Circulatory System Blood Circulatory System -arterial system -capillaries -venous system Lymphatic System -capillaries and ducts -lymphatic organs spleen, tonsils, thymus, lymph nodes

Arteries* and Veins: Three layers tunica intima squamous epithelium basal lamina subendothelial layer * internal elastic membrane tunica media smooth muscle * external elastic membrane tunica adventitia connective tissue vasa vasorum nervi vascularis

Arteries elastic arteries (large :aorta, pulmonary vein) reduced internal elastic membrane tunica media- elastic fibers, smooth muscle muscular arteries (medium) prominent internal elastic membrane tunica media:>smooth muscle <elastic fibers small arteries/ arterioles classified by # smooth muscle layers arterioles 1-2; small artery 3-8 precapillary sphincter- smooth muscle

Aorta Medium artery arteriole

Venous System Large veins: 3 layers not distinct lumen larger than artery lumen often collapsed valves Medium veins: similar to large vein structure adventenia thicker than media several layers of muscle Venules: postcapillary- fluid/cell loss - histamine muscular: 1-2 layers of muscle

Vein Artery Vein 3 layers not as distinct lumen larger than artery lumen often collapsed valves

Vein and valve venul e arteriole capillary Medium artery vein

Capillaries - simple squamous epithelium - no smooth muscle - basal lamina (basement membrane) - pericytes within basal lamina - large surface area for exchange - primary site of exchange for fluid electrolytes, gases, and macromolecules

Capillary Bed

Capillaries Types: continuous fenestrated discontinuous (sinusoidal)

Continuous Capillaries - close cellular interconnections junctional complexes - permeable to small molecules <10nm in diameter - most transport via pinocytotic vesicles - muscle, skin, lungs, adipose tissue, CNS*, retina and mammary glands

Transcellular Transport - pinocytotic vesicles Junctional Complex - zonula occludens - zonula adherens - desmosome apical basal

Pericyte: undifferentiated cell with multiple processes give rise to new endothelial cells contained within basal lamina

Fenestrated Capillaries - contain 'windows’, fenestrations - easy passage of larger molecules (10-100nm) - number of fenestrations varies with absorption - pinocytotic vesicles - diaphragms -nonmembranous - basal lamina intact - kidneys, pancreas, gallbladder, intestine

Continuous capillary Fenestrated capillary

Discontinuous (sinusoidal) Capillaries - large diameter - wide gaps between cells - relatively free movement (even cells) - gaps or missing basal lamina - liver, spleen, ovaries, some endocrine glands

PERMEABILITY Low High Extremely High

Blood flow through Capillary Bed -controlled by precapillary sphincters -smooth muscle band at arteriole/capillary fajerpc.magnet.fsu.edu/.../ 30_Circulatory.htm

Fluid Movement across Capillary Wall: Starling’s Law of Capillaries - Governed by Hydrostatic and Osmotic Pressures Capillary Hydrostatic Pressure (HP): blood pressure forces fluid OUT Osmotic Pressure (OP): pressure due to plasma proteins trapped in capillary draws fluid IN

HP > OP -->fluid moves from cap to tissue--> FILTRATION occurs at arteriole end of capillary HP fluid moves from tissue to cap-> REABSORPTION occurs at venous end of capillary SMALL NET LOSS OF FLUID FROM BLOOD

Residual Fluid is taken up by Lymphatic Capillaries -lymphatic ducts -returned to blood

Lymphatic Capillaries and Vessels -blind end capillaries -interstitial fluid pressure drives lymph into lymph capillary

Lymphatic Capillaries and Vessels - one cell thick: overlapping pattern– shingles - one-way valves ensure flow away from tissues

Lymphatic Capillaries and Vessels - one cell thick: overlapping pattern– shingles - one-way valves ensure flow away from tissues

Lymphatic Capillaries and Vessels

The flow of lymph is regulated by: 1. Skeletal Muscle Pump. 2. Respiratory Pump. 3. Contraction of smooth muscle in larger lymphatic vessels walls 4. Pressure on lymphatic vessels by expansion/recoil of nearby arteries Skeletal muscle pump Cardiac%20Function/CF018.htm

A. A 62 year old woman has marked swelling of ankles and lower legs. Form a hypothesis stating what you think could account for this symptom. B. Design an experiment that will test your hypothesis.

Edema: accumulation of fluid in interstitial spaces Hypotheses: 1.Increased capillary hydrostatic pressure - gravitational forces - in heart failure 2.Decreased osmotic pressure - loss of plasma proteins from kidney or liver disease 3.Increased capillary permeability - inflammatory compounds- histamine, Anaphylaxis - trauma- burns 4.Lymphatic obstruction (as occurs in filariasis) - side effect of surgery - Elephantiasis (filariasis)

Lymphatic filariasis (elephantiasis) - caused by parasitic worm, Wuchereria bancrofti - transmitted to humans by mosquitoe bites - painful, disfiguring chronic enlargement of arms, legs and genitals

Lymphangiogram Visualization of lymph system of legs Inject dye between toes, visualize lymph vessel Inject dye directly into lymph vessel Image dye-stained lymphatic system Capillary Permeability Inject tracers of variable sizes Identify location within and outside vessels

Lymphatic System - monitor body surfaces and internal fluids - react to potentially harmful substances

Lymphatic Tissues - Concentrated near respiratory tract digestive tract reproductive tract

Antigen: foreign substance First Encounter->Nonspecific Inflammatory Response Mast cells -Histamine release -Vasodilation -Increase permeability Neutrophils -enzymatic digestion of virus Macrophages -cytokine release -phagocytosis -antigen presentation