02 Cdp Ma Cardiovascular

MEDICAL MICROSCOPIC ANATOMY CARDIOVASCULAR SYSTEM Prof. Daniel Djakiew GEORGETOWN UNIVERSITY MEDICAL CENTER

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

THE VASCULAR SYSTEMS CIRCULATORY SYSTEM

CARDIOVASCULAR SYSTEM

LYMPHOID SYSTEM

LYMPHATIC SYSTEM

Blood

Lymph

Heart pump

No pump

Circulates

Unidirectional

HEART A double-pump ARTERY Carries blood away from the heart VEIN Returns blood to the heart CAPILLARY Connects arterial side to venous side, with special exceptions

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

CAPILLARIES

KEY POINT: Capillaries and postcapillary venules are the exchange vessels for the tissues.

STRUCTURE OF CAPILLARIES Endothelial cells Basal lamina Pericytes

TYPES OF CAPILLARIES

Muscle

Intestines

Liver

Skin

Endocrine

Spleen

Lung

Kidneys*

Bone marrow

Brain

Endocrine

CONTINUOUS CAPILLARY

FENESTRATED CAPILLARY SINUSOIDAL CAPILLARY

CAPILLARY EXCHANGE MECHANISMS  Open pores/gaps  Diffusion  Filtration  Vesicular transport (“transcytosis”)  Transendothelial channels

VESICULAR TRANSPORT

KEY POINT: System of pinocytotic pits and vesicles which move large molecules across the endothelium.

TRANSENDOTHELIAL CHANNELS

SECRETORY & METABOLIC FUNCTIONS OF ENDOTHELIAL CELLS Adhesion molecules Produce Vasoactive compounds (NO, endothelin) Antithrombogenic factors Metabolic conversions (angiotensin I to II)

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

HEART

ELASTIC ARTERY

LARGE VEIN

MEDIUM VEIN

MUSCULAR ARTERY

POSTCAPILLARY VENULE

ARTERIOLE

CAPILLARY

STRUCTURE OF ARTERIES & VEINS

TUNICA INTIMA - endothelium & connective tissue TUNICA MEDIA - smooth muscle TUNICA ADVENTITIA - connective tissue + vv + nerves

DIFFERENCES BETWEEN ARTERIES & VEINS

ARTERY

VEIN

DIFFERENCES BETWEEN ARTERIES & VEINS

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

AORTA (elastin stain)

MUSCULAR ARTERIES

MUSCULAR ARTERIES

H&E

Elastin

ARTERIOLE

H&E

TEM

Types of Microcirculation 1. Arteriolecapillary bed – venule 2. Arteriovenous anastomosis (skin) 3. Arteriole-capillaryarteriole (kidney) 4. Venule-capillaryvenule (liver)

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

POSTCAPILLARY/COLLECTING/MUSCULAR VENULES

MEDIUM SIZED VEIN

LARGE VEIN - Inferior Vena Cava

UNIDIRECTIONAL BLOOD FLOW IN VEINS

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

STRUCTURE OF THE HEART Endocardium - homologous to tunica intima Myocardium - homologous to tunica media Epicardium - homologous to tunica adventitia

EPICARDIUM

ENDOCARDIUM

SA node

Purkinje fibers

CARDIOVASCULAR SYSTEM • • • • • • •

Circulatory System Capillaries Structure of Larger Vessels Structure of Arteries Structure of Veins The Heart Lymphatics

THE VASCULAR SYSTEMS

CIRCULATORY SYSTEM

LYMPHOID SYSTEM

CARDIOVASCULAR SYSTEM

LYMPHATIC SYSTEM

LYMPHATIC VESSELS & LYMPH NODES FUNCTIONS: Return excess 10% of interstitial fluid to blood Transport lipids absorbed from intestines Immunologic support

LYMPHATICS

KEY POINT: Lymphatic capillaries have unique permeability characteristics

LYMPHATICS & LYMPH NODES

KEY POINT: All lymph gets filtered by at least one lymph node before it re-enters the blood.

CLINICAL CONTEXT: Myocardial Infarction (MI)

KEY POINT: Myocardial infarction alone is responsible for 20-25% of all deaths in the US.

CLINICAL CONTEXT: Berry Aneurysm

KEY POINT: Berry aneurysms are related to defects in the tunica media of cerebral arteries.

CLINICAL CONTEXT: Varicose Veins KEY POINT: Varicose veins are abnormally dilated, tortuous veins with valve insufficiency. About 15-20% of the general population will develop varicose veins in the lower legs.

THE END