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