A & P CH 3-4 Flashcards
Cell
structural and functional unit of life
Biochemical activities of cells dictated by
the cells shapes or forms, and specific subcellular structures
regenerative cells
Some cells are Regenerative they can replicate and divide when they are stimulated like Fat cells bone cells can replicate and divide to heal
Human cells have three basic parts: what are they
Plasma membrane—flexible outer boundary
Cytoplasm—intracellular fluid containing organelles
Nucleus—control center
selectively regenerative cells
They are selectively regenerative cells, Liver cellsAre also selectively regenerativeMeaning when stimulatedThey can regenerate.
what are the three types of muscle cells
smooth, cardiac, skeletal cells
Permanent cells
they rarely regenerate Once the cells are dead Or damaged They generally Don’t divide, Permanent cells are neurons, heart, and skeletal muscles.
what do lysosomes do?
Breakdown, so inside a cell, we might have a lot of invaders, microorganisms invading inside the cell, or viruses infecting the cell, or anything undesirable.
exocytosis
exo meaning outside. So it’s being released outside of the cell. So these products can go wherever they are destined to go.
what do Lysosomes contain
contain digestive enzymes. So it’s kind of like the stomach in our body. Whatever we consume, the stomach initiates or helps to break down those protein bonds by secreting the hydrochloric acid to break the protein bonding. and will start the degradation process. So now some of these substances can become the very enzymes that the lysosomes want.
Mitochondria
is sort of like a strange creature inside the cell. They’re very independent, and they’re very autonomous in what they do. They sort of do their own stuff, But they do have that critical role of providing energy, ATP, for us to utilize so that the cells can survive
Cells are undergoing a lot of metabolic activities or chemical reactions, right? Anytime you go through a chemical reaction, you’re going to create and produce some of the undesirable side effects, or in which case, I can call
these the free radicals. Free radicals are the highly, highly reactive oxidative species. They’re very unstable. If they bind to some toxic substance, it’s like it’s a ticking time bomb. They can just go crazy and in the end, start damaging your cells. So free radicals are highly reactive species
and they are tissue damaging.
endomembrane system, meaning
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these structures right here, right, that are contained within its own membrane is a structure with an exception of the mitochondria, their overall function is, for example, to produce something or to break down or to store or even to export biological molecules. So degradation, meaning potentially getting rid of
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or eliminating the harmful substances that are coming into our body, including the ER, Golgi, some of the secretory vesicles, lysosomes and nuclear and plasma membranes as well.
these free radicals,
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they can often end up damaging the genetic information and transform that cell into a cancer cell. So cancer cells might be transforming or created constantly, but our immune system is healthy enough to suppress them and kill these newly created cancer cells at all times.
peroxisomes, we have two main categories of enzymes, oxidases and also the catalases. When these enzymes come across these oxidative species that are highly unstable, the oxidases are going to convert them
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to what’s called the hydrogen peroxide, H2O2, which is still considered a little bit toxic and tissue damaging. And then the catalases will convert the hydrogen peroxide into something more stable, water and oxygen. Water and oxygen is good.
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We can accept that as the more stable or less toxic form of the final product. So what they do, they help to neutralize the highly reactive species to make sure that your cells are surviving. We’re doing this constantly, even while you’re sitting down.
the peroxisomes do. They help to neutralize all these highly unstable oxidative species. and neutralize free radicals
lysosomes,
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they are surrounded by its own wall on the outside, containing the enzymes, the digestive enzymes within themselves, right? Sort of like what happens if our stomach lining is exposed to the rest of the abdomen? Then all those digestive enzymes, including hydrochloric acid,
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will go out and will be exposed to the abdominal cavity. What happens then? Acid will eat up and just degrade everything on its way. So basically, it’s autodigestion of your gut, right? We don’t want that. Stomach is active, but it has to be contained in a wall.
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Right, so these enzymes are safely stored inside the lysosomes, so they can do one thing that they’re good at, eliminating the, or starting the digestive process.
cytoskeletal structures. All these sort of like elongated cylindrical structures
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within the cell. We have the three main categories. From the smallest to the largest. The smallest structures are microfilaments, and the intermediate structures are the intermediate filaments and the biggest in terms of the diameter. We call them the microtubules.
Starting with the microfilaments. These are the thinnest in terms of the diameter. Their main structures are known as the actin substances. They basically polymerize and bundle up and then sort of start twisting around one another. So we have the strands of actin subunits making up the microfilaments.
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And the diameter right here, it’s about 7 nanometers, which is super, super tiny. So their primary functions are getting involved in cell motility, the way that the cell moves, or the change in shape of the cell. So some of the cells might want to travel
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through a little tiny opening. So in order to squeeze through that opening, they might have to reconfigure their shape so that they can sneak through that opening. Or participate in endocytosis or exocytosis. So bringing something into the cell or secreting something outside the cell.
And then we have the intermediate filaments.
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called the tetramer subunits, meaning four subunits are intertwined and then forming a bigger polymeric structure. And if you take a look at the diameter, you don’t have to memorize the size of the diameter, it’s slightly bigger than the seven nanometers of the microfilaments, right? So we’re coming in at about 10. So what do they do?
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They resist the pulling forces on the cell. So for example, right here, what am I doing? I’m pinching on my skin, right? So I’m pulling on it. So these intermediate filaments will help to maintain its proper shape if I let go.
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So they don’t become damaged after I stop pulling on it. So resisting the pulling forces on the cell.
desmosomes. So we’ve got one cell and an adjacent cell, and then we have another cell. And on the bottom, we have what’s
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called the scaffolding, or the platform, known as the BN, the basement membrane, holding the cells together like on a sort of like a straight platform. So in between the two cells, if we zoom in on this section,
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you see these filaments right there, these are the intermediate filaments. So you have an anchoring system between the two adjacent cells. You’ve got the length of protein. And these flat structures are known as the plaque. That is a lot of information.
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Collectively, we call these the desmosomes. So what they’re doing, their main responsibility is to hold the two adjacent cells together by creating sort of like that Velcro effect. So that when the cells are pulled in one direction, they can stand to get strengthened number, right? They can stand together without getting pulled apart. Okay, sort of like interlocking between the mechanism between the two cells.
And then we have the largest cytoskeletal structure, the microtubules. And so this is the largest, determining the overall shape of the cell or redistributing the position or the location of the organelles. So some of the organelles can migrate from one area to next within the cell. These bigger micro tubular structures will help to pull them and transport them sort of like an Uber or Lyft service pushing them, taking them from place A, point A to point B. Some of them can help to move these organelles using what’s called
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the motor proteins.
motor proteins
Their primary function is in their involvement of the cell motility or the organelle motility.
Plasma membrane
is the gate of the cell, inside the cell there is a liquid holding everything together and that is called the cytoplasm and including the organells that are found in the cytoplasm.
prokaryotes
is a simple, single-celled organism that lacks a nucleus and membrane-bound organelles.
Eukaryotic cells
have a nucleus enclosed within the nuclear membrane and form large and complex organisms.
sperm
cell of reproduction
nerve sell
cell that gathers information and controls body functions
fat cell
cell that stores nutrients
macrophage
cell that fights disease
smooth muscle cells
cells that move organs and body parts
erythrocytes, fibroblasts, and epithelial cells
cells that connect body parts, form linings, or transport gases.
skeletal muscle cells
cells that move organs and body parts
Cytoplasmic Organelles
- Membranous
- Mitochondria
- Peroxisomes
- Lysosomes
- Endoplasmic reticulum
- Golgi apparatus
- Nonmembranous
- Cytoskeleton
- Centrioles
- Ribosomes
Inclusions
- Vary with cell type; e.g., glycogen granules, pigments, lipid droplets, vacuoles, crystals
Organelles
- Metabolic machinery of cell; each with specialized function; either membranous or nonmembranous.
Cytosol
- Water with solutes (protein, salts, sugars, etc.)
Cytoplasm
Located between plasma membrane and nucleus
- Composed of
* Cytosol
* Organelles
* Inclusions
Phases of ciliary motion and cell surface
has a Layer of mucus
Traveling wave created by the activity of many cilla acting together propels mucus across cell surfaces.
Nucleus
Recovery stroke
After a power stroke, a recovery transition completes the cycle and returns the molecular motor to its prestroke state.
Power, or propulsive, stroke
During the power stroke, the cilium is stretched out straight and moves rather fast in one direction while during the recovery stroke, it bends and slowly retracts
cellular extensions: Microvilli
Minute, fingerlike extensions of plasma membrane
- Increase surface area for absorption
- Core of actin filaments for stiffening
Each villus can have many microvilli as in your intestines!!!
Ville INCREASE THE SURFACE AREA
THE VILLUS is MADE UP of MANY cells
EACH CELL IN THE VILLUS HAS MICROVILLI ON ITS SURFACE
FOUND IN THE SMALL INTESTINE
Nucleoli
Dark-staining spherical bodies within nucleus
* Involved in RNA synthesis and ribosome subunit assembly (ribosome ~ 60% rRNA & 40% protein)
* Associated with nucleolar organizer regions
- Contains DNA coding for rRNA
* Usually one or two per cell
Chromatin
Threadlike strands of DNA (30%), histone proteins (60%), and RNA (10%)
* Arranged in fundamental units called nucleosomes
* Histones pack long DNA molecules; involved in gene regulation
* Condense into barlike bodies called chromosomes when cell starts to divide
Plasma Membrane
- Lipid bilayer and proteins in constantly changing fluid mosaic
- Plays dynamic role in cellular activity
- Separates intracellular fluid (ICF) from extracellular fluid (ECF)
- Interstitial fluid (IF) = ECF that surrounds
cells
Membrane Lipids
phospholipids (lipid bilayer)
- Phosphate heads: polar and hydrophilic
- Fatty acid tails: nopolar and hydrophobic
* 5% glycolipids- Lipids with polar sugar groups on outer membrane surface
* 20% cholesterol- Increases membrane stability
Peripheral proteins
- Loosely attached to integral proteins
- Include filaments on intracellular surface for membrane support
- Function as enzymes; motor proteins for shape change during cell division and muscle contraction; cell-to-cell connections
Integral proteins
- Firmly inserted into membrane (most are transmembrane)
- Have hydrophobic and hydrophilic regions
- Can interact with lipid tails and water
- Function as transport proteins (channels and carriers), enzymes, or receptors
Six Functions of Membrane Proteins
- Transport
- Receptors for signal transduction
- Attachment to cytoskeleton and extracellular matrix
- Enzymatic activity
- Intercellular joining
- Cell-cell recognition
Membrane Proteins
- Allow communication with environment
- ½ mass of plasma membrane
- Most specialized membrane functions
- Some float freely
- Some tethered to intracellular structures
- Two types:
- Integral proteins; peripheral proteins
Transport
A protein (left) that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute.
Some transport proteins (right) hydrolyze
ATP as an energy source to actively pump substances across the membrane.
Receptors for signal transduction
A membrane protein exposed to the outside of the cell may have a binding site that fits the shape of a specific chemical messenger, such as a hormone.
When bound, the chemical messenger may cause a change in shape in the protein that initiates a chain of chemical reactions in the cell.
Attachment to the cytoskeleton and extracellular matrix
Elements of the cytoskeleton (cell’s internal supports) and the extracellular matrix (fibers and other substances outside the cell) may anchor to membrane proteins, which helps maintain cell shape and fix the location of certain membrane proteins.
Others play a role in cell movement or bind adjacent cells together.
Enzymatic activity
A membrane protein may be an enzyme with its active site exposed to substances in the adjacent solution. A team of several enzymes in a membrane may catalyze sequential steps of a metabolic pathway as indicated (left to right) here.
Intercellular joining
Membrane proteins of adjacent cells may be hooked together in various kinds of intercellular junctions. Some membrane proteins (cell adhesion molecules or CAMs) of this group provide
temporary binding sites that guide cell migration and other cell-to-cell interactions.
Cell-cell recognition
Some glycoproteins (proteins bonded to short chains of sugars) serve as identification tags that are specifically recognized by other cells.
