LMS

Heartbeat starts when the sino-atrial node sends out electrical impulses to the atrial muscles, thus causing both atria to contract. Then conductance from the S-A node to A-V node takes place and A-V node spreads impulses to wall of ventricles for ventricular contraction.

Electrical impulses are generated by pacemaker which initiate heart beat.

P wave: Atrial depolarizationQ R S: Ventricular depolarizationT wave: Ventricular repolarization

Maximum force is generated by left ventricle so the blood vessel most near to it will have highest pressure of blood.

Maximum oxygen will be present in blood before it reaches the tissues where exchange of materials take place.

Pulmonary artery carries deoxygenated blood towards heart while pulmonary vein carries oxygenated blood towards heart.

Capillaries are not elastic and muscular. They are made up of a single layer of cells.

Arteries carry blood away from heart towards tissues while veins carry blood towards heart from tissues.

The change in diameter of blood vessels is done by contraction of smooth muscles which are controlled by both nervous and hormonal control.

The arteries that provide blood to heart do not arise from arch of aorta or descending aorta.

First artery is coronary artery that supplies blood to heart.

Atherosclerosis involves deposition of lipoid material in the inner most layer of arteries along with hardening of middle layer which can lead to cardiovascular problems.

Normal blood pressure range is 120/80 mmHg

Pressure is due to elasticity of the vessels and capillaries do not have elasticity power, that’s why difference becomes zero.

The function of lymphatic system is to return fluid back to blood in vessels that carry blood towards heart.

Interstitial fluid is formed due to leakage of plasma as blood cells cannot cross capillaries.

Circulatory system transports materials to tissues whereas urinary system is involved in removal of nitrogenous wastes.

Digestive system has lymphoid masses in mucosa and submucosa.

Destruction of pathogens through body fluids is done by antibodies as they are released in body fluids.

T lymphocytes mature in Thymus and B lymphocytes were firstly discovered from the Bursa of fabricius.

1st line defense consists of physical barriers (Mucous membrane, skin and blood clot) and chemical barriers (HCl, tears and saliva).

See the V region in diagram

Anti-tetanus serum produces such immunity which is induced when high levels of antibodies specific to a pathogen or toxin are transferred to non-immune persons. 

Facilitated transport is passive transport which is done by carrier proteins present in cell membrane. It is done according to concentration gradient. So uphill movement is not done during facilitated transport.

Dry wood has cellulose, pectin and lignin that take up water and increase the volume. These components don’t dissolve in water.

Symplast is the system of interconnected protoplasts in the root cells. The cytoplasm of neighboring cells(Protoplasts) is connected with one another by Plasmodesmata which are cytoplasmic strands that extend through pores in adjacent cell walls.

Wilting appears when the amount of water lost from the plant during transpiration is greater the amount of water absorbed from the soil.

The total water pulled up in the leaves is transpired, except about 1% which is used by plant in various activities including photosynthesis. 1% of 10 liters is 0.1 liter.

Water is found in the spaces between the soil particles. Water and mineral salts first enter through the cell wall and cell membrane of the root hair cell, only when the concentration of solute sap is high, by osmosis. 

The ascent of sap in the xylem tissue of plants is the upward movement of water and minerals from the root to the aerial parts of the plants. 

The uptake of minerals by the root hair cells is a combination of passive and active uptakes, involving simple diffusion, facilitated diffusion, and active transport.

Factors affecting absorption of water in plants are:Available soil waterConcentration of soil solutionSoil airSoil temperatureIncreased rate of transpiration

Tension is between the molecules of water by hydrogen bonding and is provided when water chain is pulled up in the xylem and the necessary force is provided by the transpiration.

Composite of honey dew drop is 10-25% dry mater, 90% or more of it is made by sucrose and nitrogenous compounds are 1%.

The pressure flow hypothesis, also known as the mass flow hypothesis, is the best supported theory to explain the movement of sap through the phloem. Movement of phloem sap occurs by bulk flow from source to sink.

Water forms 90% of plasma and 10% are dissolved substances out of which 7-9% are proteins and rest are other substances.

Site of production of RBCs is bone marrow while the recycling occurs in a lymphoid mass.

Among blood cells only erythrocytes are pigmented.

Lymphoid stem cells give rise to lymphocytes.

Atrio ventricular valves are attached to muscular extensions of walls of ventricles by fibrous cords called chordae tendinae.

Systemic circulation starts with the pumping of oxygenated blood to whole body.

ECG is the measure of electrical rhythm of heart and it can help in diagnosis of problems related to conduction system of heart.

P wave: Atrial depolarizationQ R S: Ventricular depolarizationT wave: Ventricular repolarization