Physiology Lab quiz 3 ch 10: Blood and Cardiovascular System

Importance of Blood

Overview

Blood is a vital connective tissue responsible for the transport of essential substances throughout the body. It plays a central role in maintaining homeostasis, supporting immune defense, and facilitating the removal of metabolic waste.

• Transport: Delivers oxygen, nutrients, hormones, and removes waste products.

• Regulation: Maintains pH, temperature, and fluid balance.

• Protection: Defends against pathogens and prevents blood loss through clotting.

Composition of Blood

Blood as Connective Tissue

Blood consists of formed elements suspended in plasma, a nonliving fluid matrix. The fibers typical of connective tissue become visible during clotting.

• Formed Elements: ~45% of blood volume (cells and cell fragments)

• Plasma: ~55% of blood volume; 90% water, remainder includes nutrients, gases, hormones, waste, proteins, and electrolytes

• Dynamic Composition: Plasma composition varies as cells add or remove substances

Main Types of Blood Cells

• Erythrocytes (Red Blood Cells): Transport oxygen via hemoglobin; also carry some carbon dioxide

• Leukocytes (White Blood Cells): Part of the immune system; defend against infection

• Platelets: Cell fragments involved in hemostasis and blood clot formation

Blood Cell Types Table

Cell Type	Description	Count/μL of Blood	Function
Erythrocyte	Biconcave, anucleate; contains hemoglobin	4-6 million	Transports oxygen and carbon dioxide
Neutrophil	Multilobed nucleus, pale granules	3000-7000	Phagocytizes pathogens
Eosinophil	Bilobed nucleus, red granules	100-400	Destroys parasites, modulates allergic responses
Basophil	Bilobed nucleus, large blue granules	20-50	Releases histamine, mediates inflammation
Lymphocyte	Large nucleus, thin rim of cytoplasm	1500-3000	Immune response (B and T cells)
Monocyte	Kidney-shaped nucleus, abundant cytoplasm	100-700	Phagocytosis, develops into macrophages
Platelets	Cell fragments	150,000-400,000	Blood clotting

Hematologic Tests

White Blood Cell Count

• Total WBC Count: Measures immune status

• Leukocytosis: Elevated WBC count; indicates infection or poisoning

• Leukopenia: Decreased WBC count; may result from toxins, reduces immune protection

• Leukemia: Uncontrolled proliferation of abnormal WBCs; reduces RBCs and platelets

Red Blood Cell Count

• Total RBC Count: Assesses oxygen transport capacity

• Anemia: Reduced RBC count or hemoglobin; leads to decreased oxygen delivery

Blood Typing

• Classification: Based on specific glycoproteins (antigens) on RBC membranes

• Genetically Determined: Inherited from parents

• Antibodies: Present in plasma; determine compatibility for transfusions

Blood Type Table (ABO System)

ABO Blood Type	Antigens on RBC	Antibodies in Plasma	% of U.S. Population (White/Black/Asian)
A	A	Anti-B	40 / 27 / 28
B	B	Anti-A	11 / 20 / 27
AB	A and B	None	4 / 4 / 5
O	Neither	Anti-A and Anti-B	45 / 49 / 40

Cholesterol Concentration in Plasma

• Atherosclerosis: Disease in which blood vessels become blocked by plaques

Cardiovascular System

Major Functions

The cardiovascular system is responsible for the transport of substances throughout the body, powered by the heart's contractions.

• Blood: Transport vehicle for oxygen, nutrients, wastes, electrolytes

• Heart: Provides the propulsive force for circulation

Anatomy of the Human Heart

Heart Structure

• Pericardium: Double-walled sac enclosing the heart; contains serous fluid for frictionless movement

• Three Layers:

  • Epicardium: Outer layer, visceral pericardium

  • Myocardium: Middle layer, cardiac muscle reinforced by connective tissue

  • Endocardium: Inner lining, covers valves, continuous with vessel lining

Heart Chambers and Valves

• Chambers: 2 atria (receiving), 2 ventricles (discharging)

• Septum: Divides heart longitudinally (interatrial and interventricular septa)

• Valves: Enforce one-way flow

  • Atrioventricular (AV) Valves: Tricuspid (right), Mitral (left)

  • Semilunar Valves: Pulmonary, Aortic

Pulmonary, Systemic, and Coronary Circulations

Circulatory Circuits

• Pulmonary Circuit: Right heart pumps blood to lungs for gas exchange

• Systemic Circuit: Left heart pumps oxygenated blood to body tissues

• Coronary Circulation: Coronary arteries supply blood to the heart muscle itself

Conduction System of the Heart

Electrical Activity

Heart contraction is coordinated by depolarization waves traveling through specialized conduction pathways.

• Intrinsic Conduction System:

  • Sinoatrial (SA) Node: Pacemaker

  • Atrioventricular (AV) Node

  • AV Bundle (Bundle of His)

  • Subendocardial conducting network (Purkinje fibers)

Electrocardiography (ECG/EKG)

ECG Waves and Intervals

• P Wave: Atrial depolarization

• QRS Complex: Ventricular depolarization

• T Wave: Ventricular repolarization

• Segments: Region between two waves

• Intervals: Region containing a segment and one or more waves

Structure of Blood Vessels

Types and Layers

• Arteries: Carry blood away from the heart; thicker walls

• Veins: Return blood to the heart; thinner walls

• Three Layers:

  • Tunica Intima: Endothelium lining, reduces resistance

  • Tunica Media: Smooth muscle, regulates diameter and pressure

  • Tunica Externa: Supportive, protective outer layer

Blood Vessel Types Table

Type of Vessel	Description	Average Lumen Diameter	Average Wall Thickness	Function
Elastic (Conducting) Arteries	Largest, most elastic; close to heart	1.5 cm	1.0 mm	Pressure reservoir, expands/recoils for continuous flow
Muscular (Distributing) Arteries	Medium-sized, more smooth muscle	0.6 cm	1.0 mm	Distribute blood to organs, regulate flow
Arterioles	Small arteries, thin tunica externa	37 μm	6 μm	Regulate flow to capillaries
Capillaries	Smallest, only tunica intima	9 μm	0.5 μm	Exchange of gases, nutrients, waste
Veins	Thinner walls, larger lumen	0.5 cm	0.5 mm	Return blood to heart, prevent backflow

Major Systemic Arteries

Key Features

• Location: Deep, well-protected body areas

• Aorta: Largest artery; includes ascending aorta, aortic arch, descending aorta

Major Systemic Veins

Key Features

• Superficial Course: Easily seen and palpated

• Venae Cavae: Veins converge here; upper body drains into superior vena cava, lower body into inferior vena cava

Special Circulations

Pulmonary Circulation

• Does not serve metabolic needs of tissues

• Brings blood into close contact with alveoli for gas exchange

Fetal Circulation

• Fetus lacks functioning lungs and digestive system

• Exchange occurs via placenta; oxygen-rich blood delivered, waste removed

Hepatic Portal Circulation

• Drains digestive organs, spleen, pancreas; delivers blood to liver via hepatic portal vein

• Allows for processing of nutrients and waste before entering systemic circulation

Cardiac Cycle

Phases of the Heartbeat

• Systole: Ventricular contraction

• Diastole: Ventricular relaxation

• Cardiac Cycle: One complete heartbeat

• Quiescent Period: Total heart relaxation

Heart Sounds

Origin and Significance

• Result from turbulent blood flow and valve closure

• Correspond to events in the cardiac cycle

• Heart murmurs indicate irregular heartbeats or valve issues

The Pulse

Pulse Measurement

• Alternating surges of pressure in an artery (expansion and recoil)

• Pulse Pressure: Difference between systolic and diastolic pressure

• Apical Pulse: Felt at apex of heart; may be slightly faster

• Radial Pulse: Found in radial artery

• Pulse Deficit: Difference between apical and radial pulse

Blood Pressure

Measurement and Significance

• Pressure exerted by blood against vessel walls

• Systolic Pressure: Pressure during peak contraction

• Diastolic Pressure: Pressure during relaxation

$\text{Blood Pressure} = \frac{\text{Force of Blood}}{\text{Area of Vessel Wall}}$

Skin Color as an Indicator of Circulatory Dynamics

Clinical Relevance

• Skin color reflects local and systemic circulation

• Pale, cold, moist skin indicates diverted blood flow, possible circulatory compromise

Additional info: These notes expand on the original slides with definitions, tables, and academic context for key terms and physiological processes relevant to college-level Anatomy & Physiology.