Heart and Circulation lecture presentation

CirculationCirculation

Cardiovascular System = Heart, Blood and Vessels
Lymphatic System = Lymph nodes, Organs and Vessels

The Lymphatic Vessels

• Function: to collect excess tissue fluid collecting at arteriole end of capillary beds, and return leaked blood proteins to blood (maintain osmotic pressure needed to take up water into bloodstream)
• Lymph is moved through vessels
• Pulse of nearby arteries
• Contraction of surrounding skeletal muscle
• Regular movement of body (wiggling legs)
• Muscle in Tunica Media

Lymphatic System…The Players:

• Lymph- clear fluid from loose CT at capillaries
• Contains small molecules of blood plasma, water, various ions, nutrient molecules, respiratory gases
• Lymphatic capillaries (near blood capillaries) à
• Lymph collecting vessels (small, 3 tunicas, # valves) à
• Lymph nodes (sit along collecting vessels)-clean lymph of pathogens, they are NOT glands
• Lymphatic trunks à(convergence large collecting vessels)
• Lymphatic ducts à empty into veins of neck

Lymphatic Ducts

• Thoracic Duct
• Receives lymph from large trunks in abdomen and thorax
• Receives lymph from ducts of thoracic lymph nodes
• Along vertebral bodies
• Contain valves to ensure 1-way flow of lymph to lymph nodes
• Drains into left Brachiocephalic Vein (or subclavian or int. jugular veins)

Functions of Heart and Cardiovascular System

• Cardiovascular System
• Bulk flow of blood
• Exchange with tissue
• Heart
• Right side receives oxygen-poor blood from body tissues and pumps the blood to the lungs
• Left side receives the oxygenated blood from the lungs and pumps the blood throughout the body

Location of Heart in Chest

• Oblique Position
• Apex = Left of Midline (5th ICS), Anterior to rest of heart
• Base (posterior surface) sits on vertebral column
• Superior Right = 3rd Costal Cartilage, 1” right midsternum
• Superior Left = 2nd Costal Cartilage, 1” left midsternum
• Inferior Right = 6th Costal Cartilage, 1” right midsternum
• Inferior Left = 5th Intercostal Space at Midclavicular line

Cardiac Conduction

• Intrinsic system initiating and coordinating contraction of heart muscle
• Sinoatrial node (where SVC enters RA)
• Atrioventricular node (in atrioventricular septum)
• AV Bundle (in IV septum then splits)
• Purkinje fibers (throughout LV)
• Cardiac Plexus (external innervation)
• Vagus (parasympathetic)
• Sympathetic trunk

Blood Flow to Supply the Heart Muscle

• Heart wall too thick for diffusion of nutrients
• Rt and Lft Coronary Arteries
• Branch from Ascending Aorta
• Have multiple branches along heart
• Sit in Coronary Sulcus
• Coronary Heart Disease
• Cardiac Veins
• Coronary Sinus (largest)
• Many branches feed into sinus
• Sits in Coronary Sulcus

Pericardium

• Pericardium (3 layers)
• 1) Outer-fibrous pericardium
• Serous pericardium
• 2) parietal
• 3) visceral (epicardium)
• Pericardial Cavity
• between layers of serous pericardium
• serous fluid
• lubricate heart while beating

External Features of Heart

• Interventricular sulcus
• Coronal/Coronary sulcus
• Auricles of atria
• Apex
• Base
• Coronary vessels
• Ligamentum Arteriosum

The Great Vessels and major branches

Aorta (from Left Ventricle)

• Ascending
• Coronary arteries
• Aortic Arch
• Brachiocephalic trunk
• Left Common Carotid
• Left Subclavian
• Descending (Thoracic/Abdominal)
• Many small branches to organs

Pulmonary Trunk (from Rt Ventricle)

• -2 Pulmonary Arteries into lungs

Inferior/Superior Vena Cava

- Coronary sinus

Layers of Heart

• Epicardium (most superficial)

– Visceral serosa

• Myocardium (middle layer)
• Cardiac muscle
• Contracts
• Endocardium (inner layer = lining)
• Endothelium on CT
• Lines the heart
• Creates the valves

Fibrous Skeleton of Heart

• Insertion for cardiac muscle
• Anchors valve cusps
• Prevents valves from opening too much
• Block electrical impulses from atria to ventricles
• Contains AV node

Heart Chambers

• 2 receiving chambers:
• Right atria
• Left atria
• 2 pumping chambers:
• Right ventricle
• Left ventricle
• Atria are superior to ventricles
• Arrangement is not linear…it’s twisted!

Right Heart Chambers: Pulmonary Pump

• Right Atrium (forms most of base of heart)
• Receives O 2-poor blood from body via IVC, SVC, Coronary sinus
• Ventral wall (w/Pectinate muscles) and dorsal wall (no pectinate muscles) separated by crista terminalis
• Fossa Ovalis- on interatrial septum, remnant of Foramen Ovale
• Right Ventricle
• Receives O 2-poor blood from right atrium through tricuspid valve
• Trabeculae Carnae- muscle ridgesalong ventral surface
• Chordae Tendinae-fibrous cords running between AV valve cusps and papillary muscles
• Papillary Muscles (3)-cone-shaped muscles within ventricles to which chordae tendinae are anchored
• Moderator Band (septomarginal trabecula)-muscular band connecting anterior papillary muscle to interventricular septum
• Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk

Left Heart Chambers: Systemic Pump

• Left Atrium
• Receives O 2-rich blood from 4 Pulmonary Veins
• Pectinate Muscles line only auricle
• Left Ventricle (forms apex of heart)
• Receives blood from Left Atrium via bicuspid valve
• Same structures as Rt Ventricle: Trabeculae carnae, Papillary muscles (2), Chordae tendinae
• No Moderator band
• Pumps blood into aorta via Aortic Semilunar Valve to body

Heart Valves: Lub*-Dub**

• *Tricuspid Valve: Right AV valve
• 3 Cusps (flaps) made of endocardium and CT
• Cusps anchored in Rt. Ventricle by Chordae Tendinae
• Chordae Tendinae prevent inversion of cusps into atrium
• Flow of blood pushes cusps open
• When ventricle is in diastole (relaxed), cusps hang limp in ventricle
• Ventricular contraction increases pressure and forces cusps closed
• *Bicuspid (Mitral) Valve: Left AV valve
• 2 cusps anchored in Left Ventricle by chordae tendinae
• Functions same as Rt. AV valve
• They close together

Semilunar Valves (the dub)

• Semilunar valves: prevents backflow in large arteries
• Pulmonary Semilunar Valve
• Right Ventricle and Pulmonary Trunk
• Aortic Semilunar Valve
• Left Ventricle and Aorta
• Made of 3 Cusps
• As blood rushes past the cusps are flattened
• As it settles they’re pushed down (valve closed)

Flow of Blood

• O 2-poor blood (S+I VC, Coronary Sinus) enters Rt Atrium
• Travels through Tricuspid Valve into Rt Ventricle
• Pumped out through Pulmonary Semilunar Valve into Pulmonary trunk (branches into Pulmonary Arteries) and to lungs
• After circulating through lungs, O 2-rich blood returns to the heart through 4 Pulmonary veins
• The O 2-rich blood enters the Left Atrium
• Travels through Bicuspid/Mitral Valve into Left Ventricle
• Pumped out through Aortic Semilunar Valve into Aorta to be distributed to rest of body by descending aorta and branches of aortic arch

Cardiovascular Flow of Blood

• Heart àArteries à(conducting-distributing) àArterioles àCapillaries of tissues
• At Capillaries O 2 is delivered and CO 2 picked up
• Capillaries àVenules àVeins àHeart
• Heart àArteries à(conducting-distributing) àArterioles àCapillaries of tissues
• At Capillaries O 2 is delivered and CO 2 picked up
• Capillaries àVenules àVeins àHeart

Circuits

• Pulmonary Circuit
• Vessels carrying blood to and from lungs
• Pulmonary arteries and veins
• Systemic Circuit
• Vessels carrying blood to and from the rest of the body
• All other vessels

Blood Vessels

• Powered by the heart!
• Carry blood to and from the heart
• 3 main types:
• Arteries
• Carry blood away from heart
• arterioles
• Capillaries
• Veins
• Carry blood toward heart
• Venules

Anatomy of Arteries and Veins

• Tunica externa
• Outermost layer
• CT w/elastin and collagen
• Vaso Vasorum
• Tiny arteries, veins, capillaries on vessels to nourish them (outer half)
• Protects, Strengthens, Anchors
• Tunica media
• Middle layer
• Circular Smooth Muscle
• Collagen & Elastic Fibers
• Vaso-constriction/dilation
• Tunica intima
• Innermost layer
• Endothelium
• Minimize friction
• Lumen

Vessels of Cardiovascular System:
Arteries

• Carry blood AWAY from heart
• Systemic Circuit: carry O 2 blood
• Pulmonary Circuit: carry de-O 2 blood
• Walls thicker than Veins
• Tunica media > Tunica externa
• 3 Types
• Conducting (elastic)
• large, elastin, high pressure
• Distributing (muscular)
• medium size, to organs
• Arterioles
• smallest

Capillaries

• Smallest blood vessels
• Lumen is typically only 1 RBC thick
• Only 1 endothelial cell layer surrounded by basal lamina (no tunica media or externa)
• Deliver O 2 and nutrients to cells and remove waste
• Capillary Beds: networks of capillaries
• Regulating amount of blood going to cells throughout tissues
• Supply tissues and organs that otherwise have poor capillary circulation
• Epithelium, cartilage has no capillaries

Vessels of Cardiovascular System:
Veins

• Carry blood from capillaries INTO the heart
• Systemic Circuit: O 2 poor blood
• Pulmonary Circuit: O 2 –rich blood
• Pressure in Veins less than that in arteries
• Thinner walls than arteries (tunica externa > tunica media, less elastin)
• Larger lumen than arteries
• Contain valves (made of T. intima)
• Normal movement, Muscular contraction push blood through
• Venules- smallest veins

Cardiovascular Blood Flow

• Portal System: Special vascular circulation where blood goes through 2 capillary beds before returning to the heart to achieve 2 nd function
• (eg) Hepatic Portal System: aids digestion by picking up digestive nutrients from stomach + intestines and delivers to liver for processing/storage
• Pick-up occurs at capillaries of stomach and intestine
• Via Hepatic Portal Vein goes to capillaries of liver
• Via Hepatic Vein blood goes back to heart

Vascular Anastomoses

• Vessels unite and connect
• Arterial Anastomoses
• Communication between arteries
• Joints, Abdominal Organs, Brain, Heart
• Venous Anastomoses
• Communication between veins
• More common
• (eg) back of hand

Fetal Circulation

• All major vessels in place by third month
• 2 main differences:
• 1. Fetus must supply blood to placenta
• 2. Lungs do not need much blood because respiratory organ is the placenta
• Blood to Placenta
• Umbilical vessels
• Run in umbilical cord
• 2 umbilical arteries
• Carry blood (little oxygen and waste) to placenta
• 1 umbilical vein
• Returns this blood (with oxygen and nutrients) to fetus and to portal vein (to liver)

2. Bypassing the Lungs:
Foramen Ovale

• Hole in the inter-atrial septum
• Allows blood to flow from RA to LA
• Bypasses the RV
• Would usually bring blood to lungs
• Becomes the fossa ovalis postnatally

2. Bypassing the Lungs:
Ductus Arteriosus

• Carries blood from pulmonary trunk to aortic arch
• Empties distal to coronary arteries
• This enables the heart and brain to receive the most highly oxygenated blood
• Bypasses the lungs
• Becomes the ligamentum arteriosum postnatally

First Breath!!

• Lungs inflate
• Ductus arteriosus constricts and closes
• Oxygenated blood begins pouring into LA for first time
• Raises the pressure within the LA
• This pushes the 2 flaps of foramen ovale together and closes it

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