Circulatory System

Transportation

Transportation

• function of blood

• oxygen from lungs and tissue and carbon dioxide and other waste products from tissue to lungs

• nutrients from digestive tract to tissues

• hormones from endocrine system to target cells

Regulation

• pH (acidity) through buffers

• temperature by carrying heat to body surface

• osmotic pressure through interactions with dissolved molecules

Protection

• limits spread of infection

• destruction of microorganisms and cancer cells

• neutralization of toxins and pathogens

• clotting to minimize blood loss

Composition of Blood

• plasma makes up 55%

• formed elements makes up 45% consisting of 41% red blood cells and 4% white blood cells

Plasma

• storage of red and white blood cells

• no real anatomy that we can study visually

• is the matrix of this connective tissue (blood)

• 91.5% water and 8.5% solutes (proteins, hormones, gases, nutrients and nitrogenous wastes)

Erythrocytes

• biconcave disks with flexible disks and lack a nucleus

• basically a sac to carry hemoglobin

• protein that binds to oxygen

Hematocrit

• % of the blood volume made up by erythrocytes (40% in females and 45% in males)

• depends on size and number of red blood cells

• used to check for various conditions including anemia

Leukocytes

• circulating white blood cells represent only a small fraction of total population

• life span of only a few days

• has a nucleus

• most cells are found in peripheral tissues

• helps defend against pathogens and removes toxins, wastes and damaged cells

Agranular

• type of leukocyte

• consists of lymphocytes (20-25%) and monocytes (3-8%)

Granular

• type of leukocytes

• consists of basophils (<1%), neutrophils (60-70%) and eosinophils (2-4%)

• particles in the cell cytoplasm that show up as small spots when the cell is examined through a microscope

Neutrophils

• type of granulocyte

• contains bactericidal compounds that kill the bacteria

• contorted nucleus

• cytoplasm packed with pale, neutral staining granules

• highly mobile, usually first to arrive at injury site

Eosinophils (or acidophils)

• type of granulocyte

• granules stain with acidic red dye

• involved in allergic reactions

• bilobed nucleus

• phagocytic cells that engulf and destroy pathogens

Basophils

• rare type of granulocyte

• granules stain purple or blue with basic dye

• involved in inflammation response

• contain histamine

Monocytes

• largest white blood cell

• highly mobile phagocytes

• type of agranulocyte

• large kidney shaped nucleus

• outside the bloodstream are called free macrophages

Lymphocytes

• type of agranulocytes

• very little cytoplasm around very large nucleus

• slightly larger than RBCs

• responsible for specific immunity

• primary cells of lymphatic system (only a small amount is found in the bloodstream)

Platelets (thrombocytes)

• platelets are pieces of megakaryocytes fragments

• membrane-enclosed packs of enzymes

• form clots to stop bleeding

Hemopoiesis

• production of formed elements of blood

• necessary for understanding leukemia, anemia, and other blood disorders

• occurs in the yolk sac, liver spleen, thymus, lymph nodes and red bone marrow

• activity of all except bone marrow stops or greatly decreases around birth

Red Bone Marrow

• from infancy onward, rbm produces all seven kinds of formed elements

• lymphocytes, thymus, tonsils and lymph nodes are produced here

• all cells can be traced back to pluripotent stem cells

Mediastinum

• mass of tissue between sternum and vertebrae

• includes all structures in thoracic cavity except lungs

• pointed end is the apex and opposite is base

Heart Pumping

• has to move about 7000L of blood every day

• adjusts the output for variable demands

• the heart creates enough pressure to overcome resistance in the arteries (left ventricle contracts and pressure increases or blood is forced into the aortic arch and pressure increases)

Pericardium

• double-walled sac that encloses heart - pericardial cavity between membranes

• covered by fibrous pericardium

Pericarditis

• inflammation of the pericardial sac

• causes incomplete filling of heart chambers

• can result in increased friction as heart rubs against sac

• can restrict the heart from stretching

Heart Wall

• consists of three layers

• epicardium

• myocardium

• endocardium

Epicardium

• outermost layer of the heart wall

• visceral layer of the pericardium

• sometimes overlying a layer of adipose tissue

• largest branches of coronary blood vessels found here

• mainly consists of simple squamous epithelium

Myocardium

• thickest muscle tissue of heart

• middle layer of the heart wall

• main cardiac muscle

• thickness is proportional to the workload of each individual chambers

Endocardium

• lines the interior of the heart chambers (inner layer of the heart wall)

• simple squamous epithelium

• no adipose tissue

• thickness varies inversely with the thickness of the myocardium

Right Atrium

• receives blood from the superior vena cava, inferior vena cava and coronary sinus

• covered externally by the right auricle

Right Venticle

• blood from right atrium passes through the tricuspid valve and enters the right ventricle

• covers most of the anterior portion of the heart

• blood is pumped into pulmonary circulation through the pulmonary trunk

Left Atrium

• makes up most of the posterior surface of the heart

• receives oxygen-rich blood from the lungs through the two right and two left pulmonary veins

Left Ventricle

• blood enters from the left atrium through the mitral (bicuspid or mitral valve)

• pumps blood into the systemic circuit through the aortic arch

First Step in Blood Movement through the Heart

• deoxygenated blood from the body into the right atrium

Second Step in Blood Movement through the Heart

• enters the right ventricle through the tricuspid valve

Third Step in Blood Movement through the Heart

• blood gas exchange occurs in the pulmonary trunk

Fourth Step in Blood Movement through the Heart

• oxygenated blood enters the left atrium

Fifth Step in Blood Movement through the Heart

• blood enters the left ventricle through the mitral/bicuspid valve

Last Step in Blood Movement through the Heart

• blood is moved into the aorta to be distributed around the body

Foramen Ovale

• in a fetus there is a hole between the left and right atria that allows blood to bypass the lungs

• the hole closes over at birth or results in a patent foramen ovale

Lub Sound

• atrioventricular valve closes

• ventricular pressure is greater than the atrial pressure

Dub Sound

• semilunar (aortic and pulmonary) valves close

• ventricular relaxation begins

Arteries

• carry oxygenated blood away from the heart

• red blood vessels

• have a thick tunica media to provide strength to offset the pressure from heart contraction

• the larger the artery, the more elastic fibers contained in middle layer

Veins

• carry deoxygenated blood to the heart

• blue blood vessels

• tunica media consists of small bundles of smooth muscle cells, reticular fibers, and some elastic fibers

• large veins (close to heart) have thin tunica media and very thick tunica external

• tunica externa is well-developed

• drainage system of the

Capillaries

• gas and nutrient exchange between blood and tissues

• blood vessels connect here

• found near most cells in the body

• composed of a single layer of endothelial cells rolled into a tube

• structurally variable to permit different levels of metabolic exchange in different organs and tissues

Tunica Interna

• first inner layer of the vessel wall

• simple squamous epithelium

• selectively permeable

Tunica Media

• middle layer of the vessel wall

• thickest consisting of smooth muscle, collagen and elastic

Tunica Externa

• outer layer of the vessel wall

• loose connective tissue with collagen and elastic fibers

Elastic Arteries

• very thick walls located near the heart

• makes up the aorta and its major branches

• about 40 layers (laminae) in newborns, 70 in adults

• important in stabilizing blood flow and acts as a pressure reservoir

Muscular Arteries

• distal to elastic arteries

• more muscle, less elastic in tunica media

• important in regulating blood pressure and flow of blood into certain organs

• may contain up to 40 layers of smooth muscle

Arterioles

• small arteries that deliver blood to capillaries

• structure changes somewhat between the artery and the capillary

• also play important role in regulating blood pressure through dilation and constriction

Continuous Capillaries

• very few gaps in the structure

• found in muscle tissue and the lungs

Fenestrated Capillaries

• many small pores within the structure

• found in the kidneys and intestines

Sinusoid Capillaries

• wider vessels and larger pores

• found in the liver and spleen

Venules

-postcapillary venules are similar to capillaries

• most venules have at least a few smooth muscle cells in their walls

• easily distinguished because of their thinner wall and (usually) collapsed lumen

• participate in the exchange of cells and molecules between blood and tissues

• usually accompany arterioles

Differences Between Veins and Arteries

• arteries are always deeps

• veins are deep and superficial

• names of superficial veins are unique (basilic vein)

Venous Pathways

• more connections between vessels

• more difficult to follow the flow of blood

What vessel is used in diagnostics?

arteries

Vein System for the Brain

Dural Venous Sinuses

Vein System for the Digestive System

Hepatic Portal System

Naming Arteries and Veins

• location

• organ served

• bone followed

Ascending Aorta

• arises from left ventricle

• only branches are two coronary arteries

Aortic Arch

• three branches run superiorly consisting of the brachiocephalic trunk, left common carotid, and left subclavian

• arteries

Descending Aorta

• runs posterior to heart and inferiorly along thoracic and lumbar vertebrae

Thoracic Aorta

• runs along thoracic vertebrae with many small branches to thoracic organs and body wall

• main vessels arising from the aorta above the diaphragm are pairs of intercostal arteries

Intercostal Arteries

• tissues between the ribs

• deep muscles of the back

• vertebrae

• spinal cord

Abdominal Aorta

• artery inferior to the diaphragm that extends to most of the bodies organs

• eventually spilts into the right and left iliac arteries

• about half the arterial flow is here when a person is at rest

• paired vessels that provide more oxygen for certain organs and unpaired vessels

Arteries that Arise from the Abdominal Aorta

• coeliac trunk (unpaired and thick wall)

• left gastric

• splenic

• common hepatic

• superior and inferior mesenteric

• renal

• gonadal

• iliac

Superior Mesenteric Artery

• most of the intestines

Renal Artery

• kidneys

Gonadal Artery

• ovaries and testes

Inferior Mesenteric Artery

• lower intestine

Iliac Artery

• legs

Common Carotid Arteries

• extends to most areas of the head and neck

• separates into two main branches; external carotids and internal carotids

External Carotid Artery

• face and neck

Internal Carotid Artery

• orbity and cerebrum

Vertebral Arteries

• blood supply to the posterior brain

• ascends through foramina in transverse processes

• right and left branch join along the ventral midline of the brain

Subclavian Artery

• main artery going into the arm

Axillary Artery

• continuation of the subclavian through the axilla

Brachial Artery

• descends along the medial side of the humerus

Radial Artery

• pulse point along radius

• thumb side

Ulnar Artery

• one of the main arteries of the forearm

• pinky side

Common Iliac Artery

• main artery extending into the leg

• branches supply the pelvic region

External Iliac Artery

• carries blood into the leg

Femoral Artery

• continuation of the external iliac

Popliteal Artery

• continuation of the femoral artery

Anterior and Posterior Tibial Arteries

• arteries of the calf region

What three major veins enter the heart?

• superior vena cava

• inferior vena cava

• coronary sinus

Superior Vena Cava

• drains all body regions superior to the diaphragm

External Jugular Vein

• exterior cranium and deep regions of the face

Internal Jugular Vein

• almost all blood leaving the brain

Inferior Vena Cava

• widest vessel in the body

• drains all body regions inferior to the diaphragm

• runs along the side of the abdominal aorta

Hepatic Portal System

• unique venous system in which blood passes through two consecutive capillary beds on the way back to the heart

• consists of the inferior vena cava, hepatic portal vein and either the anterior mesenteric vein, splenic vein or posterior mesenteric vein

Anterior Mesenteric Vein

• apart of the hepatic portal system

• drains blood from the small intestine, large intestine and stomach

Splenic Vein

• apart of the hepatic portal system

• drains blood from the spleen, stomach and pancreas

Posterior Mesenteric Vein

• apart of the hepatic portal system

• drains from the large intestine and rectum

Movement of Blood in Arteries and Capillaries

• contraction of left ventricle supplies pressure

Movement of Blood in Veins

• contraction of major muscles supplies pressure

• little pressure left over from the heart

Varicose Veins

• deep and superficial veins are linked by a perforating vein

• superficial vein can become varicose because a perforating vein is allowing blood to flow the wrong way (outwards)

Left Ventricle Contracting

• very high blood pressure to very low blood pressure

Left Ventricle Contracting Affecting Large Arteries

• very high blood pressure to high blood pressure

• muscle and elastic expand or contract to maintain the blood pressure

Left Ventricle Contracting Affecting Arterioles

• low blood pressure due to vessel length

Atherosclerosis

• damage to arterial walls can cause a buildup of fatty deposits and narrowing of the artery leading to high blood pressure