The Heart Flashcards
Open circulatory system
Heart pumps blood into vessels that are opened
Blood flows around all the cells of the body
Insects
Advantages of closed circulatory system
Blood pumped around the body faster
Blood pumped in different restes in different parts as required
Arteries
Away from heart High pressure Thick, strong walls Small lumen No valves Divided into arterioles Blood in pulses Oxygenated
Veins
To heart Low pressure Thin, weaker walls Large lumen Valves Divided into veniole No pulse Deoxygenated Prevents back-flow and stores blood
Function of capillaries
One cell thick for Exchange of materials
E.g. gases, foods
Blood Pressure
The force the blood exerts on the wall of the blood vessels
Advantages of double circulation
Keeps oxygen rich and oxygen poor blood separate
Blood pressure is high enough to reach all parts of the body
Diastole
Heart muscle relaxes
Systole
Heart is contracted
Cardiac Cycle
Blood enters atria by different vessels
The bicuspid and tricuspid valve remain closed
The chambers are relaxed in diastole
Increased volume of blood cause increased pressure in atria
Atria contrast in systole
Valves open and blood flows in ventricles
Atria relaxes and ventricles filled with blood contract
Bicuspid and tricuspid valve close and semi-lunar valves open
Blood is pumped out to the lungs and body
Ventricles relax and semi-lunar valves close
Cycle starts again
Pacemaker
- Sino-atrial node
- Wall of the right atrium near the entrance of the vena cava
- Control the rate of heartbeat
- Sends out electrical impulses to cause atria to contract
Closed circulatory system
Blood remains in a continuous system of the vessels and exchange materials through the cell of blood vessels
Human
Transports blood out of the muscles of the heart
Cardiac vein
Carries very little CO2
Pulmonary vein
Doctor
Brings blood into the right atrium
Vena cava
Hepatic portal vein
Links liver with stomach and intestines
Movement of blood through veins
Voluntary muscles contract
Valves prevent backflow
Pulse
The alternate contraction and relaxation of an artery as blood passed through it
Heart beat
Regular, rhythmic contraction of the heart
Blood pressure
The force the blood exerts on the wall of the blood vessels
Which structure is carbon dioxide produced
Mitochondrion
Why do veins have CO2
Veins has collected carbon dioxide from respiration
Arteries has been cleared of CO2 in lungs
Role of carbon dioxide in breathing system
Medulla oblongata registers blood carbon dioxide levels
More CO2 results in faster breathing
Name of two circuits
Systematic circuit
Pulmonary circuit
Systematic circuit
Carries blood away from heart
Delivers it to most of organs and tissues
Returns it to heart again
Pulmonary circuit
Carries blood between heart and lungs
Diet
• High in saturated fats
Increases blood pressure and atherosclerosis, causes a build up of cholesterol
• High in salt
Increases blood pressure, salt levels increase in blood volume without increase in circulatory system volume (water is taken in)
Exercise
Stimulates an increase in heart rate and blood pressure
Increases strength of heart
Long term: stronger heart, lower BP
Strengthens cardiac muscle
Smoking
Highly addictive
Nicotine - addictive drug
Causes an increase in heart rate and blood pressure
Can lead to heart disease and stroke
Atrial-ventricular node
- Near the septum wall between the atria and ventricles
* Receives electrical impulses from SA node to control the heart rate
Cardiac Cycle
Stage 1
- Atria receives blood and begins to fill at the same time
- Bicuspid and tricuspid valve remain closed
- Chambers are in diastole
- Increased volume of blood causes increased pressure in atria
- Atria contracts (systole)
Cardiac Cycle
Stage 2
- Bicuspid and tricuspid valve open and blood flows into the ventricles
- Atria relaxes and ventricles now filles with blood contract (systole)
- Bicuspid and tricuspid valve close and semi-lunar valve open
- Blood is forced to pulmonary artery and aorta
- Ventricles relax (diastole)
- Semi-lunar valves close
- Cycle starts again
What are the arteries made from
- Outer layer - collagen (connective tissue)
- Inner layers - elastic tissue and smooth muscle
- Innermost layer is called endothelium
How Pacemaker works
- Pacemaker sends out electrical impulses that cause Atria to contract
- Impulses reach AV node and pulse is strengthened and sent to Purkinje fibers
- Causes wall of ventricles to contract and heart beats
