Physiology Flashcards
what is human physiology
the science/study of human body structure/function
what are the parts of the human body
cell: smallest living unit
tissue: collection of cells performing similar to function
organ: two or more tissues combine to make a structure that performs specific function
system: collection of organs that combine to perform certain functions
The body functions as an integrated/interdependent unit.
Does a single organ play in multiple systems
Yes, a single organ may play a role in multiple system, and organ systems always work together to allow our bodies to function
What does a simplified body plan illustrate
a simplified body plan illustrates functional relationships between organ systems and outlines major processes required for human life.
What are body compartments filled with and why
body compartments are filled with fluid (water) because cells live in an aqueous environment, and most cellular molecules are hydrophilic (likes water)
What are the different types of fluid in the body
ICF: intracellular fluid (fluid within cells)
ECF: extracellular fluid (fluid outside cells -but within body)
Plasma: fluid surrounding blood cells
Interstitial fluid: fluid “between” other cells
cell membranes are semipermeable which means
The cell allow passage of only certain substances
regulated transport often occurs between compartments
does significant exchange occur between external-internal environments
Yes, significant exchange occurs between external-internal environments, but exchange occurs only in certain organ systems: lungs, gastrointestinal tract, kidneys.
This exchange allows the body to stay in a relatively uniform condition: oxygen content, water volume, energy
what is homeostasis
Homeostasis is the ability to maintain a relatively constant/uniform internal environment
- temperature
- blood pressure
- molecular concentrations (pH, Na+, CO2)
Homeostasis requires organ system integrations and is a unifying theme in physiology. The disruption of homeostasis can lead to disease and/or death
What are the general body structures that underlie negative feedback
the receptor: molecular sensor (proteins) that detect stimuli (thermoreceptors, chemoreceptors) sends an input to the brain via an afferent signal (neuron or hormone) to the integrating center which orchestrates appropriate response and sends the response via an efferent signal is sent to the effector organs: tissues/organs responsible for appropriate body responses
what is a positive feedback loop
positive feedback loops cause rapid change (burst) away from set point.
- neuronal action potential
* Na+ influx into cell causes more Na+ to come in leading to a burst away from -65 mV
Positive feedback loops need to be terminated: during action potential – Na+ channels eventually close and K+ leaves
What is negative feedback
Negative feedback is a major physiologic mechanism used to maintain homeostasis
if a regulated variable increases-system responds to make it decrease, and vice versa
Important body conditions “hover” around specific homeostatic set points:
- temperature- 37 celcius
- blood glucose = 72 mg/dL
- blood pH = 7.4
can set points change
Yes, set points can occasionally “change”
fever is an appropriate increase in body
temperature set point
rise in core body temperature - accompanying viral/bacterial infection
white blood cells note pathogen, and secrete pyrogens (interleukins)
interleukins cause the hypothalamus to transiently reset set point upwards.
fever enhances immune response by: increasing mobility of leukocytes, increasing phagocytosis, increasing “T” cell proliferations
after the infection is cleared the set point returns to normal.
what are the physiologic mechanisms at the cellular level
- thermoreceptor (proteins) change shape in response to a change in temperature
- thermoreceptor shape change results in chemical/molecular changes inside cell
- chemical/molecular changes are converted to a signal (AP) in afferent nerve cell
- afferent nerve communicates via neurotransmitter across synapse to integrator cell
- integrator cell binds neurotransmitter via receptor
what are the 4 major categories of cells
epithelial, muscle, connective, neurons
describe epithelial cells
epithelial cells form sheet-like layers of cells that function as a barrier. Lines external body surfaces and hollow organs - skin, lungs, glands, stomach, intestines, blood vessels
describe muscle cells
muscle cells are specialized cells designed to contract
voluntary or involuntary
smooth, skeletal, cardiac
define connective tissues
connective tissues are a diverse set of cells that connect or ling body structures
bone, tendons, fat, blood
many have extensive extracellular matrix
what are the 4 primary macromolecules
Proteins, Nucleic acids, Polysaccharides, Lipids
what are lipids
lipids are not soluble in water (hydrophobic) and have a heterogeneous chemical structure (sterol rings, long hydrocarbon tails, etc)
Lipids function in
- membrane structure, energy storage, signaling: intercellular (DAG), intercellular (steroids)
some lipids have long hydrophobic tails, other lipids also have hydrophilic head groups
phospholipids are part water soluble and part water insoluble (amphipathic)
what is the cell membrane structure
cell membrane contains amphipathic phospholipids that spontaneously coalesce to form a lipid by layer.
the hydrophobic nature of membrane makes it a barrier for water soluble substances: ions, glucose, amino acids
the plasma membrane is a lipid bilayer primarily composed of a variety of amphipathic phospholipids and associated proteins. some proteins act as transporters to regulate traffic across membrane.
cell membranes are composed of a variety of lipids: different head groups, different hydrocarbon tails
Lipids have different degrees of saturation (# of double bonds) that affects fatty acid structure. saturated FA are straight, can therefore pack together tightly
unsaturated FA are kinked and don’t pack together well.
Degree of saturation affects fluidity of lipids/membranes
what are triglycerides
triglycerides are a major form of energy storage
adipose cells store/metabolize fatty acids to help maintain blood glucose/energy levels near homeostasis
what are steroids
steroids are derived from cholesterol and are majoring signaling molecules
cholesterol also helps form the plasma membrane
what are polysaccharides/carbohydrates
polysaccharides/carbohydrates are the most abundant class of organic molecule found in nature and are derived from photosynthesis
Cn(H2O)n
polar so they don’t dissolve in water
Functions in
building blooks of other macromolecules, energy source, modify structure/function of other macromolecules
what are monosaccharides
mono saccharides serve as energy sources for cells and are building blocks for other macromolecules such as polysaccharides and nucleotides and often exist in a ring shaped structure
common monosaccharides contain 3-6 carbons
monosaccharides join via glycosidic bonds to form polymers called polysaccharides.
glycogen: common “early use” energy stores composed of many linked glucoses
what are polysaccharides function
polysaccharides function is energy; glucose- major input to ATP production
glycogen storage in animal cells
modify structure/function of other macromolecules: glycolipids - outside membrane - adhesion etc.
glycoproteins - posttranslational - affects trafficking/folding
what are nucleic acids
nucleic acids are templates for proteins.
DNA gets transcribed to mRNA in the nucleus then gets translated in the cytoplasm via nuclear pore to be synthesized.
proteins do the work of the cell
store and express genetic code.
triplet code: 3 nucleotides = 1 amino acids
nuclear storage of code: double stranded, antiparallel, complementary
expression of code: single stranded, u, functions in cytoplasm
what is DNA
DNA is typically a right handed double helix that store the genetic code in the nucleus
sugar-phosphate backbone nitrogenous bases
template for transcription (and replication)
gene: small section of DNA that codes for a specific protein
what are nucleotides
nucleotides are involved in energy transfer and cell signaling
energy transfer nucleotides;
- adenosine di(tri)phosphate ADP/ATP
- adenine + ribose + 2 or 3 phosphates
-guanosine di(tri)phosphate GDP/GTP
what are proteins
proteins perform most cellular functions
ubiquitous, “workhorses” for the cell
composed of 20 different amino acids. R-group chemistry dictates amino acid interaction, and ultimate protein folding
hydrophobic end tends to be on interior of proteins
hydrophilic amino acids tend to cluster on protein surface
charged (ionic interaction)
