Circulatory System Flashcards
types of circulatory system:
close circulatory system - blood closed at all times within vessels of different size and wall thickness
open circulatory system - common mostly in anthrops and mollusks
Specific Functions of the Circulatory System:
- distribution of nutrients
- transportation and exchange of oxygen and carbon dioxide
- removal of waste materials
- distribution of endocrine secretions
- prevention of excessive bleeding
- prevention of infection
- regulation of body temperature
The cardiovascular system:
consists of heart and blood vessels that send blood to:
lungs for oxygen
digestive system for nutrients
CV system also circulates waste products to certain organ systems for removal from the blood
The Heart: Structures
- Cone-shaped organ about the size of a loose fist
- In the mediastinum
- Extends from the level of the second rib to about the level of the sixth rib
- Slightly left of the midline
Covers the heart and large blood vessels attached to the heart
Pericardium
- Innermost layer
- Directly on the heart
Visceral pericardium
Layer on top of the visceral pericardium
Parietal pericardium
Heart walls:
Epicardium
* Outermost layer
* Fat to cushion heart
Myocardium
* Middle layer
* Primarily cardiac muscle
Endocardium
* Innermost layer
* Thin and smooth
* Stretches as the heart pumps
Four chambers:
Two atria
* Upper chambers
* Left and right
* Separated by interatrial septum
Two ventricles
* Lower chambers
* Left and right
* Separated by interventricular septum
prevents blood from flowing back into the right atrium when the right ventricle contracts
Tricuspid valve
prevents blood from flowing back into the left atrium when the left ventricle contracts
Bicuspid valve
prevents blood from flowing back into the right ventricle
Pulmonary valve
prevents blood from flowing back
into the left ventricle
Aortic valve
Cardiac Cycle
Influenced by:
- Exercise
- Parasympathetic nerves
- Sympathetic nerves
- Cardiac control center
- Body temperature
- Potassium ions
- Calcium ions
First Sound
Lubb
Second sound
Dubb
Wall of the right atrium: Natural pacemaker
and sends impulse to AV node
Sinoatrial node (SA node)
Between atria just above ventricles that sends impulse to the bundle of His
Atrioventricular node (AV
node)
Between ventricles
Two branches
Sends impulse to Purkinje fibers
Bundle of His
- Lateral walls of ventricles
- Ventricles contract
Purkinje fibers
Group of structures that send electrical impulses through the heart
Cardiac Conduction System
Arteries
- Strongest of the blood vessels
- Carry blood away
from the heart
Under high pressure
* Vasoconstriction
* Vasodilation
Small branches of arteries
Arterioles
Takes blood from the heart to the body
Aorta
Supply blood to heart muscle
Coronary arteries
Veins
Blood under no pressure in veins
* Does not move very easily
* Skeletal muscle contractions help move blood
* The sympathetic nervous system also influences the pressure
- Valves prevent backflow
Capillaries
- Branches of arterioles
- The smallest type of blood vessel
- Connect arterioles to venules
- Only about one cell layer thick
- Oxygen and nutrients can pass out of a capillary into a body cell
- Carbon dioxide and other waste products pass out of a body cell into a capillary
How do arteries control blood pressure?
The muscular walls of arteries can constrict to increase blood pressure or dilate to decrease blood pressure.
Blood Pressure
Force blood exerts on the inner walls of blood vessels
* Highest in arteries
* Lowest in veins
- Ventricles contract
- Blood pressure is at its greatest in the arteries
Systolic pressure
- Ventricles relax
- Blood pressure in arteries is at its lowest
Diastolic pressure
It is located in the aorta and carotid arteries. It also help regulate blood pressure
Baroreceptors
What is the difference between the systolic pressure and diastolic pressure?
systolic pressure: contraction of ventricles increasing the pressure in the arteries.
diastolic pressure: the result of the relaxation of the ventricles lowering the pressure in the arteries.
Pulmonary circuit
right atrium 🡪 right ventricle 🡪 pulmonary artery trunk 🡪 pulmonary arteries 🡪 lungs 🡪 pulmonary veins 🡪 heart (left atrium)
Systemic circuit
left atrium 🡪 left ventricle 🡪 aorta 🡪 arteries 🡪 arterioles 🡪 capillaries 🡪 venules 🡪 veins 🡪 vena cava 🡪 heart (right atrium)
Carry oxygen-rich blood away from the heart
Arterial system
Carries oxygen-poor blood toward the heart
Venous system
Collection of veins carrying blood to the liver
Hepatic portal system
carry oxygen-poor blood
Pulmonary arteries
