Diyashika Education: Recent Episodes
Diyashika Education
CELL ENVELOPE AND IT’S MODIFICATIONS
- · Bacteria that can take up gram stain is Gram positive bacteria and that does not take up gram stain is gram negative bacteria.
- · Cell envelope has 3 layered structure – outermost glycocalyx followed by cell wall and then plasma membrane. it acts as a protective unit.
-
· Glycocalyx differs in composition and thickness among different bacteria.
-
Slime layer- Made up only polysaccharides. It is a loose sheath.
2.Capsule- Made up of both polysaccharides and polypeptides. It is thick and tough.
- · Cell wall determines shape of cell and provides strong structural support to prevent bacterium from bursting and collapsing.
- · Plasma membrane is semi- permeable membrane interacts with outside world.
- · Mesosome is a special membrane structure formed by extension of plasma membrane into the cell. These are in form of vesicles, tubules, lamellae, help in cell wall formation, DNA replication and distribution to daughter cell.
- · Mesosomes help in respiration, secretion process, to increase the surface area of plasma membrane and enzymatic content.
- · In some prokaryotes called cyanobacteria, there are other membranous extensions into the cytoplasm called chromatophores which contain pigments.
- · Flagellum in bacterial cell helps in motility. Bacterium flagellum has 3 parts – filament, hook, and basal body. The filament is the longest portion and extends from the cell surface outside.
- · Pili and Fimbriae are also present; they do not play any role in motility. The pili are elongated tubular structures made of a special protein.
- · The fimbriae are small bristle like fibers sprouting out of the cell.
TOPIC INDEX BIOLOGY/NCERT/ISBN 81-7450-496-6/P125/8.1
INTRODUCTION TO CELL AND PROKARYOTIC CELLS
- · Cell is the fundamental structural and functional unit of a living organism.
-
· Cell theory states that :-
-
All living organisms are composed of cells and products of cells.
-
All cells arise from pre-existing cells.
-
Cell has dense membrane bound structure called nucleus which contains chromosomes, which in turn contains DNA (genetic material).
- · Cells that have membrane bound nuclei are called as eukaryotic cells, while the cells which lack membrane bound nucleus are called as prokaryotic cells.
- · Eukaryotic cells have other membrane bound organelles like Endoplasmic Reticulim(ER), the golgi complex, lysosomes, mitochondria, microbodies and vacuoles. These are absent in prokaryotic cells.
- · RIBOSOME:- It is a non- membrane bound organelle found in both eukaryotic and prokaryotic cells.
- · Ribosomes are also found in chloroplasts(in plants), mitochondria and on Rough Endoplasmic Reticulum(RER) .
- · CENTRIOLE:- It is a non- membrane bound organelle in animal cells, which hels in cell division.
- · MYCOPLASMAS:- These are smallest cells.
- · Egg of ostrich is largest isolated cell.
- · Nerve cells are some of the longest cells.
PROKARYOTIC CELLS
- · They are represented by bacteria, blue- green algae, mycoplasma and PPLO(Pleuro Pneumonia Like Organism).
- · Smaller and multiply more rapidly than Eukaryotic cells.
- · 4 basic shapes of bacteria- Bacillus(rod like), Coccus (spherical), Vibrio (comma) and spirillum (spiral).
- · Prokaryotes have a cell wall surrounding the cell membrane except in mycoplasma.(Execption)
- · No well defined nucleus.
- · Genetic material is basically naked.
- · Plasmids:- Many bacteria have small circular DNA outside the genomic DNA called plasmids.
- · UNIQUE FEATURE:- A specialized differentiated form of cell membrane called mesosome is the charcterstic feature of prokaryotes. They are infoldings of cell membrane.
Pacemaker
The entire heart muscles are controlled by the heart itself so it is called as myogenic , it does not depend upon CNS for its working.
Heart has specialized cardiac musculature called as nodal tissues, which are distributed in our heart ,which controls heart beating.
SAN (Sino-Atrial Node): SAN is present in the top right corner in right auricle. It is also called as pacemaker also .It is responsible for initiating and maintaining the rhythmic contractile activity of heart.
AVN (Atrio-Ventricular Node): AVN is in the lower left corner of right auricle close to atrio-ventricular septum.
Purkinjie Fibers:These minute fibers extend in the interventricular septum and around left and right ventricles.
Bundle of His: The fibers which divides into purkinje fibers are called as Bundle of His.
Note: Our heart normally beats 72 per min, which is controlled by SAN.
Image source:
https://i.pinimg.com/originals/b4/b3/ba/b4b3ba8b1dc4680fb894d946dba80f73.jpg
Coagulation of blood
Coagulation of blood is also called as clotting of blood. Have you ever seen the formation of brown coloured scum formed on your wound sometimes , that is called as clot. This clotting is done by blood platelets or thrombocytes.
Process
-
The injured tissues or cells release a substance called thromboplastin or thrombokinase (also known as “X -factor” and Straut Factor).
-
Thromboplastin reacts with calcium ions in our body and converts prothrombinase (which inactivates heparin (anti-coagulant)) into prothrombin (inactive form) present in plasma and again with the help of calcium ions, prothrombin is converted into thrombin (active form).
-
Thrombin in the presence of calcium ion reacts with soluble fibrinogen and converts into insoluble fibrin which is thread like structures. Blood cells get trapped in thread like structures.
-
This network then shrinks and squeezes rest of the plasma, free from fibrinogen called as serum.
-
The solid mass which is left is called as clot or thrombus.
Note: If in a person clot does not form then he suffers from disease called as haemophilia , he can even bleed to death. Calcium plays an important role in clotting, so deficiency of calcium should also not be there.
Image source:
https://d2jmvrsizmvf4x.cloudfront.net/TT5G3TeMQleoyne6R6dA_ca.png
Blood flows twice in the heart before it complete one full round: 1. Pulmonary circulation and 2. Systemic circulation. So blood circulation is called as double circulation.
1. Pulmonary circulation: It is the shortest circulation. Pulmonary artery takes blood from right ventricle to lungs, and after oxygenation of the blood in the lungs, pulmonary veins carry blood from lungs to left auricle of the heart.
2. Systemic circulation: It is long circulation. Aorta which divides further into arteries in the body carries blood from left ventricle to whole body and veins in the body collects the deoxygenated blood from whole body and pour back into the heart via venacava.
Note: both types of circulation take place simultaneously.
MEB3: Why blood circulation is also called as double circulation?
MEB3: Explain the types of circulation?
Image source:
https://images.topperlearning.com/topper/tinymce/imagemanager/files/769c203341ee71958573d806676448a55b2a5938238a10.37771893Doublecirculation2.png
Disorders of circulatory system
High blood pressure (Hypertension): High blood pressure occurs when normal blood pressure exceeds 140/90 mm of Hg repeatedly (>120/80mm of Hg) .Hypertension can lead to many other heart diseases or kidney problems.
Coronary Artery Diseases (CAD): CAD occurs due to the deposition of fats, cholesterol and calcium etc, which narrows coronary arteries. If T wave in ECG shows flat then it can lead to Coronary Artery Disease (CAD), which is also known as atherosclerosis which affects vessels that supply oxygen via blood to the heart muscles (Coronary artery).
Angina pectoris: It is a disease in which muscles of heart do not receive proper oxygen supply from the blood. The person suffering from the disease experiences acute chest pain. In common words it is termed as heart attack.
Heart Failure: Heart failure means when heart is not pumping enough blood to the body. It usually occurs due to the congestion of the lungs so it is also called as congestive heart failure.
Note: Heart failure is not same as cardiac arrest( when heart stops beating) or heart attack (heart muscles do not get enough oxygen supply).
Image source:
https://www.cdc.gov/heartdisease/images/coronary-artery-disease-medium.jpg
https://3.imimg.com/data3/SY/NV/GLADMIN-11144303/related_links-images-angina-500x500.png
https://upload.wikimedia.org/wikipedia/commons/thumb/d/d0/Blausen_0486_HighBloodPressure_01.png/310px-Blausen_0486_HighBloodPressure_01.png
18.6 What is atherosclerosis?
18.6 Is heart failure is same as heart attack?
Blood can be grouped by using two groupings ABO grouping, Rh grouping.
ABO Grouping
Antigens are present on the surface of the RBCs .Therefore, ABO grouping depends on the presence of type of antigen on the RBCs, and namely antigens are only A, B. So blood groups are A, B, AB, and O.
A blood group have only A antigens on the surface of the RBC and B blood group have only B antigens on the surface of the RBCs . Since AB blood group have both A and B antigens on the surface of the RBCs and O blood group have no antigens on the surface of RBCs. Therefore, there are only two type of antigens.
Antibodies are the proteins present in the plasma in response to antigens .There are also A and B antibodies only. A blood group have B antibody in plasma and B blood group have only A antibody in plasma. Since AB blood group have no antibody in plasma and O blood group have both A and B antibodies in plasma. Therefore, there are only two types of antibodies.
Blood Transfusion
Donor is the person who gives his blood to recipient. Whereas recipient is a person who takes blood from donor . the transfer of blood from donor to recipient is called as blood transfusion.
Image source
https://www.pmfias.com/wp-content/uploads/2016/03/Blood-Groups-ABO-Grouping.jpg
From above image we can understand that A Blood group can take blood from O and A blood group donors only. B Blood group can take blood from O and B blood group donors only. AB Blood group can take blood from O and AB, A ,B blood group donors . O Blood group can take blood from O blood group donors only.
From above you can see O can give blood to the recipients of every blood groups so it is called as Universal Donor. AB can take blood from all the donors of every blood groups so it is called as Universal Recipient.
Note: if wrong transfusion of blood will be done then antibodies will be produced which will lead to clumping of blood ,it can even lead to death.
Rh grouping
Other type of the antigen which was first found in Rhesus monkey , are also present on the surface of the RBCs of the human beings. there are two types of antigens Rh +ve , Rh -ve. So blood groups are always assisted by +ve,-ve. Check your blood group only, suppose it is O+, A- . Similarly if there would be wrong transfusion then antibodies will be produced, it can lead to death also.
During pregnancy
If the Rh+ve mother carries Rh-ve child then the first delivery will be normal but antibodies will be formed for Rh –ve antigens, but second time if she carries again Rh –ve child ,because the antibodies produced during first pregnancy will destroy the foetus RBCs. And the child will die. But if because of medical treatment the baby takes birth he would be anaemic or would have jaundice .this disease is also called as erythroblastosis fetalis.
ECG is representation of electrical activity of heart during a cardiac cycle. To obtain ECG a patient is connected to a machine that monitors the activity of the heart. Each peak of ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart.
P-Wave :It represents depolarization (or electrical excitation) of atria. It leads to contraction of both the atria (Atrial systole).
QRS-Complex :It represents depolarization of ventricles which initiates ventricular contraction (Ventricular systole).
T-Wave: It represents return of ventricles from excited to normal state (Repolarization). The end of T- wave marks the end of systole.
The heartbeat of a person can be determined by counting the number of QRS complexes that occur in a given time period.
It has a great clinical significance. As if QRS complex becomes wider then it can lead to heart attack or myocardial infarction.
If T wave becomes flat then it can lead to Coronary Artery Disease (CAD) also known as atherosclerosis which affects vessels that supply blood to the heart (Coronary artery).
IMAGE SOURCE: https://upload.wikimedia.org/wikipedia/commons/thumb/9/9e/SinusRhythmLabels.svg/280px-SinusRhythmLabels.svg.png
Human circulatory system is also called blood vascular system. Heart is also called myogenic because it is not operated by CNS ,it control itself by nodes. Heart is situated in the thoracic cavity slightly towards the left in between the lungs this is why left lungs is little smaller than the right one .It has size the of a clenched fist. Structure Heart is protected by double walled membrane called as pericardium which is filled by pericardial fluid which prevents friction between two walls during beating of the heart. Heart has four chambers the upper two chambers are called as auricles and other two are called as ventricles. The auricles are divided by tissue called as auricle septum and The ventricles are divided by tissue called as ventricular septum. Auricles and ventricles are divided by atrio-ventricular valves also called as cuspid valves. Between right auricle and right ventricle there are three cuspid valves also called as tricuspid valve. Between left auricle and left ventricle there are two cuspid valves also called as bicuspid valve .Aorta which is the largest artery in our body and which carries oxygenated blood from left ventricle to whole body also, have valves at its opening in left ventricle called as semilunar valves .Pulmonary artery ,which carries deoxygenated blood from right venticles to the lungs also have valves at its opening in right ventricle called as semilunar valves .Blood is brought to the heart by venacava. Functioning Blood is brought to the heart from upper part of the body by superior venacava and from lower part of the body by inferior venacava. And is poured in the right auricle which is deoxygenated ,then blood is passed to right ventricles which is then pushed into pulmonary artery ,which carries deoxygenated blood to lungs for oxygenation,then from there the blood is carried to the left auricle by the pulmonary viens. Then the blood is poured into left ventricle,the the bood is pushed into aorta ,and the blood is distributed to whole body. Note: Ventricles walls are thicker than auricles espeacially left ventricle because it has to pump the blood to whole body regions which needs pressure since right ventricle carry blood only to lungs which needs quiet low pressure. While pumping blood from auricles into ventricles ,semilunar valves are closed. while pumping blood from ventricles into aorta or pulmonary artery ,cuspid valves are closed, to prevent back flow of blood. Image source https://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Diagram_of_the_human_heart_%28cropped%29.svg/1200px-Diagram_of_the_human_heart_%28cropped%29.svg.png