Circulatory System Objectives

Understand the roles of the cardiovascular and lymphatic systems and

their relationship to each other

Know the tissue layers that characterize blood vessels

Know the anatomical and functional differences between arteries, veins

and capillaries

Distinguish systemic and pulmonary circulation and portal circulation

Describe differences in adult and fetal circulation with respect to the

hepatic portal and pulmonary systems

Know the cellular components of blood

Know where hematopoeisis occurs and where blood cells are removed

from circulation

Know the relationship of cerebrospinal fluid (CSF) to blood

Relate the function of the following organs to the circulatory system:

spleen, thymus, lymph nodes, tonsils, carotid bodies, hypothalamus,

brown fat, lungs, kidneys, liver, bone marrow, endocrine glands,

choroid plexus

Major divisions of the circulatory system Cardiovascular system

functions

distributes nutrients, wastes, O2, CO2, hormones

thermoregulation, osmoregulation, physiological homeostasis

components

heart, arteries, veins, capillaries

blood

Lymphatic system (cont’d)

Major divisions of the circulatory system Lymphatic system

functions

immune response, lipid absorption, returns fluids from

tissues to venous cardiovascular system

components

Lymph Capillaries, Vessels, Ducts

Lymph Organs

Lymph Nodes

Thymus

Spleen

Tonsils

Peyer’s Patches

Vermiform Appendix

Lymph

Layers of the cardiovascular system listed from luminal to superficial:

Vessels Heart

Endothelium Tunica Intima Endocardium

Muscle and CT Tunica Media Myocardium

Covering Tunica Adventitia Pericardium

General terms Collateral Circulation

Anastomosis

Arteries by definition: conduct blood away from heart

typically conduct O2-rich blood

exceptions are pulmonary arteries and umbilical arteries

narrow diameter (than veins)

thicker wall (than veins)

Tunica Intima maybe Stratified Squamous Epithelium

Tunica Media alternating bands of Smooth Muscle and Elastic CT

high pressure

located deep (not merely subcutaneous) except to pass joints

typically co-occur with veins and nerves of same name

Veins by definition: conduct blood towards the heart

typically conduct O2-depleted blood

exceptions are pulmonary veins and umbilical vein

large diameter

thin wall

low pressure

passive valves

two tier system of both superficial (subcutaneous) and deep vessels

Capillaries leaky vessels

consist only of Tunica Intima only

Blood Plasma – extracellular matrix

water, dissolved salts, proteins, nutrients, urea, hormones, CO2

Albumin – osmolarity

Fibrinogen – clotting

Globulins – immune response

Formed elements of blood – cellular

Hematopoiesis from pleuripotent stem or progenitor cells

Red Bone Marrow in adults

Yolk Sac, Spleen, Liver, Kidneys in embryo and fetus

Erythrocytes or Red Blood Cells (RBC’s) carry hemoglobin, four-ringed protein that binds iron (hence O2)

most numerous blood cell type

biconcave

anucleate

7.5 µm in diameter

Rollo formation

~120 day lifespan

unlike leucocytes, RBC’s do not escape capillaries

Leucocytes or White Blood Cells (WBC’s) Granulocytes or Polymorphonuclear Cells

extracellular digestion by release of lytic enzymes

innate immune response

types distinguished by hemotoxylin and eosin (H&E) staining

Neutrophils – neutral pH, red and blue

most numerous granulocyte, major constituent of pus

Eosinophils – acid, red

Basophils and Mast Cells – basic, blue

produce edema, release heparin and histamine

Agranulocytes

Monocytes or Macrophages (mature)

amoeboid cells, internal digestion by phagocytosis

Lymphocytes

many types: t-lymphocytes, b-lymphocytes, natural killer-lymphocytes

recognize, target, and kill antigens

adaptive immune response

Thrombocytes or blood platelets

small pieces of cells involved in clotting

Heart Pericardial cavity – middle mediastinum

Parietal Pericardium

Serous Pericardium

Fibrous Pericardium

Heart suspended by great vessels superiorly (anterior and posterior)

tissue layers of heart

Visceral pericardium (or simply “pericardium”) – serosa

Myocardium – cardiac striated muscle

Endocardium – simple squamous epithelium

margins of the heart

superior – sternal angle to 4th thoracic intervertebral disc

right – ½ inch parasternal

apex – left midclavicular line or ½ inch medial to areola in males

inferior – xiphisternal joint to 8th thoracic intervertebral disc

Pulmonary circulation – to and from lungs

Systemic circulation – to and from body

Intrinsic circulation of the heart

Hepatic Portal circulation

separated as right and left chambers of the heart

2 Atria (s. atrium)

2 Ventricles

Interatrial Septum

Interventricular Septum

Atrioventricular Septum

Systemic circulation Superior vena cava – from upper ½ body

Inferior vena cava – from lower ½ body

Coronary sinus – intrinsic circulation of heart

↓

Right atrium

↓

Right ventricle

↓

Pulmonary circuit Pulmonary trunk to pulmonary arteries

Lungs

Pulmonary veins

↓

Left atrium

↓

Left ventricle

↓

Systemic circulation Ascending Aorta – to everything

General features of Atria smaller and thinner walled than ventricles

Musculi Pectinati

Auricles

Atria separated from one another by Interatrial Septum

Atria separated from ventricles by Atrioventricular Septum

contains Atrioventricular (AV) Node – beginning of Moderator Band

Right Atrium Sinus Venosus

posterior right, smooth surface

receives Superior and Inferior Venae Cavae and Coronary Sinus

Crista Terminalis

Sinoatrial (SA) Node – the “pacemaker”

Fossa Ovalis – vestige of Foramen Ovale (fetal interatrial bypass)

Left Atrium receives Upper and Lower Right and Upper and Lower Left Pulmonary Veins

General Features of Ventricles larger and thicker walled than atria

Trabeculae Carnae

Atrioventricular (AV) Valves – active, muscular

Cusps

Chordae Tendineae

Papillary muscles

Semilunar Valves – passive

Ventricles separated from one another by interventricular septum

contains Moderator Band or Purkinje Fibers

Right Ventricle Right AV or Tricuspid Valve – three cusps

opening of Pulmonary Trunk – anterior superior left

Pulmonary Semilunar Valve

Left Ventricle Left AV or Bicuspid or Mitral Valve – two cusps

opening of Ascending Aorta – anterior superior right

Aortic Semilunar Valve

Electrical conduction of the heart Sinoatrial Node – pacemaker

Atrioventricular Node

Moderator Band or Bundle of HIS or Purkinje Fibers

Locations to listen to heart valves

Aortic Semilunar – Right 2nd intercostal space parasternal

Pulmonary Semilunar – Left 2nd intercostal space parasternal

Tricuspid – Right 5th intercostal space parasternal

Bicuspid or Mitral – Left 5th intercostal space midclavicular

Fetal circulation

fetal structure fate

R&L Umbilical Arteries Vesical Arteries and Median Umbilical Ligament

Umbilical Vein Ligamentum Teres in Falciform Ligament

Ductus Venosus Ligamentum Venosus

(also Portal Sinus Hepatic Portal Vein)

Foramen Ovale Fossa Ovalis

Ductus Arteriosus Ligamentum Arteriosum

Fetal Definitive

Branches of the Thoracic Aorta listed in order of branching

1) Ascending Aorta – branches:

Right and Left Coronary Arteries

2) Aortic Arch – branches:

a) Brachiocephalic Artery – branches:

i) Right Common Carotid

ii) Right Subclavian Artery

b) Left Common Carotid Artery

c) Left Subclavian Artery

3) Descending Aorta – branches:

segmental Esophageal and Intercostal arteries

Superior Vena Cava venous counterpart to the Thoracic Aorta

drains entire upper half of body

located to right side of Aortic Arch, on mediastinal surface of right lung

begins with the union of Right and Left Brachiocephalic Veins

terminates in Sinus Venosus of Right Atrium

Tributaries

1) Left Brachiocephalic or Left Innominate Vein

long, horizontal, anterior to branches of aortic arch

begins with union of L Subclavian and L Internal Jugular Veins

2) Right Brachiocephalic or Right Innominate Vein

short, vertical

begins with union of R Subclavian and R Internal Jugular Veins

3) Azygos Vein

drains right Intercostal Veins

drains left Intercostal Veins via Hemiazygos Veins

Branches of the Abdominal Aorta listed in order of branching

1) Coeliac Trunk – to superior abdominal organs

2) Superior Mesenteric Artery – to Jejunum, Ileum, Large Intestine up

to and including Transverse Colon

3) Right and Left Renal Arteries

4) Right and Left Gonadal (Testicular or Ovarian) Arteries

5) Inferior Mesenteric Artery – to Descending and Sigmoid Colons

and superior Rectum

6) Right and Left Common Iliac Arteries – to pelvic region and lower

limbs

Inferior Vena Cava venous counterpart to the Abdominal Aorta

drains entire lower half of body

its main tributaries are those corresponding only to paired arterial

branches of the Abdominal Aorta, except the Hepatic vein

located to right side of Abdominal Aorta, anterior to lumbar vertebrae

begins with the union of the Right and Left Common Iliac veins

terminates in Sinus Venosus of Right Atrium

Tributaries of the Inferior Vena Cava listed in order of union

1) Right and Left Common Iliac Veins

2) Right Gonadal (Testicular or Ovarian) Vein

3) Right and Left Renal Veins

Left Renal Vein - long, crosses anterior to Abdominal Aorta

tributary of Left Renal Vein:

Left Gonadal (Testicular or Ovarian) Vein

4) Hepatic Vein

Arterial Branches

Intrinsic circulation of the heart “Coronary” Arteries vs “Cardiac” Veins

Branches of Right Coronary Artery Marginal (coronary) Artery

on right margin of heart

Circumflex (Coronary) Artery (right side)

at Atrioventricular Septum

Branches of Left Coronary Artery

Anterior Interventricular or Descending Artery

at anterior interventricular septum

anastomoses with Posterior Interventricular Artery

Circumflex (Coronary) Artery (left side)

branch:

Posterior Interventricular or Descending Artery

at posterior interventricular septum

anastomoses with Anterior Interventricular Artery

Cardiac veins Small Cardiac Vein

corresponds to Marginal Artery

on right margin of heart

Great Cardiac Vein

corresponds to Anterior Interventricular Artery

at anterior interventricular septum

Middle Cardiac Vein

corresponds to Posterior Interventricular Artery

at Posterior Interventricular Septum

Coronary Sinus

alongside Circumflex Artery

at Atrioventricular Septum

receives Cardiac Veins and

drains into Sinus Venosus of Right Atrium

All subsequent descriptions are for paired right and left

vessels even though this is not specified in each case

Branches of the Common Carotid Arteries and their branches ends in two terminal branches at level of laryngeal eminence in carotid

triangle

1) Internal Carotid Artery

major branches of the Internal Carotid Artery:

a) Middle Cerebral Artery – to majority of Cerebrum via Carotid Canal

passes through the Cavernous Sinus (a venous “dural sinus”

surrounding the sella turcica)

b) Ophthalmic Artery – to orbit via optic canal

select branches of Ophthalmic Artery:

i) Central Artery – enters eye within optic nerve

branches of the Central Artery:

Superior and Inferior Temporal Arteries – to retina

Superior and Inferior Nasal Arteries – to retina

ii) Supraorbital Artery

2) External Carotid Artery

(continued)

Branches of the External Carotid Artery and its branches

1) Lingual Artery – to tongue

2) Facial Artery – crosses face from mandibular ramus to medial orbit

3) Superficial Temporal Artery – to temporal fossa, scalp

4) Occipital Artery

5) Maxillary Artery – to muscles of mastication, palate, teeth, and

infraorbital region

select branches of maxillary artery:

a) Sphenopalatine Artery – to nasal cavity and palate

b) Middle Meningeal Artery – to cranial cavity via foramen spinosum

c) Alveolar Arteries (3) – to teeth

d) Infraorbital Artery – to middle face

Branches of the Subclavian Arteries and their branches 1) Vertebral Artery – to cranial cavity via foramen magnum

2) Thyrocervical Trunk – to scapular and cervical regions

3) Internal Thoracic Artery

4) Costocervical Trunk

5) Dorsal Scapular Artery

6) Axillary Artery (terminal branch, simply a change of name)

Subclavian Artery → Axillary Artery at first rib

to anterior and lateral thoracic regions

branches:

a) Thoracoacromial Artery (travels with Lateral Pectoral nerve)

b) Subscapular Artery

c) Lateral Thoracic artery (travels with Long Thoracic nerve)

d) Circumflex Humeral Artery

e) Brachial Artery (terminal branch)

Axillary Artery → Brachial Artery at Teres Major muscle

(continued)

Location of the Brachial Artery Proximally: on medial side of brachium between anterior and

posterior compartments but within anterior compartment

Distally: medial to tendon of biceps brachii in antecubital region

Major Branches of the Brachial Artery 1) Profunda Brachii Artery – serves posterior compartment

2) Superior and Inferior Ulnar Collateral Arteries

3) Radial Artery (one terminal branch of brachial artery)

terminates in manus as:

Deep Palmar Arch – anastomoses with Ulnar Artery

4) Ulnar Artery (another terminal branch of brachial artery)

branches:

Common Interosseous Artery and its branches:

Anterior Interosseous Artery

Posterior Interosseous Artery

terminates in manus as:

Superficial Palmar Arch – anastomoses with Radial Artery

Circulation of the cranial cavity 1) Internal Carotid Artery → Middle Cerebral Artery (at carotid canal)

serves frontal, parietal, and temporal lobes of the cerebrum

passes through Cavernous Sinus (a venous plexus of the dural

sinuses)

four levels from deep to superficial

emerges through Central Sulcus or Fissure between frontal and

parietal lobes of cerebrum

emerges through Sylvian or Lateral Sulcus or Fissure between frontal

and temporal lobes of cerebrum

branches:

Anterior Cerebral Artery - to anterior inferior frontal lobe

Right and Left Anterior Cerebral Arteries anastomose via:

Anterior Communicating Artery

Posterior Communicating Artery – an anastomosis with posterior

cerebral artery

(continued)

Circulation of the cranial cavity 2) Right and Left Vertebral arteries anastomose to form:

Basilar artery (unpaired)

branches:

Cerebellar arteries

Posterior cerebral artery – terminal paired branches

anastomoses with middle cerebral artery via posterior

communicating artery

3) Middle meningeal Artery – to meninges and calvarium

Branches of the coeliac trunk and their unpaired major branches 1) Left Gastric Artery

branches to lesser curvature of stomach and esophagus

2) Common Hepatic Artery

branches:

a) Hepatic Artery

b) Gastroduodenal Artery

branches to (right side of) greater curvature of stomach,

duodenum, and head and neck of pancreas

3) Splenic Artery

branches to fundus and (left side of) greater curvature of stomach,

and body and tail of pancreas

Branches of Common Iliac arteries and their major branches 1) Internal iliac Artery

branches:

a) Iliolumbar Artery (serves iliopsoas muscle)

b) Lateral Sacral Artery

c) Superior and Inferior Gluteal Arteries

d) Umbilical Artery of fetus…

or Superior Vesical Artery of adult

e) Uterine and Vaginal Arteries of female…

or Inferior Vesical Artery of male

f) Middle Rectal (“Middle Hemorrhoidal”) Artery

g) Obturator artery – to obturator muscles

h) Internal Pudendal Artery - to perineum

Branch (one among many):

Inferior Rectal (“Inferior Hemorrhoidal”) Artery

2) External Iliac artery

(continued)

Branches of Internal Iliac artery

Branches of

Internal Iliac artery

Branches of External Iliac Artery and its branches 1) Inferior Epigastric artery

2) Circumflex Iliac artery

3) Femoral Artery (terminal branch – a simple change of name)

External Iliac Artery → femoral artery at inguinal ligament

Branches of Femoral Artery:

a) External Pudendal arteries – to external genitalia, i.e., scrotum in

males or labia majora in females

b) Profunda Femoris Artery – to muscles of medial and posterior

compartments

its branches:

Medial and Lateral Circumflex Femoral Arteries – and their

branches descend medial and lateral thigh

c) Popliteal Artery (terminal branch, a simple change of name)

Femoral Artery → Popliteal Artery at adductor hiatus

(continued)

Branches of Popliteal Artery and their major branches 1) Genicular arteries (superior medial and lateral, inferior medial and

lateral)

2) Sural Arteries

3) Anterior Tibial Artery (terminal branch of Popliteal Artery)

branch (terminal):

Dorsalis Pedis Artery

4) Posterior Tibial Artery (terminal branch of Popliteal Artery)

branches:

a) Peroneal Artery

b) Medial and Lateral Plantar Arteries (terminal branches of

Posterior Tibial Artery)

Pulse Superficial Temporal Artery

temporal fossa

Carotid Artery (Common or External)

anterior to sternocleidomastoid at level of laryngeal eminence

Brachial Artery

antecubital fossa medial to tendon of biceps brachii

Radial Artery

anterior distal radius

Femoral Artery

femoral triangle

Popliteal Artery

popliteal fossa

Posterior Tibial Artery

posterior to medial malleolus

Dorsalis Pedis Artery

between tendons of extensor hallucis longus and extensor digitorum

longus

Venous drainage of the Head and Neck for most arteries there are corresponding veins of the same name except:

Internal, External, and Common Carotid arteries

veins with no corresponding arteries:

1) Internal Jugular Vein

drains cranial cavity, anterior face, tongue and pharynx

Sigmoid Dural Sinus → Internal Jugular Vein at jugular foramen

major tributaries:

a) Facial Vein

b) Lingual Vein

2) External Jugular Vein

drains lateral and posterior scalp, posterior face, infratemporal fossa

major tributaries:

a) Maxillary Vein

b) Superficial Temporal Vein

3) Anterior Jugular Vein

drains superficial thyroid region

Brain Ventricles, Cerebrospinal Fluid, Meninges, Dural Sinuses Choroid Plexus – a capillary-like structure within some ventricles

Cerebrospinal Fluid (CSF) – blood filtrate produced by choroid plexus that

bathes the central nervous system from within and without

Structures filled with CSF:

1) Subarachnoid Space

2) Brain Ventricles - derivatives of the embryological neural tube (CNS)

a) Lateral Ventricles – in paired cerebral hemispheres of forebrain

b) Third Ventricle – between right and left thalami and within

hypothalamus of forebrain

c) Cerebral Aqueduct – narrow tube in midbrain uniting third and

fourth ventricles

d) Fourth Ventricle – between cerebellum and pons of hindbrain

e) Central Canal of the spinal cord

Meninges 1) Pia Mater

2) Arachnoid Mater

Subarchnoid Space – location of CSF between pia and

arachnoid maters

Arachnoid Villi – drain CSF from subarachnoid space to dural sinuses

3) Dura Mater

continuous with periosteum of calvarium and vertebral canal

extensions of dura extending into fissures of brain:

a) Falx Cerebri – midsagittal septum between cerebral hemispheres

b) Falx Cerebelli – midsagittal septum between cerebellar

hemispheres

c) Tentorium Cerebelli – horizontal septum between occipital

lobes of cerebrum and cerebellum

Dural Sinuses 1) Superior Sagittal Sinus – superior margin of falx cerebri inferior to

sagittal suture

2) Inferior Sagittal Sinus – along inferior margin of falx cerebri

3) Straight Sinus – along union of falx cerebri and tentorium cerebelli

4) Transverse Sinuses – along lateral margin of tentorium cerebelli

Superior Sagittal Sinus → Right Transverse Sinus at internal occipital

protuberance

Straight Sinus → Left Transverse Sinus at internal occipital

protuberance

5) Sigmoid Sinuses

continuation of Transverse Sinuses

sigmoid sinus → Internal Jugular Vein at jugular foramen

(continued)

Dural Sinuses (continued)

6) Cavernous Sinus

venous plexus surrounding Sella Turcica

passed through by Internal Carotid Artery, nIII, nIV, nV1, nV2, nVI

receives Ophthalmic Vein*

drains indirectly to Transverse and Sigmoid sinuses

* Facial Vein anastomoses with Ophthalmic Vein, unlike arteries of

same names – this is a superficial venous pathway into the cranial

cavity and potential source of infection

Hepatic Portal Vein terminates in liver

tributaries:

1) Splenic Vein

2) Superior Mesenteric Vein

3) Inferior Mesenteric Vein

Venous drainage of the upper extremity and girdle for every artery there are corresponding veins of the same name

Superficial veins with no corresponding arteries:

1) Cephalic Vein

drains dorsum of hand, lateral antebrachium and brachium

ends in Axillary Vein at Deltopectoral Triangle

2) Basilic Vein

Anterior medial antebrachium and medial brachium

ends in Brachial Vein

3) Median Cubital Vein

Antecubital anastomosis of Cephalic and Basilic Veins

Venous drainage of the lower extremity and pelvic region for every artery there are corresponding veins of the same name

Superficial veins with no corresponding arteries:

Great or Long Saphenous Vein

drains medial crus and thigh

ends in Femoral Vein in femoral triangle

Short Saphenous Vein

drains sural region

ends in Popliteal Vein in popliteal region

Lymphatic system

Functions

Immune response

lipid absorption

removes dead blood cells from circulation, produces bilirubin

returns fluids and mobile leucocytes from extracellular tissues to

venous cardiovascular system

Terminal lymph vessels 1) Right Lymphatic duct

drains upper right ¼ of body

terminates in right subclavian vein

2) Thoracic duct

drains all but upper right ¼ of body

terminates in left subclavian vein

Cysterna Chyli – bulb-like expansion of inferior end of thoracic duct

Lymph Nodes scattered and concentrated in locations throughout body, especially

major joints, the cervical region, and digestive organs

Leucocytes within nodes attack antigens and impede them from circulating

Afferent and Efferent lymph vessels - lead to and from nodes

parts of the node:

Capsule

Trabeculae

Nodules

Germinal Centers

site of maturation and acquisition of new antibodies by b-lymphocytes

and their clonal proliferation

Reticular fibers

Macrophages and Lymphocytes

Distribution of Select Major Groups of Lymph Nodes of head:

Parotid

Submaxillary or Submandibular

Occipital

of neck:

Cervical

superior and inferior deep – surround internal jugular veins

Superficial – superior anterior triangle

(continued)

Distribution of Select Major Groups of Lymph Nodes of upper limb and girdle:

Axillary

Pectoral, Subclavicular, Subscapular, Brachial

of lower limb and girdle (including genitals and perineum):

Inguinal – femoral triangle

of thoracic cavity:

Tracheobronchial, Intercostal

Mediastinal – mostly concentrated around arteries

of abdominal Cavity:

Lumbar – efferents to cisterna chyli

many groups, mostly concentrated around and named after all arteries

and their branches, as well as viscera of pelvic cavity (e.g., rectum)

Thymus site of maturation of t-lymphocytes primarily in youth

located posterior to manubrium in superior mediastinum

size at age 2 (maximal): from laryngeal eminence to mid-sternal body

size at adolescence (replaced by adipose): jugular notch to sternal angle

Spleen blood filter

removes dead erythrocytes from circulation

populated by monocytes and macrophages

degrades hemoglobin to bilirubin (subsequently excreted by liver)

located in left hypochondriac region, to left of stomach

Capsule

Cords of Billroth – reticular fibers