Transport in Animals Key Terms and Processes Flashcards
Describe cardiac muscle
- cardiac cells are connected by intercalated disks which both transmit the force of a contraction and allows the rapids spread of depolarisation from one cell to another (electrical excitation) so all the muscle cells operate as one unit
Depolarisation
Myocardium is made up of cardiac muscle fibres, when the muscle fibre is excited through the electrical activity, it is called depolarisation, it starts at the atrium and spreads all over the heart and ends at the apex.
Repolarisation
After complete depolarisation, the heart muscle will be relaxed for a while, this is repolarisation
Function of the:
Coronary Artery
1st branch of the aorta, provides oxygenated blood to the cardiac muscle
Function of the:
Cardiac Muscle
The cells will contain numerous mitochondria (to provide ATP) and myoglobin. Cells arranged in long columns to form a fibre, cells are myogenic
Function of the:
Septum
This separates the two sides of the heart, to prevent mixing of oxygenated and deoxygenated blood
Function of the:
Tendinous Cord
These insert into the ventricle wall, are v, tough and prevent what they’re attached to from turning inside out
Function of the:
Left Ventricle
Blood passes into this chamber before being pumped out through the aorta, blood is under high pressure, so the wall is very thick and muscular
Function of the:
Left Atrium
Oxygenated blood from the lungs enter via the pulmonary vein
Function of the:
Right Atrium
Deoxygenated blood in the vena cava passes into this chamber, it is under low pressure
Function of the:
Right Ventricle
Blood passes into this chamber before being pumped out into the pulmonary artery going to the lung
Function of the:
Tricuspid Valve
This thin bit of tissue prevents blood from flowing backwards when the blood underneath it exerts a high pressure causing it to stay shut
Function of the:
Semi-Lunar Valve
This thin bit of tissue prevents blood from flowing backwards into the ventricles when they relax in the cardiac cycle
Open Circulatory System
- Blood flows freely in body cavity
- Pumped by the heart
- In contact with body cells
Closed Circulatory System
- Blood enclosed in blood vessels, no direct contact with body cells
Single Circulatory System
- Blood flows through the heart once during each circulation of the body
Double Circulatory System
Blood flows through the heart twice for each complete circulation of the body
Pulmonary Circulation
Circuit carrying blood to and from the lungs
Systematic Circulation
Circuit of blood carrying blood around the body to the tissues
Systole
The period of contraction of the heart, especially of the ventricles, during which blood is forced into the aorta and pulmonary arteries
Diastole
The period of relaxation of the heart, where the blood passively fills the atria of the heart
Bradycardia
- Pattern of electrical activity is normal but slow
- A reduced heart rate could indicate; good aerobic fitness, drugs (tranquilisers), but patient may be at risk of stagnation and blood disease if not investigated into
Fibrillation
- Contraction of cardiac muscle is usually coordinated, the ventricle fibrillation. the ventricles contract but it is uncoordinated, this is felt as fluttering, and little blood is pumped.
- Defibrillation may work; the heart is shocked, the heart stops and is restarted, hopefully with a regular, coordinated heartbeat
Tachycardia
- An elevated heart rate for no reason, sometimes heart rate is so high, little blood is being pumped round the body
- Treatment can include relaxation therapy or taking beta blockers
Ectopic Heartbeats
These heartbeats are small changes in an othewise normal heartbeat, there are two types:
- premature ventricular contractions (PVC)
- premature atrial contractions (PAC)
Causes could include :
- changes in blood, eg low potassium levels
- decrease in blood supply to the heart
- if the heart is enlarged
it can also also be caused by smoking, alcohol use, caffeine, stimulant medicines and some street drugs
Cardiac Cycle
Right Side
-deoxygenated blood enters the right atrium of the heart from the upper body and head in the superior vena cava, and from the lower body in the inferior vena cava, at a relatively low pressure
- as the blood flows in, pressure builds up until the atrioventricular valve (tricuspid) opens to let blood pass into the right ventricle
- when both the atrium and ventricle are filled with blood, the atrium contracts, forcing all the blood into the right ventricle, stretching the ventricle walls
- as the right ventricle starts to contract, the tricuspid valve closes, preventing any backflow inbto the atriujm
-the tendinous cords make sure the valves do not utnr inside out due to pressure exerted when the ventricle contracts
- the right ventricle contracts fully and pumps deoxygenated blood through the semilunar valves into the pulmonary artery, which transports it to capillary beds of the ungs
- the semilunar valves prevent the back flow of blood
-
The Cardiac Cycle
Left Side
- oxygenated blood from the lungs neters the left atrium from the pulmonary vein
- as pressure in the atrium builds, the bicuspid valve opens between the left atrium and the left ventricle
- the ventricle fills with oxygenated blood
- when both the atrium and ventricle are filled with tblood the atrium contacts to force any additional blood into the ventricle
- the left ventricle then contracts and pumps oxygenated blood through the semi-lunar valves into the aorta and around the body
Why is the left side of the heart so much thicker than the right?
The left side is significantly more muscular as the left side has to produce sufficient force to overcome the resistance of the aorta and the arterial systems of the whole body and move the blood under pressure to all the extremities of the body
