Cardio Vascular System

(Circulatory system)Ajith SominandaDepartment of Anatomy

Lecture outlineWhy a circulatory system ?Arrangement of the CVSVascular tree-Gross AnatomyCVS histology

Circulatory system; Why?

Amoeba in motion

Circulatory system; Why?

Circulatory system; Why?

Functions of circulatory system

Transport of materials and cells by continuous movement of blood GasesNutrientsWaste productsComponents of immune and endocrine system

Thermoregulation

Components of human circulatory systemBlood vascular system

(closed) HeartArteries and arterioles

(conduction / distributing vessels)Capillaries (exchange vessels)Venules and veins (capacitance

vessels)

Lymph vascular system (open)LymphaticsLymph nodes

Pulmonary circulation Heart: left

chambers (oxygenated blood)

Heart: right chamber s (De-oxygenated blood)

Conducting vessels

Arterioles

Exchange vessels

(Capillaries)

Venules

Lymph nodes

Lymphatics

Capacitance vessels(Veins)

Distributing vessels

Vascular tree- Gross anatomy

Overall arrangement

Aorta(2-2.5 cm)

Large and medium

size arteries

(100-200)

Arterioles(4 * 106 )

(<300 µm)

Capillaries(16 * 106 )

(7 µm)

LV

RV

RA

Arch of aortaSuperior vena

cava

Pulmonary artery

Intercostal vessels

Inferior vena cava

Heart, great vessels and circulation in thorax

Heart, great vesselsCirculation in axilla and upper arm

Pulmonary artery

Left bronchus

Subclavian artery &

vein

Axillary artery &

vein

Brachial artery &

vein

Common carotid arteries

External & internal carotid

arteries

Arch of aorta

Circulation in head & neck

Circulation in abdomen, upper and lower limbs

Abdominal aorta

Common iliac artery

External & internal iliac

arteries

Femoral artery

Radial & ulnar arteries

Branching patterns of arterial tree

1. Terminal branches

2. Co-lateral branches

1. End-to-end anastomosis1. Vaginal artery-ovarian artery2. Left gastro epiploic arteries3. Ulnar artery and superficial palmar branch of

radial artery

2. Anastomosis by convergenceVertebral arteries forming basilar artery

3. Transversal anastomosis1. Between anterior cerebral arteries2. Between radial and ulnar at wrist3. Between posterior tibial and peroneal arteries

Anastomosis of arteries

Venous systemSuperficial veins

Deep veins Venae comitantes

Valves & Venous

drainage

Venous system: problemsFailed superficial veins:

’’Varicosities’’Obstructed deep veins:

’’Deep vein thrombosis (DVT)’’

CVS Histology

General arrangement of cardio-vascular tissues

(CARDIO VASCULAR TUBE)

’’ Tunic = coat ’’

1. Tunica externa / adventitia

2. Tunica media

3. Tunica intima

Vasa vasorum

(Vessels of vessels)

Nervi vasorum

(Nerves of vessels)

Has three-layered structure

General arrangement of cardio-vascular tissues

Heart Arteries Capillaries Veins

Note the changes occurring in the wall of the structures

Structure for Function !The heart is a (muscular) pump !

Heart

1. Endocardium (Tunica intima)

2. Myocardium (Tunica media)

3. Epicardium / viceral pericardium (Tunica adventitia)

Cardiac wall consists of three layers:

1. Endothelium (single layer of flattened epithelial cells)

2. Sub-endothelial connective tissue

Heart• Endocardium

Tunica intima

1. Consists of cardiac muscle fibers (Cardiocytes) arranged in a network ’’ Syncytium’’

2. Cardiocytes have central nucleus and are connected by junctional complexes ’’intercalated discs’’

3. Mitochondria and sarcoplasmic reticulum are abundant in cytoplasm

4. Muscle contractions are Strong , continuous and inherent

Heart• Myocardium

Heart• Cardiocyte-Ultra structure

Transverse junctional complexes (Intercalated discs)

Striations

Longitudinal junctional complexes(GAP junctions)

Heart• Epicardium

1. Consists of flattened epithelium (Mesothelium) that secretes serous fluid into pericardial space

2. Epithelium is supported by Sub-endothelial connective tissues

3. Contains coronary vasculature

Heart Arteries Capillaries Veins

Arterial tree• Arteries conduct and distribute blood to periphery

Blood pressure

Vascular anatomy

High pressure tubal system for conduction of blood to periphery

Low pressure tubal system for drainage of blood

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Structural adaptation for Function !

Conform to the three-layered tissue arrangement

Main types of vessels in arterial system1. Large elastic arteries

(Aorta , Brachiocephalic, common carotid, subclavian & common iliac arteries)

2. Medium-sized muscular arteries(Intercostal, axillary, radial arteries)

3. Arterioles

Arterial tree

• Elastic arteries

1. Tunica media contains large amounts of fenestrated sheaths of elastin and lesser amounts of collagen and smooth muscle cells

2. Tunica adventitia contains collagen tissues

Arterial tree

• Muscular arteries

1. Tunica intima has three layers:1. Endothelium2. Sub endothelial connective tissues3. Internal elastic lamina (sheath of

elastin)

2. Tunica media has thick layer of smooth muscle cells

3. Larger vessels have external elastic lamina

Arterial tree

• Arterioles

1. Arterioles are final branches of arterial system that regulate blood flow to capillary bed

2. Tunica media has concentric layers of smooth muscles

3. Innervated by sympathetic nerves and control the vascular tone

Arterial tree

• Arterioles and micro circulation

Arterial tree

Arteriloes

Venule

Sympathetic nerve

Pre-capillary spincters

1. Continuation of endothelium

2. No smooth muscle and adventitial layers

3. Occasion pericytes are found

Capillaries: the exchange compartment

Capillaries: different types

1. Continuous

2. Fenestrated

3. Discontinuous

Q: List the sites where different capillary types are found

Venous system• Veins & venules

Venules (Post capillary, Muscular & Collecting venules)

Capillaries

Veins

• Has relatively Large lumen & thinner wall • Elastic and muscular components are much less prominent compared to arteries•Acts as reservoirs of blood; Capacitance vessels

Lymph vascular system

• Reuptake excess tissue fluid that accumulates in ECS

• Similar to venous system

Things that are good to read (know) !

Formation of EdemaThickening of arterial walls i.e.

Arteriosclerosis & AtherosclerosisEndothelium and inflammationEndothelium and blood coagulationBiology of vessel formation and tumors

(tumor angiogenesis )

References1. Wheaters functional histology2. Histology and cellbiology by Abraham L

Kierszenbaum3. Grays Anatomy4. WWW.

The ENDThank you