Cardiovascular system 2: blood vessels and the heart Flashcards
Name the two types of circulation in the body
- Systemic circulation - blood pumped from the heart around the body, and back again.
- Pulmonary circulation - blood pumped from the heart to the lungs, and back again.
Name the 3 main types of blood vessels…
- Arteries
- Veins
- Capillaries
Which blood vessel specialises in the exchange of substances between blood and cell/tissues?
The capillaries
Which blood vessels carry blood away from the heart?
Arteries and arterioles
arterioles are smaller arteries
Which blood vessels carry blood toward the heart?
Veins and venules
Except the pulmonary and umbilical blood vessels describe the blood content and pressure of both Arteries/arterioles and Veins/venules
Arteries and arterioles are oxygenated with high pressure
Veins and venules are Deoxygenated with low pressure
Most blood vessels are formed of three layers. Name the three layers and their positions.
- Tunica Externa - outermost layer made of collagen and elastic fibres.
- Tunica Media - middle layer of smooth muscle, controls diameter of blood vessel and therefore blood pressure.
- Tunica Intima - innermost layer made of endothelium. This layer is in direct contact with the blood and is well positioned to respond to changes.
The thickness (and presence) of each layer depends on the type of blood vessel. Give a structural characteristic for each type; 1. Arteries and arterioles, 2. Veins and Venules, 3. Capillaries
- Arteries and arterioles have a THICKER Tunica MEDIA, and are hence more MUSCULAR
- Veins and venules generally have THIN WALLS. The Tunica EXTERNA is their THICKEST layer.
- Capillaries contain ONLY an ENDOTHELIUM.
Fill in the missing words.
Arteries contain large portions of 1.______ tissue. 2._______nerve fibres innervate 3._____ muscle and cause 4._________, which increases blood pressure.
If reduced sympathetic activity, 5._____ _____ is released which causes vasodilation.
- elastic
- sympathetic
- smooth
- vasoconstriction
- Nitric dioxide
Why are arterioles vital for maintaining blood pressure?
Because there are a large volume of arterioles which constrict or dilate depending on the sympathetic nerve activity. (the smooth muscle constricts)
Veins have a low blood pressure, name 3 ‘actions’ which aid the return of venous blood to the heart.
- Skeletal muscle contraction
- Pumping action of the heart
- Respiratory pump - (the diaphragm when breathing)
*(Veins also contain valves which prevent back flow of deoxygenated blood)
How many layers do Capillaries have (name them)
Capillaries only have ONE layer of cells - endothelium
Fill in the missing words…
Capillaries function in the 1._____ of substances between 2.____and 3.____. Found near every cell in the body. Tissues with a high 4._______ demand have 5._____ capillary networks.
- exchange
- blood
- cells
- metabolic
- extensive
The key function of the cardiovascular system is to keep blood flowing through capillaries to allow the exchange of …. name 3 and their forms of transport (osmosis etc)
- Water - by osmosis
- Nutrients - by facilitated diffusion and active transport
- Gases - carbon dioxide and oxygen by diffusion down the gradient
Where is your blood? Give an approximate percentage for each vessel. 1. Veins/Venules
2. Arteries/arterioles 3. Pulmonary vessels 4. Capillaries 5. the heart
- 64% in systemic veins/venules
- 13% in systemic arteries/arterioles
- 9% in pulmonary vessels
- 7% in capillaries
- 7% in the heart
All blood vessels have smooth muscles (except capillaries) which are influenced by the autonomic nervous system. Name the two systems and their cause.
- SYMPATHETIC nervous system stimulation causes vasoconstriction (increasing the blood pressure)
- PARASYMPATHETIC nervous system has little influence. Vasodilation reduces blood pressure.
How big is the heart and how many times a day does it beat?
The heart is a fist-sized muscular organ that beats approx 100,000 times a day.
How many miles of blood vessels does the heart pump blood through within the human body.
60,000 miles of blood vessels
What is the approximate size of the average heart?
And what is the average mass in grams of the female and male heart?
12cm long, 9cm wide.
Average mass: 250g in females, 300g in males.
Where is the heart situated? (use correct terminology)
The heart rests on the diaphragm near the midline of the thoracic cavity, pointing left.
Where is the apex of the heart and what forms it?
The Apex of the heart is formed by the left ventricle and lies in the fifth intercostal space.
Name the three layers of the heart…
- Pericardium
- Myocardium
- Endocardium
Where is the pericardium layer of the heart, describe its characteristics and main function.
- Pericardium is the outer layer of the heart.
- Thin, double layered membrane. Contains a fibrous pericardium that attaches to the diaphragm and an inner serous pericardium that consists of a visceral and parietal layer.
- Functions to keep the heart in position within the thorax and allow free movement during contractions
Where is the myocardium layer of the heart, describe its characteristics and main function
- middle layer
- Consists of cardiac muscle and makes up 95% of the heart
- functions to pump blood out of the heart
Where is the Endocardium layer of the heart, describe its characteristics and main function
- Innermost layer
- Thin layer of endothelium overlaying a thin layer of connective tissue
- Provides a smooth lining for the heart chambers (also covers heart valves)
Fill in the missing words…
The thickest layer of the heart is the 1.______ making up 95% of the heart. The myocardium is formed of 2._______ _______, this is striated and 3.________.
- Myocardium
- Cardiac Muscle
- Involuntary
Name the FOUR heart chambers in order of blood flow…
- Right Atrium
- Right Ventricle
- Left Atrium
- Left Ventricle
How thick is the right Atrium, where and what type of blood does it receive and where does it pump blood?
The right atrium is:
- 3mm thick.
- Receives deoxygenated blood from superior and inferior vena cava.
- Pumps blood into the right ventricle through the tricuspid valve
How thick is the right Ventricle, where and what type of blood does it receive and where does it pump blood?
The right ventricle is:
- 5mm thick
- receives deoxygenated blood from the right Atrium
- Pumps blood to the lungs through the pulmonary valve into the pulmonary trunk which divides into the left and right pulmonary arteries.
How thick is the left Atrium, where and what type of blood does it receive and where does it pump blood?
The left atrium is:
- 3mm thick
- receives oxygenated blood from the lungs via the pulmonary vein
- pumps blood to the left ventricle through the mitral/bicuspid valve
How thick is the left Ventricle, where and what type of blood does it receive and where does it pump blood?
The left ventricle is:
- 10 to 15mm thick
- receives oxygenated blood from the left atrium
- pumps blood through the aortic valve into the ascending aorta, which is then pumped around the body (Some of the blood in the aorta flows into the coronary arteries which carry blood to the heart wall).
The myocardium performs periodic contractions through a network of cardiac fibres that are self excitable (auto rhythmic) Name the two nervous systems that increase and decrease rate and strength of contraction.
- Sympathetic nervous system
2. Parasympathetic nervous system
What is the Sinoatrial node? (SA node) and where is it located?
The SA node is the pacemaker of the heart, that sets rate and rhythm of contraction.
It initiates cardiac conduction, and is located in the right arterial wall.
Name the five parts of the conduction system of the heart…
- Sinoatrial Node (SA node)
- Atrioventricular Node (AV node)
- Atrioventricular Bundle (bundle of His)
- Right and left bundle branches
- Purkinje fibres
What is the Atrioventricular Node and where is it located?
A relay station - conducts impulses once the atria has finished contracting. It is located in the bottom right of the interatrial septum (the wall of tissues that seperates the right and left atria of the heart)
What is the Atrioventricular Bundle?
The only site where action potential can conduct from the atria to the ventricles.
What are the right and left bundle branches in regards to the conduction system of the heart?
The left bundle branch conducts impulses to the left ventricle, and the right bundle branch conducts impulses to the right ventricle.
They are offshoots of the ‘bundle of His’ in the heart’s ventricle. They play an integral role in the electrical conduction system of the heart by transmitting cardiac action potentials from the bundle of His to the Purkinje fibers.
What do Purkinje fibres do?
The Purkinje fibres rapidly conduct the action potential beginning at the apex of the heart, up the remainder of the ventricular myocardium causing ventricular contraction.
What type of organ is the cardiac muscle?
Aerobic organ
What percentage of body weight does the heart account for, and what percentage of total body oxygen does it consume?
1% of body weight
10% of total body oxygen consumption
What are the predominant fuel in cardiac muscle (50-70%)
And which fuel is used 30% of the time
Predominant fuel are Fatty acids
Followed by glucose
During exercise the heart can use what, to produce ATP.
Lactic acid
What does ECG stand for and what does it do?
Electrocardiography
An ECG amplifies the electrical currents generated by the action potentials in the heart that can be detected on the surface of the body.
ECG - What does the P wave represent?
P wave represents atrial depolarisation (from the SA (sinoatrial) node over the atria)