- One heartbeat lasts about 0.85 seconds and includes atrial contraction, ventricular contraction, and relaxation of all chambers.
- The first sound "LUBB" is caused by the closure of tricuspid and bicuspid valves at the start of ventricular contraction.
- The second sound "DUP" is due to the closure of semilunar valves at the start of ventricular relaxation.
- Smaller animals and newborns have faster heart rates because of higher metabolism and heat loss.
- The full sequence of contraction and relaxation in a heartbeat is called the cardiac cycle.
Definitions [15]
Definition: Diffusion
Diffusion is the free movement of molecules of a substance (solute or solvent, gas, liquid) from the region of their higher concentration to the region of their lower concentration when the two are in a direct contact.
Define diffusion.
Diffusion is the free movement of molecules of a substance (solute or solvent, gas, or liquid) from the region of their higher concentration to the region of their lower concentration when the two are in direct contact.
Example: Perfume fills a whole room.
Definition: Active Transport
Active transport is the passage of a substance (salt or ion) from its lower to higher concentration through a living cell membrane using energy from the cell. [Active transport is in a direction opposite to that of diffusion.]
Define the following term:
Active transport
Active transport is the passage of a substance (salt or ion) from its lower to higher concentration through a living cell membrane using energy from the cell. Active transport is in a direction opposite to that of diffusion.
Definition: Imbibition
Imbibition is a phenomenon by which the living or dead plant cells absorb water by surface attraction.
Define the following term:
Imbibition
Imbibition is a phenomenon in which living or dead plant cells absorb water by surface attraction.
Definition: Guttation
The loss of water in the form of tiny droplets from the tips or edges of leaves, especially during early morning, due to high root pressure is called guttation.
Define root pressure.
During the absorption of water, the continuous flow of water develops hydrostatic pressure in the living cells of the root. This is called root pressure.
Definition: Root Pressure
The pressure developed in the roots due to cell-to-cell osmosis that helps push water upward through the xylem is called root pressure.
Define the following term:
Blood
Blood is a fluid that circulates in the heart, arteries, capillaries, and veins of vertebrate animals. It transports nutrients and oxygen throughout the body and removes waste.
Define the Veins.
Veins are the blood vessels that carry deoxygenated (impure) blood from the body cells to the heart.
Define the Circulatory system.
The circulatory system is a transport system moving substances throughout our body with the help of blood.
Define the Arteries.
Arteries are the blood vessels in which oxygenated blood is going away from the heart to all parts of the body.
Define portal vein.
A portal vein is one that starts with capillaries and also ends in capillaries.
Definition: Cardiac Cycle
The complete sequence of events that occurs during one heartbeat, including contraction and relaxation of the atria and ventricles, is called the cardiac cycle.
Key Points
Key Points: Circulation of Blood in the Heart
- The cycle begins with atrial contraction (atrial systole) while the ventricles are relaxed; blood flows easily from atria into ventricles through open cuspid valves.
- As ventricles contract (ventricular systole) and atria relax, pressure closes the cuspid valves, preventing blood from flowing back into the atria.
- Chordae tendinae, attached to papillary muscles, hold the cuspid valve flaps in place and prevent their inversion during ventricular contraction.
- Blood is pushed out of the ventricles into the pulmonary artery and aorta through semilunar valves, which open under pressure from below.
- When ventricles relax again, blood tends to return, but the semilunar valves fill and close, preventing backflow into the heart.
Key Points: Heart Beat
Concepts [14]
- Transport System in Plants
- Diffusion
- Active Transport
- Imbibition
- Factors Affecting the Rate of Transpiration
- Root Pressure
- Uptake of Minerals
- Forces Contributing to Ascent of Sap
- Blood
- Functions of Blood
- Blood Circulatory System
- Circulation of Blood in the Heart (Functioning of Heart)
- Types of Closed Circulation
- Heart Beat
