Circulatory system

Circulatory System

The circulatory system of craniates consists + heart + capillaries or sinusoids+ arteries + blood vascular system + veins or venous sinuses + lymphatic system

The blood is an important agent for circulation:1. Carries oxygen, nutrients, hormones, waste products

and other substances2. Conducts heat

Lymph channels – terminate in venous channels•Collect interstitial fluids and lipids

Arteries Veins or Venous Sinuses

Capillaries or Sinusoids

Function Carry blood away from heart

Blood towards the heart

Site of gas exchange

Structure Muscular and elastic walls can distend

Less muscle and elastic tissue, more fibrous tissue than arteries less distention

Endothelium; some mesenchyme & smooth muscle fibersLumen diameter = size of RBC Precapillary sphincter Capillary shunts

Special terms Smallest: Arterioles (diameter <=0.3mm) – dilate and constrict reflexly thereby assist in regulating blood pressure

Smallest: Venules – provide direct connection to capillariesPortal system

Capillary bed or network – all individual capillaries served by a single arteriole

Covering Loose connective tissue adventitia

Loose connective tissue adventitia

- short section where capillary emerges from arteriole -has smooth muscle fibers that given an adequate neural or hormonal stimulus close off entrance of capillary bed- ex: blushing of skin

- connects arterioles and venules directly - - assure uninterrupted circulation between arterial and venous sides of capillary beds when other capillaries are constricted

-system of veins bounded by capillary beds 1.Renal portal system2.Hepatic portal system 3.Hypophyseal portal system

Structure of Blood Vessels

Renal portal system Hepatic portal system

Hypophyseal portal system

Blood from capillaries of the tail digestive tract, pancreas and spleen

Hypothalamus (contains pituitary regulating hormones)

To capillaries of kidney liver Adenohypophysis

Continue to Heart Heart Heart

Portal Systems

Hepatic portal system

Renal portal system

Arteries Arterioles (Precapillary sphincter) Capillaries (capillary shunts)

Venules

Veins

Pathway of Blood

Development

• Mechanisms of vessel formation– Vascularization

• Process of vessel formation from endothelial precursors with the formation of vessels potentially occurring prior to the onset of blood flow

• May be an inductive interaction with the surrounding tissue (notochord and the axial dorsal aorta)

– Angiogenesis• The remodeling of existing vessels and can occur both

prenatally and postnatally

Angiognesis

Serum-plasma without fibrinogen (clotting substance)

Blood

Hemopoiesis-formation of blood cells-earliest sign: large number of blood islands (produce hemocytoblasts, which are stem cells from which all later blood cells arise)

-blood islands also have extensive network of endothelial-lined spaces. These connect to other blood channels to establish an

early circulatory system

Hemopoiesis (cont.)-descendants of hemocytoblasts form in the tissues within the body

Hemopoietic source Product

Liver, kidney, spleen Craniate RBCs

spleen Craniate WBCs

Bone marrow Amniote RBCs and Granular Leukocytes

Intestinal submucosa Teleost granular leukocytes

Lymphatic tissues lymphoctes

Deteriorating these formed elements in the blood of craniates are done by Macrophages through phagocytosis and amboeboid WBCs in any traumatized tissue of the body

Formed Elements

Formed Elements

Lifespan: 3-4 monthsNumber: 25 trillion Reduces hemoglobin- when oxygen is freed

Formed Elements

Formed Elements

Platelets-participate with fibrinogen in the clotting of blood-tiny fragments of stem cells (megakaryotes) found in the bone marrow

Heart and Its Evolution

• Muscular pump that occupies pericardial cavity

Heart Arteries Walls Endocardium

Myocardium Epicardium

Intima Media Adventitia

Muscle Cardiac Smooth

Heart

• Visceral pericardium – lying on epicardium; = visceral pleuroperitoneum

• Pericardial cavity – space between pericardia

• Coronary arteries and veins

Single Circuit

Blood passes from heart to the gills

From gills directly to all parts of the body

Systemic circuit – oxygenated blood to organs and returns oxygen depleted blood to the heart

Pulmonary circuit – deoxygenated blood from heart to lungs

Returns to the heart

Double CircuitFishes

Craniates who abandoned gills

Hearts of Gill-Breathing Fishes

• 4 chambers – Sinus venosus

• Sinoatrial aperture

– Atrium• Atrioventricular aperture

– Ventricle• Semilunar valves

– Conus arteriosus (truncus arteriosus) or Bulbus arteriosus

Except dipnoans

1. Ventricular contraction – creates suction

2. Filling of sinus venosus

3. Atrium relaxes – blood from sinus venosus valves sinoatrial aperture atrium

Atrial contraction atrioventricular septum valves relaxing ventricle

Conal constriction

Hearts of Dipnoans and Amphibians• Modifications in heart – correlated with aerial respiration

– Separates oxygenated blood returning from swim bladders or lungs from deoxygenated blood from other organs

– Establishment of a partial or complete interatrial septum right (O2 poor) and left atrial (O2 rich) chambers

– Formation of a partial interventricular septum (dipnoans & Siren) or ventricular trabeculae (amphibians)

- Fxn: maintain separation of oxygenated and unoxygenated blood - trabeculae – shelves or ridges projecting from the ventricular wall into the chamber and running mostly cephalo caudad

1. Formation of a spiral valve in the conus arteriosus-valves direct O2 poorblood into aortic arches that lead to gills or

lungs and channelize oxygenated blood into arches that supply other organs 4. Shortened ventral aorta

- Blood moves from conus arteriosus directly to appropriate vessels

Hearts of Amniotes • 2 atria, 2 ventricles

+ 1 ventricular chamber in turtles and squamates

- Sinus venosus in birds and mammals sinoatrial (SA) node

Sinus venosus in crocodiles is partially incorporated to wall of right atrium

Hearts of Amniotes

• Interatrial septum – completely separates right and left atria – Interarterial foramen or foramen ovale –

confluence of right and left atria during embryonic development; closes during birth, becomes fossa ovalis in medial wall of right atrium

• Sinus venosus right atrium • Pulmonary veins left atrium

• One-way valves guard the passageways from atria into ventricles.

• Each valves consist of one or more fibrous flaps or cusps, connected chiefly in mammals by tendonous cords (chordae tendineae) to papillary muscles that project from the ventricular walls

Heart valves

Innervation of the Heart

• Hagfish heart – no external innervation; only modified intrinsic cells that respond to circulatory signals


• Vertebrate heart – Autogenic – require no external neural stimulus

only to produce a regular beat that can be increased or slowed reflexly by CNS

– Pulsation depends on appropriate concentrations of certain electrolytes (Na, K, Ca ions)

– Purkinje fibers – intrinsic conduction system composed of atypical cardiac muscle that constitute a conduction network with high conductile competence


ARTERIAL CHANNELS AND THEIR MODIFICATIONS

Circulatory System

ARTERIAL CHANNELSsupply most organs with oxygenated

blood, although they carry deoxygenated blood to respiratory

organs

PRIMITIVE PATTERS OF GNANOSTOMES

VENTRAL AORTA(paired in early embryogenesis) –

emerges from the heart and passes forward beneath the pharynx

DORSAL AORTA(paired above the pharynx only) –

extends caudad in the roof of the coelom

SIX PAIRS OF AORTIC ARCHES – connects the ventral aorta with the dorsal aorta

FIGURE 14.16Page 327

SQUALUSVENTRAL AORTA extends forward under the pharynx and connects with the developing aortic arch (fig. 14.17)FIRST TO DEVELOP aortic arches in mandibular arch

posttrematic arteries → sprout crosstrunks crosstrunks = grows caudad in the holobranch and by further budding establish the last four pretrematic arteries

AORTIC ARCH OF FISHES

AORTIC ARCH FATE

1st pair (before the 6th pair appears)ventral segments – disappears

dorsal segments – efferent spiracular arteries2nd pair first pretrematic arteries

3rd pair posttrematic arteries

4th pair posttrematic arteries

5th pair posttrematic arteries

6th pair posttrematic arteriesFIGURE 14.17

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SQUALUSAortic Arches II to VI becomes occluded at oneSite. (broken lines in fig. 14.17(a)) → Afferent Branchial Arteries – segments ventral

to the occlusion → Efferent Branchial Arteries – dorsal segments

(III to VI)Capillary Beds develops within the ninedemibranchAfferent Brachial Arterioles connect theafferent brachial arteries with the capillaries.Efferent Brachial Arterioles return oxygenatedblood from the capillaries to the pretrematicand posttrematic arteries Δ blood entering an aortic arch from the ventral

aorta must pass through gill capillaries before proceeding to the dorsal aorta


FIGURE 14.17(a)

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TELEOSTSimilar developmental changes: convert the embryonic aortic arches into afferent and efferent brachialarteriesΔ The specific numberconverted determines thenumber of functional gills.1st and 2nd aortic arches tends to

disappear. (fig. 14.18a)


FIGURE 14.18(a)

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PROTOPTERUS (fig. 14.18b)3rd and 4th embryonic arches do not

become interrupted by gill capillaries.4th pharyngeal arches bear external gills.DIPNOANS, AMIA, POLYPTERUS6th aortic arch - pulmonary vein sprouts

off the left and right and vascularizes swim bladder

* other archinopterygians – swim bladders are supplied from the dorsal aorta


FIGURE 14.18(b)Page 329

SUMMARY OF AORTIC ARCH OF FISHES

AORTIC ARCH SQUALUS TELEOST PROTOPTERUS DIPNOANS, AMIA, POLYPTERUS

1st pair (before the 6th pair appears)

ventral segments – disappears

dorsal segments – efferent spiracular

arteries

disappear

2nd pair first pretrematic arteries

disappear

3rd pair posttrematic arteries posttrematic arteries not become interrupted by gill

capillaries

4th pair posttrematic arteries posttrematic arteries - not become interrupted by gill

capillaries- bear external gills

5th pair posttrematic arteries posttrematic arteries

6th pair posttrematic arteries posttrematic arteries Pulmonary Vein

Consists of six pairs ofembryonic aortic arches(fig. 1.6)1st and 2nd – transitoryand regress fairly soon(fig. 14.19 and 14.20)After arches I and IIdisappear: arch III (carotid arch) and thepaired dorsal aortaanterior to arch IIIconstitute the internalcarotid arteries (fig.14.18C, 14.19, 14.20)

AORTIC ARCH OF TETRAPODS



FIGURE 14.18(c)

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6th pair – vasculized the lung bud to form PulmonaryArteries (fig. 1.6 and 14.20d)Amniotes with theexception of some limblesssquamates lose the 5th aortic arch during embryonic life. (fig. 14.18f-hand 14.19e-h)Frogs and someSalamanders independentlylose the 5th aortic arches.


FIGURE 14.18(f-h)Page 329

FIGURE 14.19(e-h)

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AMPHIBIANSMost terrestrial urodeles retain four pairs of

aortic arches. (fig 14.18c)Perennibrachiate urodeles* 3 aortic arches (5th arch either disappear or

unite in part with the 4th during embryogenesis) (fig.14.18d and 14.21)

* Gill Bypass: Larval afferent and efferent branchial arterioles that carry blood from the aortic arches into the gills and back functions throughout life and a short section of the 3rd, 4th, 5th (fused to 6th in Necturus)→ constricted while the animal is using its gills but when the dissolved oxygen in the pond becomes low enough to cause the animal to gulp air, the gills shrink, and the bypasses carry more blood

* Bulbus Arteriosus – maintains a steady non-pulsating arterial pressure in the gills


FIGURE 14.18(c-d)Page 329


ANURANSRetain four aortic arches (III through VI).• 3rd, 4th, 5th – supply the larval external gills during the five or six days these gills function (after) supplies

internal gills until metamorphosis• 6th – sprouts a pulmonary artery that vascularizes the developing lung bud• Changes (fig 14.18e):

1. Aortic Arch V disappears2. Dorsal aorta between the aortic arches III and IV (ductus caroticus) disappears3. Segment of aortic arch VI dorsal to the pulmonary artery (ductus arteriosus) disappears

Δ Result of changes 1&2: blood entering aortic arch III (carotid arch) can pass only to the head• 3: blood entering arch VI (pulmonary arch) can now pass only to the lungs and skin• Systemic arch (4th) – distribute blood to the rest of the body


FIGURE 14.18(e)

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Ventricular Trabeculae – separates oxygenated blood in the left atrium and deoxygenated blood in the right atriumHOW?: expulsion from the ventricle of right atrial blood and by action of the spiral valve in the conus arteriosus Ventricular Systole: (1) the valve is flipped into a position that closes off the entrance to the systemic and carotid arches (diverting oxygenated blood into the common aperture that leads to the two pulmonary arches ( fig 14.12b))(2) back pressure builds up in the pulmonary arteries because of filling of the lung capillaries, spiral valve flips into an alternate position that directs exygenated blood into the systemic and carotid arches


FIGURE 14.12(b)

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ADULT APODANS• Retain III, IV, VI and the ductus carotices• Ductus arteriosus and ductus caroticus are of

small diameter and carry little blood.


In adult – exhibits three adultaortic arches – III, IV, base of VINo ductus arteriosus and ductuscaroticus except basal lizards andsometimes limbless squamates.INNOVATION: instead ofaeveloping a spiral valve to shuntfresh and deoxygenated bloodInto appropriate arches, theembryonic ventral aorta splitsinto three separate channels: twoaortic trunks (left and rightsystemic arches) and apulmonary trunk (figs 4.18f, arv,alv, and prv; 14.19e and14.22,2,3,4)

AORTIC ARCH OF NONAVIAN REPTILES

FIGURE 14.18(f)

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FIGURE 14.19(e)

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FIGURE 14.22(2,3,4)Page 332

CROCODILES(1) the pulmonary trunk emerges from the rightventricle and leads to the left and rightpulmonary arches (fig 14.19e, vessel in blue) -deoxygenated blood sent to the lungs(2) one aortic trunk emerges from the leftventricle and carries oxygenated blood to theright systemicarch and the carotid arches(fig.14.23)(3) second aortic trunk emerges from the rightventricle and leads to the left systemic arch

* from (1)(2)(3) – one would expect than bloodin the left systemic arch would be low in oxygenbecause it comes from the right ventricle –HOWEVER IT IS NOT THE CASE WHEN THEANIMAL IS BREATHING:

FORAMEN OF PANIZZA


FIGURE 14.19(e)

Page 330


Foramen of Panizza: an aperture that connects the two aortic trunks at their base

During normal respiration: Left-Right Shunt (assure delivery of oxygenated blood to all parts of the body):- the valve at the exit from the right ventricle into the aortic trunk remains closed - the blood from the right ventricle can pass only to the lungs- some oxygenated blood from the left ventricle is shunted through the foramen of panizza to the left systemic arch

Submerged in water: Right-Left Shunt (diverts considerable blood away from the lungs and into the systemic circulation):- pulmonary arteries constrict reflexly, causing a backup of blood in the right ventricle- the valve between the right ventricle and its aortic trunk is forced to open (fig. 14.23b) - some right-ventricular blood is shunted to the aortic trunk that emerges from the left ventricle

→ utilization of the shunt is facilitated by a mild reduction in the blood pressure within the left ventricle


FIGURE 14.23(a)

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FIGURE 14.23(b)

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TURTLES AND SQUAMATES- have a cavum venosum at the upper limit of the Interventricular septum Cavum venosum: receives deoxygenated blood from the right atrium and is confluent with both the left and right ventricles (fig 14.24)- How do reptiles avoid mixing of oxygenated and deoxygenated blood in the heart? (1) Ventricular Diastole: blood from the right atrium – venous blood – passes through the cavum venosum and enters the right ventricle (cavum pulmonale)

(2) Ventricular Systole: when cavum venosum discharge the deoxygenated blood into the cavum pulmonale to the lungs

(3) Ventricular Diastole: blood from the left atrium – enters the left ventricle (cavum arteriosum)

* MUSCULAR ACTIVITY: displaces the septal wall, blocking the passageways between the cavum venosum, the right atrium, and the cavum pulmonale and opening the passage between the cavum venosum and cavum arteriosum

BLOOD FLOW: Right atrium → Cavum venosum → Cavum Pulmonale → Pulmonary Artery → Lungs → Pulmonary Veins → Left Artery → Cavum arteriosum → Cavum venosum → Aortic trunk → Left and Right systemic arches


When submerged in water or radiant heat is applied to reptile:- pulmonary arteries are constricted- deoxygenated blood in the cavum venosum is shunted away from the cavum pulmonale and into the left aortic arch* if oxygen is insufficient: additional adaptation provides energy for metabolic needs by glycolysis, an anaerobic process

Basal Lizard – retain 5th aortic arch and ductus caroticus on both sidesLimbless lizard and snakes -left lung atrophies and may lose entireleft sixth aortic arch, retaining only a single pulmonary artery

* snakes – left third aortic arch also disappears* adult snake – retain only the right third, the left and right fourth, ductus caroticus, ventral segment of the right sixth aortic arch to the right pulmonary artery arises


First tetrapods in which there is no opportunity in mixing

oxygenated and deoxygenated blood in the heart afterhatching. (fig. 14.6)

- complete interventricular septum- division of embryonic ventral aorta into two trunks (pulmonary trunk from right ventricle/ single aortic trunk from the left) (fig. 14.19 g and h)

Truncus arteriosus and bulbus cordis – vessel carrying the blood from the heart to the early aortic arches

Pulmonary Trunk – leads to the sixth aortic archesAortic Trunk – leads to the third and 4th aortic archesDuctus Arteriosus – shunts blood away from the lungs

and into the dorsal aortaDorsal Aorta – supplies the embryonic respiratory

membranes with the bloodRight –Left Shunt – divert blood away from the lungs

functions in unhatched chicks and fetal mammals

AORTIC ARCH OF BIRDS & MAMMALS

FIGURE 14.6Page 319

FIGURE 14.19(g-h)Page 330

Part Birds Mammals

1st Aortic Arch

x x

2nd Aortic Arch

x x

3rd Aortic Arch

internal carotid internal carotid

4th Aortic Arch

x- arch of aorta directed

to the right(fig. 14.25)

Base remains- arch of aorta directed to the

left(14.26)

5th Aortic Arch

x x

6th Aortic Arch

Right - xLeft - Pulmonary artery

Right – xLeft - Pulmonary Artery

Ductus Caroticus

x x

Ductus Arteriosus

closes before hatching closes with the first gasp of air into the lungs

Paired embryonic

ventral aorta

left and right common carotid and external

carotid arteries

left and right common carotid and external carotid arteries

AORTIC ARCH OF BIRDS & MAMMALS



• Respiratory surface develops on pharyngeal derivative – buds off the nearest aortic arch usually vascularize the surface

• Pharyngeal arch develops an external or internal gill – aortic arch in that pharyngeal arch vascularizes that gill

• Pharyngeal floor evaginates to form a lung bud – a sprout from the nearest aortic arch vascularis the bud

• Vascularization of pharyngeal derivatives for the respiration has phylogenetic roots that extend back to the first chordate.

AORTIC ARCH & VON BAER’S LAW

• Paired in the head above the pharynx in embryos and some adult fishes and gill-breathing amphibians

• Remains paired in the head in all adults as the internal carotid arteries

• Unpaired in the trunk where it gives off a series of paired somatic branches to the body wall and appendages and a series of paired and unpaired visceral branches.

• Continues to the tail as caudal artery

DORSAL AORTA

• Subclavian Arteries – enlarges segmental arteries (see figs 14.16 and 14.20)- arise in embryos as branches of the paired or unpaired dorsal aortas or from the third aortic archs (somebirds) or fourth aortic arches (some mammals) close to the aorta

- transverse the axilla = axillary artery- Parallels the humerus – brachial artery -Divides in the forearm = ulnar and radial arteries

• Vertebral Artery – passes cephalad in the beck to contribute blood to the curcle of willis (fig. 16.27) - not well developed in birds and some reptile

• Vertebromuscular branches – dorsally directed and branches to the epaxial muscle, skin and vertebral column

• Parietal Branches – encircle the body wall to the midventral line1. Intercostal branches – in long ribs2. Sacral – in Sacral Vertebrae3. Lumbar – in Lumbar Vertebrae

• Iliac- segmental arteries that supply the pelvic fins or limbs1. Femoral – in the thigh2. Popliteal – in the knee3. Tibial – in the shank

• *Anatomose (unite end to end) – ensure that if one of the anastomosing vessels supplying a region becomes occluded, the vessel approaching from the opposite direction will fill the affected arterial tree beyond the occlusion

SOMATIC BRANCHES

A. Series of unpaired visceral branches (splanchnic vessels) pass via dorsal mesenteries to the unpaired viscera, chiefly digestive organs suspended in the coelom

• Necturus – most number of vessels• Celiac, Cranial (Superior) mesenteric and caudal (inferior) mesenteric – as few as 3 may occur

in mammals, birds, Squalus• Anatomoses between two successive visceral branches occur along the entire length of the

gut• Anatomosing Visceral Branches in Mammals:

1. cranial (superior) Pancreaticoduodenal branch of the celiac – caudal (inferior) Pancreaticoduodenal branch of the celiac mesentery2. middle colic branch of the cranial mesenteric – left colic branch of the caudal mesenteric3. cranial rectal branch of the caudal mesenteric – middle rectal branch of the internal iliac* common in greater and lesses curvatures of the stomach

B. Paired Visceral Branches – include arteries to the urinary bladder, reproductive tract, gonads, kidneys and adrenals* series of gonadal and renal arteries occur in basal craniates, several pairs in reptiles and usually a single pair in mammals

VISCERAL BRANCHES

Embryonic dorsal aorta of amniotes ends at the level of the future hind limbs by bifurcation into the left and right allantoic (umbilical) arteries

Internal Iliacs sprout off the umbilical arteries as limbs develop, and as the umbilicals become branches of the external and internal iliacs

ALLANTOIC ARTERIES OF AMNIOTES

Vasa vasorum – vessels of the vessels, found in the walls of arteries and veins.

Coronary arteries and veins – vessels in the heart.(in urodels, the coronary supply consists of many small arteries

Origin:Elasmobranch- from hypobranchial arteries around the gill chambersFrogs – carotid archReptiles – from aortic trunk and brachiocephalicMammals- from the base of the ascending aorta

CORONARY ARTERIES

-‘wonderful networks’-segments of arteries

that are highly tortuous

Examples:-glomeruli -arterial networks in the

pseudobranch of sharks

RETIA MIRABILIA

Cetacians and pinnipeds– Location: trunk and within bony vertebral

canal that houses the spinal cord. They are drained by arteries that are en route to the brain

– Function: constitute a reservoir of RBCs that were oxygenated before a dive, they supply oxygen to the brain when submerged.

RETIA MIRABILIA: FUNC DEPENDS ON LOCATION

Birds that wade in icy waters, polar bears and arctic seals– Location: thigh (retia having arteries and veins side by

side)– Function: countercurrent results in the transfer of

heat

Fishes – Location: swim bladders (retia are called red gland)– Function: provide countercurrents that help maintain

an appropriate level of gaseous oxygen in the bladder


Mammals– Location: testes in

scrotal sacs have a rete, pampiniform plexus, in each inguinal canal

– Function: heat is transferred from spermatic artery to spermatic vein, assuring that the temperature within the scrotal sacs is lower than the body temperature, a necessity for the viability of sperm in those species.


VENOUS CHANNELS AND THEIR MODIFICATIONS

GENERALIZED VENOUS SYSTEM– Cardinals [ant, pos, common cardinals]– Renal portal– Lateral abdominal– Hepatic portal– Hepatic sinuses– Coronary veins

Lungs and tetrapods– Pulmonary stream– Postcava from the kidneys – -drains the whole body

BASIC PATTERN: SHARKS

CCardinal streamsC1. Cardinal veins

- Where blood [except that from the digestive organs] enter to the sinus venosus that which receives blood returning to the heart

- Interior cardinal (precardinal) veins- Blood from the head other than the lower jaw- Empties into the common cardinal

1. E Embryonic Posterior cardinal (postcardinal) vein- Continuous with the caudal vein- Receives renal veins as they pass through the kidneys - Empty into the common common cardinals- Posterior cardinal sinuses

Renal Portal System• Caudal vein continues forward beneath the

gut as a subintestinal vein• When the old postcardinals are lost, blood

from the tail enter the peritubular capillaries


Lateral Abdominal Stream• Lateral abdominal vein

– from the pelvic and receives an iliac vein– Receives a brachial vein at the pectoral level

before entering the common cardinals– Subclavian vein – between the brachial and the

common cardinals– Cloacal vein – metameric series of parietal veins

from the lateral body wall


Hepatic Portal Stream and Hepatic Sinuses• Omphalomesenteric (vitelline) veins

– One of the first vessels to appear in any craniates embryo– Yolk sac to heart– Breaks into sinusoidal channels due to the enlarging liver during

development– The vitelline vein from caudal to the liver disappears, while another

associates with the subintestinal vein to become the hepatic portal system

• Subintestinal vein– Joins the vitelline vains and drains the digestive organs

• Hepatic system– two v.veins between the liver and the sinus venosus


OTHER FISHESLiving agnathans

No renal portal sysNo left common cardinal

Ray-finned fishes

Most have no abdominalsPelvic fins: postcardinalsBlood from swim bladdershepatic/hepatic portal/postcardinal/commoncardinal

dipnoan Pelvic fins: unpaired ventral abdominal emptying into sinus venosusSwim bladders: left atrium

CORONARY VEINS SINUS VENOSUS

TETRAPODS• Embryonic venous channels is the same as that of the sharks

Cardinal Veins and the Precavae– Post cardinals, precardinals, common cardinalsPOSTCARDINALS:

Urodeles - Persist bet caudal and common cardinalsAnurans - Anterior to kidneys disappears

- Connection with the caudal is lostAmniotes Anterior to kidneys disappears in embryonic stage due to

POSTCAVA developmentmammals Ant. of the RIGHT postcardinal persist –AZYGOS

LEFT: HEMIAZYGOS Azygos old right common cardinals precava]

o Receives shunts from the Hemiazygos Both drain intercostals spaces

Amniotes:common cardinals

Precavae

Anterior cardinals

Internal Jugular veins

cats and humans lose most of the left precavao BRACHIOCEPHALIC VEIN, a

transverse vessel drains the left side of the head left anterior limb to the right precava

o Coronary sinus – remnant of the left precava

- On the surface of the <3 that receives coronary veins then empties into the right atrium

o Superior vena cava – right precava precava of nonavian reptiles: sinus venosus birds and humans: right atrium

TETRAPODS

Postcava– subcardinal venous plexus – receives renal veins from

kidneys– postcava – a subcardinal that predominates. Grows into

the mesentery in which is the liver is developing, becomes associated with hepatic sinuses

» kidneys to heart via hepatic sinuses• tetrapods:

– hepatic sinuses fuse forming a median vessel that becomes part of the postcava

– mammals: caudal (inferior) vena cava– crocodilians: blood from the hindlimb passes directly to the postcava

bypassing the kidneys– birds: all blood directly to the postcava

TETRAPODS

AAbdominal Stream1.body wall at the site for future hindlimbs2.cepahalad to the lateral body wall3.receives veins from the developing forelimbs4.common cardinals or sinus venosus

TETRAPODS

TETRAPODSAmphibian Ventral abdominal vein – connects with the venous channels in the falciform ligament

connecting liver to the body wall-one of these channels enlarges making all the blood form the ventral abdominal pass through the falciform ligament to the liverportal stream- between the capillaries of the developing hind limb and that of the liver-due to the disappearance of the segments of the lateral abdomninal vein anterior to the liver-aids in the draining of the digestive organs and spleen

Non-avian reptiles

Lateral abdominals do not unite Uses the falciform ligament as a bridge from the coelom to the liver capillaries Loses connection with the commons (2) allantoic veins –temporary tributaries as the abdominals pass thru the ventral body wall -regress when the allantois is lost prior to hatching

Birds None of the embryonic abdominal stream is seenMammals - Fetal life only

-umbilical [allantoic] vein- all that is left of the abdominalsNo connection with the drainage of the hindlimbsGrows out the umbilical cord and vascularizes the placentaUnite to form a single umbilical vein-functions only to drain the placentaRound ligament of the liverDuctus venosus – eroded by umbilical veinAfter birth becomes the ligamentum venosum

Renal Portal systemAmphibians External [transverse] iliac vein – blood

from hindlimbs to renal port-alternate route to heart- seen also in REPTILES

SnakesCrocodilians

Rps is seen as primitive relationshipSome blood from hindlimbs bypass the kidneys

Birds Hindlimb blood bypass the kidneysTherian mammals

disappears

TETRAPODS

HHepatic Portal System Similar in all craniates Stomach, pancreas, intestines spleen Terminates at the capillaries of the liver Tributaries: abdominal stream [from amphibians

up]

: veins from the swim bladders [bony fishes

TETRAPODS

Coronary veins

TETRAPODS

Amphibians

Frogs:

No definitive coronary system

One c.v enters the left precava,the other empties into the ventral abdominal

Reptiles Coronary veins coronary sinus or directly into the right atriumCoronary sinus lies at the coronary sulcus [between left atrium and ventricle]

Mammals

CIRCULATION IN THE MAMMALIAN FETUS, AND

CHANGES AT BIRTH

Caudal end of dorsal aorta

Umbilical arteries

Umbilical cord

Placenta

Umbilical Vein

Ductus Venosus Liver

Postcava

Right atrium

Interarterial foramen

Left atrium

Left ventricle

Systemic arch

Major venous channels

Right ventricle

Pulmonary Trunk

Lungs

Fetal Adult

foramen ovale fossa ovalis

ductus arteriosus ligamentum arteriosum

extra-hepatic portion of the fetal left umbilical vein

ligamentum teres hepatis (the "round ligament of the liver")

intra-hepatic portion of the fetal left umbilical vein (the ductus venosus) ligamentum venosum

proximal portions of the fetal left and right umbilical arteries

umbilical branches of the internal iliac arteries

distal portions of the fetal left and right umbilical arteries medial umbilical ligaments (urachus)

MAJOR CIRCULATORY CHANGES WHICH ADAPT THE ORGANISM FOR PULMONARY RESPIRATION

The ductus arteriosus closes as a result of nerve impulses passing to its muscular wall.

The interarterial valve is pressed against the interarterial foramen by the sudden increase in pressure in the left atrium that results from the greatly increased volume of blood entering from the lungs.

The umbilical arteries and vein are severed at the umbilicus. Eventually, the umbilical arteries from bladder to navel are converted into lateral umbilical ligaments.

No blood flows through the umbilical vein since source has been cut off. This becomes the round ligament of the liver and the it becomes the ligamentum venosum.

Failure of the foramen ovale to close or of the ductus arteriosus to constrict results in….

CYANOSIS- Blueness of the skin, lips and nail bed in humans

SYSTEMATIC SUMMARY OF RESPIRATION AND CIRCULATION

Amphioxus- transverse muscle in the artrial wall provides a “cough” reflex to dislodge grains and of sand

Gnathostomes- possesses a complex jointed pharyngeal skeleton requiring both inspiratory and expiratory muscles to pump water over the gillsOsteichthyans-air sac- buccopharyngeal muscles used to pump water over the gills are also used to pump a pulse of air into an air sac

See fig. 14.40

Gill – breathing fishes can resort to pulse pumping when challenged by low-oxygen partial pressures.

A species may shift strategies during its life history ( a gill-breathing larva shifting to pulse pumping at metamorphosis).

Any shift to aspiration mode would potentially conserve energy.

Aspiration breathing is seen in all amniotes.

Fossil rhipidistian fishes with lungs were incapable of pulse pumping due to their heavy overlapping ribs and scales.

The large body size and ribs of early tetrapods preclude pulse pumping.

LYMPHATIC SYSTEM

The LYMPHATIC SYSTEM consists of…

1. thin-walled LYMPH CHANNELS

2. LYMPH (fluid)3. LYMPH HEARTS4. LYMPH NODES (birds

and mammals)

5. solitary or aggregated masses

of LYMPH NODULESex. SPLEEN

The system begins in LYMPH CAPILLARIES

or in LYMPH SINUSOIDS.

Fluid empties to a vein.

Valves at these exits prevent the influx of venous blood into the lymph channels.

Capillaries and sinusoids penetrate most of the soft tissues of the body other than the liver and the nervous system. They also collect interstitial fluids.

A lymphatic network consisting of long, narrow, discrete tubular vessels with a modicum of smooth muscle in the walls is found only in birds and mammals.

LACTEALS- lymphatics in intestinal

villi- CHYLE – lymph found

in these vessels; milky appearance

HEMOLYMPH- lymphatics which

contain red blood cells- Living agnathans,

cartilaginous fishes and humans

Lymph channels that drain the body wall, limbs, and tail of craniates empty into nearby veins at the base of the tail, trunk and neck.

Lymph channels draining viscera are often paired in most craniates but in mammals, a single thoracic duct commences in a large abdominal lymph sinus, the cisterna chyli and empties into a branchicephalic of left subclavian vein, or into external or internal jugular veins.

ANURANS-Have numerous sinusoids which form huge lymph reservoirs separated by connective tissue septa that attaches the skin to the underlying muscles

Subcutaneous lymph sinuses – buffers the underlying muscles from the drying effect of air

FACTORS THAT CONTROL THE FLOW OF LYMPH

Lymph hearts at advantageous locations along lymph pathways in fishes, amphibians and reptiles (except postembryonic birds).

Frogs: 2 pairs of lymph heartsUrodeles: 16 pairsCaecilians: 100 pairs

Amphibians have more tissue fluids to manipulate than other craniates so their lymph hearts move a proportionately larger volume of fluid than the hearts of other craniates.

Semilunar valves at the exit of the hearts prevent backflow.

Lymph hearts are not present in birds after hatching but embryonic birds have them.

None has been described in humans.

CRANIATE LYMPH FLOW is maintained…

….by activity of the skeletal muscles as they contract and relax

….by movements of the viscera

….by rhythmical changes in intrathoracic pressure that results from breathing

LYMPH NODES are masses of hemopoietic tissue interposed along the course of lymph channels of birds and mammals.

They are the “swollen glands” you feel in the neck, axilla and groin in humans when there is inflammation in areas drained.

The endothelium of the sinusoidal passageways include phagocytes that ingest bacteria and other particles.

The nodes are the 2nd line of defense against bacterial infections acquired through the skin, the first line being granulocytes that assemble at the invaded area.

LYMPHOID MASSES

Spleen

Thymus(absent in hagfishes)

Tonsils (in humans)

Peyer’s Patches (in amniotes)

Bursa of fabricius (in young birds)

Circulatory system

Education

posttrematic arteries

pulmonary arteries

efferent brachial arteries

afferent brachial arteries

th aortic arch

aortic arch fate

internal carotid arteries

carotid arch