11971 questions

How does the heart pump blood around the body

The heart is divided into four chambers: the right atrium, right ventricle, left atrium and left ventricle [insert diagram]. The right side of the heart pumps blood to the lungs. The left side of the heart pumps blood to the rest of the body. First, deoxygenated blood arrives from the body, through the superior vena cava, into the right atrium. This is blood where all the oxygen has already been used up by the tissues of the body. It needs to get more oxygen, so it can be pumped around the body again and continue to provide oxygen to the tissues. To get more oxygen, it has to get to the lungs. So, it is pumped from the right atrium into the right ventricle, which then pumps it though the pulmonary artery to the lungs. Remember - Arteries carry blood Away from the heart, and pulmonary means relating to the lungs. So you know that the pulmonary artery carries blood away from the heart, to the lungs.  This blood goes to the lungs and gets more oxygen. But, by this time it does not have the power to get all around the body to deliver the oxygen. So, it goes back to the heart, but this time it enters through the pulmonary veins (remember, if arteries go away from the heart, veins must go towards the heart - and pulmonary means lungs. So the pulmonary veins must take blood from the lungs, towards the heart). It goes through the pulmonary veins into the left atrium. The left atrium pumps blood into the left ventricle, which is a very muscular part of the heart. The left ventricle then pumps blood out, through the aorta (which is an artery), to the rest of the body, to supply the body with oxygen. 
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Rosanna L.

14 hours ago

Answered by Rosanna, tutor with MyTutor


What is co-transport and why do I sometimes hear it being called active transport?

Example: absorption of sodium ions (Na+) and glucose by cells lining the ileum (a part of the small intestine)  1. Na+ actively transported into the blood from epithelial cells, by the sodium-potassium pump. 2. Creates a concentration gradient of Na+ - lower conc. of Na+ in epithelial cell than in lumen.) 3. Na+ and glucose move by facilitated diffusion into the epithelial cell from the lumen, via a co-transporter protein (glucose can move against its conc. gradient by using the conc. gradient of sodium.) 4. Creates a concentration gradient of glucose - higher conc. of glucose in epithelial cell than blood. 5. Glucose can move out of cell into blood by facilitated diffusion through a protein channel. Why is co-transport considered active transport? - Secondary active transport - Doesn't directly depend on ATP i.e. ATP is not directly involved in the functioning of the co-transporter - Instead, it relies on the ion gradient acquired by pumping ions in and out of the cell, by (primary) active transport
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Olivia L.

1 day ago

Answered by Olivia, tutor with MyTutor


How do I find the derivative of two functions multiplied by each other?

To find the derivative of two functions multiplied by each other we would use the product rule. The product rule: (fg)'(x) = f '(x).g(x) + f(x).g'(x) First we need to split our function into the two parts that are multiplied by eachother, and label these f and g. For example, h(x) = sin(x)(2x + 1) For this we would label f(x) = sin(x) and g(x) = (2x + 1) Now we need to find the derivatives of these, to use in the above formula: f '(x) = cos(x)  g'(x) = 2 So then we put these together in the formula above to get our answer as follows: h'(x) = cos(x)(2x + 1) + 2sin(x)
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Eleanor S.

1 day ago

Answered by Eleanor, tutor with MyTutor


Describe the different phases involved in mitosis

In mitosis there are four phases: Prophase, Metaphase, Anaphase and Telophase. The first step is early Prophase, where chromosomes condense and become visible through supercoiling and simultaneously spindle microtubules are synthesised. At late Prophase, spindle microtubules extend from the equator to each pole and each chromosome consists of two identical sister chromatids, held together by a centromere. This is followed by Metaphase, where the nuclear membrane breaks down and chromosomes move to the equator to allow spindle microtubules from both poles to attach to each centromere on opposite sides. In Anaphase, the centromeres divide and the sister chromatids become individual chromosomes. Moreover, spindle microtubules shorten pulling the genetically identical chromosomes to opposite poles. In early Telophase all chromosomes are located at either pole, a nuclear membrane forms around them and spindle microtubules break down. Finally, in late Telophase chromosomes uncoil and decondense, hence they are no longer individually visible and the cell undergoes cytokinesis to form two cells with genetically identical nuclei. 
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Arabella H.

1 day ago

Answered by Arabella, who has applied to tutor with MyTutor


When should I use the perfect tense and the imperfect tense?

The perfect tense is used to describe a completed action in the past. (Sometimes, time connectives are used as an indication that an action is complete). e.g. Hier soir, j'ai fait mes devoirs - Yesterday evening, I did my homework. The imperfect tense is used to describe ongoing actions in the past that had a duration, or habitual actions in the past (i.e. things that 'used to' happen) e.g. Quand j'étais plus jeune, je jouais au foot  - When I was younger, I used to play football. These two tenses can be used together to describe an interrupted action in the past. For example, 'I was eating my dinner when the phone rang'. The ongoing action of eating (imperfect tense) is interrupted by the completed action of the phone that rang (perfect tense). Therefore it translates as: Je mangeais mon dîner quand le téléphone a sonné. 
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Jenai C.

2 days ago

Answered by Jenai, tutor with MyTutor


What are the differences between osmosis and active transport?

Osmosis is the net movement of water molecules from an area of less negative water potential to an area of more negative water potential through a selectively permeable membrane. Pure water has a water potential of 0 kilopascals and the higher the concentration of solutes the more negative the water potential becomes. Water molecules are said to move down a water potential gradient until an equilibrium is reached. Active transport is the net movement of ions or molecules against the concentration gradient by carrier proteins or protein channels. Active transport is an active process because it requires ATP, but osmosis is passive and so requires no energy. Active transport requires ATP as an energy source as the molecules are moving against the concentration gradient, imagine walking into the wind, it will require more energy than walking with the wind
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Annabel  F.

2 days ago

Answered by Annabel , tutor with MyTutor


X is a prime number higher than the square of 5 and lower than the square of 7. What are the smallest and largest possible values for X?

The square of 5 is 25 and the square of 7 is 49. The prime numbers found between these 2 values are: 29, 31, 37, 41, 43 and 47. This means the smallest value fitting the criteria is 29 and the largest value will be 47.
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Oana C.

2 days ago

Answered by Oana, tutor with MyTutor


How does synaptic transmission across a neuromuscular junction work?

In order to answer the question, it is important to understand the terminology used. The neuromuscular junction refers to the communication between a neuron (neuro) and muscle cell (muscular). There are many neuromuscular junctions throughout the muscle, and they are required for simultaneous muscle contraction.  The synapse is the space between the neuron and muscle cell, with the presynaptic membrane being the part of the neuron that faces the synapse and the post synaptic neuron being the part of the muscle cell that faces the synapse. Now to address the question asked, as the nerve impulse travels down the neuron it causes an influx of calcium ions into the neuron. This causes the synaptic vesicles to fuse with the presynaptic membrane. The vesicles contain a neurotransmitter called acetylcholine which diffuses across the synapse and stimulates the post synaptic membrane to allow sodium ions to enter the muscle cell, this results in muscle cell depolarization resulting in muscle contraction. The acetylcholine is then broken down by an enzyme called acetylcholinesterase, and then diffuses back into the presynaptic neuron.
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Ellie T.

2 days ago

Answered by Ellie, tutor with MyTutor


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