Lecture 20 Flashcards
Major functions of cardiovascular system
- Transportation of substances
- Helps fight infection
- Assists in thermoregulation
The most basic needs of cells (o2 and nutrients) can be obtained from
Blood in nearby blood vessels
Waste from cells is picked up by what
Blood
For food to go into blood, i must first
Be digested (broken down) into glucose or amino acids by mouth/stomach/small intestines
Once digested, food molecules can get absorbed to blood through
Walls of small intestines
Nutrient rich blood from small intestines go to what first
Liver
Why does nutrient rich blood go to liver
To initially process nutrients absorbed, then goes to heart then rest of body
Steps of nutrient rich blood
- Products of digestion are absorbed into capillaries within vili of small intestines
- Food molecules travel through hepatic portal veins to liver
- Liver monitors blood content
- Hepatic veins deliver blood to cardio system
Hormones secreted by glands of endocrine system are transported by
Blood
Hormones are one of the means of the body by which cells from diff systs do what
Communicate with each other
A hormone is a molecule that is
Made and secreted into blood by a cell which triggers action in another cell
What is insulin
Released by pancreas
Hormone regulating blood sugar by moving from blood into cells
Blood circulates throughout whole body and therefore picks up
Lot of heat generated by cells
We can control heat distribution to body by
Regulating blood flow to certain areas
Core temp should be maintained at 37, so
Limbs kept warm but never at expense of core
Can control blood flow to certain areas by
Vasodilation (widening) or vasoconstriction (narrowing) of blood vessels
When core temp is above 37, vasodilation which
Increases blood flow in skin and encourages heat to be lost into atmosphere
If core under 37, vasoconstriction to
Minimize heat loss in core
Cardiovascular is major component of what system
Immune (WBC circulate and sense for chemical changes indicating tissue damage/foreign particles)
When damage is sensed, wbc in blood do what
Leave bv in attempt to remove via endocytosis the invading organism (ex bacteria)
Circulatory system gives access to how many cells
Almost every cell
Organs of cardio syst are
Heart and blood vessels (subcategorized as arteries, veins, capillaries)
Heart generates pressure needed to
Move blood throughout network of bv
Heart characteristics
- Human fist size, less than a pound
- Located in thoracic cavity between lungs in inferior mediastinum (mid of thoracic cav)
- About 2/3 of heart mass lies to left of body’s midline
- Apex (left ventricle) rests on diaphragm
- Base (great bv emerging area) towards right shoulder, formed by atria
Pericardium is
Double walled sac enclosing heart, two main parts:
1. Parietal layer (dense fibrous tissue)
2. Visceral layer
Fibrous parietal layer
- Tough inelastic dense CT
- Protects heart, anchors it to surrounding structures and prevents overfilling by blood
Visceral layer of serous pericardium
- Thinner, called epicardium, integral part of heart wall
In pericardial cavity, pericardial fluid does what
Lubricates, reduces friction between visceral and parietal layers as heart moves
3 parts of serous pericardium
- Parietal layer
- Pericardial cavity (contains fluid)
- Visceral layer
Heart wall composed of
- Myocardium
- Endocardium
Myocardium (muscle)
- Responsible for pumping of heart
- Composed of cardiac muscle tissue
- Approximately 95% of heart wall
- Part that contracts
Myocardium (muscle)
- Responsible for pumping of heart
- Composed of cardiac muscle tissue
- Approximately 95% of heart wall
- Part that contracts
Endocardium
- Thin layer of CT
- Internally reinforces myocardium
- Dense fibrous CT
Interventricular septum divides heart how
Longitudinally
4 chambers of heart
Atria (x2)
Ventricles (x2)
Atria
Receive blood from body (right atrium) and from lungs (left atrium)
Ventricles
- Pump blood to lungs (right) and body (left)
- Thick walled chamber
Why is workload of right ventricle smaller than left
Bc right pumps short distance (to lungs) and left pumps to all parts of body
Left side thicker walled than right
In properly functioning heart, blood forced in
One direction (result from unidirectional valves preventing backwards flow)
4 heart valves
- Right atrioventricular valve (tricuspid valve)
- Left atrioventricular valve (bicuspid valve)
- Pulmonary semilunar valve
- Aortic semilunar valve
AV valves
- Open when ventricles are relaxed (blood passively fills chambers)
- Closed during ventricular contraction
- Chordae tendinae anchors cusps to walls of ventricles
Semilunar valves
- Closed during relaxation
- Opens during ventricular contraction
Valves open and close in response to
Pressure changes in heart
Arteries vs capillaries vs veins
Arteries: carries blood away from heart
Capillaries: very thin vessels enabling gas/nutrients/waste exchange w tissues
Veins: carry blood towards heart
What are the only vessels enabling exchange between blood and cells of body
Capillaries
Every organ and virtually every tissue in body contains
Capillary network (aka capillary bed)
Two circuits in blood vessels organization
Pulmonary and systemic
Pulmonary circuit
- Passing blood through lungs
- Enters o2 in blood (oxygenation)
- Expels co2 from blood
- Once oxygenated, blood enters heart where pumped back to systemic circuit
Systemic circuit (systemic = systems of body)
- Distributes oxy blood to all tissues in body
- As blood passes, releases o2 and takes co2
- Deoxy blood returns to heart then to pulmonary circulation
Steps of deoxy blood (right side)
- Deoxy blood enters right atrium via inferior/superior vena cava
- Right atrium pumps blood to right ventricle
- Right ventricle pumps to both lungs via pulmonary arteries (they carry deoxy blood)
Steps of oxy blood circulation
- Oxy blood enters left atrium via pulmonary veins
- Left atrium pumps blood to left ventricle
- Left ventricle pumps to rest of body via aorta (largest artery in body)
What is special about pulmonary veins and arteries
Veins : carry oxy blood (unlike rest of veins)
Arteries: carry deoxy blood unlike rest
Aorta branches into what to deliver bood
Arteries, arterioles and capillaries
Once capillaries are deoxy and filled with co2, go back to heart through
Veins, inferior/superior vena cava, heart…
Each heartbeat involves a
Contraction: systole
Relaxation: diastole
Left and right sides contract
Simultaneously (atria together and ventricles together)
As a chamber of heart contracts, bp increases, so
Blood flows out of it (high to low pressure)
Systole phase stages
- Atrial systole
- Ventricular systole
Atrial systole
Atria contracting , ventricles relaxed
As atria contracts, exert pressure on blood which forces through open AV valves into ventricles
Ventricular systole
Ventricles contract, atria relaxed in atrial diastole
P rises inside ventricles and pushes blood out against AV valve, forcing them shut. When P exceeds aorta and pulmonary trunk P, semilunar valves open and blood flows through
Ventricular diastole
Ventricles relax, P inside drops, blood in aorta and pulmonary trunk begin to fall back into ventricles which catches in valves cusps and close semilunar valves
When ventricular P drops below atrial P, AV valves open and ventricular filling begins (atrial systole)
Cardiac excitations begins in sinoatrial (SA) node in right atrial wall. SA node is
Heart pacemaker, sends electric signals 70-80x per min through muscles of atria to contract them
SA node signal reaches atrioventricular (AV) node through conduction along atrial muscle fibers and
Signal enters AV bundle, then the Purkinje fibers conduct signal to ventricular myocardium, then ventricles contract pushing blood to semilunar valves (slide 33)
Atherosclerosis
Sticky substance of cholesterol, fat, calcium, other (plaque) builds up inside walls of arteries
Can put blood flow at risk bc blocked arteries, can lead to clots
Usually cause of heart attacks and strokes
Myocardial infraction (heart attack)
Blood supply decreases/stops to a portion of myocardium
No blood supply=no o2 supply so heart muscle damage and begin to die
Ischemic stroke
Blood supply to part of brain is blocked/reduce
Prevents brain tissues from o2 and nutrients, brain cells die in minutes
Hemorrhagic stroke
Bv in brain leaks or bursts -> bleeding in brain, P on brain cells increases and damages them
