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Function of blood include
Carrying respiratory gases, nutrients, wastes, and hormones; Helps body regulate temp.
Hematocrit
percentage of blood volume occupied by red blood cells
Males RBC
47% +/- 5%
Females RBC
42% +/- 5%
Serum
plasma without clotting factors
Blood plasma
straw-colored, sticky fluid portion of blood about 55% of whole blood
Blood Plasma Protein: Albumin
most abundant; maintain osmotic pressure
Blood Plasma Protein: Globulins
Alpha and beta globulins: some transport metal ions and some transport lipids; Gamma globulins: immunoglobulins (antibodies)
Blood Plasma Protein: Fibrinogen
converted to fibrin - major component of blood clot
Red blood cells are also called
erythrocytes
Acidic dyes
eosin, stains pink
Basic dyes
hematoxylin or methylene blue - stains blue and purple
Hemoglobin
oxygen-carrying protein
Leukocytes
white blood cells
Diapedesis
circulating leukocytes leave the capillaries by squeezing between endothelial cells
Type of Leukocyte: Granulocytes
contain enzyme filled vesicles in cytoplasm
Type of Leukocyte: Arganulocytes
lack vesicles
Type of Granulocytes: Neutrophils
(appear neutral - both pink and purple) Most numerous leukocyte (60%) phagocytize bacteria and release enzymes
Nucleus is multi-lobed; 2 to 6 lobes
polymorphonucleated granulocytes
Type of Granulocytes: Eosinophils
(appear pink) Turn off allergic reactions and help fight off parasitic infections
Type of Granulocytes: Basophils
(appear purple) secrete histamine
Histamine
Functions in inflammation mediation
Type of Agranulocytes: Lymphocytes
(stains dark purple) the most important cells of the immune system
Lymphocyte: T-Cells
attack foreign cells directly
Lymphocyte: B cells
secrete antibodies and multiply to become plasma cells
Type of Agranulocytes: Monocytes
largest leukocyte that trasnform into macrophages and are phagocytic cells
Platelets
Cell fragments and seal small tears in blood vessels; instrumental in blood clotting
Hematopoiesis
process by which blood cells are formed (all originate in bone marrow)
Red marrow
actively produces blood cells
Location of red marrow
remains in proximal epiphyses, girdles, and all of axial skeleton
Tissue framework for red marrow: Reticular connective tissue
Reticular fibers support developing blood cells
Tissue framework for red marrow: Blood sinusoids
Large capillaries with wide-open intercellular junctions
Yellow marrow
dormant; contains many fat cells; located in long bones of adults
hemopoietic stem cell
most undifferentiated blood stem cell
Lymphoid stem cells
give rise to lymphocytes
Myeloid stem cells
give rise to all other blood cells which then become committed to specific cells
Erythrocytes are formed from
proerythroblasts
Megakaryocytes are formed from
megakaryoblasts (which break apart into platelets)
Granulocytes form from
myeloblasts (one cell line for each type)
Monocytes form from
monoblasts (myeloid line)
Lymphocytes from directly from
lymphoid stem cells
Arteries
carry blood away from the heart; smaller lumen/vessel size ratio
Capillaries
The smallest blood vessels, and the site of exchange molecules between blood and the tissues.
Veins
carry blood to the heart; thicker tunica externa
Structure of blood vessels: Tunica intima
composed of simple squamous epithelium Subendothelial layer - thin layer of loose connective tissue
Structure of blood vessels: Tunica media
primarily sheets of smooth muscle; also collagen and elastin in larger vessels
Structure of blood vessels: Tunica externa (adventitia)
composed of dense connective tissue
Lumen
central blood-filled space of a vessel
Types of Arteries: Elastic arteries
the largest arteries; high elastin content in tunica media stores energy for continuous flow of blood
Types of Arteries: Muscular (distributing) arteries
internal and external elastic laminae; thick tunica media relative to vessel size
Types of Arteries: Arterioles
smallest arteries, tunica media contains smooth muscle and diameter of lumen can change
Capillaries structure
only tunica intima and has intercellular clefts (gaps of unjoined membrane between tight junctions; overlap)
Pericytes
supporting cells of capillaries
Continuous capillary
most common type of capillary contains very small gaps in the endothelial lining that permit exchange
fenestrated capillaries
have pores in vessel wall; found in kidneys, intestines, and endocrine glands
4 routes of capillary permeability are...
Direct diffusion
Through intercellular clefts
Through fenestrations (pores)
Through cytoplasmic vesicles (pinocytosis)
Sinusoids
Wide, leaky capillaries found in spleen, liver, bone marrow; intercellular clefts are wide open
Capillary beds
network of capillaries running through tissues (Metarteriole and Thoroughfare channels)
precapillary sphincters
regulate blood flow into tissues
What tissues lack or have sparse capillary beds?
Epithelia and cartilage Cornea and lens of eye Tendons and ligaments
Venules are the smallest veins, but what are the smallest venules?
postcapillary venules
Mechanisms to Counteract low venous pressure
one way valves and skeletal muscle pump
Vascular Anastomoses
interconnections of blood vessels so that organs can receive blood
"Great Vessels" of Circulation (4 listed)
Aorta
Pulmonary Trunk/Pulmonary Arteries and veins
Inferior vena cava
Superior vena cava
Pulmonary Circuit of the heart
takes blood to and from the lungs
Systemic circuit of the heart
vessels transport blood to and from body tissues
Atria of the heart
receiving chambers; blood from the pulmonary and systemic circuits
Ventricles of the heart
the pumping chambers of the heart
Heart Development - Embryo
Blood vessels begin as condensations of lateral plate (splanchnic) mesoderm
Angioblasts
immature endothelial cells
Heart Development - Sinus Venosus
becomes part of right atrium and determines heart rate
Heart Development - Bulbus cordis
becomes great arteries and right ventricle
Pericardium: Fibrous
strong layer of dense connective tissue
Pericardium: Serous
formed from parietal layer and visceral layer with the pericardial cavity between
epicadium
Visceral layer of the serous pericardium
serosal membrane
(epicardium) simple squamous epithelium + thin connective tissue layer
Myocardium
consists of cardiac muscle arranged in circular and spiral patterns
Endocardium
simple squamous epithelium resting on a layer of loose connective tissue (lines internal walls of heart)
Pathway of blood through the heart: Oxygen Poor Blood
in Superior and inferior venae cavae
pulmonary circulation (Deoxygenated blood)
Right atrium, right ventricle, pulmonary trunk. right/left pulmonary arteries, lungs
Returned to heart (systemic Circuit)
left atrium, left ventricle, aorta, distributing arteries to body
Systole
ventricular contraction
Diastole
ventricular relaxation and expansion due to filling with blood
Right Atrioventricular valve
between atria and ventricles and is a tricuspid valve
Left atrioventricular valve
between atria and ventricles and is a mitral (bicuspid) valve
Aortic and pulmonary valves
at junction of ventricles and great arteries and is a semilunar valve (3 crescent shaped leaflets)
What is each valve composed of?
endocardium with connective tissue core
Chordae tendineae
connective tissue strands that connect AV valves to small muscles extending from lower ventricle walls
Papillary muscles
contraction pulls chordae tendineae taut and prevents eversion of AV valves into atria
"lub" sound in heart
AV valves closing
"dup" sound in heart
the semilunar valves closing
2 auto-rhythmic cardiac cells
pacemaker cells and conducting cells
Sinoatrial node
upper right atrium; sets inherent rate of contraction (primary pacemaker)
Atrioventricular node
between atria and ventricles
conducting system of the heart
a series of specialized cardiac muscle cells that conduct action potential throughout heart
Purkinje fibers
through each ventricle wall (between endocardium and myocardium); conduct action potential rapidly, BUT do not contract or contract poorly
Nerves to/from the heart
Visceral sensory fibers
Parasympathetic branches (of the vagus nerve)
Sympathetic Fibers (from cervical ganglia)
Fetal circulation
All major vessels in place by month 3 of development.
Fetus circulation difference
most blood bypasses liver, fetus must supply blood to placenta, very little blood is sent through pulmonary circuit
Paired umbilical arteries
oxygen poor blood to placenta
Note
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