TEAS 7 Cardiovascular system

Anatomy & physiiology

Function of system

Gas exchange, delivers nutrients, delivers hormones, & waste removal

Blood

Red liquid that circulates in the arteries & veins of humans & vertebrate animals

Transportation

• Carries oxygen & carbon dioxide to and from the tissues of the body

Characteristics

• Always red in color

• Brighter red = more oxygen

Function

• Maintains Homeostasis

• PH, Temperature, Osmostic pressue

Transports

• Hormones

• nutrients

• Gases

Blood composition

TOP: Plasma 55%

• Liquid: Lipids, salt, proteins, water

MID: Luekocytes + platelets 1%

• WBC- fight infection

• Platelets- Blood clotting (think scraping knee)

BOT: Erythrocytes 44%

• RBC- transport gases

• Hemoglobin - Iron rich protein in RBC (makes blood red)

Heart

Pump that pushes blood through the arteries

Arteries

Blood vessels that carry blood away from the heart

Veins

Blood vessels that carry blood to the heart

Capillaries

Blood vessels that exchange material between blood & cells

• Site of gas exchange

• Smallest blood vessels

Nemonic memorization for blood flow through the heart

A= AWAY

Arteries

• Carry blood away from the heart

• Oxygen rich

V= VERB= Veins efficiently return blood

Veins

• Carry blood away from the heart

• Oxygen poor (except in pulmonary circulation)

Capilaries

• SIte

The heart: 3 tissue layers

Epicardium(outer layer): Protects the heart & secretes lubricating serous fluid

Myocardium (middle layer): Contracts to pump blood

Endocardium (inner layer): Lines the chambers & valves

The heart: 4 chambers

Right atrium: Recieves blood form vena cava

Left atrium: Recieves blood from pulmonary veins

Right ventricle: Pumps blood into the pulmonary trunk

Left ventricle: Pumps blood into the aorta

• Atria- thin walls

• Ventricle- thick walls

Memory trick: A comes before V = atria on top, ventricles on bottom

Heart valves

Heart valves prevent backflow of blood

-Tricupsid valve (AV): Prevents backflow into the atrium when the ventricle contracts

-Pulmonary semilunar valve: Prevents return of blood into the right ventricle

-Bicupsid valve (Left AV): Prevents blood from entering the left atrium when the ventricle contracts

Coronary Blood flow

Coronary Arteries:

• Originate from the aorta and delivers nutrients & oxygen to the heart

Coronary Veins:

• Deoxygenated blood returns to the right atrium from the coronary sinus

Cellular respiration

Glucose is burned or combined with oxygen

• The oxygen allows cells to transfer energy in glucose to ATP

O2, CO2, waste, & nutrients

Oxygen: Moves down partial pressure gradient from air to blood of alvelor capillaries

• O2 binds to hemoglobin in RBC or diffueses in RBC

Nutrients (glucose, fats, amino acids): Circulate & are absorbed (target cells)

• Hormones: released by endocrine glands in the same way ^^

• Lipid soluble molecules: Require use of carrier protein

WASTE

Carbon dioxide: Transported away from tissues & diffuses out of alvelor capillaries

• CO2 CAN bind to hemoglobin or diffuse in blood; usually travels in the form of bicarbonate ions (similar to oxygen)

Other waste (like urea) are brought to the kidneys and filtered

• Kidneys also regulate fluids & ions in blood

Thermoregulation

Human body: 98.6 degree F

• Sensory neurons (thermoreceptors) detect temp changes »

• Send impulses to hypothalamus »

• to effectors to»

• smooth muscles so they relax with heat

Endothelial cells

Thin inner lining of blood vessels, inside of heart and entire circulatory system

• Squamous endothelial cells connected by tight junctions & adherens junctions

• Selectively permeable barrier between the blood & surrounding tissue

• Secrete chemicals which inhibit coagulation of blood

Systolic & diastolic pressure

Blood pressure: Force per unit area exerted by blood on vessel walls

Systolic pressure: Maximum pressure exerted in arteries

• Contraction of the heart

• LUB sound

• Under 120

Diastole: Lowest pressure in arteries

• Relazation of the heart

• DUB sound

• Under 80

• Ventricles relax & blood pressure is at lowest point

Ideal Blood Pressure = 120 over 80

Systemic circuit

Delivers oxygen rich blood to body, oxygen poor blood to the heart

• Longest body circuit

• Higher blood pressure than pulmonary circulation

Path: Left ventricle » aorta » arteries » arterioles » capillaries » venules » veins » superior & inferior vena cava » right atrium

What happens?: Oxygen & nutrients leave the blood & enter body cells, carbon dioxide & wastes enter blood

• Blood returning to the heart is deoxygenated (low O2)

Arteries oxygen blood content

Oxygen- rich blood

Veins oxygen blood content

Oxygen- poor blood

Pulmonary circuit

Get rid of carbon dioxide & pick up oxygen carries blood from the heart to lungs back to the heart

Path: Right ventricle » lungs » left atrium

Pulmonary arteries: Carry deoxygenated blood

Pulmonary veins: Carry oxygenated blood

(Opposite of systemic)

Electrical conduction system

The hearts natural pacemaker

• SA node (sinoatrial): Starts the electrical signal, atria contracts » P wave on ECG (60 to 100 BPM)

Bachman bundle:

• signal from SA node to left atrium

Internodal pathways

• Anterior, middle, posterior

• Signal from SA node to AV node

Secondary pacemaker

• AV node (Atrioventricular): Shows signal briefly, delays signal from SA node, contracts atria, gives ventricle time to fill with blood » PR on ECG (40 to 60 BPM)

Bundle of his

• ONLY route between atria & ventricles

• Right bundle branch: Signal to right ventricle

• Left bundle branch: Signal to left ventricle

Purkinje fibers- Last ditch pacemaker if SA & AV node fail

• Connect with myocytes

• Initialize depolarization » contraction (20 to 40 BPM)

Path: Bundle of his » bundle branches » purkinje fibers (carries electrical impulse to ventricles that depolarize & contract (QRS complex))

Electrical conduction system mnemonics

Strong: SA node (sinoatrial) 60-100 BPM

Arteries: AV node (atrioventricular) 40-60 BPM

Benefit: Bundle of his

Bodys: Bundle branches

Performance: Purkinje fibers 20-40 BPM

The cardiac cycle (ECG waves simplified)

QRS complex: Ventricles squeeze, Ventricle depolarization (electrical activation)

• Inverted V on chart (memory trick V = ventricles)

• Conceals atria repolarization

P wave: Atria squeeze, Atria depolarization (electrical activation)

T wave: Ventricles relax, ventricle repolarization

Depolarization = Contract

Repolarization = Relax

Aorta blood pressure

Blood pressure is highest in the aorta

Walls of blood vessels (EXCEPT capillaries) 3 layers

1. Tunica intima (innermost)

2. Tunica media (middle)- smooth muscle cells & elestci fibers

3. Tunica adventitia (outer)

Arterioles (Atrial systems)

Structure

• Tiny vessels lead to capillary beds

• Tunica media is thin but mostly smooth muscle cells

Fucntion:

• Primary vessels involved in vasoconstriction/ vasodilation. Control blood flow to capillaries

Elastic arteries (Atrial systems)

Structure:

• Aorta + major branches

• Tunica media has most elastin

• Largest vessel in artial system

Function:

• Stretch when blood is forced out of heart, recoils under low pressure

Muscular arteries (Atrial systems)

Structure

• Arteries that branch off of elastic arteries

• Tunica media has more smooth muscle cells

Function

• Regulate blood flow by vasoconstriction/vasodilation

Venules (Venous systems)

Structure:

• Tiny vessels exit capillary beds

• Thin pourus walls

• Few muscle cells & elastic fibers

Function

• Empty blood into larger veins

Veins (Venous systems)

Structure:

• Thin tunica media & intima

• Wide lumen

• Valves prevent backflow of blood

Function:

• Carry blood back to the heart

Capillary bed

Interconnected capillaries that facillitate gas exchange & solutes between blood and interstital

• Continuous capillaries

• Fenstrated capillaries

• Sinusoidal capilaries

Blood flow through the heart

Deoxygenated blood

1. Superior vena cava (upper half of body blood ) /inferiior vena cava (lower healf of body blood)

2. Right atrium

3. Tricupsid valve

4. Right ventricle

5. Pulmonic valve

6. Pulmonary artery

7. Lungs

^ Oxygenated after this and pumped to heart

Oxygenated blood

1. Lungs

2. Pulmonary vein

3. Left atrium

4. Bicupsid/mitral valve

5. Left ventricle

6. Aorta

Septal defects

Opening in the septum (wall) that separates the hearts upper and lower chambers.

• Septum defects are often congential (from birth)

Septum function in heart: Separtes oxygen rich blood from oxygen poor blood between the chambers

1. Interatrial septum: Thin, muscular structure that consists of 2 parts- fossa ovalis & limbus of fossa ovalis. (Separate right & left atria)

• An opening here would cause- Atrial septal defect (ASD)

-Congenital heart defect where there’s an abnormal opening, allowing blood to flow betweem the 2 atria

2. Interventricular septum: Thick, muscular wall that consists of 2 parts- a membranous & muscular portion (Separate the right & left ventricle)

• An opening here would cause- Ventricular septic defect (VSD)

-Congenital heart defect charactered by 1 or more holes in the interventricular septum, allowing blood to mix between the ventricles

WBC leukocyte

granulocytes

monocyte

lymphocyte

Blood types

blood composiiton

erythrocute production destruction function