The circulatory system brings nutrients, oxygen, and hormones to tissues via two circuits: the cardiovascular system uses blood and the lymph vascular system uses lymph. The cardiovascular system consists of pulmonary and systemic circulation loops. The heart is the hollow muscular pump located in the chest that circulates blood through four chambers and two atria that receive blood and two ventricles that pump blood into the arteries. The lymph vascular system consists of a network of lymphatic capillaries and vessels that collect lymph from tissues and return it to the cardiovascular system.

1. CIRCULATOR
Y SYSTEM

2. brings :
 nutrients
 oxygen
 hormones
Functions :

3. Cardiovascular system
 the circulating fluid is blood.
Lymph vascular system
 the circulating fluid is milky substance
called lymph.*

4. CARDIOVASCULAR SYSTEM
*
Pulmonary circulation (pulmonic
circulation)
 brings blood from the heart to the lungs &
then back to the heart.
Systemic circulation
 brings blood from the heart to all other
tissues and organs of the body & then
back to the heart.

5. HEART
 hollow muscular organ
 about the size of clenched fist
 located at the central mediastinum of the
thoracic cavity
*

6. Four chambers of the heart :
Ventricles - occupy the inferior part of the
heart.
 right ventricle - pump of the pulmonary
circulation
 left ventricle - pump of the systemic
circulation
Atria - superior part of the heart
 right atria
 left atria

7.  interatial septum - right side & left side
 interventricular septum - superiorly &
inferiorly
right atrium → right ventricle
(right atrioventricular orifice ; right atrioventricular valve)
left atrium → left ventricle
( left atrioventricular orifice ; left atrioventricular valve)

8. superior vena cava
inferior vena cava
coronary sinus
bring unoxygenated
blood from thr different
parts of the body to
the right atrium
Pericardium
 CT that envelops the heart
consists of two pouches:
 fibrous pericardium - made up of dense CT and lines
the central mediastinum
 serous pericardium - has two layers
parietal (external layer) - made up of loose CT that
is covered on its free surface by mesothelium.
visceral (internal layer) - also covered by
mesothelium & synonimous w/ the epicardium.

9. Histologic Layers of the Heart
 Endocardium
- thinnest layer of the heart
- lines all the internal surfaces of the heart
 endothelium - a simple squamous ET that
adjoins the cardiac lumen
 subendothelium - very thin layer of loose CT
 subendocardium - external layer of loose CT
 Purkinje fibers - comprise the impulse-
conducting system of the heart

10.  Myocardium
- thickest layer of the heart
- consists of cadiac muscle fibers
- myocardial muscle fibers are originate & insert
in the cardiac skeleton
- secrete atleast two polypeptide hormones
 atrial natriuretic peptide (ANP)
 brain natriuretic peptide (BNP)

11.  Epicardium
- outermost layer
- consists loose CT that is lined on its external
surface by mesothelium
Cardiac skeleton - forms the central support of the
heart into w/c the cardiac muscles & valves are
attached.
3 components :
 septum membranaceum *
 annuli fibrosi *
 trigona fibrosa *

12. Cardiac valves (AV & Semilunar valves)
- consists of reduplicated endocardia & dense CT;
avascular.
Impulse-conducting system has three components :
 sinoatrial (SA) node - also called as cardiac pacemaker;
consists of a dense network of interwoven Purkinje
fibers*
 atrioventricular (AV) node - located in the myocardium
of the posterior lower part of the interatrial septum
 three internodal tracts;
 AV bundle;
 two bundle branches;
 Purkinje fibers

13. Blood & Lymphatic vessels and Nerves
of the heart
 Main coronary arteries & their major
branches are located in the inner
epicardium.
 smaller branches go deep into the
myocardium w/c terminate as capillaries.
 Lymph channels - closely associated w/
the musculature of the heart; abundant in
the myocardium, subendocardium, and
subepicardium.

14. LYMPH VASCULAR SYSTEM

15. Lymph - milky substance contains water, proteins,
lymphocytes & fat droplets.
Lymphatic capillaries
 wall consists of endothelium
 unite to form small lymphatic vessels then unite
to large vessels that ultimately converge into 2
lagre lymphatic ducts.
 present in all tissues, organs & oragan system
except in cartilage, bone, bone marrow, teeth,
placenta, and CNS.

16. Lymphatic vessels
 thick walls & has a large size of lumen
 composed of endothelium & an
underlying thin layer of CT
Layers of blood vessel :
tunica intima
tunica media
tunica adventitia

17. Lymphatic ducts
*
 right lymphatic duct - smaller & shorter
than thoracic. *
 thoracic lymphatic duct - collects the
lymph from the parts of the body that are
not served by tributaries of the right
lymphatic duct. *