Intro to Exercise Physiology Exam 3

Characteristics of blood

• connective tissue

• formed elements - blood cells and platelets

• 4x more viscous and heavier than water

• males: 5-6 L, females: 4-5 L

• 1 drop of blood - 250 million RBCs

Functions of blood

• transport of gases O2 and CO2, nutrients, wastes, processed molecules, regulatory molecules

• regulate of pH and osmosis

• maintenance of body temperature

• protection against foreign substances

• clot formation

Plasma

• fluid portion of the blood

• over 90% water - liquid carrier of plasma solutes (dissolved substances) and formed elements

• contains variety of solutes

• nutrients, enzymes, hormones, antibodies, waste products, electrolytes, and respiratory gases

• plasma proteins: most abundant solutes, not used for energy - remain in the blood, and 3 major groups (albumin, globulins, fibrinogen)

Albumin

• transport hydrophobic substances (lipids, lipid-soluble vitamins, some hormones and certain ions)

• buffer for blood pH

• maintaining osmotic pressure

Globulins

• Alpha and Beta: make up protein portion of LDLs and HDLs and function to transport lipids

• Gamma: antibodies (immunoglobulins) produced by B lymphocytes

Fibrinogen

Soluble protein that converts in insoluble fibrin to form blood clots

Nitrogenous wastes

• breakdown products of proteins, nucleic acids, and creatine phosphate

• ex: ammonia and creatine

Electrolytes

• help regulate blood pH, osmotic pressure and ionic balance between blood and interstitial fluid

• common electrolytes: sodium ions, potassium ions, calcium ions, chloride ions, bicarbonate ions, phosphate ions

Respiratory gases

1.5% of O2 and 7% of CO2 transferred in blood dissolved in plasma

Erythrocytes (RBCs): structure

• biconcave discs

• no nucleus/mitochondria

Erythrocytes (RBCs): hemoglobin

• Heme: iron-containing pigment

• Globin: globe-like protein

• oxyhemoglobin: O2 binds with hemoglobin (bright red)

• deoxyhemoglobin: releases O2 and picks up CO2 to bring to lungs for removal (dark red)

Erythrocytes (RBCs)

• primary means of oxygen delivery → circulatory system

• life span 120 days

• young cells: flexible (slide through small blood vessels)

• old cells: lose flexibility and become fragile and damaged

• macrophages remove RBC from circulation in the liver and spleen

• Globin protein is broken down into amino acids and reused

• Heme is broken down to iron ion and bilirubin

Erythropoiesis

• create red blood cells

• requires for erythropoiesis: iron, folic acid, vitamin B)

• stimulated by erythropoietin (EPO)

• developed primarily in red bone marrow

• approximately 2.4 million new RBCs are produced per second

Hematopoiesis

All formed elements are produced by stem cells (hemocytoblasts) in red bone marrow

Hematocrit

Percentage of blood volume composed of RBCs

Adult male RBCs per micro liter

• 4.7-6.1 million RBCs per micro liter

• higher due to presence of testosterone → increases hormone erythropoietin → stimulates red bone marrow to produce more RBCs

• greater amount of muscle tissue - need extra oxygen carrying ability

Adult females RBCs per micro liter

• 4.2-5.4 million RBCs per micro liter

• lower due to menstruation and higher body fat (hematocrit decreases with higher body fat)

White blood cells

• get name from the white color of pus

• have nuclei and other organelles

• healthy adult WBC count: 4,500-10,000 per micro liter of blood

• derived from hemocytoblasts in red bone marrow

• lifespan: a few hours to many years

Functions of WBCs

• defense and immunity

• certain types promote inflammatory responses, others decrease inflammatory responses

• move through capillary walls into tissue

• chemotaxis: follows a “chemical trail (important for blood clots)

Types of WBCs

• classified by the presence or absence of granules when stained

Granulocytes

• contain granules

• neutrophils

• eosinophils

• basophils

Neutrophils

• first responders

• help with tissue damage

• release lysosomes

• get rid of bacteria

Eosinophils

• attach parasites

• reduce inflammation (neutralize histamine)

Basophils

• release histamine/heparin

• increase blood flow to damaged tissue

Agranulocytes

• lack granules

• lymphocytes

• monocytes

Lymphocytes

• T cells and B cells

• 1st line of defense against pathogens

• make up about ½

Monocytes

• become macrophages (chronic inflection clean up)

• learned line of defense to be able to produce antibodies against pathogens

• make sure everything stays clean

Platelets

• thrombocytes

• not cells

• cytoplasmic fragments of megakaryocytes

• essential for blood coagulation (blood clotting)

Hemostasis

The process by which bleeding ceases after trauma

Hemostasis steps

1. vascular spasm: immediate constriction to reduce blood flow to that area

2. platelet plug formation: collagen is exposed and platelets stick to collagen so we don’t lose RBCs

3. coagulation: platelet and fibrin form a plug to prevent excessive bleeding (calcium is important to help reduce blood loss)

Agglutination

Clumping of RBCs

Anemia

Decrease in the O2 - carrying capacity of the blood (most common blood disorder)

Polycythemia

Condition of excess RBCs in the blood

Infectious Mononucleosis (mono)

• infects B lymphocytes

• caused by Epstein-Barr virus

Leukemia

• group of cancers of the red bone marrow cells that form WBCs

• excessive production of WBCs that crowd out RBCs

Hemophilia

Group of inherited disorders that cause spontaneous bleeding and reduced ability to form clots

Thrombocytopenia

Condition of low platelet count that spontaneous bleeding can’t be prevented

Thrombosis

Blood clot in an unbroken vessel, usually occurs in veins

Embolus

Moving blood clot or foreign body in the blood. Causes embolism (stroke or heart

attack)

Acute responses to exercise

• decrease plasma volume – temporary hemoconcentration

• increase in WBCs

• decrease in pH

• increase in CO2

• increase in temperature

Chronic adaptation to exercise

• increase plasma volume

• increase total blood volume

• increase capillary density

Rh

Inherited protein found on surface of RBC

Primary function of the cardiovascular system

Transport O2, nutrients, and hormones to tissues while removing CO2 and metabolic wastes

Major components of the cardiovascular system

• heart

• blood vessels

• blood

Heart

The pump generating pressure

Blood vessels

The pipes (arteries, veins, capillaries)

Pulmonary circulation

• right side of heart → lungs → left side of heart

• how blood gets to our lungs

Systematic circulation

• left side of heart → body → right side of heart

• supplies oxygen and nutrients to all organs and tissues while removing carbon dioxide and metabolic wates

Coronary circulation

• blood supply to the heart itself

• how blood moves through the heart

Anatomy of the heart

• location: mediastinum, between the lungs, behind the sternum

• size: roughly the size of a fist, 250-350 g in adults

Layers of the heart wall (outer layer-inner layer)

• pericardium

• epicardium

• myocardium

• endocardium

Endocardium

Inner lining helping to minimize friction

Myocardium

• contractile cardiac muscle; rich in mitochondria, branched cells connected by intercalated discs (gap junctions → electrical syncytium)

• thickest

Epicardium

Outer layer of serous membrane

Pericardium

Protective sac around the heart filled with pericardial fluid to reduce friction and limit overfilling

Heart chambers

• right atrium

• right ventricle

• left atrium

• left ventricle

Heart valves

• tricuspid valve

• pulmonary valve

• mitral valve

• aortic valve

Right atrium

• receives from superior/inferior vena cava and coronary sinus

• pumps to right ventricle

• deoxygenated blood

Right ventricle

• receives from right atrium

• pumps to pulmonary artery → lungs

• deoxygenated blood

Left atrium

• receives from pulmonary veins

• pumps to left ventricle

• oxygenated blood

Left ventricle

• receives from left atrium

• pumps to aorta → systematic circulation

• oxygenated blood

Atrioventricular valves (AV valves)

• tricuspid valve

• bicuspid valve

Tricuspid valve

Between right atrium and ventricle

Bicuspid (mitral) valve

Between left atrium & ventricle

Semilunar valves

• open under pressure during ventricular systole

• pulmonary valve

• aortic valve

Pulmonary valve

Right ventricle → pulmonary artery

Aortic valve

Left ventricle → aorta

Blood flow through the heart

1. deoxygenated blood enters the heart chambers from: superior vena cava (upper body), inferior vena cava (lower body), and coronary sinus (supply directly to heart)

2. right atrium contracts, pushing blood through the tricuspid valve

3. into the right ventricle

4. right ventricle contracts, forcing blood through the pulmonary valve

5. into the pulmonary arteries/trunk

6. blood travels to the lungs, where gas exchange occurs (CO₂ out, O₂ in)

7. oxygenated blood returns via pulmonary vein

8. into the left atrium

9. left atrium contracts, sending blood through the mitral (bicuspid) valve

into the left ventricle

10. left ventricle contracts powerfully, ejecting blood through the aortic

valve

12. into the aorta

13. blood then flows to the entire body

Electrical conduction system parts

• SA node: intrinsic pacemaker

• AV node: delay

• Bundle of His

• Purkinje fibers: rapid spread enabling synchronized ventricular contraction

• Right and left branches

Electrical conduction system

• coordinates heart contractions before ventricles

• pathway: SA node → AV node → Bundle of His → R + L bundle branches → Purkinje fibers

Autonomic influence

• parasympathetic: slows heart rate

• sympathetic: increases heart rate

Diastole

Relaxation phase

Systole

Contraction phase

Cardiac cycle

1. atriole systole begins → atrial contraction forces blood into ventricles

2. ventricular systole (first phase) → ventricular contraction pushes AV valves closed

3. ventricular systole (second phase) → semilunar valves open and blood is ejected

4. ventricular diastole (early) → semilunar valves closed and blood flows into atria

5. ventricular diastole (late) → chambers relax and blood fills ventricles passively

Heart sounds

• Sound 1: (lub) AV valves closing

• Sound 2: (dub) semilunar valves closing

Electrocardiogram (ECG)

• P wave: atrial depolarization

• QRS complex: ventricular depolarization

• T wave: ventricular repolarization

Factors affecting heart rate

• autonomic innervation

• hormones

• fitness levels

• age

Factors affecting stroke volume

• heart size

• fitness levels

• gender

• contractility duration of contraction

• preload (EDV)

• afterload (resistance)

Stroke volume (SV)

• SV = EDV - ESV

• ml/beat

• blood volume and vascular resistance

Cardiac output

• CO = HR x SV

• ml/min

• nerves and hormones

Function of arteries

• Carry blood away from heart

• under high pressure

• control blood low and blood pressure

Features of the arteries

• Tunica intima

• tunica media and tunica media; thicker walls than veins

Function of capillaries

Exchange materials (gases, nutrients, wastes) between blood and interstitial fluid

Features of capillaries

• Microscopic vessels composed of endothelium, supported by connective tissue

• 1-2 cells thick

• thin

Function of veins

• Return blood from capillaries to heart

• storage site/reservoir for blood (~65 % of blood volume)

Features of veins

• Tunica intima

• tunica media: thinner walls than arteries

• large veins have valves

Factors that can affect blood pressure

• cardiac output

• resistance

• blood volume

Blood pressure

The force of your blood moving against the walls of your arteries

Top number for blood pressure

• systolic

• the pressure of force in the arteries when the heart beats

Bottom number for blood pressure

• diastolic

• the pressures measured between heartbeats

Normal blood pressure

120/80

Acute exercise responses

• increased heartrate

• increased stroke volume

• increased cardiac output

• increased oxygen delivery

Chronic adaptations

• lower resting heartrate

• increased stroke volume

• improved capillarization