Module One Flashcards
Communication within the body is essential for homeostasis and is accomplished chiefly by _____ and ____.
Nervous and Endocrine Systems
Homeostatic Control Mechanisms:
Receptor
Essentially, it is some type of sensor that monitors and responds to changes in the environment. It responds to such changes, called “stimuli” by sending information (input) to the second element, the control center. Information flow from the receptor to the control center along the afferent pathway.
Homeostatic Control Mechanisms:
Control Center
Determines the level (set point) at which a variable is to be maintained, analyses the information it receives and then determines the appropriate response or course of action.
Homeostatic Control Mechanisms:
Effector
Provides the means for the control center’s response (output) to the stimulus. Information flows from the control center to the effector along the efferent pathway. The results of the responses then feed back to influence the stimulus, either depressing it (negative feedback) so the whole control mechanism is shut off or enhancing it (positive feedback) so the reaction continues at an even faster rate.
Examples:
- when a fly lands on them (positive feedback)
- stressing the horse (negative feedback)
Most homeostasis control mechanisms are _____
negative feedback mechanisms.
What happens to us when we age?
Our body organs become less efficient and our internal conditions become less and less stable.
What are the four primarily elements that cells are made of? And what are the smaller amounts of several other elements are made of?
1) Carbon, Oxygen, hydrogen and nitrogen.
2) iron, sodium, and potassium
Why are sodium and potassium ions essential?
Because they are needed for nerve impulses to be transmitted and muscles are to contract.
Types of cells: Prokaryotic
- cells have very little visible internal organization, for instance, the genetic material is stored in the molecule DNA, is free within the cell
- all their intracellular water soluble components (proteins, DNA, and metabolites) are located together in same volume enclosed by cell membrane, rather than in separate cellular compartments.
Types of Cells: Eukaryotic
- larger
- can be large enough to see with the naked eye
- structurally more complex
- contain a variety of specialized structure’s known collectively as orangelles, surrounded by viscous substance called cytosol
- their DNA is held within the largest organelle, the nucleus
- the defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear envelope, within which the genetic material is contained
Structures Within the Cell: Nucleus
- seed inside that contains most of the cell genetic material, organized as multiple long linear DNA molecules on complex with large variety of proteins to form chromosomes.
Structures Within the Cell: Nucleoli
- the nucleus contains one or more small, round bodies
- are sites where ribosomes are assembled
- migrate into the cytoplasm and serve as the actual sites of protein synthesis
Structures Within the Cell: Chromatin (primary functions)
- to package DNA into smaller volume to fit in cell
- strengthen DNA to allow mitosis
- to prevent DNA damage
- to control gene expression and DNA replication
Structures Within the Cell: Chromatin
- when a cells is not dividing, its DNA is combined with protein and forms a loose network of bumpy threads called chromatin that is scattered throughout the nucleus. When a cell is dividing to form two daughter cells, the chromatin threads coil and condense to form dense rod-like bodies called chromosomes, much the way a stretched spring becomes shorter and thicker when allowed to relax
- is the combination or complex of DNA and proteins that make up the contents of the nucleus of a cell.
Structures Within the Cell: Plasma Membrane
- is a fragile, transparent barrier that contains the cells contents and separates them from the surrounding environment.
- has a core of two lipid layers
- has proteins in bi-layers
- involved in transport functions
- proteins mounted on the cell exterior are receptors for hormones or other chemical messengers.
What is microvilli?
tiny finger like projections that greatly increase the cell’s surface are for absorption so that the process occurs more quickly
What determines your blood type:
glycoproteins, which act as receptors that certain bacteria viruses or toxins can bind to, and play a role in cell to cell interactions.
What are sugar proteins?
Glycoproteins because of their presence, the cell surface is fuzzy, sticky, sugar rich area.
What are desmosomes?
anchoring junctions that prevent cells subjected to mechanical stress from being pulled apart. (such as skin cells)
In tight membrane junctions what do the adjacent plasma membranes do?
Fuse together tightly like a zipper.
Tight membrane junctions are impermeable junctions that bind cells together into leak proof sheets that prevent substances from passing through the extracellular space between cells. True or False. Give an example
True. Example: in the small intestine these junctions prevent digestive enzymes from seeping into the bloodstream.
How are desmosomes structurally?
These junctions are button-like thickening of adjacent plasma membranes which are connected by fine protein filaments.
Where are gap junctions commonly seen?
They are commonly seen in the heart and between embryonic cells allow communication. Chemical molecules, such as nutrients or ions, can pass directly from one cell to another.
In gas junctions, the neighbouring cells are connected by hollow cylinders (connexions) composed of proteins that span the entire width of the abutting membranes. True or False
True
Structures Within the Cell: Cytoplasm
- the factory area of the cell
- the cellular material outside the nucleus and inside the plasma membrane
What are the three elements of the cytoplasm?
- cytosol: a semitransparent fluid that suspends the other elements
- organelles: the metabolic machinery of the cell (each have a specific function, ex. some synthesize proteins, others package those proteins), “little organs” specialized cellular compartments each performing its own job to maintain the life of the cell
- inclusions: are not functioning units but instead are chemical substances that may or may not be present, depending on the specific cell type. Most inclusions are stored nutrients or cell products.
Structures Within the Cell: Ribosomes
- tiny, round, dark bodies made of proteins and a variety of RNA called ribosomal RNA
- ribosomes are the actual sites of protein synthesis.
When ribosomes are attached to membranes, the whole ribosome membrane combination is called the smooth endoplasmic reticulum (ER). True or False
False. Rough ER
Structures Within the Cell: Endoplasmic Reticulum
- network within the cell
- system of fluid filled cisterns (tubules or canals) that coil and twist through the cytoplasm
- serves as a mini circulatory system for the cell because it provides a network of channels for carrying substances (primarily proteins) from one end to the other
What are the two forms of ER?
Smooth ER and Rough ER
Explain what Rough ER is:
Rough ER is studded with ribosomes. Essentially all of the building materials of cellular membranes are formed either in it or on it, the rough ER can be thought of as the cell’s membrane factory.
In general the amount of rough ER a cell has is a good clue to the amount of protein that cell makes. True or False
True
Explain Smooth ER:
Smooth ER is a continuation of the rough variety, it plays no role in protein synthesis. Instead it functions in cholesterol synthesis and breakdown, fat metabolism and detoxification of drugs.
What ER is found in liver cells mainly?
Smooth ER
What ER is found in pancreas cells mainly?
Rough ER
What is the first structure within the cell to disfunction in an unhealthy cell?
Golgi Apparatus
Structures Within the Cell: Nucleolus
- a structure found in the nucleus of cells, it forms around specific chromosomal regions in the nucleus of Eukaryotic cells made up of mostly proteins and ribonucleic acids
Whats the nucleolus’s function?
- to transcribe ribosomal RNA and combine it with proteins to from incomplete ribosomes
What does RNA stand for?
Ribonucleic Acid
Structures Within the Cell: Golgi Apparatus
- part of the cellular endomembrane system, the Golgi apparatus packages proteins inside the cell before they are sent to their destination. It is particularly important in the processing of proteins for secretion
What does lysosomes mean?
Breakdown bodies
Structures Within the Cell: Lysosomes
- many sizes
- membrane bags containing powerful digestive enzymes
- capable of digesting worn-out or non-useable cell structures and most foreign substances that enter the cell.
- lysosomes are especially abundant in white blood cells that engulf bacteria and other potentially harmful substances because they digest and rid the body of such foreigners.
The enzymes that lysosomes contain are formed by ribosomes and packaged by the golgi appartus. True or False
True
What are peroxisomes?
Membranous sacs containing powerful oxidase enzymes that use molecular oxygen to detoxify a number of harmful or poisonous substances including alcohol and formaldehyde.
What are peroxisomes convert free radicals into?
Hydrogen peroxide
What are free radicals and what disarms them?
Free radicals are highly reactive chemicals with unpaired electrons that can scramble the structure of proteins and nucleic acids. Also Peroxisomes disarm them.
What happens after the peroxisomes convert the free radicals into hydrogen peroxide?
The enzyme catalase then converts excess hydrogen peroxide to water.
Peroxisomes are especially numerous in the small and large intestine cells, which are very active in detoxification. True or False.
False: liver and kidney cells
How do peroxisomes replicate?
They simply pinch in half.
Mitochondria are not found in red blood cells. True or False
True
What happens when enzymes dissolve in the mitochondria?
When they dissolve in the fluid within the mitochondria, as well as enzymes that form part of the cristae membranes, carry out the reaction in which oxygen is used to break down foods. As the foods are broken down, energy is released. Much of the energy escapes as heat, but some is captured and used to form ATP molecules.
What does ATP stand for?
adenosine triphosphate
What does ATP do?
Provides the energy for all cellular work and every living cell requires a constant supply of ATP for its many activities.
What cells have huge amounts of ATP and have hundreds of mitochondria?
Liver and muscle cells, because they are metabolically busy.
What are some of the other tasks does the mitochondria do other than supply cellular energy?
- signalling
- cellular differentiation
- cell death
- the control of the cell cycle and cell growth
What is the cytoskeleton?
- elaborate network of protein structures extends throughout the cytoplasm
- acts as the cells bones and muscles by furnishing and internal framework that determines cells shape
- supports other organelles
Cytoskeleton is made up of mircotubles there are three different types:
- intermediate filaments: help form desmosomes and provide internal guy-wires to resist pulling forces on the cell
- microfilaments (such as actin and myosin): are most involved in cell motility and in producing changes in cell shape
- microtubules determine the overall shape of the cell and the distribution of organelles
Mircotubules are very important during _____.
Cell division
Draw and label a Cell.
look at picture on phone
What are centrioles?
They are rod-shaped bodies, that lay close to the nucleus and lie at right angles to each other. Made up of microtubules.
What is the purpose of cilia?
the ciliated cells of the respiratory system lining move mucus up and away from the lungs to take away bad bateria
What is a solution?
A homogenous mixture of two or more components.
What is a solvent?
The substance largest present in the solution is the solvent. Water is the body’s chief solvent.
What is a solute?
Components or substances present in the smaller amounts are solutes.
What is intracellular fluid?
A solution containing small amounts of gases, nutrients and salts, dissolved in water.
What is interstitial fluid?
Also dissolved in water. The fluid that continuously bathes the exterior of our cells.
The plasma membrane is a ______ ________ barrier which means that a barrier allows some substances to pass through it while excluding others.
Selectively Permeable
When a cell dies, the plasma membrane can no longer be selective and becomes permeable to nearly everything. True or False.
True
Movement of substances through the plasma membrane happen in two ways. Which two ways and explain.
Passive: transported across membrane without any energy input from the cell.
Active Transport: the cell provides the metabolic energy ATP
Molecules will move passively through the plasma membrane by diffusion if one of two things happens. What is this called and what are the ways?
Simple Diffusion: The unassisted diffusion of solutes through the plasma membrane.
1) they are small enough to pass through its pores.
2) they can dissolve in the fatty portion of the membrane.
What is osmosis?
Diffusion of water through a selectively permeable membrane such as the plasma membrane.
Osmosis into and out of cells is occurring all the time as water moves down its concentration gradient. True or False.
True.
Is a protein carrier needed as a transport vehicle in facilitated diffusion?
Yes
What does facilitated diffusion provide?
It provides a means for certain substances, notably glucose, that are both lipid-insoluble and too large to pass through the membrane pores, to enter the cell.
What is filtration?
Filtration is the process by which water and solutes are forced through a membrane (or capillary wall) by fluid, or hydrostatic pressure in the body.
Filtration is necessary for the liver to do its job properly. True or False
False the kidneys.
What are the two most important examples of active transport mechanisms?
Solute Pumping and Bulk Transport
Solute Pumping is similar to facilitated diffusion in that both __________________.
Require protein carries that combine reversibly with substances to be transported across the membrane.
What are some examples that are transported by solute pumps?
Amino acids, some sugars and most ions.
The _____-______ ____ that simultaneously carries ____ ions out and ________ ions into the cell is absolutely necessary for normal transmission of impulses by nerve cells.
Sodium-potassium pump, sodium, potassium
What does bulk transport do?
Some substances that cannot get through the plasma membrane in any other way are transported with the help of ATP into or out of the cell by bulk transport.
What does exocytosis do?
Moves substances out of the cell. It is the means by which cells actively secrete hormones, mucus and other cell products or eject certain cellular wastes. The product to be release is first packaged, typically by the efforts of the golgi apparatus.
What does endocytosis do?
Moves substances in the cell by including those ATP requiring processes that take up, or engulf, extracellular substances by enclosing them in a small membranous vesicle.
What does phagocytosis mean?
Cell Eating
What does pinocytosis mean?
Cell Drinking
Where are pinocytosis most likely to be found?
Cells forming the lining of the small intestine and kidney tubule cells because it is especially important in cells that function in absorption.
Once the vesicle or sac is formed it detaches from the plasma membrane and moves into the cytoplasm, where it fuses with _____ and its contents are ______ by ________ enzymes.
Lysosome, digested by lysosomal.
Bulk Transport:
Exocytosis and endocytosis.
1) during _____, vesicles fuse with the plasma membrane and dump their contents to the outside of the cell.
2) during ______, extracellular substances are incorporated into the cell in vesicles formed by an inward folding of the plasma membrane.
1) exocytosis
2) endocytosis
The cell cycle has two major periods, what are they and what happens?
Interphase, in which the cell grows and carries on its usual metabolic activities and Cell Division, during which it reproduces itself.