Cellular and Membrane Flashcards
What does the term cell cycle refer to?
It refers to the events that somatic cells which include all of the cells in our bodies, except the reproductive cells go through from the moment they are formed until the moment they divide into two identical, daughter cells
How long does a cell cycle last?
It varies in length, depending on the type of cell for rapidly dividing cells like skin cells it takes less than a day or as for other cells like liver cells it can last year’s
What are the two phases of the cell cycle?
Interphase in mitosis
What happens during interphase in the cell cycle?
It is the longest part of the cell cycle, and it is a state of preparation during which the cell carries out its cell functions, grows and replicate its DNA to prepare for mitosis
What happens during mitosis in the cell cycle?
This is when the cell divides into two daughter cells, and separates the replicated DNA into two distinct nuclei, and the separation of the daughter cells into two distinct cells called cytokinesis
What are the four sub phases of mitosis?
Prophase, metaphase, anaphase and telophase, then immediately followed by cytokinesis
What does the G0 phase represent?
A phase outside the cell cycle, because while the cells are living, they are neither dividing nor preparing to divide
What is hyperplasia?
Refers to the process were cells in an organ or tissue increase in number
What is hypertrophy?
It is when these cells in an organ or tissue increase in size
What is an example of physiologic hypertrophy?
It is like lifting a 10 pound sack of potatoes, which puts a bigger functional demand on your skeletal muscles in response, the muscle cells produce more proteins or myofilaments and get larger in size, allowing the biceps as a whole to generate more force as a result, your muscle also becomes bigger and tougher
What is an example of pathologic hypertrophy?
It is when the heart undergoes hypertrophy to deal with high blood pressure or hypertension and hypertension. The heart has to pump blood against a higher resistance, and cardiac myocytes, once again, adapt by increasing the synthesis of myofilaments, causing individual cells to get bigger.
Does hyperplasia occur in relatively permanent cells like cardiac nerve and adult skeletal muscle tissue?
No hyperplasia doesn’t occur in relatively permanent tissues without stem cells like cardiac nerve and adult, skeletal muscle tissue
What are two types of hyperplasia and in what tissues or organs does each typically occur?
Compensatory, hyperplasia and hormonal hyperplasia.
Compensatory hyperplasia occurs in organs that regenerate like the skin lining of the intestines, the liver and bone marrow hormonal hyperplasia occurs in organs that are regulated by hormones like organs in the endocrine and reproductive system
What is an example of physiologic hyperplasia?
When an enlargement of the female breast during pregnancy
What is an example of pathologic hyperplasia?
Having excessive hormonal stimulation for example, if there is an overproduction of estrogen by an ovarian tumor, it can lead to excessive endometrial growth, also called endometrial hyperplasia
Is hyperplasia synonymous with cancer
No, but hyperplasia is sometimes associated with cancer. Normally hyperplasia is an adaptive response to stress, so it’s tightly regulated process meaning the tissues don’t grow out of control that’s different from cancer where there’s uncontrolled cell division however, as cells divide in hyperplasia some can mutate and that’s how hyperplasia can result in dysplasia, and eventually into cancerous malignancy
What is the definition of atrophy in the body?
Reduction in the size of a cell organ or tissue after it has attain normal, mature growth, or either a decrease in cell number or cell size
What is apoptosis?
Controlled type of cell death
Is muscle atrophy reversible?
Yes, except for very extreme situations
What is aplasia?
No development of a tissue or organ during embryogenesis
Defined the term hypoplasia
Under development or formation of a tissue or organ during embryogenesis
What is metaplasia?
When a mature, differentiated cell type is replaced by another mature, differentiated cell type often this happens because there’s an environmental stressor that the new cell type is better suited to handle
Is metaplasia reversible
Yes
What is dysplasia?
The tissue develops a large number of immature cells that have weird shapes typically due to chronic environmental stressors
Which type of cellular adaptation is most likely to develop into cancer
Dysplasia
What are stem cells?
Non-differentiated, non-specialized cells of the body found in blastocysts that can become any type of body cell
What are transcription factors?
They are typically proteins that determine which area of the DNA code will get transcribed into mRNA, which then can eventually be used to make specific proteins that can impact what the cell will look like and what a cell will do
What are somatic stem cells?
Non-embryonic stem cells that are found in cells in the body like muscle skin, liver and bone marrow
Which type of stem cell can differentiate into more cell types?
Embryonic stem cells
What is selective permeability of the cell membrane?
It helps regulate what comes in or out of the cell
What are the two types of transport across the cell membrane and how are they different?
Passive transport, which requires no energy and active transport, which requires energy in the form of adenosine triphosphate
What are the three types of passive transport?
Diffusion, facilitated, diffusion and osmosis
What is diffusion?
It helps small nonpolar molecules like oxygen and carbon dioxide move across the membrane from an area of high concentration to low concentration down the concentration gradient
When does diffusion stop?
When there are equal concentrations of the molecules on both sides of the cell membrane
What is meant by the term concentration gradient
The difference in concentration of a molecule between the intracellular fluid and extracellular fluid
What is facilitated diffusion?
It helps larger molecules and polar molecules move across the membrane, using transport proteins, like channels and carrier proteins
What is the difference between channels and carrier transport proteins?
Channels are not very specific and they can open or close to allow water and small polar molecules like ions that is dissolved in it to pass through carrier proteins are very specific. They have special binding sites that only allow certain molecules to bind to them, and they also have gates at both ends, which opens sequentially.
What is osmosis?
It describes the movement of water across the cell membrane. It’s a special case of facilitated diffusion, because water uses channels called aquaporins to move across the membrane.
What drives osmosis?
It is driven by osmotic pressure, which is a force, determined by the difference in solutes between the two sides, osmotic pressure, drives water from the hypotonic side, or the one with lower concentration of solutes to the hypertonic side, or the one with a higher concentration of solutes
How are molecules transport against a concentration gradient
Active transport across the cell membrane, which requires energy
What are the two kinds of active transport and how are they different?
Primary and secondary active transport, primary active transport directly uses ATP as fuel, and it’s done by enzymes, called ATPase. secondary active transport, does not directly require ATP, but uses an electrochemical gradient
How does the sodium potassium pump work?
For each ATP molecule, it pumps three ions of sodium out of the cell while at the same time pumping two ions of potassium into the cell. The resulting difference in concentrations of ions on either side of the membrane creates a concentration gradient, but since ions also carry electrical charges it’s considered an electrochemical gradient, and the cell can use this in secondary active transport.
What is endocytosis?
A form of boat transport, where the cell membrane invaginate and pulls in something from the outside
What is exocytosis?
A form of bulk transport were a vesicle from within the cell pushes something out of the cell
When is equilibrium reach during the process of osmosis
When the net movement of water across the membrane is zero
If the concentration of solute in solutions, a and B, on either side of the membrane is the same what is the tonicity of these solutions to one another?
A and B are isotonic to each other
If the concentration of solute in solution a is higher than the solution b, what is the tonicity of these solutions to one another
Solution a is hypertonic to solution b and solution b is hypotonic solution a
If the concentration of solute in solution a is higher than the solution b, what is the expected direction of water molecule movement
Since solution a is hypertonic to solution b its osmotic pressure increases, and we expect to see a bigger net migration of water molecules to solution a until the concentration of the solutes is equal on both sides
What is endocytosis?
A form of boat transport that cells used to engulf extracellular material that uses energy from adenosine triphosphate
What is exocytosis?
A form of bulk transport that cells used to expel material into the extracellular space that uses energy from adenosine triphosphate
What are the three types of endocytosis?
Phagocytosis pinocytosis and receptor mediated endocytosis
What is phagocytosis?
A type of endocytosis, where cells eat, debris, bacteria, and dead cells to bring them into the cell, forming a phagosome
What is pinocytosis?
A type of endocytosis, where cells drink the cell membrane invaginate’s to form a small cup around the portions of extracellular, fluid and solutes that are dissolved in it then the edges of the cup come together, forming a vesicle
Where in the cell does exocytosis begin?
In an organelle called the Golgi apparatus
What is the process of exocytosis?
In the Golgi apparatus, the proteins, lipids, and hormones that are generated in the rough Endo plasmic, reticulum and smooth Endo plasmic reticulum are packaged into a vesicle that can be moved around the cell using the cytoskeleton. The vesicle moves towards the cell surface, fuses with the cell membrane and ruptures on its external side, spilling its contents into the extracellular space
What are the two major fluid compartments in the body?
Intracellular fluid and extracellular fluid
How much is the average percent of total body water weight in humans?
60% of body weight on average
What is the breakdown of total body water in intracellular and extracellular fluid?
2/3 or 40% of body weight is intracellular fluid the other 1/3 or 20% of body weight is extracellular fluid. This is also known as the 60 40 20 rule.
What are the two subdivisions of extracellular fluid?
Interstitial, fluid and plasma
What is interstitial fluid?
Fluid surrounding the cell
What is plasma?
Fluid that circulates within blood vessels
What is osmolarity and how is it measured?
The concentration of a solution it is measured as the number of particles of solute per liter of solution
If the osmolarity of a specific solute in the ECF is higher than the ICF what is likely to happen
Water will flow in the direction of more solutes to lower the concentration and maintain the balance through osmosis
Regarding ECF concentration, what does the term iso osmotic disturbance mean?
There is no change in ECF osmolarity