exert pressure on valves and they’ll close
How are capillaries adapted for the exchange of materials
1) Capillary wall is one layer of flat endothelial cells – short diffusion distance and increased SA to maximize exchange efficiency
2) Wall surrounded by basement membrane (extracellular fibrous protein) that serves as a filtration barrier, preventing larger molecules from entering and exiting the capillary
3) Pores between cells enable some of the plasma to leak out and form intercellular fluid (flow out due to higher pressure) – fenestration (fenestrated endothelium) is when the pores between cells are larger than normal in tissues whose main function is exchange of materials (kidneys)
4) Narrow lumen of capillaries enables them to fit into narrow species and to reach all tissue parts, causes slow blood flow (cells flow in one file) to ensure thorough exchange of materials between blood and tissue
5) Substances provided to tissue by capillaries are O2, food molecules and hormones/enzymes and substances dissolved in tissue fluid that goes into capillaries are CO2 and other waste products (detoxified by liver or excreted by lungs or kidneys)
6) Density of the capillary network depends on tissues’ metabolic demands (bone vs liver tissue) – it is particularly large when capillaries exchange materials with the external environment (lungs and small intestine)
Blood composition
55% plasma, 45% cellular components
Erythrocytes (RBC) carry O2, leukocytes fight infection (some produce antibodies, some directly fight the pathogens), platelets are cell fragments (megakaryocyte) that heal wounds and cause blood clotting. Plasma is a yellowish liquid composed mostly of water which carries dissolved substances like CO2, O2, salts, urea, nutrients, hormones, heat (high heat capacity) and plasma proteins (albumin, fibrinogen and antibodies (globulins))
heart anatomy
myocardium/cardiac muscle – striated muscle controlled by autonomic nervous system
four chambers: left valve, left atrium, right valve and right atrium
two sets of valves: atrio-ventricular (tricuspid and bicuspid/mitral) and semi-lunar valves
right side of the heart carries deoxygenated blood and the left oxygenated
blood flow in the heart (systemic and pulmonary system)
1) Blood from body fills RA by vena cava and blood from lungs the LA by pulmonary vein
2) Atriums push the blood into RV and LV by weak contractions
3) The high p from atriums keeps atrio-ventricular valves open so that blood can pass through
4) Once the blood is in ventricles the atrio-ventricular valves close to prevent backflow (p(V) > p(A))
5) Ventricles pump blood into aorta and pulmonary artery by powerful contractions (especially LV because it pumps to further distance and against gravity)
6) High pressure from ventricles keeps semi-lunar valves open so that blood can pass through
7) Once the blood is in arteries the semi-lunar valves close to prevent backflow (p(artery) > p(V))
Tissue fluid, formed as a result of what? What happens to excess of tissue fluid?
makes up 20% of human body mass
pressure filtration – some components of blood plasma are pushed through the membrane into tissue fluid due to the relatively high pressure in capillaries
3/14 L drains into the lymphatic system, otherwise it would cause swelling (oedema)
usually waste goes from tissue fluid into capillaries but the molecules from the tissue fluid that are too large to pass though the capillary wall (e.g. pathogens) will be introduced into the lymphatic system by larger pores in lymphatic vessels and they will create lymph
Lymphatic system (vessels)
Small lymphatic vessels merge into larger vessels and then flow into a lymphatic node which enlarge when there is an infection. All lymph is returned to the blood circulation through two large lymphatic ducts which merge with the right and left subclavian veins (flows into vena cava, right atrium)
Lymphatic vessels are not pulsatile (no muscles surrounding them), they are much larger than blood vessels (larger lumen) and they have one-way valves
Cardiac cycle - phases
a repeating sequence of actions in which the heart chambers contract and relax in a coordinated manner to send blood around the circulatory system. One cycle = diastole (relaxation) and systole (arterial and ventricular contraction) = 0.8s
1. atrial systole – atria contract, p in atria increases, blood pushed from atria to ventricles, AV valves are open, SL valves are closed
2. ventricular systole – ventricles contract, p in ventricles rises, blood is pushed from ventricles into arteries, AV valves are closed, SL valves are opened
3. diastole – heart muscle is relaxed, SL valves are closed, when p(ventricles) < p (atria) AV valves open and blood spontaneously fills ventricles, blood starts filling the ventricles, next cardiac cycle starts when atria contract again
Measuring pulse rate
measuring the number of beats per minute – radical pulse at wrist or carotid pulse on the neck – systolic blood pressure
Heartbeat initiation and control
It is myogenic (originating in muscle) – initiated within the heart muscle itself by the SA node which sends an electrical impulse that causes atrial contraction (75 beats per minute, independent of activity)
Impulse is prevented from spreading immediately into ventricles because they are transmitted by AV node and a layer of fibrous, isolated bundles that lead to the heart apex
This short delay between atrial and ventricular systole ensures that all the blood transferred from atria to ventricles before ventricles contract as impulse spreads from the apex upwards into the arteries
Nerve impulses from the medulla of the brain together with hormones (e.g. epinephrine) can speed up or slow down the heartbeat (activity, sleeping, etc.)
ECG interpretation
P wave – voltage given off by SA node, atrial systole
Q-point – point at which AV node sends its impulse
The QRS complex – represents ventricular depolarization and contraction
PR interval – the transit time for the electrical signal from SA node to ventricles
T-wave – represents ventricular repolarization (relaxation)
Atherosclerosis vs coronary thrombosis vs ischemia
slow build-up of plaque (cholesterol, lipids, cell debris, Ca) inside arteries which causes arteries to become hard and less flexible and which decreases the lumen decreases. This can lead to hypertension which can cause further and long-term damage to the vessel like inflammation
if plaque forms in one of the three major coronary arteries or in some of their branches, the O2 supply to the myocardium “downstream” from the occlusion would be impaired or blocked, leading to a heart attack (a stroke if carotids are blocked)
less than normal supply of blood to tissues due to a blockage or narrowing in vessels (not enough oxygen supplied)
Monocots vs dicots – cotyledon (embryonic leaf), leaf veins, vascular bundles, root and floral parts
Monocots – one cotyledon, parallel leaf veins, complexly arranges vascular bundles in the stem, fibrous roots and floral parts in multiples of 3
Dicots – two cotyledons, net-like veins in the leaf, vascular bundles arranges in a ring, taproot and floral parts in multiples of 4 or 5
Draw an annotated diagram of a stem (cross-section) and explain the function of each structure
- Epidermis – single layer of cells with waxy cuticle on the outside
- Cortex – medium-sized thin-walled cells, strengthen the stem when turgid
- Phloem – thin-walled cells, transport sugars and other food
- Cambium – small cells with thin walls which divide xylem and phloem, they undergo mitosis, causing the thickness of vascular bundles to increase (stem increases in diameter)
- Xylem – wide tubular structures with thick walls, transport water and mineral ions
- Pith – large thin-walled cells in the center of the stem
Xylem adaptations for water transport:
- Thick wall and lignification (providing structural support and strength to the plant) – walls are impregnated with a polymer called lignin (prevents the vessels from collapsing when p is low)
- Lack of wall and cell components – end walls between adjacent cells are removed during xylem development (long continuous tubes)
- Pores for entry and exit of water (wall is impermeable to water but it can move through pores)
Phloem adaptations for water transport
- Phloem sap dissolves compounds (it flows due to a concentration gradient between sources and sink)
- Cell walls not broken down completely as in xylem to withstand higher pressures
- Thin, non-lignified cell wall
- Companion cell (helps with loading, provide ATP for active transport) and plasmodesmata (cytoplasmic connection, sucrose-rich sap flows to adjacent sieve tube from the cell)
- Sieve plate with pores through which phloem sap can flow in either direction but not in both directions simultaneously
Root anatomy
- Epidermis – small cells that may have root hairs protruding (elongated epidermal cells), absorbs water and mineral ions from the soil often using root hairs, tougher to mitigate the effect of friction from the growing of the root
- Cortex – large and thin-walled cells, bulks out the root to strengthen it and increase the surface area of the root
- Xylem – transports up the stem and leaves, larger than phloem
- Phloem – transports from leaves to the roots
Water transport in leaves
Water leaves the leaf by transpiration making the WP (air spaces) < WP (xylem) which is full of xylem sap – H2O not transported directly from xylem to air spaces, but the water first enters spongy mesophyll and is then drawn to air spaces through pores between cellulose fibers which are hydrophilic and can form H-bonds with water (adhesion and cohesion) – a type of capillary action
Transpiration stream vs transpiration pull
Constant evaporation of metabolic water from leaves causes a constant low WP in the leaf which draws water from the xylem upwards
Because of cohesion between water molecules, tension generated in the leaf is transmitted down the continuous columns of water in xylem vessels to the roots. The energy that drives it (???) comes from the heat used in transpiration and the rope-like resistance to breaking of the column of water due to H-bonds
Water transport in roots
When a plant is transpiring – xylem vessels filled with sap under tension (low WP) – drawig water into xylem vessels
When a plant is not transpiring and the WP is not as low in the xylem (not enough to cause passive uptake of nutrients) root pressure is used – water molecules move by capillary action (form higher to lower WP by attaching from one cell wall to another) until they reach the barrier to capillarity outside of the xylem – then, endodermal cells pump mineral ions into the xylem which makes the sap hypertonic (decreasing WP) so water molecules move inside by osmosis – p (xylem) rises and sap is push up against gravity (continues to climb due to capillary action)
When is root pressure used?
When the plant is not transpiring so:
a) At high atmospheric humidity
b) At night
c) In deciduous trees during winter
