Contraction of myofibrils within a muscle fiber begins when

Answers

Answer 1

Answer: calcium is released from the sarcoplasmic reticulum

Explanation:

Muscle contraction is the stimulation of sites that produce stress within muscle fibres.

Calcium ions bind to tropomyosin in inducing muscle fibre contraction, exposing active site for Crossbridge formation on actin. Then ATP binds to myosin, transferring the myosin to its high-energy state, freeing the myosin head from the active actin site. Triggering tension-generating sites within muscle fibres.

Hence, the contraction process is initiated with teh relaease of calcium from  sarcoplasmic reticulum.

Answer 2

Contraction of myofibrils within a muscle fiber begins when calcium ions are released from the sarcoplasmic reticulum.

The sarcoplasmic reticulum releases calcium ions to contract muscle fibre myofibrils. Calcium ions are released into the cytoplasm by muscle fibre nerve impulses. Calcium ions bind to troponin on myofibril thin filaments.

Calcium binding to troponin promotes a conformational shift that pushes tropomyosin away from actin filament myosin-binding sites. The exposed myosin-binding sites allow myosin heads to build cross-bridges with actin filaments.

The cross-bridge cycle follows for myosin heads. Myosin heads swivel and create force using hydrolyzed ATP, causing actin filaments to slide through. ATP hydrolysis and calcium ions power cross-bridge cycling, which contracts myofibrils and shortens muscle fibres.

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Related Questions

Microscopic examination of a tissue reveals an open framework of fibers with a large volume of fluid ground substance and elastic fibers. this tissue would most likely come from:____________.
a. inner wall of a blood vessel
b. lungs
c. spleen
d. tissue that separates skin from underlying muscle
e. bony socket of eye

Answers

Answer:

d.

Explanation:

Based on the scenario being described within the question it can be said that this tissue would most likely come from tissue that separates skin from underlying muscle. Also known as the superficial fascia, this is the main coating beneath the skin that is mainly made up of different amount of fat, which also surrounds the bodies organs.

State if the body had been dead for more than or less than 12 hours based on the number of degrees lost (19 degrees). *

Answers

After the first 12 hours, the body loses about 0.39°C (0.7°F) per hour. than 12 hours. you use the rate of 0.78°C per hour to estimate the time of death. Temperature of dead body is 32.2°C (90°F)

Explanation:

This phase is known as algor mortis, or the death chill. Each hour, the body temperature falls about 1.5 degrees Fahrenheit (0.83 degrees Celsius) until it reaches room temperature. At the same time, without circulation to keep it moving through the body, blood starts to pool and settle.

he decrease in body temperature follows a somewhat linear progression: 3  two degrees Celsius in the first hour; one degree each hour thereafter.

Which example is a short-term environmental change?
O
ice age
O
global warming
large asteroid impact
tsunami

Answers

Answer:

tsunami

Explanation:

Final answer:

A tsunami is an example of a short-term environmental change.

Explanation:

A short-term environmental change is a change in the environment that occurs over a relatively brief period of time. Out of the examples given, the tsunami would be considered a short-term environmental change. Tsunamis are powerful ocean waves caused by movements in the seafloor. They often result from earthquakes, volcanic eruptions, or large underwater landslides. While tsunamis can have devastating effects, their impact on the environment is relatively short-lived compared to other examples like global warming or ice ages.

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One more question!
Glucose is an example of a ______ sugar.
simple
complex
starchy

Answers

Glucose is a simple sugar or monosaccharide.

Glucose is a simple sugar :)

A sample of DNA from an unknown organism is analyzed and found to contain histone proteins, more than 2 billion base pairs, and large segments of noncoding DNA. From this information, one can conclude that the organism is:

Answers

Answer:

The correct answer is an eukaryote.

Explanation:

The DNA present in eukaryotes comprises chromosomes bundles, these bundles contain molecules of linear DNA, which is wrapped around the protein, that is, alkaline known as histones. These histones help the DNA to turn into a more composite composition.  

The DNA present in a eukaryote may comprise more than two billion base pairs, and because of the linear characteristic, the DNA within a eukaryote comprises sequences of non-coding DNA known as telomeres found on each terminal of the chromosomes.  

A cross section of a seed is shown.
Which is represented by the letter X?
embryo
seed coat
stored food
leat
S
IL

Answers

Answer:

The correct answer is embryo

Explanation:

The atrial cells and ventricular cells are connected to each other using gap junction so that the wave of depolarization can directly spread from the atrium to the ventricle without the AV node.a.true b.false.

Answers

Answer:

The given statement is true.

Explanation:

The atrial cells and ventricular cells are connected to each other using gap junction so that the wave of depolarization can directly spread from the atrium to the ventricle.  This is true.But, not without using the AV nodes. Through myocytes, the depolarizing waves pass much slower than the atrioventricular cells. AV nodal cells conduct them much faster than the atrial and ventricular cells. This system works as a standby. If there is some problem with the AV node, the atrial and ventricular cells will be able to spread the depolarizing waves with the help of gap junctions and without bothering the AV node.

A man with the autosomal recessive disorder phenylketonuria (PKU) and a woman without PKu heve a son named Peter, who does not have PKU. Peter is curious about whether hs mother is a carrier for PKiu Which fact would allow him to know Peter's matemal grandmother does not have PkU.
1. Peter's maternal grandfather does not have PkU
2. Peters maternal grandfather has PKu
3. Peter submits his own blood semple to a local genotyping lab, which establishes that he is a carrier for Pku
4. Peter's own daughter has PKU

Answers

Answer:

2. Peter's maternal grandfather has PKU.

Explanation:

Such type of the genetic disorder in which two copies of a gene must be mutated at a time is called autosomal recessive disorder such as sickle cell anemia, phenylketonuria, and some other diseases. When a sing copy of a gene is mutated in a person then this disorder is not appeared and the person is called a carrier.  So when a child is born by two carrier parents then there is a chance that a child will be affected if both the parents donate mutated genes. In the case of Peter, since peter does not show this defect this means his maternal grandfather was affected by this disorder.

What is the process of water vapour moving out of the leaves?​

Answers

The process of water vapor moving out of the leaves is known as transpiration. Transpiration is a vital physiological process in plants, whereby water is absorbed by the roots from the soil and transported upwards through the plant's vascular system (xylem) to the leaves. Once in the leaves, water molecules evaporate from the surfaces of specialized cells called stomata into the surrounding air as water vapor.

Transpiration serves several essential functions in plants. Firstly, it facilitates the uptake of water and minerals from the soil, providing necessary nutrients for growth and metabolism. Additionally, transpiration helps to cool the plant by dissipating heat through the process of evaporation. This cooling effect is particularly crucial for plants growing in hot environments, as it helps prevent overheating and maintains optimal physiological conditions.

Stomata, small pores located primarily on the undersides of leaves, control the rate of transpiration. These pores are surrounded by specialized guard cells that can open and close to regulate the movement of gases, including water vapor, into and out of the leaf. When stomata are open, water vapor diffuses out of the leaf into the surrounding air, driven by differences in water vapor pressure between the leaf interior and the external environment.

Factors such as light intensity, temperature, humidity, and wind speed influence the rate of transpiration. Higher light intensity and temperatures generally increase transpiration rates, as they enhance the evaporation of water from the leaf surfaces. Conversely, high humidity levels reduce transpiration rates, as the concentration gradient for water vapor between the leaf and the air is diminished.

Overall, transpiration plays a crucial role in plant water balance, nutrient uptake, and temperature regulation, making it a fundamental process in the physiology and ecology of plants.

How does the loss of bicarbonate due to diarrhea increase the protons in the blood?

Answers

Answer:

Increase of protons (H+) in the blood causes acidosis. These effects decrease hemoglobin’s affinity for oxygen and weakens its capacity to bind and increasing the haemoglobin dissociation.

Loss of bicarbonate stores by diarrhoea or tubular renal waste results in a state of metabolic acidosis leads increased concentration of plasma chloride and decreased concentration of plasma bicarbonate. Decrease in plasma bicarbonate leads to increase in H+ ions causing acidosis.

Carbon cycles between the biotic and abiotic worlds mainly through

Answers

Answer:

your heart

Explanation:

Where does blood go after it leaves the right side of the heart

Answers

Answer: Blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs.

Explanation:

Question 25
4 pts

Artificially transported sand is associated with which type of stabilization?

A. groin
B. seawall
C. beach nourishment
D. relocation

Answers

i believe it is D but i’m not 100%

Answer:

C. Beach nourishment

Explanation:

Beach nourishment the process by which sand lost through erosion or longshore drift is replace by other sources.

Its also known as beach renourishment or replenishment.

In Shorthorn cattle, both red coat color and white coat color are true breeding. Crosses of red cattle x white cattle produce offspring that are uniformly reddish brown but thickly sprinkled with white hairs. This type of coat color is called roan. Crosses of roan x roan produce 1/4 red : 2/4 roan: 1/4 white. What kind of genetic inheritance can explain these results

Answers

Final answer:

The results can be explained by incomplete dominance, where neither allele is dominant and the heterozygous individual displays an intermediate phenotype.

Explanation:

The kind of genetic inheritance that can explain the results of crosses between roan cattle is incomplete dominance. In incomplete dominance, neither allele is dominant over the other, and the heterozygous individual displays an intermediate phenotype. When red cattle (RR) are crossed with white cattle (WW), the offspring have a genotype of RW, resulting in the roan phenotype, which is a mix of red and white hairs.

This type of inheritance is similar to what is observed in snapdragons, where a cross between a homozygous parent with white flowers (CWCW) and a homozygous parent with red flowers (CRCR) produces offspring with pink flowers (CRCW). In both cases, the heterozygous genotype produces an intermediate phenotype.

Enkephalins and endorphins are peptides that act like morphine. True or False

Answers

Answer:

True.

Explanation:

Enkephalins and endorphins are endogenous peptides while morphine is an exogenous peptide.

Enkephalins and endorphins are powerful analgesics 18 to 500 times more than morphine. Hence, morphine is less analgesic than enkephalins and endorphins.

Enkephalins and endorphins act on the  mu, kappa , delta receptors and morphine also acts on the same receptors. All of them has same effects on the body.

Hence, Enkephalins and endorphins are peptides that act like morphine.

Answer:

True

Explanation:

Endorphins are hormones of the body that are internally derived. They are opioid neuropeptides produces in humans and some other animals and are able to bind to opiate receptors. These endogenous peptides are similar to opiod drugs e.g morphines, they help to relieve pain and stress. It can also be referred to as the happy hormone.

Also, enkephalins are endogenous hormones produced in the body. They are opioid pentapeptides and are similar to morphines as they are able to bind opiate receptors. They also help in relieving stress.

You and your partner Amy arrive on scene to find a woman with hives over much of her body. She is wheezing and complaining of difficulty breathing. Her husband says she was stung by a hornet and has no prior history of allergies. What would be the best course of action?

Answers

Answer:

Explanation:

Based on the scenario being described within the question it can be said that the best course of action would be to place a high flow of O2 and rapid transportation if the patient appears to be going into anaphylaxis. Mainly because this is a severe life threatening allergic reaction, that occurs at a moments notice and closes the individuals airway causing breathing to become very difficult.

Consider a hypothetical locus with two segregating alleles (A and B). Population size is small, mutation is absent, and neither of the two alleles has a selective advantage. After a long period of time (many generations), what will occur?a) The population will eventually become monomorphic for one of the two alleles.b) Allele frequencies will cycle over time.c) Balancing selection will maintain both alleles.d) Allele frequencies will change over time, but both alleles will remain.e) Allele frequencies will remain constant.

Answers

Answer:

The preferable option will be - A.

A. The population will eventually become monomorphic for one of the two alleles.

Explanation:

The population will eventually become monomorphic for one of the two alleles because  -

Here mutation is absent. No other allele is allowed to get involved here. The population size is small. As allele A and B are fixed for that population after many generations the population will become monomorphic for that two alleles.

On-center cells: A. are excited by light that falls in the periphery of their receptive field. B. are excited by light that falls in the center of their receptive field. C. are inhibited by light that falls in the center of their receptive field. D. are excited by light that falls across their entire receptive field.

Answers

Answer: B) are excited by light that falls in the center of their receptive field.

Explanation:

There are two types of bipolar cells present in the retina which are differentiated on the way the centres of their receptive fields respond to light. The names of bipolar cells are ON-centre and OFF-centre.

If a light fall at the centre of the receptive field of a bipolar cell, it will experience an exciting effect on that cell, resulting in it being depolarized, it is an ON-center cell.

Hence, the correct option is B.

Final answer:

On-center cells are excited by light that falls in the center of their receptive field. These cells are part of the retina's ganglion cells, which are connected to the photoreceptors through the bipolar cells and contribute to visual contrast and sharpness.

Explanation:

A student asked whether on-center cells are excited by light that falls in the periphery of their receptive field, in the center of their receptive field, or across their entire receptive field, or if they are inhibited by light that falls in the center of their receptive field. The answer to this question is: B. are excited by light that falls in the center of their receptive field.

In the visual system, particularly the retina, there are photoreceptors like rods and cones that respond to light. These photoreceptors connect to bipolar cells, which in turn connect to ganglion cells. These ganglion cells have receptive fields with distinctive on-center and off-center characteristics. On-center cells become excited when light stimulus is applied to the center of their receptive field and become inhibited when the light stimulus is applied to the periphery of the receptive field. This process is part of a complex neural circuitry including photoreceptors, horizontal cells, bipolar cells, and amacrine cells, which helps to enhance the visual contrast and sharpness of the image.

What is a defining characteristic that all protocells had in common?

Answers

Answer:

a surrounding membrane or membrane-like structure

Explanation:

A protocell (or protobiont) is a self-organized, endogenously arranged, spherical array of lipids suggested as a step-stone in the direction of life's origin.  

Protocells are thought to have enabled the reproduction of RNA and hence the exchange of genetic information at a time prior to the advent of DNA and proteins (the world RNA hypothesis).

A common characteristic common in all the protocells is the surrounding membrane through which the exchange of genetic information or proteins takes place.

Final answer:

Protocells, the precursors to modern cells, primarily share two key characteristics: maintaining an internal chemical environment and carrying out fundamental metabolism. This was enabled by their lipid bilayer makeup.

Explanation:

A defining characteristic that all protocells shared is their capacity to maintain a separate internal chemical environment and to carry out primitive forms of metabolism. This was made possible because protocells were likely composed of a lipid bilayer, which allowed them to maintain a separate internal environment from the surrounding medium. Furthermore, they are also believed to have the ability to carry out basic metabolic processes.

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Which is the SIMPLEST level of organization in a human being?

Answers

Answer: Cells? If not this, then probably atoms, but most likely cells.

Explanation: Everything in the human body is made of cells. All cells are made of atoms.

Atoms, we are made up of atoms

What are the most common symptoms of
musculoskeletal diseases and disorders?

Answers

Answer:

Common symptoms of musculoskeletal disorders include pain, weakness, stiffness, joint noises, and decreased range of motion. Inflammation may cause pain, swelling, warmth, tenderness, impaired function, and sometimes redness of the overlying skin.

Includes Diseases: Rheumatoid arthritis

Explanation:

Answer:

Common symptoms of musculoskeletal disorder includes pain, stiffness, weakness, swelling, and motion range decreases.

Explanation:

Musculoskeletal disorder is combination of Muscles and skeleton.

It is a disorder that affect the body movement.

For e.g. tendon strain (disease) is an example.

A close friend has joined a clinical trial. When you ask her about the types of treatment she might be given, she tells you that neither she nor the doctor running the trial will know until the process has been completed. What type of trial has she joined?

A. double-blind
B. peer reviewed
C. unsafe
D. theoretical
E. epidemiological

Answers

Answer:

A. double-blind

Explanation:

Based on the scenario being described within the question it can be said that the type of trial that she has joined is known as a double-blind study. This is a type of study in which individuals are chosen randomly for each clinical intervention and the results are not given to the researchers until after the trial. This also includes any and all information that may influence the researchers behavior or thoughts on the study.

Answer:

A. double-blind

Explanation:

In Medicine, Double-blind study is a type of trial in which neither the patient nor the doctor running the trial will know until the process has been completed.

It is usually aimed at preventing bias in a scientific research or experiment to the placebo effect.

Which of the following planets is a terrestrial planet with an iron and nickel core? Saturn Jupiter Mars Neptune

Answers

Answer:

Mars

Explanation:

Proccess of elimination:

Mars is the only terrestrial planet of the 4 options; the rest are Jovian Planets

Answer: I believe it’s Mars

Explanation:

A female zebra finch reared by a father with a red feather taped to his head will select a mate with a similar ornament over an unornamented male. What are plausible ultimate explanations for this behavior (i.e., why it occurs in the context of natural selection)?1.Zebra finches are able to perceive ornamentation on other birds.2.A female zebra finch learns to recognize suitable mates by observing her father.3.A female zebra finch that chooses a mate that resembles her father is more likely to reproduce successfully.

Answers

Answer: 3.

Explanation:

The concept is based on sexual imprinting which results from selection for recognition of conspecifics.

Sexual imprinting is the mechanism by which a young animal discovers the properties of a desired mate. Male zebra finches, for example, tend to favor mates with the presence of the female bird rearing them, rather than that of the birth parent when they're special.

A female zebra finch select a male that resembels her father with a red feather taped to his head for reprodcution because there are sufficient opportunity of sexual imprinting.

Hence, the correct option is 3.

What is the end result of mitosis and meiosis?a.Mitosis and meiosis result daughter cells for growth, development and reproduction in the living world.b.Mitosis results similar daughter cells generally for growth and development. In asexual mode of reproduction, mitosis helps in increasing the number of cells.c.Meiosis results variations and helps the sexual mode of reproduction. The resultant daughter haploid cells unite during the fertilization process and retains the diploid number of chromosomes.

Answers

Answer:

one cell with two identical copies of DNA

Explanation:

Final answer:

Meiosis produces genetically unique and haploid daughter cells for sexual reproduction, while mitosis produces genetically identical and diploid daughter cells for growth and development.

Explanation:

Meiosis results in genetically unique and haploid daughter cells, which are involved in sexual reproduction. It involves two rounds of nuclear division, resulting in four daughter nuclei. Mitosis, on the other hand, produces genetically identical and diploid daughter cells that are used for growth, development, and tissue repair. It is a single nuclear division process.

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Which adrenal gland homeostatic imbalances is characterized by persistent elevated blood glucose levels

Answers

Answer:

Cushing's syndrome

Explanation:

Cushing's syndrome or hypercortisolism is a syndrome caused by high levels of the hormone cortisol in the body.

The prolonged exposition to high levels of glucocorticoids such as cortisol has been associated with the occurrence of this syndrome

A mammalian skull is found in a forest. The skull has incisors, small canines, and many large premolars and molars with prominent surface ridges. Based on this information, what conclusions can be drawn about the feeding behavior of this organism?

Answers

Answer:

The animal was most likely an omnivore.

Explanation:

From the dentition, the animal is most likely an omnivore. Carnivores have large and sharp canines for tearing of flesh while most herbivores lack canines altogether.

Answer:

The feeding behavior of this organism is omnivorous.

Explanation:

Omnivorous are those organisms which feed on both plants and animals for the uptake of energy. There are various types of teeth are present in the jaw of omnivorous organisms such as incisors, canines, premolars and molars. Every teeth have a specific function i . e.  incisors helps in cutting of food, the canines helps in tearing and the molars and premolars is responsible for crushing the food materials.

Scientists believe the Archaebacteria to be survivors of an ancient group of organisms that bridge the evolutionary gap between prokaryotes and

Answers

Answer:

Explanation: Scientists believe that Archaebacteria are the survivors of an ancient group of organisms that bridge the evolutionary gap between prokaryotes and eukaryotes. Eukaryotes are the true evolved cells and they differ from prokaryotes

Explanation:

Which characteristic is found in liquids and gases?


particles stay in a fixed position


takes the shape of the container


has a fixed volume


no particle movement

Answers

Answer:

Takes the shape of the container

_______ is an organism’s genetic makeup, while ________ is an organism’s physical appearance.

Answers


Answer: D



Explanation: An organism's genetic makeup is called its genotype, and it reflects all of the alleles, or forms of the gene, that are carried by the organism. Consequently, a test cross can help determine whether a dominant phenotype is homozygous or heterozygous for a specific allele.

The term "phenotype" refers to the observable physical properties of an organism; these include the organism's appearance, development, and behavior. An organism's phenotype is determined by its genotype, which is the set of genes the organism carries, as well as by environmental influences upon these genes.

Hope this helps :)
the organic makeup works in three different ways 3
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