The lecture discusses the anatomy and functions of the autonomic nervous system, specifically the sympathetic and parasympathetic divisions. It describes the central and peripheral structures of these systems, including sympathetic centers in the brain and spinal cord, and ganglia in the periphery. The sympathetic system activates the fight or flight response and increases heart rate and respiration. It diverts blood flow away from the digestive system. The parasympathetic system stimulates rest and digestion functions like salivation and digestion.

1. TOPIC OF THE LECTURE:TOPIC OF THE LECTURE:
Anatomy of vegetative part ofAnatomy of vegetative part of
nervous system.nervous system.
The central and peripheralThe central and peripheral
structures of the sympathetic andstructures of the sympathetic and
parasympathetic parts.parasympathetic parts.
Vegetative plexuses.Vegetative plexuses.

3.  The autonomic nervous systemThe autonomic nervous system
 (ANS or visceral nervous system) is the part of the(ANS or visceral nervous system) is the part of the
peripheral nervous systemperipheral nervous system that acts as athat acts as a control systemcontrol system
functioning largely below the level of consciousness, andfunctioning largely below the level of consciousness, and
controlscontrols visceralvisceral functions. The ANS affectsfunctions. The ANS affects heart rateheart rate,,
digestiondigestion,, respiration raterespiration rate,, salivationsalivation,, perspirationperspiration,,
diameter of the pupils,diameter of the pupils, micturitionmicturition (urination), and(urination), and
sexual arousalsexual arousal. Whereas most of its actions are involuntary,. Whereas most of its actions are involuntary,
some, such as breathing, work in tandem with the conscioussome, such as breathing, work in tandem with the conscious
mind.mind.
 It is classically divided into two subsystems: theIt is classically divided into two subsystems: the
parasympathetic nervous systemparasympathetic nervous system (PSNS) and(PSNS) and
sympathetic nervous systemsympathetic nervous system (SNS). Relatively recently, a(SNS). Relatively recently, a
third subsystem of neurons that have been named 'non-third subsystem of neurons that have been named 'non-
adrenergic and non-cholinergic' neurons (because they useadrenergic and non-cholinergic' neurons (because they use
nitric oxide as a neurotransmitter) have been described andnitric oxide as a neurotransmitter) have been described and
found to be integral in autonomic function, particularly infound to be integral in autonomic function, particularly in
the gut and the lungs.the gut and the lungs.

4.  General Characteristics of the ANS:General Characteristics of the ANS:
 1. It is a two-neuron pathway.1. It is a two-neuron pathway.
2. Sensory signals from viscera and skin send signals2. Sensory signals from viscera and skin send signals
to autonomic neurons in brain and spinal cord.to autonomic neurons in brain and spinal cord.
3. A preganglionic neuron cell body is located within3. A preganglionic neuron cell body is located within
the CNS (brain stem or spinal cord).the CNS (brain stem or spinal cord).
4. Preganglionic fibers (efferent fibers) synapse with a4. Preganglionic fibers (efferent fibers) synapse with a
ganglionic neuron located in the PNSganglionic neuron located in the PNS
5. A postganglionic fiber terminates on the effector5. A postganglionic fiber terminates on the effector
organ (heart, stomach, etc).organ (heart, stomach, etc).
 Divisions of the ANSDivisions of the ANS
 1. Sympathetic Division1. Sympathetic Division
 2. Parasympathetic Division2. Parasympathetic Division

6. Sympathetic nervousSympathetic nervous
system ( function)system ( function)
 EyeEye – dilates pupil– dilates pupil
 Heart - iHeart - increases rate and force ofncreases rate and force of
contractioncontraction
 Lungs - dLungs - dilates bronchiolesilates bronchioles
 Digestive tract - iDigestive tract - inhibits peristalsisnhibits peristalsis
 Kidney - iKidney - increases renin secretionncreases renin secretion
 Penis – promotesPenis – promotes ejaculationejaculation

8.  The sympathetic nervous system is responsible for up- andThe sympathetic nervous system is responsible for up- and
down-regulating many homeostatic mechanisms in livingdown-regulating many homeostatic mechanisms in living
organisms. Fibers from the SNS innervate tissues in almostorganisms. Fibers from the SNS innervate tissues in almost
every organ system, providing at least some regulatory functionevery organ system, providing at least some regulatory function
to things as diverse asto things as diverse as pupilpupil diameter,diameter, gut motilitygut motility, and, and urinaryurinary
output. It is perhaps best known for mediating the neuronal andoutput. It is perhaps best known for mediating the neuronal and
hormonal stress response commonly known as thehormonal stress response commonly known as the fight-or-fight-or-
flight responseflight response..
 This response is also known asThis response is also known as sympatho-adrenal responsesympatho-adrenal response ofof
the body, as thethe body, as the preganglionicpreganglionic sympathetic fibers that end in thesympathetic fibers that end in the
adrenal medulla (but also all other sympathetic fibers) secreteadrenal medulla (but also all other sympathetic fibers) secrete
acetylcholine, which activates the great secretion of adrenalineacetylcholine, which activates the great secretion of adrenaline
(epinephrine) and to a lesser extent noradrenaline(epinephrine) and to a lesser extent noradrenaline
(norepinephrine) from it.(norepinephrine) from it.
 Therefore, this response that acts primarily on theTherefore, this response that acts primarily on the
cardiovascular systemcardiovascular system is mediated directly via impulsesis mediated directly via impulses
transmitted through the sympathetic nervous system andtransmitted through the sympathetic nervous system and
indirectly viaindirectly via catecholaminescatecholamines secreted from the adrenalsecreted from the adrenal
medulla.medulla.

9. Sympathetic nervous systemSympathetic nervous system
 1. Central part1. Central part 2. Peripheral part2. Peripheral part
 Sympathetic centers:Sympathetic centers:
 Over segmental: Cortical: located inOver segmental: Cortical: located in
cerebral cortex ( frontal lobecerebral cortex ( frontal lobe,, limbiclimbic
system)system)
 Subcortical – in diencephalon areSubcortical – in diencephalon are
common for sympathetic andcommon for sympathetic and
parasympathetic partsparasympathetic parts

11.  TheThe limbic systemlimbic system (or Paleomammalian brain)(or Paleomammalian brain)
is a set of brain structures including theis a set of brain structures including the
hippocampushippocampus,, amygdalaamygdala,, anterior thalamic nucleianterior thalamic nuclei
,, septumseptum,, limbic cortexlimbic cortex and fornix, whichand fornix, which
seemingly support a variety of functionsseemingly support a variety of functions
includingincluding emotionemotion,, behaviorbehavior,, long term memorylong term memory,,
andand olfactionolfaction..
 The term "limbic" comes from theThe term "limbic" comes from the LatinLatin limbuslimbus,,
for "border" or "edge". Some scientists havefor "border" or "edge". Some scientists have
suggested that the concept of the limbic systemsuggested that the concept of the limbic system
should be abandoned asshould be abandoned as obsoleteobsolete, as it is, as it is
grounded more in transient tradition than ingrounded more in transient tradition than in
facts.facts.

14.  Segmental level – in lateral horns of spinal cordSegmental level – in lateral horns of spinal cord
( intermediolateral nucleus)( intermediolateral nucleus)
 Nucleus include: tropicNucleus include: tropic,, functionalfunctional,, vasomotorvasomotor,,
visceromotorvisceromotor,, secretorysecretory ссenters.enters.

15.  TheThe parasympatheticparasympathetic nervous systemnervous system ((PSNSPSNS) is) is
one of the two main divisions of theone of the two main divisions of the
autonomic nervous systemautonomic nervous system (ANS).(ANS).
 The ANS is responsible for regulation of internalThe ANS is responsible for regulation of internal
organs and glands, which occurs unconsciously. Theorgans and glands, which occurs unconsciously. The
parasympathetic system specifically is responsible forparasympathetic system specifically is responsible for
stimulation of "rest-and-digest" activities that occurstimulation of "rest-and-digest" activities that occur
when the body is at rest, including sexual arousal,when the body is at rest, including sexual arousal,
salivationsalivation,, lacrimationlacrimation (tears),(tears), urinationurination,, digestiondigestion
andand defecationdefecation..
 Its action is described as being complementary to thatIts action is described as being complementary to that
of one of the other main branches of the ANS, theof one of the other main branches of the ANS, the
sympathetic nervous systemsympathetic nervous system, which is responsible for, which is responsible for
stimulating activities associated with thestimulating activities associated with the
fight-or-flight responsefight-or-flight response..

18. SYMPATHETIC NERVOUSSYMPATHETIC NERVOUS
SYSTEM.SYSTEM.
 Diverts blood flow away from the gastro-intestinalDiverts blood flow away from the gastro-intestinal
(GI) tract and(GI) tract and skinskin via vasoconstriction.via vasoconstriction.
 Blood flow toBlood flow to skeletal musclesskeletal muscles and theand the lungslungs isis
enhanced (by as much as 1200% in the case ofenhanced (by as much as 1200% in the case of
skeletal muscles). Dilates bronchioles of the lung,skeletal muscles). Dilates bronchioles of the lung,
which allows for greater alveolar oxygen exchange.which allows for greater alveolar oxygen exchange.
 IncreasesIncreases heart rateheart rate and theand the contractilitycontractility of cardiacof cardiac
cells (cells (myocytesmyocytes), thereby providing a mechanism for), thereby providing a mechanism for
the enhanced blood flow to skeletal muscles.the enhanced blood flow to skeletal muscles.
 Dilates pupils and relaxes the ciliary muscle to theDilates pupils and relaxes the ciliary muscle to the
lens, allowing more light to enter the eye and farlens, allowing more light to enter the eye and far
vision. Provides vasodilation for thevision. Provides vasodilation for the coronary vesselscoronary vessels
of theof the heartheart..

19.  Constricts all the intestinalConstricts all the intestinal sphincterssphincters
and the urinary sphincter.and the urinary sphincter.
 InhibitsInhibits peristalsisperistalsis..

20. Parasympathetic nervous systemParasympathetic nervous system
 Dilates blood vessels leading to the GI tract,Dilates blood vessels leading to the GI tract,
increasing blood flow. This is importantincreasing blood flow. This is important
following the consumption of food, due tofollowing the consumption of food, due to
the greater metabolic demands placed on thethe greater metabolic demands placed on the
body by the gut.body by the gut.
 The parasympathetic nervous system canThe parasympathetic nervous system can
also constrict the bronchiolar diameter whenalso constrict the bronchiolar diameter when
the need for oxygen has diminished.the need for oxygen has diminished.
 Dedicated cardiac branches of theDedicated cardiac branches of the VagusVagus
and thoracicand thoracic Spinal AccessorySpinal Accessory nerves impartnerves impart
ParasympatheticParasympathetic control of thecontrol of the HeartHeart oror
MyocardiumMyocardium..

21.  DuringDuring accommodationaccommodation, the parasympathetic, the parasympathetic
nervous system causes constriction of thenervous system causes constriction of the
pupil and contraction of the ciliary muscle topupil and contraction of the ciliary muscle to
the lens, allowing for closer vision.the lens, allowing for closer vision.
 The parasympathetic nervous systemThe parasympathetic nervous system
stimulates salivary gland secretion, andstimulates salivary gland secretion, and
acceleratesaccelerates peristalsisperistalsis, so, in keeping with the, so, in keeping with the
rest and digest functions, appropriate PNSrest and digest functions, appropriate PNS
activity mediates digestion of food andactivity mediates digestion of food and
indirectly, the absorption of nutrients.indirectly, the absorption of nutrients.
 Is also involved in erection of genitals, via theIs also involved in erection of genitals, via the
pelvic splanchnic nervespelvic splanchnic nerves 2–4.2–4.
 Stimulates sexual arousal.Stimulates sexual arousal.

24.  TheThe sympathetic trunkssympathetic trunks ((sympathetic chainsympathetic chain,,
gangliated cordgangliated cord)) are a paired bundle of nerveare a paired bundle of nerve
fibers that run from the base of thefibers that run from the base of the skullskull toto
thethe coccyxcoccyx..
 The sympathetic trunk travels in a downwardThe sympathetic trunk travels in a downward
direction from the skull, just lateral to thedirection from the skull, just lateral to the
vertebral bodies. It interacts with thevertebral bodies. It interacts with the
spinal nervesspinal nerves or their ventral rami by way ofor their ventral rami by way of
rami communicantesrami communicantes..
 The superior end of it is continued upwardThe superior end of it is continued upward
through thethrough the carotid canalcarotid canal into the skull, andinto the skull, and
forms aforms a plexusplexus on theon the internal carotid arteryinternal carotid artery;;
the inferior part travels in front of thethe inferior part travels in front of the coccyxcoccyx,,
where it converges with the other trunk at awhere it converges with the other trunk at a
structure known as thestructure known as the ganglion imparganglion impar..

26.  Along the length of the sympathetic trunkAlong the length of the sympathetic trunk
areare gangliaganglia known asknown as paravertebral gangliaparavertebral ganglia..
 FunctionFunction
 The sympathetic trunk is a fundamentalThe sympathetic trunk is a fundamental
part of the sympathetic division of thepart of the sympathetic division of the
autonomic nervous systemautonomic nervous system. It allows nerve. It allows nerve
fibers to travel to spinal nerves that arefibers to travel to spinal nerves that are
superior and inferior to the one in whichsuperior and inferior to the one in which
they originated. Also, a number of nerves,they originated. Also, a number of nerves,
such as most of thesuch as most of the splanchnic nervessplanchnic nerves, arise, arise
directly from the trunks.directly from the trunks.

29.  The sympathetic division (thoracolumbarThe sympathetic division (thoracolumbar
outflow) consists of cell bodies in theoutflow) consists of cell bodies in the
lateral horn of spinal cordlateral horn of spinal cord (intermediolateral cell(intermediolateral cell
columns) of the spinal cord from T1 to L2.columns) of the spinal cord from T1 to L2.
These cell bodies are GVE (general visceralThese cell bodies are GVE (general visceral
efferent) neurons and are the preganglionicefferent) neurons and are the preganglionic
neurons. There are several locations upon whichneurons. There are several locations upon which
preganglionic neurons can synapse for theirpreganglionic neurons can synapse for their
postganglionic neurons:postganglionic neurons:
 Paravertebral gangliaParavertebral ganglia of the sympathetic chainof the sympathetic chain
(these run on either side of the vertebral bodies)(these run on either side of the vertebral bodies)
 Prevertebral gangliaPrevertebral ganglia (celiac ganglia, superior(celiac ganglia, superior
mesenteric ganglia, inferior mesenteric ganglia)mesenteric ganglia, inferior mesenteric ganglia)

33.  Chromaffin cellsChromaffin cells ofof adrenal medullaadrenal medulla (this is the one(this is the one
exception to the two-neuron pathway rule: synapse isexception to the two-neuron pathway rule: synapse is
direct onto cell bodies) These ganglia provide thedirect onto cell bodies) These ganglia provide the
postganglionic neurons from which innervation ofpostganglionic neurons from which innervation of
target organs follows. Examples of splanchnictarget organs follows. Examples of splanchnic
(visceral) nerves are:Cervical cardiac nerves &(visceral) nerves are:Cervical cardiac nerves &
thoracic visceral nerves which synapse in thethoracic visceral nerves which synapse in the
sympathetic chainsympathetic chain
 Thoracic splanchnic nerves (greater, lesser, least)Thoracic splanchnic nerves (greater, lesser, least)
which synapse in the prevertebral ganglionwhich synapse in the prevertebral ganglion
 Lumbar splanchnic nerves which synapse in theLumbar splanchnic nerves which synapse in the
prevertebral ganglionprevertebral ganglion
 Sacral splanchnic nerves which synapse in the inferiorSacral splanchnic nerves which synapse in the inferior
hypogastric plexushypogastric plexus
 These all contain afferent (sensory) nerves as well,These all contain afferent (sensory) nerves as well,
also known as GVA (general visceral afferent)also known as GVA (general visceral afferent)
neurons.neurons.

34.  Parasympathetic divisionParasympathetic division
 The parasympathetic division (craniosacral outflow) consists ofThe parasympathetic division (craniosacral outflow) consists of
cell bodies from one of two locations:cell bodies from one of two locations: brainstembrainstem (Cranial Nerves(Cranial Nerves
III, VII, IX, X) or sacral spinal cord (S2, S3, S4). These are theIII, VII, IX, X) or sacral spinal cord (S2, S3, S4). These are the
preganglionic neurons, which synapse with postganglionicpreganglionic neurons, which synapse with postganglionic
neurons in these locations:neurons in these locations:
 Parasympathetic gangliaParasympathetic ganglia of the head (Ciliary (CN III),of the head (Ciliary (CN III),
Submandibular (CN VII), Pterygopalatine (CN VII), Otic (CNSubmandibular (CN VII), Pterygopalatine (CN VII), Otic (CN
IX)IX)
 In or near wall of organ innervated by Vagus (CN X), SacralIn or near wall of organ innervated by Vagus (CN X), Sacral
nerves (S2, S3, S4))nerves (S2, S3, S4))
 These ganglia provide the postganglionic neurons from whichThese ganglia provide the postganglionic neurons from which
innervations of target organs follows. Examples are:innervations of target organs follows. Examples are:
 The preganglionic parasympathetic splanchnic (visceral) nervesThe preganglionic parasympathetic splanchnic (visceral) nerves
 Vagus nerveVagus nerve, which wanders through the thorax and abdominal, which wanders through the thorax and abdominal
regions innervating, among other organs, the heart, lungs, liverregions innervating, among other organs, the heart, lungs, liver
and stomachand stomach..

35. VEGETATIVEVEGETATIVE
PLEXUSESPLEXUSES

36.  TheThe abdominal aortic plexusabdominal aortic plexus (aortic plexus) is(aortic plexus) is
formed by branches derived, on either side,formed by branches derived, on either side,
from thefrom the celiac plexusceliac plexus andand gangliaganglia, and, and
receives filaments from some of thereceives filaments from some of the
lumbar ganglialumbar ganglia..
 It is situated upon the sides and front of theIt is situated upon the sides and front of the
aortaaorta, between the origins of the superior and, between the origins of the superior and
inferior mesentericinferior mesenteric arteries.arteries.
 From this plexus arise part of theFrom this plexus arise part of the spermaticspermatic, the, the
inferior mesenteric, and theinferior mesenteric, and the hypogastrichypogastric
plexuses; it also distributes filaments to theplexuses; it also distributes filaments to the
inferior vena cavainferior vena cava..

37.  The celiac plexus includes a number ofThe celiac plexus includes a number of
smaller plexuses:smaller plexuses:
 Hepatic plexusHepatic plexus
 Splenic plexusSplenic plexus
 Gastric plexusGastric plexus
 Pancreatic plexusPancreatic plexus
 Suprarenal plexusSuprarenal plexus
 Other plexuses that are derived from theOther plexuses that are derived from the
celiac plexus:celiac plexus:
 Renal plexusRenal plexus
 Testicular plexusTesticular plexus // ovarian plexusovarian plexus
 Superior mesenteric plexusSuperior mesenteric plexus


39.  TheThe celiac plexusceliac plexus oror coeliac plexuscoeliac plexus, also known as the, also known as the
solar plexussolar plexus, is a complex network of nerves (a, is a complex network of nerves (a plexusplexus))
located in the abdomen, where thelocated in the abdomen, where the celiac trunkceliac trunk,,
superior mesenteric arterysuperior mesenteric artery, and, and renal arteriesrenal arteries branchbranch
from thefrom the abdominal aortaabdominal aorta. It is behind the. It is behind the stomachstomach andand
thethe omental bursaomental bursa, and in front of the, and in front of the cruracrura of theof the
diaphragmdiaphragm, on the level of the first, on the level of the first lumbar vertebralumbar vertebra, L1., L1.
 The plexus is formed (in part) by the greater and lesserThe plexus is formed (in part) by the greater and lesser
splanchnic nervessplanchnic nerves of both sides, and also parts of theof both sides, and also parts of the
rightright vagus nervevagus nerve..
 The celiac plexus proper consists of theThe celiac plexus proper consists of the celiac gangliaceliac ganglia
with a network of interconnecting fibers. Thewith a network of interconnecting fibers. The
aorticorenal gangliaaorticorenal ganglia are often considered to be part ofare often considered to be part of
the celiac ganglia, and thus, part of the plexus.the celiac ganglia, and thus, part of the plexus.

41.  TheThe renal plexusrenal plexus is formed by filamentsis formed by filaments
from thefrom the celiac plexusceliac plexus, the, the
aorticorenal ganglionaorticorenal ganglion, and the, and the
aortic plexusaortic plexus ..
 It is joined also by theIt is joined also by the
least splanchnic nerveleast splanchnic nerve..
 The nerves from these sources, fifteen orThe nerves from these sources, fifteen or
twenty in number, have a fewtwenty in number, have a few gangliaganglia
developed upon them.developed upon them.
 They accompany the branches of theThey accompany the branches of the
renal arteryrenal artery into theinto the kidneykidney; some; some
filaments are distributed to thefilaments are distributed to the
spermatic plexusspermatic plexus and, on the right side, toand, on the right side, to
thethe inferior vena cavainferior vena cava..

43. Inferior hypogastric plexusInferior hypogastric plexus

47. Parasympathetic centersParasympathetic centers

62.  AA nerve fibernerve fiber is a threadlike extension of a nerve cellis a threadlike extension of a nerve cell
and consists of anand consists of an axonaxon andand myelin sheathmyelin sheath (if present)(if present)
in thein the nervous systemnervous system. There are nerve fibers in the. There are nerve fibers in the
central nervous systemcentral nervous system andand peripheral nervous systemperipheral nervous system..
A nerve fiber may be myelinated and/or unmyelinated.A nerve fiber may be myelinated and/or unmyelinated.
In the central nervous system (CNS), myelin isIn the central nervous system (CNS), myelin is
produced byproduced by oligodendrogliaoligodendroglia cells.cells.
 Schwann cellsSchwann cells form myelin in the peripheral nervousform myelin in the peripheral nervous
system (PNS). Schwann cells can also make a thinsystem (PNS). Schwann cells can also make a thin
covering for an axon which does not consist of myelincovering for an axon which does not consist of myelin
(in the PNS). A peripheral nerve fiber consists of an(in the PNS). A peripheral nerve fiber consists of an
axon, myelin sheath, Schwann cells and itsaxon, myelin sheath, Schwann cells and its
endoneuriumendoneurium. There are no endoneurium and Schwann. There are no endoneurium and Schwann
cells in the central nervous systemcells in the central nervous system..

63.  In theIn the autonomic nervous systemautonomic nervous system, fibers from, fibers from
thethe CNSCNS to theto the ganglionganglion are known asare known as
preganglionic fiberspreganglionic fibers..
 All preganglionic fibers, whether they are in theAll preganglionic fibers, whether they are in the
sympathetic divisionsympathetic division or in theor in the
parasympathetic divisionparasympathetic division, are, are cholinergiccholinergic (that(that
is, these fibers useis, these fibers use acetylcholineacetylcholine as theiras their
neurotransmitterneurotransmitter).).
 Sympathetic preganglionic fibers tend to beSympathetic preganglionic fibers tend to be
shorter than parasympathetic preganglionicshorter than parasympathetic preganglionic
fibers because sympathetic ganglia are oftenfibers because sympathetic ganglia are often
closer to the spinal cord than are thecloser to the spinal cord than are the
parasympathetic ganglia.parasympathetic ganglia.

65.  In theIn the autonomic nervous systemautonomic nervous system, fibers from the ganglion to the, fibers from the ganglion to the
effector organ are calledeffector organ are called postganglionic fiberspostganglionic fibers..
 NeurotransmittersNeurotransmitters
 The neurotransmitters used for postganglionic fibersThe neurotransmitters used for postganglionic fibers
differ:differ:
 In the parasympathetic division, they areIn the parasympathetic division, they are cholinergiccholinergic
(that is, they use acetylcholine as their(that is, they use acetylcholine as their
neurotransmitters.)neurotransmitters.)
 In the sympathetic division, most areIn the sympathetic division, most are adrenergicadrenergic (that is,(that is,
they use norepinephrine as their neurotransmitters.) Onethey use norepinephrine as their neurotransmitters.) One
exception of this is the sympathetic innervation of sweatexception of this is the sympathetic innervation of sweat
glands, which uses acetylcholine as a neurotransmitter, atglands, which uses acetylcholine as a neurotransmitter, at
both pre and post ganglionic synapses. Furthermore,both pre and post ganglionic synapses. Furthermore,
another exception is the sympathetic innervation of theanother exception is the sympathetic innervation of the
adrenal glands, which is done directly by theadrenal glands, which is done directly by the
preganglionic fiber, and subsequently uses acetylcholinepreganglionic fiber, and subsequently uses acetylcholine
as a neurotransmitter.as a neurotransmitter.

72. CCeliac plexus injury fundoplicationeliac plexus injury fundoplication

87. BLOOD SUPPLY OFBLOOD SUPPLY OF
LIVER.LIVER. The liver receives a blood supply from two sources. TheThe liver receives a blood supply from two sources. The
first is the hepatic artery which delivers oxygenatedfirst is the hepatic artery which delivers oxygenated
blood from the general circulation. The second is theblood from the general circulation. The second is the
hepatic portal vein delivering deoxygenated blood fromhepatic portal vein delivering deoxygenated blood from
the small intestine containing nutrients.the small intestine containing nutrients.
 The blood flows through the liver tissue to the hepaticThe blood flows through the liver tissue to the hepatic
cells where many metabolic functions take place. Thecells where many metabolic functions take place. The
blood drains out of the liver via the hepatic vein.blood drains out of the liver via the hepatic vein.
 The liver tissue is not vascularised with a capillaryThe liver tissue is not vascularised with a capillary
network as with most other organs, but consists of bloodnetwork as with most other organs, but consists of blood
filled sinusoids surrounding the hepatic cellsfilled sinusoids surrounding the hepatic cells..

90. By- Dr. Pradeep JangirBy- Dr. Pradeep Jangir