What are the functions of the circulatory system? Transport -- nutrients, proteins, cells Protection Pathogens -- immunity Damage -- clotting Homeostasis Heat control Reservoir Cardiovascular System

What is blood? Comprised of 2 major categories… fluid 55% (Plasma) & formed elements 45% Plasma is mostly H2O with some suspended proteins and other solutes Formed elements consist of RBC, WBC and TC Cardiovascular System

Where does blood come from? Fluid obtained via diet and then osmosis into blood stream. Formed elements result from the process of making new blood cells… Hemopoiesis or Hematopoiesis from precursors (stem cells) that reside & multiply in red bone marrow. Before birth = yolk sac, liver, thymus, spleen & red marrow Postpartum = red marrow Cardiovascular System

Vascularization of the yolk sac involves the formation of endothelial cells near the yolk sac membrane. These surround islands of cells that become “blood islands” These cells (hemocytoblasts) are the stem cells that give rise to all other hemopoietic stem cells Where do erythrocytes come from? Cardiovascular System

Figure 12.07

Where does blood come from? Cardiovascular System

Structure: Biconcave cells w/ no nucleus can’t conduct cell repair Purpose: Carry gases O 2 (98% w/ hemoglobin) CO 2 (23% w/ hemoglobin, 70% HCO 3 - ) Life Span: ~120 days Contents: Hemoglobin, lipids, ATP and enzymes What’s important about Erythrocytes? 7.5 μm Cardiovascular System

Hemoglobin: 1/3 of RBC content is hemoglobin. Each hemoglobin has 4 hemes and 4 globins. 1 O 2 binds with 1 heme What’s important about Erythrocytes? Cardiovascular System

3 Main layers (or tunics) 1) Tunica adventitia connective tissue 2) Tunica media smooth muscle and elastic fibers 3) Tunica intima connective tissue, basement membrane and endothelium What are the similarities between vessels? Cardiovascular System

What are the similarities between vessels? Cardiovascular System

The 3 tunics not present Endothelial cells continuous with endocardium Basement membrane Pericapillary cells What’s unique about capillaries? Cardiovascular System

What function(s) do these sphincters accomplish? How is capillary flow regulated? Cardiovascular System

Figure 12.26

Figure 12.27

Figure 12.29

Figure 12.36

Figure 12.37

What is the external anatomy of the heart? Cardiovascular System

Vessels associated with sulci… Coronary arteries (Right and Left) Interventricular arteries (anterior and posterior) What is the external anatomy of the heart? Cardiovascular System

Vessels associated with sulci… Great & small cardiac veins return blood to heart via… To what chamber? ? What is the external anatomy of the heart? Coronary sinus Cardiovascular System

Right atrium -3 entrances *vena cavas *coronary sinus Right ventricle -Chordae tendineae -Papillary muscles -Exit semilunar valves...to pulmonary trunk What is the internal anatomy of the heart? Tricuspid valve Cardiovascular System

SA node “fires” Impulse reaches AV node, 0.1 sec delay Impulse travels to AV bundle (Bundle of His) Impulse travels down R and L bundle branches Finally back up Purkinje fibers What controls the timing and sequence of a heart beat? Cardiovascular System

Receptors monitor conditions including: 1) Changes in pressure (baroreceptors) in major arteries work with medulla oblongata 2) Changes in chemistry (chemoreceptors) in medulla oblongata (CO2) and major arteries (O2) How is homeostasis of the heart achieved? Cardiovascular System

Figure 12.52

Figure 12.19

Figure 12.03

What are the key events during the fetal period?

Figure 12.41

What are the key events during the fetal period?

Figure 12.43

Figure 12.44

Figure 12.45

Figure 12.46