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Circulatory System

- facilitates the exchange of materials
- provides an internal transport system the brings substances and gases close to cells

3 Components of the Circulatory System

1. fluid materials can be transported or dissolved
2. network of vessels/ tubes
3. pump to drive fluid

2 Types of Circulatory Systems

1. Open System
2. Closed System

Open Circulatory System

- insects and plants
- blood is not always enclosed in tubes
- have open-ended vessels
- fluid directly bathes tissues

Closed Circulatory System

- vertebrates
- blood is confined in tubes
- blood is separate from interstitial fluid that directly bathes (surrounds) in tissues

Cardiovascular System

Heart: artery, arteriole
Lungs: capillaries
Heart: venules, veins


- majority carry oxygenated blood (excluding the pulmonary artery)
- lead away from heart


smaller arteries


- smallest blood vessels
- one cell thick
- create venules


- small veins
- come together and form veins


- carry deoxygenated blood (excluding the pulmonary vein)
- bring blood back to heart
- created from venules


- no circulatory or respiratory systems
- cells have direct with environment
- diffusion
- cytoplasmic streaming- cytoplasm is made mostly of water materials, so it moves the material


- no circulatory or respiratory systems
- diffusion
- outer layer- ectoderm
- inner layer- endoderm
- water goes in through mouth, then to gastrovascular cavity, lastly to body wall


- blood carries gases and waste ( blood contains hemoglobin)
- has 5 aortic arches (hearts) which pump blood
- closed circluatory system
- respiratory surface- skin


1. Blood goes to gills
2. Gas exchange occurs
3. Arteries
4. Arterioles
5. Capillaries
6. Deoxygenated blood goes to heart
7. Venules
8. Veins
9. Back to gills
- Closed circulatory system


- open ciculatory system
- only deoxygenated blood
- colorless blood- lacks hemoglobin (transports nutrients and waste, no gases)
- blood goes from dorsel --> anterior. open vessels. low pressure
- blood keeps moving through spaces by breathing and body movements

General Characteristics of the Heart

- double pump
- right side pumps deoxygenated blood
- left side pumps oxygenated blood
- larger than your fist
- located beneath sternum and to the left
- composed of cardiac muscle (only found in heart)
- involuntary (can't make heart contract)
- single celled
- cardiac cells are branched forming an interlocking
- strong to withstand contraction

Heart Structure

- covered by pericardium- tough protective covering
- 4 chambers: Right atrium and ventricle, Left atrium and ventricle
- septum- separates right and left sides preventing the mixing of blood

Patterns of Circulation

1. Pulmonary circuit
2. Systemic Circuit
3. Coronary
4. Renal
5. Hepatic-portal

Pulmonary Circuit

blood flow between heart and lungs

Systemic Circuit

blood flow between heart and rest of body


blood supply to the heart muscle


quarter of blood goes to kidneys to filter waste


- deals with liver
- nutrients are picked up by capillaries in small intestine and are transported to liver
- excess nutrients, such as glucose stored as glycogen, can be stored in liver
- detoxification center

Blood Flow Through Cardiovascular System

1. Deoxygenated blood goes in through inferior and superior vena cavas
2. Right atrium
3. Through tricuspid valve
4. Into right ventricle
5. Pulmonary semilunar valve
6. Pulmonary trunk
7. Pulmonary arteries
8. Lungs
9. Pulmonary veins
10. Left atrium
11. Bicuspid (mitral) valve
12. Left ventricle
13. Aortic semilunar valve
14. Aorta
15. Travels through rest of body back to superior and inferior vena cavas

Cardiac Cycle

- 2 phases- diastolic and systolic
- can have murmurs
- open- lub= semilunar diastoly
- dub= ventricular systoly


- relaxing
- in ventricular diastoly
- atrialventricular valves fill with blood (would be open)
- semilunar valves are closed


- contraction of ventricles
- blood goes to open semilunar valves
- AV valves close to prevent backflow of blood


- valves aren't closing properly and you get a backflow of blood
- can get it through infection (infection= strep throat untreated. bacteria attacks. rheumatic)
- can be present at birth

Control of Heart Rate and Pacemaker

1. Pacemaker generates electric pulse
2. Impulses spread through atria
3. Impulses reach the ventricles

Sinoatrial (SA) Node

- pacemaker
- in right atrium
- specialized group of muscle cells initiates an electrical impulse for the heart to contract

Atrioventricular (AV) Node

- located in septum between atria
- relays the impulse to the muscle cells of ventricles

Artificial Pacemaker

- implanted device to aid pacemaker

Electrocardiogram (ECG/EKG)

QRS- ventricles- signals contraction through electricity
P- atria
T- ventricles relaxing

EKG Rate is Regulated by...

1. Vagus Nerve- slows heart reate
2. Cardioaccelerator- speeds heart rate
3. Epinephrine (adrenaline)- increases heart rate
4. Temperature: hot- speeds up
cold- slows down

Blood Vessels

- pulmonary artery carries deoxygenated blood
- arteries and veins- 3 layers
- epithelium
- smooth muscle
- connective tissue
- vein- smooth muscle is thinner
- have valves (prevent backflow of blood)
- capillaries- one layer = epithelium
- blood vessels branching
- site for diffusion

Skeletal Muscle

- squeezes vein during contraction
- pushes blood upward to heart

Blood Pressure

- the force blood exerts against the wall of blood vessels (from heart to capillaries)
- pressure in arteries is highest
- walls have to stretch


the rhythmic stretching of the arteries caused by the pressure of blood during...


instrument that measures blood pressure
- has 2 numbers : systolic pressure/ diastolic pressure

Systolic Pressure

- pressure during systoly
- artery expands

Diastolic Pressure

- pressure that remains in arteries during diastoly
- artery shrinks


- high blood pressure
- asymptomatic- can't tell if you have hypertension just by looking (can cause stroke)

Pressure in Capillary Beds

- has to be low for blood tostay slow for diffusion
- precapillary sphincters muscles- prevent blood flow through capillaries to get more for other parts of body (ex. happens when you immediately start running)

Pressure in Veins

nearly 0

Vericose Veins

- can be caused with weight gain
- veins stretch
- valves weaken and don't close fully

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