BSCI202 LAB PRACTICAL 1

Blood & Hematocrit - Formed Elements (cells)

• Erythrocytes use hemoglobin to carry oxygen to tissues throughout the body

  • The most abundant formed element in the blood

• Leukocytes have many different immune functions

  • Granulocytes: neutrophils, eosinophils, basophils

  • Agranulocytes: lymphocytes, monocytes

  • Can travel out of blood vessels into tissues by diapedesis

• Platelets are critical in blood clotting

  • Not complete cells – cytoplasmic fragments

  • Originate from megakaryocytes that fragment

Blood & Hematocrit - How to perform a hematocrit

• Place a capillary tube into blood sample to draw up blood

• Centrifuge the capillary tube

• Measure total length of the fluid in the tube from the bottom

• Then also measure in cm: RBC, WBC and plasma from the bottom

• Calculate percentage of RBC/total, WBC/total, and plasma/total

• Detailed instructions are in your lab manual

Blood & Hematocrit - Understanding Hematocrit

• When blood is centrifuged:

  • Erythrocytes sink to the bottom (～45% of blood, a percentage known as the hematocrit)

  • Buffy coat contains leukocytes and platelets (less than 1% of blood), the buffy coat is a thin, whitish layer between the erythrocytes and plasma

  • Plasma rises to the top (～55% of blood)

Ranges:

• Normal Adult Female Range: 37 – 47%

• Normal Adult Male Range: 42 – 52%

• Normal Newborn Range: 49 – 61%

Blood & Hematocrit - Conditions Detected by Hematocrit

• Leukocytosis → leukocyte count too high

  • Buffy coat constitutes > 1%

  • caused by infection and some types of leukemia

• Anemia → erythrocyte count too low

  • hematocrit value is below average

  • aplastic anemia → bone marrow doesn’t produce enough new erythrocytes

  • iron-deficiency anemia → erythrocytes are smaller

  • hemolytic anemia → erythrocytes are destroyed too quickly

  • sickle cell anemia → sickle-shaped erythrocytes

  • hemorrhagic anemia (caused by blood loss) NOT DETECTED by hematocrit

• Individuals that live at high altitude tend to have higher hematocrit due to lower level of oxygen in the air

  • to compensate, these individuals produce more erythrocytes to increase blood oxygen levels

• Dehydration: plasma percentage decreases

  • loss of water = less plasma

Lymphatic System

• consists of two parts

  • lymphatic vessels

  • lymphoid tissues and organs

• functions

  • transports escaped fluids back to the blood

  • plays essential roles in body defense and resistance to disease

  • also has a role in digestion

Lymphatic Characteristics

• lymph fluid is carried by lymphatic vessels

  • fluid within bodily tissues (leaks out of the capillaries of the cardiovascular system)

  • fluid picked up by the lymphatic vessels

• properties of lymphatic vessels

  • lymphatic vessels are one-way system that moves lymph back towards the heart

  • there is NO heart-like pump that moves lymph through lymphatic vessels

  • the “skeletal muscle pump” moves lymph through lymphatic vessels

    • squeezing motion of skeletal muscles

  • valves prevent back flow of lymph

Lymph Nodes

• filter lymph (fluid) before its returned to the blood

• defense cells within lymph nodes

  • macrophages engulf and destroy foreign substances

  • lymphocytes provide immune response to antigens

• harmful materials that may enter lymph vessels

  • bacteria

  • viruses

  • cancer cells

  • cell debris

Lymph Node Filtration

• filter lymph before its returned to the blood

  • typically kidney-shaped and less than one inch long

  • anatomy

    • cortex (outer part) → contains follicles that house collections of lymphocytes

    • medulla (inner part) → contains macrophages (phagocytosis cells)

  • lymph enters through afferent lymphatic vessels and exits through efferent lymphatic vessels

  • lymph enters the convex side through afferent lymphatic vessels

  • lymph flows through number of sinuses inside the node

  • lymph exits through efferent lymphatic vessels

  • fewer efferent than afferent vessels causes flow to be slowed

Lymphatic Vessels

• collect lymph from lymph capillaries

• carry lymph towards and away from lymph nodes

• return fluid to circulatory veins near the heart

  • right lymphatic duct

  • thoracic duct

Lymphoid Organs

• red bone marrow → site of lymphocyte production; B cells mature here

• spleen → filters blood and destroys worn out blood cells

• thymus → produces hormones to program lymphocytes

• tonsils → trap and remove bacteria and other foreign material

• peyer’s patch → capture and destroy bacteria in the intestine

• appendix → reservoir for gut bacteria; may assist in B cell maturation

Primary Lymphoid Organs

• Bone Marrow

  • Hematopoietic stem cells: precursors for all blood cells

  • Leukocytes except T lymphocytes full develop here

• Thymus

  • T lymphocytes migrate from bone marrow to thymus

  • develop maturity in thymus

Secondary Lymphoid Organs + Tissues

• spleen, tonsils, adenoids, appendix, peyer’s patches

• collection of B cells, T cells, and macrophages

• function to trap microorganisms and foreign particles

• works to expose them to leukocytes in high concentrations

• spleen and lymph nodes filter blood and lymph

Lymphoid Organs & Lymphatic Function

Lymphoid Organs that Contribute to Lymphatic Function:

• Spleen → located on the left side of the abdomen

  • filters blood and destroys worn out blood cells

  • forms blood cells in the fetus

  • acts as blood reservoir

• Thymus → located low in the throat, overlying the heart

  • functions at peak levels only during childhood

  • produces hormones (like thymosin) to program lymphocytes

• Tonsils

  • small masses of lymphoid tissue around the pharynx

  • trap and remove bacteria and other foreign materials

  • tonsillitis is caused by congestion with bacteria

• Peyer’s patches

  • found in the wall of the small intestine and capture and destroy bacteria in the intestine

  • resemble tonsils in structure

Lymphocytes Originate in Lymphoid Organs

Functions of Cells Involved in Immunity

Antibodies

Overview

• plasma cells (effector B cells) produce antibodies

• antibodies are also called immunoglobulins

• fiver major antibody classes: IgM, IgD, IgG, IgA, and IgE

• antibodies are Y shaped and contain antigen-binding sites on their arms

• each antibody binds to a specific antigen

Functions

• binds to specific antigen

• aids in inactivation or destruction of antigen

Structure

• four amino acid chains linked by disulfide bonds

• two identical amino acid chains are linked to form a heavy chain

• other two identical chains are light chains

• 2 specific antigen-binding sites are present

• constant region same within a class of antibodies

• variable region gives specificity to antigen-binding site

Antibodies

Human Blood Groups

• blood contains genetically determined proteins

• antigens (a substance the body recognizes as foreign) may be attacked by the immune system

• antibodies are “recognizers”

• blood is typed by using antibodies that will cause blood with certain proteins to clump (agglutination or precipitation)

• over 30 common red blood cell antigens

• most vigorous transfusion reactions caused by ABO and Rh blood group antigens

Blood Groups

• blood types are classified according to antigens found on the plasma membrane of erythrocytes

  • antigens are genetically determined proteins

• blood plasma contains antibodies that can target antigens

• blood is typically classified by two blood groups

  • ABO blood groups → based on the presence or absence of A and B antigens

  • Rh blood groups → based on presence of absence of one of the eight Rh antigens (agglutinogen D)

  • person’s blood is typically classified according to both groups (ex: B+)

• blood transfusions from someone with antigens to which a patient has antibodies will result in a transfusion reaction

  • blood will agglutinate

Rh Blood Group

• most people in the US are Rh-positive

• denoted by a + or - added onto the ABO blood type

  • ex: O+, AB-, etc

• Rh-negative individuals do not have Rh antibodies in their plasma

  • will become sensitized if they receive a blood transfusion from an Rh-positive individual

  • subsequent exposures will result in a transfusion reaction

How to Type & Read Blood

How to Type:

1. Collect a blood sample from a patient

2. Add a drop of blood from the sample to each well on a blood typing tray

3. Add antibody sera

   1. To the A well → add anti-A serum

   2. To B well → add anti-B serum

   3. To Rh well → add anti-Rh serum

4. Mix contents of each well with a separate toothpick

How to Read Blood Type:

• antibodies in sera will interact with corresponding antigens present within the blood

• if antigens are present on the blood cell surface, interaction with the antibodies in the sera will cause agglutination

  • agglutination: clumping of particles in the blood; makes the sample appear clumpy/precipitated

Heart & Blood Vessel Anatomy

• Location → Thoracic Cavity

  • size of a human fist, weighing less than a pound

  • located between the lungs in the inferior mediastinum (medial section of the thoracic cavity)

Gross Anatomy of Heart

• Exterior

  • Apex is inferior, base is superior

  • Arteries carry blood away from the heart

  • Veins carry blood to the heart

  • Four chambers:

    • Two atria (singular: atrium) → receive blood from the vena cavae and pulmonary vein

    • Two ventricles → receive blood from atria, pumps blood into aorta and pulmonary artery

• Interior

  • Septa (singular: septum) → separate the chambers of heart

    • intertrial septum separates the left and right atrium

    • interventricular septum separates the left and right ventricle

  • Four valves → prevent backflow of blood between heart chambers

    • semilunar (SL) valves → pulmonary and aortic

    • atrioventricular (AV) valves → tricuspid and mitral (bicuspid)

Valves

• Semilunar Valves

  • located at the openings to the arteries

  • each semilunar valve consists of 3 moon-shaped cusps/flaps

  • pushed flat against artery wall during ventricular contraction

  • as ventricles relax, SL valves prevent the backflow of blood into the ventricles

• Atrioventricular Valves

  • located between atria and ventricles

  • during diastole, blood flows through the valves (from atria into ventricles)

    • right AV valve: tricuspid (3 cusps/flaps of endocardium)

    • left AV valve: bicuspid or mitral (2 cusps/flaps of endocardium)

  • prevent the backflow of blood into the atria

    • valves close passively as pressure builds in ventricles (during systole)

  • associated structures

    • chordae tendineae → cords prevent AV valve inversion

    • papillary muscle → anchors chordae tendineae

Features of the Heart

• Pericardium

  • double-walled sac around the heart

    • outer wall → fibrous pericardium

    • inner wall → serous pericardium (double layered)

      • parietal pericardium → outer layer lining the fibrous pericardium

      • visceral pericardium → inner layer which forms the outermost layer of the heart wall called the epicardium

Heart Wall Layers

1. Epicardium → outermost layer of the heart (also called the visceral pericardium)

2. Myocardium → middle layer, made of cardiac muscle

   • striated, has intercalated discs, under involuntary control

   • fibrous skeleton composed of fibrous connective tissue that supports the cardiac muscle fibers and heart valves

3. Endocardium → innermost layer

   • composed of simple squamous epithelium

Circulatory Systems

1. Systemic Circulation → carries blood to all tissues for nourishment, then transports deoxygenated blood back to heart

   • left ventricle → aorta → other arteries → arterioles → capillaries (within tissues) → venules → veins → venae cavae → right atrium

2. Pulmonary Circulation → carries deoxygenated blood back to the lungs for gas exchange, then brings oxygenated blood back to the heart

   • right ventricle → pulmonary trunk → pulmonary arteries → capillaries in lungs → pulmonary vein → left atrium

Circulatory System is Closed Transport System

• path of blood flow in systemic circuit

  • heart → large arteries → medium arteries → arterioles → capillary beds → venules → medium veins → large veins → heart

• substances diffuse across the capillary walls

  • from blood to tissues: O2 and nutrients

  • from tissues to blood: waste and CO2

Cardiac Tissue Response to Myocardial Infarction

Types of Blood Vessels

1. Arteries → transport blood away from the heart

   • elastic arteries → large, highly expandable arteries close to the heart

   • muscular arteries → medium sized arteries that distribute blood around the body

   • arterioles → smallest arteries, with very thin tunica externa and tunica media

2. Capillaries → provide for exchange of materials in tissues

   • narrow vessels with very thin walls

3. Veins → transport blood toward the heart

   • low pressure vessels because of thing walls and large lumens

   • venules (smallest veins) drain capillary beds and then merge to form larger veins

Layers of Arteries and Veins

1. Tunica Intima → forms a friction-reducing lining to the lumen

   • composed of endothelium of simple squamous cells

   • innermost (deep)

2. Tunica Media → controls lumen diameter

   • composed of circulatory arranged smooth muscle and elastic CT

3. Tunica Externa → protects and anchors blood vessels

   • Composed of areolar or fibrous CT

   • outermost (superficial)

Venous Blood Return

blood pressure in veins is low, so three main mechanisms facilitate venous blood return to the heart

1. skeletal muscle pump → skeletal muscle contractions from normal movement squeeze veins and push blood through them

2. valves → prevent the backflow of blood

3. respiratory pump → during inspiration, a decrease in intra-thoracic pressure and increase in intra-abdominal pressure causes blood to flow from veins in the abdominal region to veins in the thoracic region

Five Special Circulations

Coronary Circulation

• nourishes the myocardium tissue

• blood in the heart chambers does NOT nourish the myocardium

• heart has own nourishing circulatory system consisting of:

  • coronary arteries → branch from aorta to supply heart muscle with oxygenated blood

    • left → anterior interventricular artery and circumflex artery

    • right → posterior interventricular artery and marginal artery

  • cardiac veins → drain the myocardium of blood

    • deliver blood to the coronary sinus, a large vein on the posterior of the heart

• blood empties into the right atrium via the coronary sinus

Pulmonary Circulation

• oxygenates the blood supply

• blood flow: right side of the heart → lungs → left side of the heart

  • pulmonary trunk and pulmonary arteries carry deoxygenated blood to the lungs

  • pulmonary veins carry oxygenated blood to the heart

• capillary beds around alveoli permit gas exchange (exchange outgoing CO2 for incoming O2)

• pulmonary circulation does NOT nourish lung tissue

  • blood supply for the lungs provided by bronchial arteries

Hepatic Portal Circulation

• major vessels of hepatic portal circulation drain the digestive organs and carry the blood to the liver

• superior mesenteric vein drains the small intestine, part of the large intestine, and stomach

• inferior mesenteric vein drains the distal portion of the large intestine

• splenic vein drains the spleen, pancreas, and stomach

• gastric vein drains the stomach

Liver Function → helps maintain proper glucose, fat, and protein concentrations in the blood

1. capillary beds of the digestive system absorb nutrients and toxins

2. nutrient-rich blood drains into veins of the hepatic portal circulatory system

3. these veins empty into the hepatic portal vein, which carries the blood to the liver

4. liver helps maintain proper glucose, fat, and protein concentrations in the blood

5. liver also filters toxins from the blood

6. blood drains into the hepatic vein as it leaves the liver

Fetal Circulation

• receives exchanges of gases, nutrients, and wastes through the placenta

• umbilical cord contains three vessels

  • umbilical vein → carries blood rich in nutrients and O2 to the fetus

  • umbilical arteries (two of them) → carry CO2 and debris-laden blood from the fetus to the placenta

• fetal blood flow bypasses:

  • the liver through the ductus venosus and enters the inferior vena cava

  • the lungs through the foramen ovale (blood entering right atrium shunted directly into the left atrium) and the ductus arteriosus (blood entering the pulmonary trunk passes through the aorta)

Cerebral Arterial Circle

• major blood supply to the brain forms the cerebral arterial circle

  • also called the circle of willis

  • anterior and posterior blood supplies (internal carotid arteries and vertebral arteries) are united by small communicating arterial branches

  • result is a complete circle of connecting blood vessels

Atherosclerosis

• condition where arteries are blocked by fat and cholesterol deposits

Major Arteries of Systemic Circulation

1. Aorta

   • largest artery in the body

   • leaves from the left ventricle of the heart

   • regions

     • ascending aorta → leaves the left ventricle

     • aortic arch → arches to the left

     • thoracic aorta → travels downward through the thorax

     • abdominal aorta → passes through the diaphragm into the abdominopelvic cavity

Arterial Branches of Ascending Aorta and Aortic Arch

• ascending aorta

  • right and left coronary arteries serve the heart

• aortic branch

  • brachiocephalic trunk

    • then splits into the: right common carotid artery and right subclavian artery

  • left common carotid artery

    • then splits into the left internal and external carotid arteries

  • left subclavian artery

    • then branches into the left vertebral artery and left subclavian artery

    • subclavian artery becomes axillary artery → brachial artery → radial and ulnar arteries

Arterial Branches of Descending Thoracic Aorta

• intercostal arteries

  • supply the muscles of the thorax wall

• bronchial arteries

  • supply the lungs

• esophageal arteries

  • serve the esophagus

• phrenic arteries

  • serve the diaphragm

Arterial Branches of the Abdominal Aorta

• celiac trunk → first branch of the abdominal aorta

  • three branches:

    • left gastric artery → serves the stomach

    • splenic artery → serves the spleen

    • common hepatic artery → serves the liver

  • superior mesenteric artery → supplies most of the small intestine and first half of the large intestine

  • left and right renal arteries → serves the kidneys

  • left and right gonadal arteries → called ovarian in females, testicular in males

  • lumbar arteries serve muscles of abdomen and trunk

  • inferior mesenteric artery → supplies the second half of the large intestine

  • left and right common iliac arteries are the final branches of the aorta

    • internal iliac arteries serve the pelvic organs

    • external iliac arteries enter the thigh → femoral artery → popliteal artery → anterior and posterior tibial arteries

Major Veins of Systemic Circulation

Vena Cavae

• two veins that return blood from the systemic circuit to the right atrium

  • superior vena cava → drains the head and arms

  • inferior vena cava → drains the lower body

Veins Draining into Superior Vena Cava

• draining the arm:

  • radial and ulnar veins → brachial vein → axillary vein

  • cephalic vein drains the lateral aspect of the arm and empties into the axillary vein

  • basilic vein drains the medial aspect of the arm and empties into the brachial vein

  • basilic and cephalic veins are jointed at the median cubital vein (elbow area)

• subclavian vein receives:

  • venous blood from the axillary vei

  • venous blood from the skin and muscles of the head and neck via external jugular vein

• vertebral vein drains the posterior part of the head

• internal jugular vein drains the dural sinuses of the brain

• left and right brachiocephalic veins receive venous blood from the:

  • subclavian veins

  • vertebral veins

  • internal jugular veins

• brachiocephalic veins join to form the superior vena cava

• azygous vein drains the thorax

Lower Limb Veins Draining into Inferior Vena Cava

• anterior and posterior tibial veins and fibial veins drain the legs

• posterior tibial vein → popliteal vein → femoral vein → external iliac vein

• great saphenous veins (longest veins of the body) receive superficial drainage of the legs

• each common iliac vein (left and right) is formed by the union of the internal and external iliac vein on its own side

Abdominal Veins Draining into the Inferior Vena Cava

• right gonadal vein drains the right ovary in females and right testicle in males

• left gonadal vein empties into the left renal vein

• left and right renal veins drain the kidneys

• hepatic portal vein drains the digestive organs and travels through the liver before it enters systemic circulation

• left and right hepatic veins drain the liver

Circulatory System Development in Fetus

• a simple “tube heart” (without chambers) develops into the embryo and pumps by the fourth of the week post-fertilization

• septa form between the atria and ventricles between 4-7 weeks post-fertilization

  • heart becomes a four-chambered organ by the end of seven weeks post-fertilization

• fewer structural changes occur after the seventh week post-fertilization, the heart mostly just grows in size and strength for the rest of gestation

Lub Dub → Sounds of a Heartbeat

• systole: contraction

• diastole: relaxation

• two sounds of heartbeat coincide with ventricular systole and diastole

  • heartbeat = sounds of blood hitting and closing the valves

  • lub (s1) → closure of the AV valves at the start of ventricular systole

  • dub (s2) → closure of the SL valves at the end of ventricular systole

Heart Rates and Beats

• normal → 60-100 bpm at rest

  • average resting heart is 70-76 bpm

• arrhythmia → irregular heartbeat

  • can describe bradycardia or tachycardia

  • or pattern of heartbeat is inconsistent

• bradycardia → a heart rate (< 60 bpm)

  • considered abnormal, except in well-conditioned athletes

• tachycardia → heart rate (>100 bpm)

  • abnormal when at rest

  • if untreated, may lead to fibrillation

• fibrillation → rapid, uncoordinated contractions

  • renders heart useless as a pump

Intrinsic Conduction System

• spontaneous contractions of the heart are coordinated by the intrinsic conduction system

• cardiac muscle contractions occur in a regular and continuous way

  • atrial cells beat 60 times per minute

  • ventricular cells beat 20-40 times per minute

• intrinsic conduction system ensures the heart beats as a coordinated unit

  • cardiac pacemaker cells cause orderly and sequential depolarization of regions of the heart

  • enforces a heart rate of 75 bpm

• autonomic nervous system helps regulate heart rate (but does NOT initiate contractions)

  • sympathetic nervous system (SNS) accelerates heart rate

  • parasympathetic nervous system (PNS) decelerates heart rate

Composition

• composed of specialized nervous tissue embedded in the myocardium

• sinoatrial (SA) node → located in the right atrium and serves as the heart’s pacemaker

• atrioventricular (AV) node → at junction of the atria and ventricles

• atrioventricular (AV) bundle (bundle of His) and bundle branches → in the interventricular septum

• purkinje fibers (or subendocardial conducting network) → spread within the ventricle wall muscles

Impulse through Intrinsic Conduction System

• impulse that triggers contraction travels sequentially through the intrinsic conduction system

• the SA node starts at each heartbeat

• impulse spreads through the atria to the AV node

  • atria contract; blood pushed into ventricles

  • at the AV node, the impulse is delayed briefly

• impulse travels through the AV bundle, bundle branches, and subendocardial network

  • ventricles contract, blood is ejected from the heart

Conduction in the Heart

• change in electric potential (depolarization) and the generation of action potentials result in muscle contraction

• cardiac muscle cells are connected through gap junctions which allow for the spread of action potential

• impulse starts at SA node (superior portion of the right atrium)

  • sets depolarization rate (it is the pacemaker)

  • stimulus travels through atria, causing atrial contraction to the AV node

• impulse is delayed at the AV node (inferior atrial septum in right atrium)

  • allows for atrial contraction to be completed before ventricular depolarization begins → prevents premature closure of the AV valves

• electrical conduction through the ventricles requires:

  • AV bundle (bundle of His) → located in interventricular septum

  • Bundle branches → located in interventricular septum

  • Subendocardial conducting network (purkinje fibers) → in muscles of ventricular walls

    • denser in left ventricle

Electrocardiograms

• measure the heart’s electrical activity from the body surface

• P wave → depolarization of the atria

• QRS complex → depolarization of the ventricles

  • atrial repolarization also happens here, concurrent with ventricular contraction

• T wave → repolarization of ventricles

Interpreting Electrocardiogram