# Make the internet a better place to learn

2

## What is the chemical energy stored in the muscles?

Mandira P.
Featured 3 weeks ago

Energy currency of all living cells is ATP (adenosine triphosphate) but this can not be stored in large amount.

#### Explanation:

• ATP molecules are generated by cellular respiration: this molecule releases energy by breaking into ADP and inorganic phosphate, the reaction is catalysed by ATPase enzyme.

• ATP stored in muscles may last only 10 seconds of exercise. Also consider the fact that ATP is a heavy molecule: molar mass of ATP is more than 500g/mol. Storage of ATP would have abnormally increased our weight. So it is natural that ATP is not stored in large amount but is continuously generated.

• In muscle tissues, a special molecule called phosphocreatine is stored which can change an ADP immediately in an ATP in presence of enzyme.

About 120 gram of phosphocreatine is stored in our muscles.

• To generate ATP, our muscle cells can use glucose as raw material for cellular respiration. About 500 gram of glycogen is stored in skeletal muscles of an adult body. The glycogen readily supplies glucose for production of ATP (both aerobically and anaerobically).

• Skeletal muscles store another molecule named myoglobin which can quickly supply oxygen for aerobic respiration when there is a decline in concentration of oxygen in muscle. Myoglobin has a higher affinity towards oxygen, hence it dissociates from oxygen only at a lower partial pressure of oxygen compared to haemoglobin.
4

## What is the difference between 1st degree and 2nd degree burns?

Shray P.
Featured 3 weeks ago

The higher the degree of the burn, the more severe it is. Second-degree burns harm the epidermal and dermal layers of skin, while first-degree burns only harm the epidermis.

#### Explanation:

First-degree Burns
The epidermis is the outermost layer of skin. A first-degree burn can occur from brief contact with something hot, like scalding from hot water. These burns are usually not very painful or severe, and unless they cover a large surface area, do not require emergency medical care. If you get a first-degree burn, place the affected area under cool water. Apply aloe vera or burn ointments afterward, and the wound should heal soon.

Second Degree Burns
Second-degree burns are more severe than first-degree burns, but still don't require emergency medical attention in most cases. They usually harm the epidermis and the layer beneath it, the dermis. Second-degree burns can often cause blisters, which should be bandaged and kept clean.

If you have suffered or think you have suffered a burn, you may want to consult your doctor, not an online forum. The above communications are meant to be educational and do not constitute a doctor-patient relationship.

1

## How do they diagnose placenta accreta?

Shray P.
Featured 2 weeks ago

Doctors diagnose placenta accreta through an ultrasound.

#### Explanation:

Placenta accreta occurs when the placenta becomes deeply attached to the uterine wall and can result in severe blood loss during childbirth. Placenta Accreta may demonstrate vaginal bleeding in some cases, but is usually detected during routine ultrasounds. Treatment for placenta accreta usually involves a C-section, followed by a hysterectomy (surgical removal of the uterus).

Understanding the Placenta
The placenta is an organ that develops during pregnancy that provides both nutrients and oxygen to the fetus. The placenta is connected to the wall of the uterus (womb), and nutrients are absorbed through the placental membrane.

What is Placenta Accreta?
Placenta accreta is a condition where the lining of the placenta becomes too deeply attached to the uterine wall. When delivering the baby, this can result in severe blood loss, because instead of detaching from the womb like a normal placenta, the placenta accreta remains partially attached to the uterine wall during childbirth.

3

## Why is placenta previa a concern?

Shray P.
Featured 2 weeks ago

Placenta previa can cause extreme blood loss in the mother and can potentially suffocate the fetus.

#### Explanation:

The placenta is an organ that develops in pregnant women to provide nutrients and oxygen to a developing fetus. Placenta previa is a condition where part of the placenta covers the cervix opening, with three different types:

1. Complete Previa: the cervical opening is completely covered by the placenta

2. Partial Previa: a portion of the cervix is covered by the placenta

3. Marginal Previa: the placenta extends just to the edge of the cervix

Placenta previa causes extreme blood loss during childbirth, as the placenta detaches from the uterine wall and placenta previa can also suffocate the fetus.

If you experience symptoms of placenta previa like painless blood loss during pregnancy, or suspect you have placenta previa, you should talk to your doctor right away. In most cases, he/she will perform a Caesarean section, although placenta previa may go away on its own as well.

1

## How do the functions of the neurotransmitters norepinephrine, serotonin, dopamine, and acetylcholine relate to depression? How do they cause or contribute to the illness?

BillytheKid
Featured 2 weeks ago

They have a second function...

#### Explanation:

The (bio-)chemicals mentioned are Neurotransmitters.

But they have a second function: they also act as Neuromodulators. There is a marked difference in both mode of operation and result:

Neurotransmitters act exclusively within the synapse between two neurons, effecting a fast impulse transfer. This results in either an IPSP (Inhibitory Post Synaptic Potential) or an EPSP (excitatory Post Synaptic Potential) in the receiving neuron.

Neuromodulators act in a different way: they seep into the nervous tissue, affecting whole regions of it.

Neurotransmitters usually bind to ionotropic receptors. More commonly referred to as Ligand-gated ion-channels. By binding, they open the channel to let ions flow through:

As mentioned, they operate strictly within the synaptic cleft, between two neurons: the Pre-synaptic and the Post-synaptic ones.

Neuromodulators act on different receptors on the neurons, and in a different way: they act on Metabotropic receptors.
Also known as secondary messengers, rather than transferring a signal like the Neurotransmitters mentioned above, they influence the mode of operation of the (post-synaptic) neuron.
To keep it simple: let's say they alter (modulate) the sensitivity of the accepting neuron: they can (indirectly) open or close ion-channels, and initiate other (intracellular) effects:

To put it in simple terms: Consider a play being performed in a theatre. The perception of the performance of the players on the stage can (will) be influenced by the lighting on the stage: Turning the lights to full power will represent a fine, sunny day, while switching them off resuls in the mood of a dark night.

Neuromodulators have the same effect: In contrast to neurotransmitters, in their role as modulators they act on multiple cells at the same time (whole regions), and the mode of operation is much slower.

But don't forget, the modulators mentioned can act as neurotransmitters as well.

To come back to the question: an imbalance in Neuromodulation WILL affect the mood a person is experiencing: a shortage will often lead to depression....

2

## How does physical fitness affect the body's anatomy and physiology?

Marta O.
Featured 1 week ago

Physical fitness is defined as a state of well-being,health and the ability to do tasks without undue fatigue. Physical fitness can be achieved through good nutrition plan, moderate physical exercise and rest.

NOTE: there are picture wich some readers might find disturbing

#### Explanation:

Lets look at the picture below so we can see the difference between a physical fit person and a unfit person and determine how does it affect on our body.
Lest assume the person with 120 lbs is physically fit and the person with 250 lbs is a physically unfit person.
In this answer the focus is on unfitness and its damage to the body because physical fitness does the opposite to a particular system$\to$our body remains stronger and more flexible to activities.

1 our heart and lungs
A person with 120 lbs is able to do longer tasks with more energy than a person with 250 lbs. This is because the person with 120 lbs has a better cardiorespiratory endurance. This is a measure which shows the ability of the circulatory and respiratory system to deliver oxygen and nutrients to cells and eliminate waste products from cells.
During physical activity our cells are "hungry" and they need oxygen and nutrients in order to fuel our muscles and they produce wastes that need to be eliminated. Cardiorespiratory endurance show us how efficent aou body is in doing this tasks.
To strenght our endurance we have to do aerobic exercises.
Atherosclerosis, the hardening of the artery walls, appears because of the high intensity of fat that accumulates inside your arteries.
Thicker walls allow a narrower space for blood to pass through and to maintain the same pressure the heart must work harder and blood circulation through the body suffers.

Picture 1. Obesity leads to development of osteoarthritis, sleep apnea...

Picture 2.The heart of the person with 250 lbs is two times heavier than the heart of the fitter person with 120 lbs. The heavier heart seems like a paper bag that is not able to pump blood.

Our lungs face risk in the presence of excess fat. Poor lung function results in lack of oxygenin blood vessels. The persin with 250 lbs has a bigger risk for obstructive sleep apnea than the person with 120 lbs.

2 Our Colon
Colon cancer has a high connection with obesity. A diet high in processed meats and red meats increases the formation of colon polyps what can lead to colon cancer.

3 Our Brain
Mental, social and emotional health is an important part of fitness. It seems reasonable to include the nerve sistem to this question.
In a 2010 study the white matter sheathing was more damaged in the brains of the obese.

4 Our Skin
Obesity has an influence on hormone changes. Acanthosis nigricans, the skin appears darker and thicker. The person with 250 lbs on the top picture has a stretched skin what can cause redness and irritation. Poor vein function in ankles can lead to ulcers, because of lacking blood flow.
Our outer layer of the skin is our "protector" form infectious agents.
Stretched layer of skin can turn into illness, because the body’s mass in not compatible with the skin’s elasticity.

Physical fitness and unfitness has an impact on other systems like: muscle strength, muscle endurance, flexibility, body composition etc.
As you can see on the top on 250 lbs body the musles are a little bit squashed and the bones are "loaded" with "unnecessary burden".

1

## What STD affects the immune system?

Shray P.
Featured 1 week ago

HIV (human immunodeficiency virus) causes AIDS (acquired immunodeficiency disorder) by destroying T-cells in your immune system that fight off pathogens.

#### Explanation:

Although HIV (human immunodeficiency virus) can be spread through sexual fluids like semen and vaginal fluids, it can also be transmitted through blood and breast milk, so it is not strictly just a sexually-transmitted disease. However, it is the most common sexually-transmitted disease (STD) that affects the immune system, and HIV works by destroying special immune cells called T-cells.

T-Cell Count and AIDS:
HIV attacks the CD4 cells (also referred to as T-cells) in your immune system that help destroy pathogens. The estimated T-cell count in most humans ranges between T-cells counts between 500 - 1500. However, As HIV progresses, it can eventually destroy so many of these immune cells that the human body is unable to effectively kill pathogens, like viruses and bacteria. In people who have been effected severely by HIV, like famous basketball player Magic Johnson, this can result in a syndrome called AIDS (acquired immunodeficiency disorder), where T-cell count drops below 200. When this happens, the body is extremely susceptible to pathogens, and people with AIDS are extremely vulnerable to a variety of deadly diseases including tuberculosis, meningitis, and pneumonia.

8

## What are the different body systems in human body and what are their functions?

Arsala K.
Featured 1 week ago

There are total $11$ systems in human body containing their specific organs hence are called as organ systems.

#### Explanation:

These are muscular system, digestive system, integumentary system, skeletal system, circulatory system, respiratory system, lymphatic system, endocrine system, excretory system and reproductive system. All these systems contain their specific organs. However, these systems are somehow related to each other.

Breif concept to their functions is as follows:

Muscular system $\to$ provide movements.

The muscular system, in vertebrates, is controlled through the nervous system, although some muscles, like cardiac muscle & muscles in stomach walls, can be completely autonomous. And others like, skeletal muscles are under conscious control.

Muscles run throughout the human body. Each muscle has a specific name according to it's location or function. All these muscles work and render human body to function normally. For example, when you want to play flute you have to pucker your lips, you can do so with the help of Orbicularis oris, a muscle surrounding the lips.

Digestive system $\to$ breakdown the food and absorb nutrients from it.

Food we eat is the body's source of fuel. Nutrients in food give the body's cells the energy they need to operate. Before food can be used it has to be broken down into tiny little pieces so it can be absorbed and used by the body. In humans, proteins need to be broken down into amino acids, starches into sugars, and fats into fatty acids and glycerol. The whole process of digestion is aided by chemical and nervous coordination.

Integumentary system $\to$ act as a barrier, protect the inner stuff of body, regulate body temperature and also eliminate waste(e.g sweat).

The outermost layer of skin i.e epidermis is responsible for keeping water in the body and keeping other harmful chemicals and pathogens out.

And the layer that lies below epidermis i.e dermis performs major functions and also nourishes epidermis. It contains a number of structures including blood vessels, nerves, hair follicles, smooth muscle, glands and lymphatic tissue. It paly major role in thermoregulation.

The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves.

Skeletal system $\to$ supports the body and protect the internal organs(e.g rib cage protect heart and lungs).

Muscular and skeletal system works together to provide movements. Besides, skeletal system provide proper shape to our body. Without this system, human body can never be so organized as it is.

Circulatory system $\to$ help to transfer blood, nutrients, hormones, oxygen and other gases to and from different body parts.

The circulatory system is extremely important in sustaining life. It’s proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide, waste products, maintenance of optimum pH, and the mobility of the elements, proteins and cells, of the lymphatic system.

Heart pumps the blood throughout the body i.e from head to toe. $\textcolor{b l u e}{\text{Veins}}$(except pulmonary veins) carry the oxygen poor blood from different organs and give it to the heart. Heart oxygenates that blood. Then $\textcolor{red}{\text{ arteries}}$(except pulmonary arteries) supply the oxygenated blood to various organs of the body. So it means that blood travels from different chambers of the heart all the time. Muscular system is also involved in this circulation if blood. The autonomous cardiac muscles relax and contract to help the heart in pumping blood.

Respiratory system $\to$ station of gaseous exchange i.e ${O}_{2}$ in and $C {O}_{2}$ out of the body.

The respiratory tract is the path of air that starts from the nasal cavity and end in smaller alveoli in lungs. It's major role is in breathing, no doubt an inevitable process. Besides, respiratory system also regulates blood $p H$ and control body temperature.

Nervous system $\to$ help all the body parts to communicate with each other via electrical and chemical impulses.

Nervous system is involved in Nervous coordination . Nervous system is divided into central nervous system(CNS) & peripheral nervous system(PNS). CNS represents the largest part of the nervous system, including the brain and the spinal cord, Together, with the peripheral nervous system (PNS), it has a fundamental role in the control of behaviour.

Nervous system communicate with several other body systems. For example: Even when we haven't started eating, our brain starts telling our digestive organs i.e pancreas and stomach via nerves about the expected entry of food. And pancreas stimulated by neural signals produce about 20% of it's total secretion because of this stimulus. Skeletal muscles also need neural inputs to start contraction.

Lymphatic system $\to$ It plays a vital role in natural defense of body against infections.

The lymphatic system helps Defend the body against foreign invaders. It destroys the bacteria and viruses through lymphocyte and macrophages with present within lymph nodes. Lymphatic system is involved in absorption of fat globules which are released by interstitial cells and the products of digestion of fats are absorbed.

Spleen filters the blood. It destroys aged red blood cells and foreign particles from blood via it's lymphocytes & macrophages.

Endocrine system $\to$ It also help different body parts to communicate by secreting chemical substances called hormones.

Endocrine system is involved in Chemical coordination. It constitutes $20$ endocrine glands/tissues. These glands secrete hormone which are poured in bloodstream. From blood these are transported to the target tissues where they perform their particular work. For example: When the sugar level in blood drops then pancreas(an endocrine gland) secrete glucagon which works to increases glucose in blood.
Endocrine system is involved in controlling growth, metabolism, sexual development, maintaining homeostasis etc...

Endocrine and nervous system work together and aid other organ systems to perform their functions.

Excretory system $\to$ help body to get rid of wastes.

Excretion is the process of eliminating, from an organism, waste products of metabolism and other materials that are of no use. The most salient organs of this system are kidneys. Kidneys with the help of their functional units i.e nephrons, maintains an appropriate fluid volume by regulating the amount of water that is excreted in the urine, regulate concentrations of various electrolytes in the body fluids, maintain normal $p H$of the blood and maintain a stable internal environment (homeostasis) for optimal cell and tissue metabolism. They do this by separating urea, mineral salts, toxins, and other waste products from the blood. They also do the job of conserving water, salts, and electrolytes. At least one kidney must function properly for life to be maintained.

Reproductive system $\to$ aid in the production of new individual.

All living things reproduce. This is something that sets the living apart from non-living. Even though the reproductive system is essential to keeping a species alive, it is not that essential for keeping an individual alive.

As in case of sexual reproduction, the specific traits are inherited from parents to their offspring. So, in this case reproduction is important in conservation of certain genetic makeups. While if we talk about asexual reproduction then its merely involved in producing new individual. Because there is no exchange of genetical materials in asexual reproduction.

Hope it helps!

2

## Bronchiolitis, commonly seen in infants due to respiratory syncytial virus, is characterized by which of the following?

Ernest Z.
Featured 17 hours ago

The main characteristic of bronchiolitis is A. airway inflammation and mucus formation.

#### Explanation:

Bronchiolitis is inflammation of the bronchioles, the passages through which air passes to the alveoli.

As the bronchioles become inflamed, they swell with edema and fill with mucus, and breathing becomes difficult.

1

## How often does the human skin regenerate itself?

Ernest Z.
Featured 17 hours ago

On average, the human skin regenerates itself about every three weeks,

#### Explanation:

New skin cells (keratinocytes) are continually forming at the bottom of the epidermis.

As new cells form, they push the more mature cells toward the skin's surface, moving them farther away from the blood supply that keeps them alive.

By the time a skin cell reaches the surface about three weeks later, it's dead.