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Cardiovascular System
The Heart
136
Science
Undergraduate 1
10/16/2011

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Term
Cardiovascular System Function:
Definition

*Perfusion

- provides oxygen to the tissues, transport nutrients and hormones and remove waste from tissues

*Temperature Regulation

Term

Vascular System

 

Definition
oxygenated blood moves through the arteries to small arteries (arterioles) to capillaries where exchange of gases occurs in the tissues
Term
Arteries
Definition

carry blood away from heart, in high pressure tubes.

* thick walled, elastic and deeper in the body

Term
Veins
Definition

carry blood back to the heart, in low pressure tubes

* thinner walled, some more superficial

Term
Capillaries
Definition
exchange of gases, nutrients and waste products, precapillary sphincters contain smooth muscle
Term
Systole
Definition
heart is contracting
Term
Diastole
Definition
heart is relaxing, heart fills, coronary arteries fill
Term
Veins are thin-walled
Definition
some veins have one-way valves to prevent backflow
Term
Both arteries and veins:
Definition
outer fibrous layer, middle layer of smooth muscle, elastic tissue and smooth inner lining of endothelium
Term
Capillary structure
Definition

single layer of squamous endothelium

- allows exchange of gases, nutrient and waste products, varying permeability

Term
Capillaries used by Sympathetic Nervous System
Definition
vasoconstriction and vasodilation
Term
How the body vasoconstricts:
Definition

*Sympathetic stimulation

-a1 receptors on precapillary arterioles

-stimulation causes peripheral vasoconstriction, shunts blood away to the fight or flight tissues

Term
On the other side of the capillaries
Definition
Blood enters venules -> veins -> back to heart
Term
Leakage occurs out of the capillaries
Definition

*fluid component of blood leaks into interstitial fluid=lymph

*drains into lymphatic vessels->lymph nodes->thoracic duct->back into the blood

Term
Where is the heart located?
Definition

*situated in the mediastinum- space between the two pleural cavities that contain the lungs.

*space between the lungs

Term
Mediastinum also contains:
Definition
Esophagus, Trachea, Vessels (aorta, vena cava), and mediastinal lymph node
Term
Pericardium
Definition
heart sac, connective tissue, tough fibrous outer layer, loosely attached to diaphragm, 2 inner layers with lubricant between
Term

Myocardium

Definition
heart muscle, made of cardiac muscle and chambers lined with endocardium
Term
The chambers of the heart:
Definition

* 2 atria - receive blood and help fill ventricles

* 2 ventricles - pump blood to lungs (right) and to body (left)

Term
Septa
Definition
separate the heart into right and left sides
Term
Heart valves
Definition
A-V valves and semilunar valves, all are one-way valves, which prevent backflow (ensures one-way flow of blood)
Term
A-V Valves
Definition

Atrioventricular valves - located between atrium and ventricle

- ensures one-way flow from atrium to ventricle

 

Term
Left A-V valve
Definition
mitral
Term
Right A-V valve
Definition
tricuspid
Term
Chordae tendonae
Definition
cord-like extensions from valve flaps, they attach to inner heart wall (to papillary muscles) to hold the valve close
Term
Semilunar Valves
Definition

located between ventricles and the arteries exiting the heart

*aorta - left

*pulmonary artery - right

 

Term
What do semilunar valves do?
Definition
prevent backflow of blood from artery back into ventricle
Term
Valves
Definition

- all have 3 cusps except left A-V (mitral/bicuspid)

- between left atrium and left ventricle

Term
Right A-V: tricuspid
Definition
- between right atrium and right ventricle
Term
Left semilunar: aortic
Definition
-between the left ventricle and aorta
Term
Right semilunar: pulmonary/pulmonic
Definition
- between right ventricle and pulmonary artery
Term
Blood draining from the body:
Definition
Unoxygenated, returning from systemic circulation, goes to right atrium thru vena cava
Term
Cranial vena cava
Definition

drains cranial body

* head, neck, forelegs

Term
Caudal vena cava
Definition

- drains caudal body

*abdomen, rear legs 

Term
Right Atrium
Definition
blood passes from right atrium thru open tricuspid valve to the right ventricle
Term
Right Ventricle
Definition
when ventricle contracts (systole) tricuspid valve closes, blood passes from the right ventricle through pulmonary valve to pulmonary artery
Term
Pulmonary Valve Closes
Definition
To keep blood from leaking back from Pulmonary Artery into the ventricle
Term
Passive Process
Definition
only depends on pressure in the vessel to close it , same with all valves
Term
Pulmonary Artery
Definition
divides into right and left pulmonary arteries to supply both sides of lungs, carries unoxygenated blood to the lungs
Term
In the lungs arteries continue to divide and ...
Definition

get smaller -> arterioles -> capillaries

- very thin walled and they surround alveoli

Term
Oxygenated Blood
Definition
from lungs goes through pulmonary vein to the left atrium
Term
Left Atrium
Definition

blood passes from left atrium through open mitral valve to the left ventricle. 

-passive ventricular filling followed by atrial contraction

Term
When the Left Ventricle Contracts
Definition
mitral valve closes, blood passes from left ventricle through open aortic valve into aorta
Term
Aortic valve closes
Definition
aorta subdivides and supplies the entire body with oxygenated blood
Term
NORMAL BLOOD FLOW
Definition
vena cavae ->right atrium -> tricuspid valve -> right ventricle -> pulmonic valve -> pulmonary arteries -> lungs ->pulmonary veins -> left atrium -> mitral valve -> left ventricle -> aortic valve and then aorta
Term
coronary circulation
Definition
they supply the myocardium itself with oxygenated blood, can only fill between beats
Term
Cardiac Veins
Definition
drain deoxygenated blood from capillary beds of the myocardium -> into right atrium
Term
Skeletal muscle
Definition
Action potential comes down neuron-> neuromuscular junction->Ach into synapse->causes Action potential on muscle cell ->T-tubules-> calcium release -> muscle contraction
Term
Resting Membrane Potential
Definition
"resting" phase :Na+ outside, K+ inside cell. Inside of cell is negative
Term
Depolarization
Definition
Na+ channels open, Na+ rushes in. Inside of cell becomes more positive
Term
Repolarization
Definition
Na+ channels close, K+ channels open, K+ rushes out, leave cell more negative.
Term
Sodium Potassium Pump
Definition
Restores ions to the proper side of the membrane, reestablishing membrane potential. (charging the battery)
Term
Heart muscles have action potentials too but...
Definition
don't rely on a nerve to start it like skeletal muscle does
Term
Automaticity
Definition
 Na+ slowly leaks in -> cells slowly becomes more positive until it reaches threshold and depolarizes
Term
Plateau Phase
Definition
Ca2+ from sarcoplasmic reticulum moves into cell cytoplasm
Term
Calcium
Definition
Actively pumped back into sarcoplasmic reticulum, requires ATP
Term
Cardiac cells are connected via intercalated discs, has gap junction
Definition
ions pass from cell to adjacent cell, causes a wave of depolarization to pass from cell to cell to cell...
Term
Wave of depolarization
Definition
allows heart to depolarize in correct order, if it doesn't happen : fibrillation
Term
Electrical Conduction
Definition
sinoatrial node depolarizes-> depolarization spreads through atria -> atrial contraction
Term
Atrioventricular Node
Definition
Impulse moves on to the AV node, where it pauses
Term
When the impulse moves on to the AV node and pauses it gives...
Definition
the atria a chance to contract and fully fill the ventricles prior to ventricular depolarization
Term
Purkinje Fibers
Definition
where is meets muscle -> calcium release -> contraction will follow
Term
What do Purkinje Fibers do?
Definition
allows the blood to be pushed from the apex of the heart up to the great vessels
Term
Absolute Refractory Period
Definition
Period when no matter how strong the stimulus, the cell can't depolarize again, sodium channels are already open so there is no resting potential.
Term
Relative Refractory Period
Definition
period when cell may be depolarize again if there is a strong enough stimulus
Term
Refractory periods are essential to...
Definition
maintain proper sequence of depolarizations so that the heart will be effective as a pump
Term
If an area depolarizes out of sequence...
Definition
much of the time, would not spread through myocardium due to cells being in their refractory periods
Term
Ectopic Focus
Definition
sometimes spreads -> depolarizations out of order -> ineffective contractions
Term
What causes an Ectopic Focus?
Definition
Some damage to cells has made them abnormally leaky to sodium -> reach threshold -> depolarize
Term

What if the Sinoatrial (SA) Node is late?

or for some reason the AP doesn't get through?

Definition
All cardiac cells are leaky, escape beats
Term

Cardiac Muscle Contraction: 

Systole

Definition
As AP reaches individual cardiac muscle cells -> release of calcium -> actin and myosin bind -> contraction occurs 
Term

Cardiac Muscle Contraction :

Diastole

Definition
Calcium pumped back into Sinoatrial Node -> relaxation of muscle
Term
Systole + diastole =
Definition
cardiac cycle
Term

Heart Sounds:

Lub = S1

Definition
closure of the AV valves at the beginning of ventricular systole
Term

Heart Sounds:

Dub = S2

Definition
closure of the semilunar valves at the beginning of ventricular diastole
Term
Murmurs
Definition
normally blood flow thru heart is silent, they are caused by turbulence in blood, usually as it flows thru valves
Term
What can cause murmurs?
Definition

- damaged valve, lets blood go the wrong way and won't let blood thru easily

- thin blood (anemia)

Term
Cardiac Imput
Definition
heart rate X stroke volume
Term
Stroke Volume
Definition
volume pumped with each stroke (systole)
Term
So the heart depolarizes all on its own due to...
Definition

- to permeability to sodium

-to intercalated discs/gap junctions

-But can be influenced by ANS

Term
Autonomic Nervous System
Definition
provides neural and hormonal stimuli which speed or slow the heart from its normal automatic rate
Term
Sympathetic Nervous System
Definition

Speeds the heart through hormones

- epinephrine

-norepinephrine

Term
During Tachycardia
Definition
heart spends a grater proportion of the cycle in systole, less in diastole
Term
Why is tachycardia so dangerous?
Definition
not only the heart working harder but the heart can't feed itself as well
Term
Parasympathetic Nervous System
Definition
Slows the heart via neural influence 
Term
The Electrocardiograph
Definition
detects action potentials as they pass thru the myocardium by P-wave, QRS complex and T-wave
Term
P-Wave
Definition
atrial depolarization
Term
QRS Complex
Definition
ventricular depolarization
Term
T-wave
Definition
ventricular repolarization
Term
What does a Electrocardiograph help determine?
Definition

- heart rate and rhythm, arrhythmias

- abnormal size of heart chambers

- abnormal electrical conduction

Term
Arrhythmias
Definition
abnormal rhythm
Term
Sinus Rhythm
Definition
normal rhythm
Term
VPC / Ventricular premature complex
Definition
abnormal electrical activity in the heart due to signal coming from an ectopic focus
Term
what is VPC also know as ..
Definition
PVC / Premature ventricular contraction
Term
Ectopic Focus
Definition
someone is leakier than the SA node, often an area of damaged myocardial cells -> leaks -> depolarization out of sequence
Term
Heart Block is also known as  
Definition
Atrioventricular Block
Term
Heart Block
Definition
Electrical impulse is being delayed more than normal at the AV node
Term
ECG just documents electrical activity of the heart not
Definition
necessarily muscular contraction
Term
Electromechanical Dissociation
Definition
what happens if the impulse does not pass from the conduction pathway into the muscle fibers themselves
Term
When does electromechanical dissociation happen?
Definition
happens at death
Term
Aorta
Definition
Largest artery, leaves left ventricle and arches over heart
Term
Thoracic Aorta
Definition
cranial to diaphragm
Term
coronary arteries
Definition
come off before aorta leaves heart - supply myocardium
Term
What are the parts of the Thoracic Aorta?
Definition
coronary arteries, brachiocephalic artery and subclavian arteries
Term
subclavian arteries supply?
Definition
 the blood for the head and front limbs
Term
Brachiocephalic Artery supplies
Definition
the head and neck
Term
Brachiocephalic Artery
Definition
gives rise to carotid arteries - left and right, deep to jugular veins
Term
Abdominal Aorta
Definition
caudal to diaphragm
Term
What does the Abdominal Aorta include?
Definition
celiac artery, mesenteric artery, renal arteries, internal and external iliac arteries
Term
 Celiac Artery branches into 
Definition

- gastric artery

-splenic artery

- hepatic artery

Term
Mesenteric Artery
Definition
supplies intestines
Term
mesentery
Definition
double fold of peritoneum supporting intestines
Term
Renal arteries
Definition
supply kidneys themselves, also present large volume of blood to kidneys for filtration and purification
Term
Internal and External iliac arteries supply
Definition
pelvis, hips, rear limbs and genitalia
Term
Systemic Veins
Definition

run along with and have the same names as arteries (ie : renal veins)

-except for jugular veins, venae cavae (cranial and caudal) and portal vein and portal circulation

Term
Cranial vena cava
Definition
drains head, neck, front limbs. thorax and empties into right atrium
Term
Jugular Veins
Definition
there are left and right, internal and external, drain head and neck then empty into cranial vena cava
Term
Caudal vena cava
Definition
drains abdomen, caudal to body, empties into right atrium
Term
Portal Vein and Portal Circulation
Definition
vein draining the stomach, spleen, intestines, pancreas come together to form the hepatic portal vein
Term
Portal Vein
Definition
flow through an organ (a second capillary bed) on their way back to heart
Term
Hepatic Portal Vein
Definition
goes through the liver so the liver can rid the blood coming from the GI tract of toxins, excess glucose etc.. before that blood makes it to the rest of the body (systemic circulation)
Term
So how does the liver get oxygenated blood?
Definition

- hepatic artery branches off aorta

- dual blood supply *hepatic artery and hepatic portal vein

-blood leaves the liver via the hepatic vein -> vena cava ->heart

Term
Placenta
Definition
is fetal tissue in contact with maternal uterus, where gas, nutrient and waste exchange takes place
Term
Umbilical Vein
Definition
carries purified, 
Term
Ductus Venosus
Definition
is a bypass for blood through the fetal liver, since the fetal liver is mostly nonfunctional
Term
so the blood flows from the umbilical vein through the liver to 
Definition
caudal vena cava to right atrium
Term
Right atrium- a fetal blood has 3 paths it can follow
Definition

-normal adult pattern

- thru ductus arteriosus 

-thru foramen ovale

Term
Normal Adult Pattern
Definition
*right atrium -> right ventricle -> pulmonary artery -> lung ->pulmonary vein -> left atrium ->left ventricle -> aorta
Term
Foramen Ovale
Definition
is a hole in the septum between the left and right atria, bypasses right ventricle and the lungs
Term
Ductus Arteriosus
Definition

Blood that doesn't go thru foramen ovale -> right atrium -> right ventricle 

-> pulmonary artery -> ductus arteriosus -> aorta

Term
The purpose of Ductus Arteriosus
Definition
bypass fetal lungs and liver, because they are nonfunctional. 
Term
Persistence beyond birth is bad because...
Definition

is pathological

- patent foramen ovale

-patent ductus arteriosus

-patent ductus venosus

Term

Patent Ductus Arteriosus 

aka: PDA

Definition
bypass from pulmonary artery to aorta, blood bypasses lungs... muy mal!
Term
What sound does a Patent Ductus Arteriosus make and can it be repaired?
Definition
"Machinery murmur" can be surgically repaired (ligated)
Term
Patent Ductus Venosus
Definition

umbilical vein -> ductus venosus through liver -> caudal vena cava

 

- bypasses liver

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