Study Guide

CHAPTER 18 — THE BLOOD

Blood Composition

Blood has 2 major components:

Plasma (about 55%)

Contains:

  • ~90% water

  • Proteins:

    • Albumin → maintains osmotic pressure

    • Globulins → antibodies/transport

    • Fibrinogen → clotting

  • Electrolytes

  • Nutrients

  • Hormones

  • Waste products

Formed Elements (about 45%)

Includes:

  • Erythrocytes (RBCs)

  • Leukocytes (WBCs)

  • Platelets (thrombocytes)

Blood Cells

Erythrocytes (Red Blood Cells)

Function:

  • Transport oxygen with hemoglobin

  • Carry some CO₂

Normal RBC count:

  • Male: ~5–6 million/µL

  • Female: ~4–5 million/µL

Hematocrit

Percentage of blood made of RBCs.

Normal:

  • Male: ~42–52%

  • Female: ~37–47%

Low hematocrit = anemia
High hematocrit = polycythemia/dehydration

Leukocytes (White Blood Cells)

Know all 5 types and their jobs.

Neutrophils

  • Most abundant

  • Fight bacteria

  • First responders in infection

  • High neutrophils = bacterial infection

Eosinophils

  • Fight parasites

  • Involved in allergies/asthma

Basophils

  • Release histamine and heparin

  • Promote inflammation

Monocytes

  • Become macrophages

  • Phagocytosis (“big eaters”)

Lymphocytes

  • B cells → antibodies

  • T cells → cellular immunity

Differential WBC Count

Normal ranges:

  • Neutrophils: 50–70%

  • Lymphocytes: 20–40%

  • Monocytes: 2–8%

  • Eosinophils: 1–4%

  • Basophils: <1%

Leukocytosis

High WBC count → infection/inflammation

Leukopenia

Low WBC count → immune suppression

Platelets (Thrombocytes)

Function:

  • Blood clotting

Normal count:

  • 150,000–400,000/µL

Low platelets = thrombocytopenia → bleeding risk

Hemopoiesis (Blood Cell Formation)

Starts with:

Hemocytoblast

Stem cell in red bone marrow

Produces:

  • Proerythroblast → RBCs

  • Myeloblast → granulocytes

  • Monoblast → monocytes

  • Lymphoblast → lymphocytes

  • Megakaryoblast → platelets

Hormones

  • Erythropoietin (EPO) → stimulates RBC production

  • Thrombopoietin → platelet production

  • Cytokines → WBC production

Immature Cells

  • Reticulocytes = immature RBCs

  • Band cells = immature neutrophils

High band cells = active infection (“shift to the left”)

RBC Destruction & Hemoglobin Recycling

Old RBCs destroyed in:

  • Spleen

  • Liver

Hemoglobin breaks into:

  • Heme

  • Globin

Globin

Recycled into amino acids

Heme

Iron removed and reused

Remaining pigment becomes bilirubin:

  • Goes to liver

  • Excreted in bile

Excess bilirubin = jaundice

Hemostasis (Stopping Bleeding)

3 steps:

1. Vascular Spasm

Blood vessel constricts

2. Platelet Plug Formation

  • Adhesion

  • Aggregation

  • Platelet plug

3. Coagulation (Clotting)

Extrinsic Pathway

Fast
Triggered by tissue damage

Intrinsic Pathway

Slower
Triggered inside blood vessel

Both end in:

Common Pathway

Prothrombin → thrombin
Fibrinogen → fibrin
Fibrin forms mesh clot

ABO Blood Types

Type A

  • A antigens

  • Anti-B antibodies

Type B

  • B antigens

  • Anti-A antibodies

Type AB

  • A and B antigens

  • No antibodies

  • Universal recipient

Type O

  • No antigens

  • Anti-A and Anti-B antibodies

  • Universal donor

Agglutination = clumping reaction

Blood Disorders

Iron-Deficiency Anemia

Not enough iron → low hemoglobin

Pernicious Anemia

Vitamin B12 deficiency

Sickle Cell Anemia

Abnormal hemoglobin causes sickle-shaped RBCs

Aplastic Anemia

Bone marrow failure

Hemolytic Anemia

RBC destruction faster than production

Polycythemia Vera

Too many RBCs → thick blood

Leukemia

Cancer of WBCs

Hemophilia

Clotting disorder

Thrombus

Clot attached to vessel wall

Embolus

Traveling clot

Septicemia

Blood infection

CHAPTER 19 — THE HEART

Conduction System

Order is VERY important:

  1. SA node

  2. AV node

  3. Bundle of His

  4. Right & left bundle branches

  5. Purkinje fibers

SA node = natural pacemaker

Cardiac Muscle Histology

Know:

  • Striations

  • Branched cells

  • Single nucleus

  • Intercalated discs

  • Gap junctions

  • Desmosomes

Gap junctions allow electrical communication.

Cardiac Action Potential

Depolarization

Fast Na+ channels open

Plateau Phase

Slow Ca²⁺ channels open

Prevents tetanus

Repolarization

K+ exits cell

EKG

P Wave

Atrial depolarization

QRS Complex

Ventricular depolarization

T Wave

Ventricular repolarization

Atrial repolarization is hidden in QRS.

Cardiac Cycle

Diastole

Relaxation/filling

Systole

Contraction/ejection

Important terms:

  • EDV = end-diastolic volume

  • ESV = end-systolic volume

  • Stroke volume = EDV − ESV

Heart Valves

AV Valves

  • Tricuspid

  • Mitral (bicuspid)

Open during ventricular filling.

Semilunar Valves

  • Pulmonary

  • Aortic

Open during ventricular ejection.

Heart Sounds

“Lub” (S1)

AV valves closing

“Dub” (S2)

Semilunar valves closing

Murmur

Abnormal turbulent flow

Mitral Valve Prolapse

Mitral valve bulges backward

Cardiac Output

Formula

CO = HR \times SV

Where:

  • CO = cardiac output

  • HR = heart rate

  • SV = stroke volume

Normal CO ≈ 5 L/min

Stroke Volume Factors

Preload

Stretch before contraction

Contractility

Strength of contraction

Afterload

Resistance heart pumps against

Frank-Starling Law

More stretch → stronger contraction

Heart Rate Regulation

Controlled by:

  • Cardiovascular center (medulla)

  • Sympathetic nerves → increase HR

  • Vagus nerve → decrease HR

  • Baroreceptors

  • Chemoreceptors

Heart Disorders

Bradycardia

HR too slow

Tachycardia

HR too fast

Angina Pectoris

Chest pain from ischemia

Coronary Artery Disease (CAD)

Blocked coronary arteries

Myocardial Infarction

Heart attack

Cardiac Tamponade

Fluid compresses heart

Pericarditis

Inflammation of pericardium

CHAPTER 20 — BLOOD VESSELS & HEMODYNAMICS

Vessel Layers

Tunica Interna

  • Endothelium

  • Basement membrane

  • Internal elastic lamina

Tunica Media

  • Smooth muscle

  • External elastic lamina

Tunica Externa

  • Connective tissue

Types of Blood Vessels

Arteries

Carry blood away from heart

Veins

Carry blood toward heart

Capillaries

Exchange vessels

Anastomoses

Connections between blood vessels

Provide alternate routes.

Capillary Exchange

Diffusion

Movement of solutes

Filtration

Fluid moves out

Reabsorption

Fluid moves in

Pressures

CHP

Capillary hydrostatic pressure

Pushes fluid OUT

BCOP

Blood colloid osmotic pressure

Pulls fluid IN

Net Filtration Pressure

Formula:
NFP = (CHP + ICOP) - (BCOP + IHP)

Positive = filtration
Negative = reabsorption

Blood Pressure

Systolic

Pressure during contraction

Diastolic

Pressure during relaxation

Normal:

  • ~120/80 mmHg

Korotkoff Sounds

Sounds heard when measuring BP

Measured with:

Sphygmomanometer

Blood Pressure Regulation

Nervous Control

  • Vasomotor center

  • Sympathetic stimulation

Hormones

  • Epinephrine

  • Norepinephrine

  • ADH

  • ANP

Baroreceptors

Monitor BP changes

Shock

4 Types:

Hypovolemic

Blood/fluid loss

Cardiogenic

Heart failure

Vascular

Poor vessel tone

Obstructive

Blocked circulation

Fetal Circulation

Know these structures:

Foramen Ovale

Hole between atria

Ductus Arteriosus

Connects pulmonary trunk to aorta

Ductus Venosus

Bypasses liver

Umbilical Vein

Carries oxygenated blood

Umbilical Arteries

Carry deoxygenated blood

Clinical Terms

Atherosclerosis

Fatty plaque buildup

Arteriosclerosis

Hardening of arteries

Aneurysm

Vessel wall ballooning

Edema

Fluid accumulation

Hypertension

High BP

Hypotension

Low BP

Varicose Veins

Dilated veins

Pulmonary Embolism

Clot in lungs

CHAPTER 21 — LYMPHATIC SYSTEM

Main Functions

  • Return fluid to blood

  • Absorb fats

  • Immune defense

Major Structures

Lacteals

Absorb fats in small intestine

Thoracic Duct

Main lymph vessel

Right Lymphatic Duct

Drains right upper body

Cisterna Chyli

Expanded lymph sac

Thymus

T-cell maturation

Spleen

Filters blood

Lymph Nodes

Know structures:

  • Capsule

  • Cortex

  • Medulla

  • Trabeculae

  • Germinal centers

  • Afferent vessels

  • Efferent vessels

  • Hilus

Tonsils

Pharyngeal Tonsil

Adenoids

Palatine Tonsils

Back of throat

Lingual Tonsils

Base of tongue