The cardiac cycle describes the sequence of mechanical events regulated by the heart's electrical activity. The sinoatrial node acts as the natural pacemaker, initiating each heartbeat around 60-80 times per minute by rapidly depolarizing cardiac muscle cells. Electrical impulses then travel to the atrioventricular node and throughout the myocardium, causing atrial contraction. The impulse then reaches the ventricles, triggering ventricular systole. Arrhythmias are irregular heartbeats that can range from harmless to life-threatening, such as ventricular fibrillation where the ventricles quiver ineffectively instead of pumping blood.
Sa nodal action potential, conducting system of heart and spread of cardiac i...Maryam Fida
SA NODE, AV NODE and Purkinje System are specialized cells of the heart having unstable phase IV.
SA Node has no role of Voltage gated sodium channels(although they are present in SA Node) and
so the depolarization in it occurs through voltage gated slow calcium channels
The membrane of SA Node is Inherently leaky to Sodium and Calcium Ions.
It is the Pre Potential Slope or spontaneous slow depolarization which accounts for the Pace maker activity of SA node i.e. Automaticity
It is caused by the inherent leakiness of SA Nodal membrane to Sodium and Calcium leading to influx of Na+ , causing a slow rise in the RMP in the positive direction.
Thus, the “resting” potential gradually rises between each two heartbeats.
When the potential reaches a threshold voltage of about -40 millivolts, the Sodium-Calcium channels become “activated,” thus causing the action potential.
It is the upstroke of action potential
When the membrane potential reaches the thresh hold level i.e. -40 mV, voltage gated slow calcium channels open up leading to influx of calcium causing depolarization
Voltage gated sodium channels has no role in SA nodal depolarization because at the level of -55 mV, the fast sodium channels mainly have already become “inactivated,” which means that they have become blocked.
The cause of this is that any time the membrane potential remains less negative than about -55 mV for more than a few milliseconds, the inactivation gates on the inside of the cell membrane that close the fast sodium channels become closed and remain so. Therefore, only the slow sodium-calcium channels can open (i.e., can become “activated”) and thereby cause the action potential.
Sa nodal action potential, conducting system of heart and spread of cardiac i...Maryam Fida
SA NODE, AV NODE and Purkinje System are specialized cells of the heart having unstable phase IV.
SA Node has no role of Voltage gated sodium channels(although they are present in SA Node) and
so the depolarization in it occurs through voltage gated slow calcium channels
The membrane of SA Node is Inherently leaky to Sodium and Calcium Ions.
It is the Pre Potential Slope or spontaneous slow depolarization which accounts for the Pace maker activity of SA node i.e. Automaticity
It is caused by the inherent leakiness of SA Nodal membrane to Sodium and Calcium leading to influx of Na+ , causing a slow rise in the RMP in the positive direction.
Thus, the “resting” potential gradually rises between each two heartbeats.
When the potential reaches a threshold voltage of about -40 millivolts, the Sodium-Calcium channels become “activated,” thus causing the action potential.
It is the upstroke of action potential
When the membrane potential reaches the thresh hold level i.e. -40 mV, voltage gated slow calcium channels open up leading to influx of calcium causing depolarization
Voltage gated sodium channels has no role in SA nodal depolarization because at the level of -55 mV, the fast sodium channels mainly have already become “inactivated,” which means that they have become blocked.
The cause of this is that any time the membrane potential remains less negative than about -55 mV for more than a few milliseconds, the inactivation gates on the inside of the cell membrane that close the fast sodium channels become closed and remain so. Therefore, only the slow sodium-calcium channels can open (i.e., can become “activated”) and thereby cause the action potential.
ECG analysis on normal sinus rhythm and atrial arrhythmias.pptxcvkrishnapriya575
ECG play a vital role in healthcare industry. Analyzing a ECG is an hectic procedure hence this slide provide simple view about an ECG analysis on normal sinus rhythm and atrial arrhythmiasThe importance of ECG in the healthcare industry cannot be overstated. It is a crucial diagnostic tool that helps doctors and other medical professionals to accurately assess a patient's cardiac health. However, analyzing an ECG can be a complicated and time-consuming process, which is why this slide has been created to provide a simplified overview of ECG analysis for normal sinus rhythm and atrial arrhythmias. With this information, healthcare providers can quickly and easily interpret ECG results and make informed decisions about patient care.The importance of ECG in the healthcare industry cannot be overstated. It is a crucial diagnostic tool that helps doctors and other medical professionals to accurately assess a patient's cardiac health. However, analyzing an ECG can be a complicated and time-consuming process, which is why this slide has been created to provide a simplified overview of ECG analysis for normal sinus rhythm and atrial arrhythmias. With this information, healthcare providers can quickly and easily interpret ECG results and make informed decisions about patient care.
Arrhythmia is also known as irregular heart beats. If SA node is not the pacemaker, any other part of the heart such as atrial muscle, AV node and ventricular muscle becomes the pacemaker. the beats may be fast, slow or miss beats.
The body's balance between acidity and alkalinity is referred to as acid-base balance. The blood's acid-base balance is precisely controlled because even a minor deviation from the normal range can severely affect many organs. The body uses different mechanisms to control the blood's acid-base balance.
Muscle spindles are proprioceptors that consist of intrafusal muscle fibers enclosed in a sheath (spindle). They run parallel to the extrafusal muscle fibers and act as receptors that provide information on muscle length and the rate of change in muscle length. The spindles are stretched when the muscle lengthens. This stretch causes the sensory neuron in the spindle to transmit an impulse to the spinal cord, where it synapses with alpha motor neurons. This causes activation of motor neurons that innervate the muscle. The muscle spindles determine the amount of contraction necessary to overcome a given resistance. When the resistance increases, the muscle is stretched further, and this causes spindle fibers to activate a greater muscle contraction.
Have you ever wondered why you sweat when you get too hot from running or shiver on a cold winter's day in this video we are going to explain why your body behaves like this.
Humans are endotherms and this means we are warm blooded we keep our body operating at thirty seven degrees Celsius regardless of the external conditions however this is a real challenge as our environment changes all the time depending on the weather, our clothes, if we are inside by the fire or outside having a snowball fight. So how does this work?
It's quite similar to the heating system in a house. in a house is a thermostat that measures the temperature if the house gets cold the thermostat will tell the radiators to turn on and heat it up if it's too hot they will be told to switch off simple.
Your body works in just the same way here in your brain as a special area called the hypothalamus and it measures the temperature of the blood flowing through it and also it collects information from temperatures senses around the body. it then decides if the temperature is too hot or too cold and we'll try and bring it back to thirty seven degrees Celsius. If you are too hot the hypothalamus can then send signals out to the body by the nervous system that can cause barriers to fact. It can send a signal to your skin and cool sweat glands to secrete the sweat on to the surface of the skin the sweat itself is not cold but it works because it takes the heat away from your body in order to evaporate it.
Another way of losing is vasodilation let kind of these blood vessels narrows this. That said the skin open white and allow blood to flow through them. They heat is radiated from the blood into the air and the blood cools down. If you get too cold you can do the opposite with these blood vessels and place them on keeping the blood away from the surface of the skin this is called vasoconstriction this is when your muscles contract in order to make. Another fact you may have noticed when you are cold against them. If you look more place the at least the Bulls what you realized is that each of the little bugger has a has to hit out at.
These has stood up on and struck a layer of air around the skin air is a fantastic insulate of heat and this will keep you nice and warm.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
2. Cardiac Cycle
• The cardiac cycle is a sequence of
mechanical events that is regulated by
the electrical activity of the
myocardium.
• Cardiac muscle cells have the ability
to contract spontaneously; that is,
nerve impulses are not required to
cause contraction.
• The heart generates its own beat, and
the electrical impulses follow a very
specific route throughout the
myocardium.
3. • The natural pacemaker of the heart is
the sinoatrial (SA) node, a specialized
group of cardiac muscle cells located
in the wall of the right atrium just
below the opening of the superior
vena cava.
• The SA node is considered specialized
because it has the most rapid rate of
contraction, that is, it depolarizes
more rapidly than any other part of
the myocardium (60 to 80 times per
minute).
4. • As you may recall, depolarization is
the rapid entry of Na ions and the
reversal of charges on either side of
the cell membrane.
• The cells of the SA node are more
permeable to Na ions than are other
cardiac muscle cells. Therefore, they
depolarize more rapidly, then contract
and initiate each heartbeat.
5. • From the SA node, impulses for
contraction travel to the
atrioventricular (AV) node.
• The transmission of impulses from the
SA node to the AV node and to the
rest of the atrial myocardium brings
about atrial systole.
• From the SA node, impulses for
contraction travel to the
atrioventricular (AV) node.
• The transmission of impulses from the
SA node to the AV node and to the
rest of the atrial myocardium brings
about atrial systole.
6. • If the SA node does not function
properly, the AV node will initiate the
heartbeat, but at a slower rate (50 to
60 beats per minute).
• The AV bundle is also capable of
generating the beat of the ventricles,
but at a much slower rate (15 to 40
beats per minute).
• This may occur in certain kinds of
heart disease in which transmission of
impulses from the atria to the
ventricles is blocked.
7.
8. • Arrhythmias are irregular heartbeats;
their effects range from harmless to
life-threatening. Nearly everyone
experiences heart palpitations
(becoming aware of an irregular beat)
from time to time.
• These are usually not serious and may
be the result of too much caffeine,
nicotine, or alcohol. Much more
serious is ventricular fibrillation, a
very rapid and uncoordinated
ventricular beat that is totally
ineffective for pumping blood.
ARRHYTHMIAS
9. • Arrhythmias (also called
dysrhythmias) are irregular
heartbeats caused by damage to
part of the conduction pathway,
or by an ectopic focus, which is a
beat generated in part of the
myocardium other than the SA
node.
ARRHYTHMIAS
10. • Flutter is a very rapid but fairly
regular heartbeat.
• In atrial flutter, the atria may
contract up to 300 times per minute.
Because atrial pumping is not crucial,
however, blood flow to the ventricles
may be maintained for a time, and
flutter may not be immediately life-
threatening.
Atrial Flutter
11. • Ventricular flutter is an
arrhythmia, more specifically a
tachycardia affecting
the ventricles with a rate over
250-350 beats/min, and one of
the most indiscernible.
Ventricular Flutter
12. • Fibrillation is very rapid and
uncoordinated contractions.
Ventricular fibrillation is a medical
emergency that must be quickly
corrected to prevent death.
• Normal contraction of the ventricles
is necessary to pump blood into the
arteries, but fibrillating ventricles
are not pumping, and cardiac output
decreases sharply.
Ventricular Fibrilation
13. • Ventricular fibrillation may follow
a non-fatal heart attack
(myocardial infarction). Damaged
cardiac muscle cells may not be
able to maintain a normal state of
polarization, and they depolarize
spontaneously and rapidly.
• From this ectopic focus, impulses
spread to other parts of the
ventricular myocardium in a rapid
and haphazard pattern, and the
ventricles quiver rather than
contract as a unit.
14. • It is often possible to correct
ventricular fibrillation with the
use of an electrical defibrillator.
This instrument delivers an
electric shock to the heart,
which causes the entire
myocardium to depolarize and
contract, then relax. If the first
part of the heart to recover is
the SA node (which usually has
the most rapid rate of
contraction), a normal heartbeat
may be restored.
