A&P The circulatory system: Heart Chapter 19

Left AV valve

"bicuspid or mitral valve", opens into the left ventricle

Myocardial infarction

(MI) Heart attack, interruption of blood supply to heart usually caused by fatty deposit or blood clot in coronary artery, long term coronary artery obstruction, cardiac muscle downstream dies, 27% of all deaths in US -Disrupt electrical conduction pathways, fibrillation, death

Alveoli

(singular alveolus.) Tiny sacs, with walls only a single cell layer thick found at the end of the respiratory bronchiole tree. Alveoli are the site of gas exchange in the respiratory system.

Aerobic respiration

(with oxygen) glucose is completely oxidized to carbon dioxide and water the total oxidation allows for the maximum amount of energy to be released, to make ATP mitochondria fill 25% of cell At rest heart gets 60% of energy from fatty acids 35% from glucose 5% from ketones, lactic acid, and amino acids

Fibrous rings

-(Anuli fibrosi) along with other masses of dense connective tissue in the portion of the septum between the ventricles constitute the skeleton of the heart, -holds orifices open and prevents them from excessively stretching when blood surges through them -nonconductor of electricity, serves as electrical insulation between atria and ventricles -Elastic recoil of skeleton may aid in refilling heart with blood after each beat -Anchors myocytes

Cardiac muscle requires ample supply of blood

-Coronary circulation-about 5% of blood flow (lots of blood goes to heart) -Collateral circulation important-anastomoses allow bypass of blockages (a lot) -Diastolic blood flow is greater than systolic blood flow, because things are relaxed

Pathway of blood through heart

1. Blood enters right atrium from superior and inferior vena cavae 2. Blood in right atrium flows through right AV valve into right ventricle. 3. Contraction of right ventricle forces pulmonary valve open. 4. Blood flows through pulmonary valve into pulmonary trunk 5. Blood is distributed by right and left pulmonary arteries to lungs where it unloads C02 and loads O2 6. Blood returns from lungs via pulmonary veins to left atrium. 7. Blood in left atrium flows through left AV valve into left ventricle 8. Contraction of left ventricle (simultaneous with step 3) forces aortic valve open. 9. Blood flows through aortic valve into ascending aorta 10.Blood in aorta is distributed to every organ in the body, where it unloads O2 and loads CO2 10. Blood returns to right atrium via venae cavae

Cardiac conduction system

1. SA node fires 2. Excitation spreads through atrial myocardium 3. AV node fires 4. Excitation spreads down AV bundle 5. Purkinje fibers distribute excitation through ventricular myocardium

Flow peaks when the heart relaxes

1. contraction of myocardium compresses coronary arteries and obstructs blood flow 2. When the ventricles contract, the aortic valve is forced open and its cusps cover the openings to the coronary arteries, blocking blood from flowing into them 3. When they relax, blood in aorta briefly surges back toward the heart. It fills the aortic valve cusps and some of it flows into the coronary arteries

Pacemaker

A group of cells located in the right atrium that sends out signals that make the heart muscle contract and that regulates heart rate

Sinoatrial node

A small mass of tissue that is made up of Purkinje fibers, ganglion cells, and nerve fibers, that is embedded in the musculature of the right atrium, and that originates the impulses stimulating the heartbeat -- called also S-A node, sinus node.

Inferior vena cava

A vein that is the largest vein in the human body and returns blood to the right atrium of the heart from bodily parts below the diaphragm.

Superior vena cava

A vein that is the second largest vein in the human body and returns blood to the right atrium of the heart from the upper half of the body.

Coronary sulcus

AKA atrioventricular sulcus, groove that marks border between atria and ventricles

Cups

AKA leaflets

Atrioventricular bundle

AV bundle or bundle of His, specialized muscle fibers connecting the atria with the ventricles and transmitting electrical impulses between them

Atriventricular node

AV node, cluster of pacemaker cells located posterior and medial to tricuspid valve; slower than SA node, with an intrinsic rate of only about 40 action potentials per minute

Atrioventricular valves

AV valves, regulate openings between the atria and ventricles.

Size of human heart

About two fists clasped together and weighs about 300g

Anterior interventricular sulcus

Also called the left anterior descending artery

Ectopic focus

An abnormal pacemaker, SA node is damaged and may take over governance of heart rhythm

Desmosomes

Anchoring junctions that prevents cells subjected to mechanical stress from being pulled apart; button like thickenings of adjacent plasma membranes connected by fine protein filaments

Fascia adherens

Anchoring sites for actin

Diastolic

Blood pressure that remains between heart contractions.

Cardiovascular system

Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood.

Circumflex branch

Branch of the left coronary artery that curves around the left side and lies in the coronary sulcus.

Sympathetic stimulation

Can raise the heart rate to as high as 230 bpm

Parasympathetic stimulation

Can slow it to as low as 20 bpm or even stop heart of a few seconds

Cardiac plexus

Cardiac branches of the parasympathetic vagus nerve and cardiac branches from the cervical and upper thoracic sympathetic trunk unite around the heart to form a bundle of nerves

Intercalated dics

Cardiocytes are joined end to end by these thick connections. An intercalated disc is a complex step like structure with three distinctive features not found in skeletal muscle:interdigitating folds, mechanical junctions, electrical junctions

Right and left bundle branches

Carries the impulse throughout the ventricles.

Mediastinum

Central compartment of the thoracic cavity. It contains the heart, the great vessels of the heart, esophagus, trachea, phrenic nerve, cardiac nerve, thoracic duct, thymus, and lymph nodes of the central chest.

Valves are open and closed by?

Changes in blood pressure that occur as the heart chambers contract and relax.

Systemic circuit

Circuit of blood that carries blood between the heart and the rest of the body.

Coronary circulation

Circulation of blood through the coronary blood vessels to deliver oxygen and nutrients to the heart muscle tissue Supply about 250 mL of blood per minute

Angina

Condition of episodes of severe chest pain due to inadequate blood flow to the myocardium, ischemia, anaerobic respiration, lactic acid production

Systole

Contraction of the ventricles of the heart. Normal systolic pressure is 120 mm Hg.

Myocardial vortex

Created by how muscle spirals around heart. When ventricles contract, exhibit twisting or wringing motion that enhances ejection of blood.

Pulmonary veins

Deliver oxygen rich blood from the lungs to the left atrium

Pericardium

Double-layered membrane surrounding the heart.

Venous drainage

Drained primarily by three veins: vertebral, external jugular, internal jugular veins

Papillary muscle

Enlarged muscles in ventricles that are attached to chordae tendinae.

Coronary sinus

Enlarged vessel on the posterior aspect of the heart that empties blood into the right atrium

Visceral pericardium

Epicardium, Innermost layer of the serous membrane around the heart, isolates heart from other thoracic organs and allows it room to expand, but resists excessive expansion

Interdigitating folds

Folds interlock with each other, and increase surface area of contact

Electrical junctions

Gap junctions that allow ions to flow between cells - can electrically stimulate neighbors

Authorhythmic

Heart cells that initiate contractions

Nodal rhythm

If the heart's normal pacemaker is nonfunctional and the AV node 20-40 bpm, provides too little flow to the brain to be survivable. Calls for artificial pacemaker

Pericarditis

Inflammation of the pericardium, the membranes may become roughened and produce painful friction rub with each heartbeat

Endocardium

Inner lining of the heart around the chambers, simple squamous epithelium overlying thin layer of areolar tissue, no adipose tissue. Covers the valves and is continuous with endothelium of BV

Mechanical junctions

Keep the myocytes from pulling apart, tight junctions

Anterior interventricular branch

Left coronary artery branches travel down anterior ventricular sulcus to apex, rounds the bend and travels short distance up posterior side AKA left anterior descending branch (LAD)

Apex

Lower end of heart, just above the diaphragm

Posterior interventricular vein

Middle cardiac vein, Posterior branch of the right coronary artery; lies in posterior interventricular sulcus, collects blood from the posterior aspect of the heart

Collateral circulation

More than one artery supplying a muscle with blood, develops when chronic ischemia occurs to meet the metabolic demands; therefore an occlusion of a coronary artery in a younger individual is more likely to be lethal than in an older individual

Trabeculae carneae

Name the needle like ridges of muscle lining the ventricles. Serve to keep walls from clinging to each other like suction cups when heart contracts.

Sinus rhythm

Normal heartbeat 70-80 bpm

Auricle

One of the two chambers of the heart which receives the blood from the veins. A small earlike extension

Pericardial sac

Or parietal pericardium, membrane around heart, has tough, superficial fibrous layer of dense irregular connective tissue and a thin, deep serous layer. Is anchored by ligaments to diaphragm

Epicardium

Outer layer of the heart, simple squamous epithelium overlying thin layer of areolar tissue, some areas have thick layer of adipose tissue

Interventricular Septum

Partition that separates the right and left ventricles

Left marginal branch

Passes down left margin of heart and furnishes blood to left ventricle.

Serous layer

Pericardial fluid that is within the pericardial cavity comes from which layer of he pericardial sac

Posterior interventricular branch

Posterior branch of the right coronary artery; lies in posterior interventricular sulcus. It ends by joining the anterior interventricular branch of the LCA.

Most of the mass of the atria is on which side of the heart?

Posterior side

Right coronary artery

RCA, courses to the right side of the heart; gives rise to the right marginal artery

Fibrillation

Rapid and uncontrolled heartbeat

Right atrium

Receives blood returning to the heart from the superior and inferior vena cava

Left atrium

Recieves blood from pulmonary veins, blood now oxy-rich

Great cardiac vein

Returns deoxygenated blood from anterior surfaces of ventricle

Aortic valve

Semi lunar valve situated between the left ventricle and the aorta

Interatrial septum

Separates atria

Fibrous skeleton

Serves as attachment site for valves and myocardium; electrical insulator of heart

Sulci

Shallow grooves that mark the four chambers of heart

Thesbian veins

Small cardiac veins that drain into the left atrium and ventricle also contribute to normal anatomic shunting

Cardiocytes

Striated, short, thick, branched cells, one central nucleus surrounded by light-staining mass of glycogen

Posterior interventricular sulcus

Sulcus on posterior part of heart

Right marginal branch

Supplies lateral aspect of right atrium and ventricle

Left ventricle

The chamber of the heart that receives arterial blood from the left atrium and pumps it into the aorta

Right ventricle

The chamber of the heart that receives venous blood from the right atrium and pumps it into the pulmonary artery

The coronary sulcus and two interventricular sulci harbor

The largest of the coronary blood vessels

Great vessels

The major arteries and veins entering and leaving the heart because of their relatively large diameters

Cardiac nerves

They include the Superior, Middle and Inferior Cardiac nerve

Myocardium

Thick middle muscle layer of the heart, performs work of the heart Cardiac muscle Forms myocardial vortex around the heart

Chordae tendineae

Thin bands of fibrous tissue that attach to the valves in the heart and prevent them from inverting (tendinous cords)

Pericardial fluid

This is used to reduce friction between the layers of membranes surrounding the heart.

Importance of electrical insulatin

Timing of electrical and contractile activity

Left marginal vein

Travels from a point near the apex up the left margin and empties into the coronary sinus

Right AV valve

Tricuspid, prevents backflow of blood into right atrium when ventricle

Base

Uppermost end of heart, where great vessels are attached

Pulmonary valve

Valve positioned between the right ventricle and the pulmonary artery

Aortic arch

a curved blood vessel from which arteries branch to the head and neck.

Myogenic

capable of contracting without stimuli from nerve cell

Pulmonary trunk

carries blood from right ventricle to pulmonary arteries

Pulmonary circuit

carries blood to the lungs for gas exchange and returns it to the heart

Pulmonary arteries

carry deoxygenated blood out of the right ventricle and into the lungs

Friction rub

described as grating, scratching sound of the heart indicative of pericarditis

Purkinje fibers

fibers in the ventricles that transmit impulses to the right and left ventricles, causing them to contract

Pericardial cavity

fluid-filled cavity between the pericardial layers, the heart is enfolded by it (like fist in balloon) 5-30 ml of serious fluid

Return of blood to right atrium

great cardiac vein, posterior interventricular vein (middle cardiac), left marginal vein, coronary sinus