what is the infrastructure of the circulatory system?
what are the three layers blood vessels are made of ?
The "infrastrucutre" of the circulatory system is its network of blood vessels.
-an outer layer of connective tissue -a middle layer of smooth muscle -an inner layer lining the lumen is endothelium.
central blood-filled space of a vessel.
what are the major types of blood vessels?
- arteries carry blood away from the heart (branch into smaller arterioles)
-capillaries are the smallest blood vessels (site of exchange of molecules between blood nad tissue fluid.)
-veins: carry blood toward the heart. (receive blood from smaller venules.)
what are the structural differences between arteries and veins?
arteries have thicker walls that accommodate the high pressure of blood pumped from the heart.
In thinner-walled veins, blood flows back to the heart with lower pressure.
compare arteries and veins: direction: walls pressure valves position caliber
arteries: move away from the heart, are thick and muscular, can stand high pressure, have few or none valves, position: deep, and small caliber
veins: move toward heart, walls are thin and elastic, have low pressure, have a lot of valves, position: superficial, and have a large diameter.
what is the job of valves?
What is the skeletal muscle pump used for in veins?
Valves in some veins counteract low pressure because blood pressure is much lower in veins than in arteries.
skeletal muscle pump muscles press against thin-walled veins which then pump blood. blood flow in veins is a result of muscle action.
describe job of capillary
its thin permeable walls allow diffusion which happen to be about 1 rbc in diameter. In mammals, blood generally only goes through one capillary bed before returning to the heart.
where is most blood held in the system?
in venous vessels. THis is because pressure drops as blood goes through the system, due to friction.
what are the functions of the lymphatic system?
-collects interstitial fluid and returns it to circulation. -assists in transporting wastes.
lymphatic system better developed in vertebrates with high blood pressure
what is the lymphatic system consisting of?
composed of vessels and blind capillaries. -closely associated with veins, connects to venous system in two places. circulation is passive.
Where are lymphatic capillaries located? Why?
They are located near blood capillaries because they receive intersittial fluid from body tissues. (Their membranes are highly permeable.)
which has more valves lymph vessels or veins? do they have the same 3 layers as blood vessels? Where are lymph nodes locatd?
Composed of the same 3 layers as blood vessels. They contain more vlaves than veis. and lymph nodes are scattered along veins.
whats in a lymph nodes?
whats in a lymph capillary
masses of lymphocytes andmacrophages
Interstitial fluid in an lymphatic capillary
whats the basic plan of arterial circulation?
1. heart: ventral position, pumps anteriorly 2. anterior vessels: a. ventral aorta (paired anteriorly) b. aortic arches (6 pairs)(with afferent and efferent branchial arteries to and from gills) c. dorsal aortae (internal + external carotids)
3. Posterior vessels: a. dorsal aorta - dorsolateral branches (to body wall & limbs) - ventrolateral branches (to kidneys & gonads) - median ventral branches (to gut tube & derivatives)
frog: what are teh arches now called after modification
1. there is a loss fo dorsal aorta and connection between arches 3 and 4 (carotid duct) 2. loss of arch 6 connection to dorsal aorta (ductus arteriosus) 3. ventral aorta between arches 3 and 4 now called hte common carotid. 4. arch 6 produces the pulmocutaneous artery (to the lungs and skin)
what is the lizard arch system like?
asymmetrical right systemic bears all the carotds.
? Similar to birds, but the right systemic is lost. ? Left systemic bears the carotids.
when did the major split within amniotes occur?
summary of tetrapod arches
? Arch 3: Carotids ? Arch 4: Systemic (aorta) ? Left + Right (amphibians) ? Right dominant (reptiles) ? Right only (birds) ? Left only (mammals) ? Arch 6: Pulmonary (+ cutaneous in amphibians) ? Arches 1, 2, and 5 are lost.
what is the basic organization of the benous sytem?
? 2 inner, deep components (drain gut and gut derivatives) ? 2 outer components (drain body wall, limbs, head, tail)
What two main veins would help the most (inner vessels)?
1. subintestinal (vitelline): flows forwards along midline and includes the hapatic portal system 2. pulmonary veins: return blood to heart from lungs.
groups of veins that drain one set of organs and lead to another set of capillaries in another organ
hepatic portal system
-picks up digested nutrients from other abdominal organs -delivers nutrients and toxins to the liver for processing. -this blood goes through 2 capillary beds.
What are the main outer vessels?
1) Cardinal vein (and vena cava): dorsal and includes the renal portal system. 2) Abdominal veins: drains ventral body wall.
Renal portal system
Renal portal system: ? Intercepts blood between the tail / hind limbs and the heart. ? Sends blood to the kidneys first. ? Absent in mammals. ? Unclear function.
major differences among vertebrates in venous system
1. Cardinal system ? paired in primitive condition, single vena cava is derived. 2. Portal systems ? all vertebrates have a hepatic portal system, and all vertebrates except mammals also have a renal portal system.
what happened to the number of capillary beds over time? why?
fish with gillls have 6 cap. beds tetraod with renal portal has 6 beds while mammals have only 4 cap. beds
Each time blood goes through a capillary bed it looses pressure.
which have higher pressure systems: fish or tetrapods?
Fish= low pressure system
tetrapods= higher pressure system (highest in endotherms) - systemic pressure in mammals is 5 times that of their pulmonary presure. -pulmonary pressure in mamalsis similar to systemic pressure of reptiles.
what are the consequences of having a hgiher pressure in mammals?
consequences -separation fo pulmonary and systemic circuits -more muscular heart and arteries -coronary arteries are best developedin endotherms due to thick muscular walls of heart.
what are the first two steps in heart developmen?
-primary vitelline arc of vessels forms -2 ventral vessels in midline fuse to form the heart.
what ar ethe 4 chambers caudal to rostral?
sinus venosus atrium ventricle conus arteriosus
contraction of the ventricles reduces pressure within pericardial cavity- sinus venosus and atrium expand- sucks in blood
what is the pace maker of hte heart in fish?
how does the beat in fish propogate
the beat start in the ventricle, and then is joined by the atrium (faster), and then the sinus venosus (faster still
waht is the pacemaker of the heart in adult mammals?
the sinoatrial (SA) node- a remnant of the sinus venosus located in the roof of the right atrium.
what are the 4 chambers in a dogfish posterior to anterior
how is a zebrafish heart development helped by( ie the forces involved)?
heart shape is produced in part by blood flow. -cardiac endothelial cells change shape when subjected to shear forces -blood flow in developing heart causes the folding, results in a heart that minimizes shear forces on blood.
how is a tetrapod's heart developed?
-heart begins as two parallel tubes -these fuse along part of their length to become the heart (this early heart is similar to the one-pump fish heart) -conjoined tubes bend, and the interatrial and interventricular septa are formed.
what major way do different vertebrate heart differ
what function does this allow?
incomplete subdivision f the ventricle is typical of amphibians and reptiles (except crocodilians). (this allows facultative shuting of blood toward or away from the lungs as needed
which have single and which have double circuits... fish amphibians reptiles mammals and birds
fish-single amphibians-double reptiles: double mammals and birds: double
what hind of circuit do fish have and how does it function?
single circuit -a fish heart has one venticle and one atrium. blood pumped from the ventrivle travels to the gills where it picks up O2 and disposes of CO2.
how does propterus (obligat air breathing fish) breathe in the water (ie which chages occur anatomically)?
aquatic breathing mode -blood from heart is shunted to arches 2, 5, 6 which bear gill filaments -pathway to lung via arch 6 (pulmonary arteries) is closed off, as are arches 3 and 4
how does propterus (obligate air breathing fish) breathe in air (what changes occur anatomically)
-oxygenated blood returns from lungs and is shunted to arches 2, 3, and 4 -systemic low oxygen blood is shunted to arch 6 and lungs, valves prevent blood from going to gills on arches 2 and 5.
what anatomical differences in the heart are evident in propterus lungs?
-nearly complete separation of left + right sides. -blood from lungs returns to left atrium, blood from body returns to sinus venosus and then right atrium -spiral septum shunts blood appropriately left side to anterior arches and head, right side to lungs (arches 5 and 6).
what are the differences between left and right sides in a tetrapod?
right side: poorly oxygenated, receives systemic flow. left side: well oxygenated, receieves pulmonary flow.
how are muscles arrangedin a tetrapod heart?
-muscle in the walls of a tetrapod's heart is arranged in spirals. -heart contracts in both diameter and length -both atria contract together and slightly before the ventricles.
how many chambers in an amphibian heart?
thus how does it function?
(when and how does it send blood to its 2 circuits, names)
3 chambers: 2 atria, 1 ventricle
some mixing in the ventricle, the ventricle pumps blood into a forked artery- splits the output into pulmocutaneous circuit and systemic circuit.
how is a frogs' heart much different?
-a single vessel exits the heart , but it divides into 3 internally: through interatrial septum divides the left atrium, sinus venosus, and right atrium spiral valve in heart divides into 3 that go either side (carotid arteries#3, systemic arteries#4, and pulmocutaneous artery#6)
where does blood with highest oxygen travel?
what are 2 types of hearts in reptiles?
1. lepidosaurs and chonia 2. crocodilians
what are the two circuits they shunt to and how do they alter teh way their blood flows?
? 2 circuits: Pulmonary & Systemic ? In both, individuals can alter blood flow away from the lungs when not breathing air. ? They use a ?right-to-left shunt? and bypass the lungs. ? Flow direction is determined by the relative resistance in pulmonary vs. systemic outflows.
what is the structure of the heart in lepidosaurs and chelonia? -ventricle subdivision? name of septum? -number of vessels leaving the heart?
-left and right atria are completely divided -ventricle is partially divided into 3 chambers by a septum interventricular septum -3 vessels leave the heart
what are the names fo the venticles in lepidosaurs and chelonia?
what changes the way blood is diverted in either circuit? in lepidosaurs
changes in resistance
what are the 4 chambers of crocodilians?
? Right atrium ? Left atrium ? Right ventricle ? Left ventricle
what connects the left and right systematics in crocodilians
foramen of panizza.
how can blood be diverted to either circuit
by changes in resistance
In general how do pumps work? left and right differences?
? In general, left side pumps and receives O2-rich blood and right side receives and pumps O2- poor blood.
what does the right to left shunt do in crocodilians
1. Bypasses lungs during diving or apnea. 2. Saves energy required to push blood through compressed lungs when diving. 3. Assists in warming body when air temperatures are cool (inhaling cool air will cool the blood). 4. CO2 concentrations rise, lowering blood pH and causing hemoglobin to more readily release free oxygen to the tissues.
what are teh 4 separate chambers in mammals and birds?
do blood vessels flowing from ventricles have any connection?
? Right atrium ? Left atrium ? Right ventricle ? Left ventricle
no they don't
how was hte 4 chambered heart a special adaptation?
? A powerful four-chambered heart was an essential adaptation of the endothermic way of life characteristic of mammals and birds. ? Endotherms use ~ 10x as much energy as equal sized ectotherms. ? Their circulatory system must deliver ~ 10x as much fuel and oxygen to tissues.
what is the ductus arteriosus imp for in lungfish fetus?
shuts blood away from lungs.
what is the foramen ovale? ductus arteriosus?
where does the oxygenated blood from fetus go back to?
? Fetus must supply blood to the placenta via umbilical arteries. ? Oxygenated blood returns from placenta via umbilical veins to right atrium. ? Foramen ovale present between right & left atria. ? Persistent ductus arteriosus. ? Lungs non-functional.
what is the pathway blood takes in a fetus?
1. oxygenated blood flows from right atium through the foramen ovale to the left atrium- left ventricle- aorta
2. poorly oxygenated blood passes from the right atrium- right ventricle-pulmonary trunk-ductus arteriosus-aorta
what happens to circulatory system at birth
-flow to R atrium is reduced due to contraction fo umbilical veins. -blood is sent to lungs, resistance to flow there is reduced. -blood flow from lungs and back to the left atrium. -ductus arteriosus closes- becomes ligamentum arteriosum -foramen ovale closes, sending all R atrium blood to R venricle - becomes fossa ovale.
how many percent of adults still have a foramen ovale
25% of adults have a patent foramen ovale
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