Exam 1 Study Guide: Blood, Heart, and Blood Vessels (Chapters 17–19)

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Blood

Formed Elements of Blood

The formed elements are the cellular components of blood, each with distinct functions and characteristics.

Erythrocytes (Red Blood Cells, RBCs): Transport oxygen and carbon dioxide; lack nuclei at maturity; lifespan is about 120 days due to absence of nuclei and inability to undergo mitosis.
Leukocytes (White Blood Cells, WBCs): Defend against pathogens; possess nuclei.
Platelets (Thrombocytes): Cell fragments involved in clotting; lack nuclei.

Thrombocytopenia is the term for a decreased number of platelets.

Plasma Components

Plasma is the liquid matrix of blood, containing:

Water
Electrolytes
Plasma proteins (albumin, globulins, fibrinogen)
Nonprotein nitrogenous substances
Nutrients (organic)
Respiratory gases
Hormones

Albumin maintains osmotic pressure; globulins include antibodies; fibrinogen is converted to fibrin during coagulation.

Erythropoiesis and Regulation

Stimulus: Hypoxia (lack of oxygen) or increased tissue demand for oxygen triggers erythropoiesis.
Erythropoietin (EPO): Hormone produced by the kidneys stimulates RBC production in red bone marrow.

Blood Disorders

Hemophilia: X-linked clotting disorder, more common in males.
Anemias:
- Iron-deficiency anemia: Due to blood loss, poor dietary intake, or impaired absorption.
- Pernicious anemia: Autoimmune destruction of stomach mucosa, leading to vitamin B12 deficiency.
- Renal anemia: Insufficient EPO production, often due to kidney disease.
- Aplastic anemia: Destruction/inhibition of red marrow by drugs, chemicals, radiation, or viruses.
- Sickle-cell anemia: Genetic mutation in hemoglobin (HbS), causing RBCs to sickle under low oxygen.

Leukocytes and Differential Count

Leukocytes are classified as granulocytes or agranulocytes:

Granulocytes: Neutrophils, eosinophils, basophils
Agranulocytes: Lymphocytes, monocytes

Leukocyte	Normal %	Main Function
Neutrophils	40–70%	Fight bacteria
Lymphocytes	20–40%	Viral defense & immune regulation
Monocytes	2–8%	Clean up debris, chronic inflammation
Eosinophils	1–4%	Allergies & parasites
Basophils	0–1%	Allergic/inflammatory response

Example: Elevated eosinophils suggest allergy or parasitic infection.

Neutrophils have multilobed nuclei.

Blood as Connective Tissue

Blood is a liquid connective tissue; fibers (fibrin) appear only during clotting.

Hemostasis and Coagulation

Three steps of hemostasis:
1. Vascular spasm: Vasoconstriction to reduce blood loss.
2. Platelet plug formation: Platelets adhere to damaged vessel.
3. Coagulation: Fibrin reinforces the plug.
Intrinsic & Extrinsic Pathways: Both lead to conversion of prothrombin to thrombin, then fibrinogen to fibrin.

Blood Groups and Transfusion

Antigens: On RBC membranes; trigger immune response.
Antibodies: In plasma; react with foreign antigens.
Universal recipient: AB+ (no antibodies in plasma).
Universal donor: O- (no antigens on RBCs).
Erythroblastosis fetalis: Occurs when Rh- mother carries Rh+ fetus in subsequent pregnancies; maternal antibodies attack fetal RBCs.

The Heart

Anatomy and Landmarks

Located in the mediastinum, atop the diaphragm.
Left ventricle forms the apex, pointing toward the left hip.
Coronary sulcus: Groove between atria and ventricles.

Coronary Circulation

Left coronary artery branches: Anterior interventricular, circumflex.
Right coronary artery branches: Posterior interventricular, right marginal.
Blockage causes ischemia (oxygen deprivation) to cardiac muscle.

Heart Chambers and Valves

Right atrium: Receives deoxygenated blood from body (via superior/inferior vena cava).
Right ventricle: Pumps deoxygenated blood to lungs.
Left atrium: Receives oxygenated blood from lungs (via pulmonary veins).
Left ventricle: Pumps oxygenated blood to body; thickest myocardium.

Valve	Location
Tricuspid (AV)	Right atrium → Right ventricle
Mitral/Bicuspid (AV)	Left atrium → Left ventricle
Pulmonary (SL)	Right ventricle → Pulmonary artery
Aortic (SL)	Left ventricle → Aorta

Blood Flow Through the Heart

Superior/Inferior vena cava → Right atrium
Tricuspid valve → Right ventricle
Pulmonary semilunar valve → Pulmonary trunk → Lungs
Pulmonary veins → Left atrium
Mitral (bicuspid) valve → Left ventricle
Aortic semilunar valve → Aorta → Body

Cardiac Cycle Phases

Ventricular filling: Ventricles fill during diastole (passive and active).
Isovolumic contraction: All valves closed; pressure rises, no volume change.
Ventricular ejection: Semilunar valves open; blood ejected.
Isovolumic relaxation: All valves closed; pressure falls, no volume change.

Example: Pulmonary valve stenosis impedes blood flow from right ventricle to pulmonary trunk.

Valves and Muscle Structures

AV valves: Closed at beginning of ventricular systole.
SL valves: Closed at beginning of ventricular diastole.
Papillary muscles: In ventricles; anchor chordae tendineae to prevent valve prolapse.
Pectinate muscles: In atria (rough part).
Trabeculae carneae: In ventricles (rough part).
Moderator band: Right ventricle; part of conduction system.

Intrinsic Conduction System

SA node: Pacemaker; initiates heartbeat.
AV node, bundle of His, bundle branches, Purkinje fibers: Coordinate contraction.

Electrocardiogram (ECG)

P wave: Atrial depolarization
QRS complex: Ventricular depolarization
T wave: Ventricular repolarization

Fetal Circulation Adaptations

Foramen ovale: Right atrium to left atrium (becomes fossa ovalis at birth).
Ductus arteriosus: Pulmonary trunk to aorta (becomes ligamentum arteriosum at birth).

Blood Vessels

Types and Structure of Blood Vessels

Elastic (conducting) arteries: Aorta
Muscular (distributing) arteries: Brachial artery
Arterioles (resistance vessels)
Capillaries (exchange vessels)
Venules
Veins: Vena cava

Vessel Type	Main Function
Arteries	Carry blood away from heart
Arterioles	Regulate blood flow into capillaries
Capillaries	Exchange of gases, nutrients, wastes
Venules	Collect blood from capillaries
Veins	Return blood to heart

All vessels except capillaries have three tunics: tunica intima, tunica media, tunica adventitia.

Major Arteries and Veins

Internal carotid artery: Supplies brain; part of Circle of Willis.
Anastomosis: Vessel connection (e.g., Circle of Willis).
Aortic arch branches: Brachiocephalic, left common carotid, left subclavian.
Ascending aorta branches: Right and left coronary arteries.
Inferior vena cava formation: Right and left common iliac veins.
Hepatic portal vein: Formed by splenic and superior mesenteric veins; carries nutrient-rich blood to liver.
Abdominal aorta branches: Celiac trunk, renal, superior and inferior mesenteric arteries.
Popliteal artery: Leads to anterior and posterior tibial arteries.
Internal iliac artery: Supplies uterus.
Veins draining into inferior vena cava: Renal, hepatic, common iliac veins.

Cardiac Output and Regulation

Cardiac output (CO): Volume of blood ejected by heart per minute.

Stroke volume (SV): Volume ejected per beat.
Heart rate (HR): Beats per minute.
Athletes maintain normal CO with low HR due to high SV.
EDV (End Diastolic Volume): Blood in ventricle after relaxation.
ESV (End Systolic Volume): Blood in ventricle after contraction.
High HR decreases EDV (less filling time).

Blood Pressure and Regulation

Essential hypertension: BP > 130/90 mmHg; cause unknown.
Tachycardia: Increased HR; Bradycardia: Decreased HR.
Sympathetic stimulation: Increases HR and contractility.
Parasympathetic stimulation: Decreases HR (via vagus nerve).
BP affected by: Peripheral resistance and cardiac output.
Blood doping: Increases peripheral resistance (more viscous blood).
Hemorrhage/shock: Vasoconstriction to maintain BP.
Chemicals increasing BP: ADH, epinephrine, angiotensin.
Chemicals decreasing BP: Atrial natriuretic peptide (ANP).