Physiology

Question 1

what is human physiology

Answer 1

the science/study of human body structure/function

Question 2

what are the parts of the human body

Answer 2

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.

Question 3

Does a single organ play in multiple systems

Answer 3

Yes, a single organ may play a role in multiple system, and organ systems always work together to allow our bodies to function

Question 4

What does a simplified body plan illustrate

Answer 4

a simplified body plan illustrates functional relationships between organ systems and outlines major processes required for human life.

Question 5

What are body compartments filled with and why

Answer 5

body compartments are filled with fluid (water) because cells live in an aqueous environment, and most cellular molecules are hydrophilic (likes water)

Question 6

What are the different types of fluid in the body

Answer 6

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

Question 7

cell membranes are semipermeable which means

Answer 7

The cell allow passage of only certain substances
regulated transport often occurs between compartments

Question 8

does significant exchange occur between external-internal environments

Answer 8

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

Question 9

what is homeostasis

Answer 9

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

Question 10

What are the general body structures that underlie negative feedback

Answer 10

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

Question 10

what is a positive feedback loop

Answer 10

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

Question 10

What is negative feedback

Answer 10

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

Question 10

can set points change

Answer 10

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.

Question 10

what are the physiologic mechanisms at the cellular level

Answer 10

1. thermoreceptor (proteins) change shape in response to a change in temperature
2. thermoreceptor shape change results in chemical/molecular changes inside cell
3. chemical/molecular changes are converted to a signal (AP) in afferent nerve cell
4. afferent nerve communicates via neurotransmitter across synapse to integrator cell
5. integrator cell binds neurotransmitter via receptor

Question 11

what are the 4 major categories of cells

Answer 11

epithelial, muscle, connective, neurons

Question 12

describe epithelial cells

Answer 12

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

Question 13

describe muscle cells

Answer 13

muscle cells are specialized cells designed to contract
voluntary or involuntary
smooth, skeletal, cardiac

Question 14

define connective tissues

Answer 14

connective tissues are a diverse set of cells that connect or ling body structures
bone, tendons, fat, blood
many have extensive extracellular matrix

Question 15

what are the 4 primary macromolecules

Answer 15

Proteins, Nucleic acids, Polysaccharides, Lipids

Question 16

what are lipids

Answer 16

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)

Question 17

what is the cell membrane structure

Answer 17

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

Question 18

what are triglycerides

Answer 18

triglycerides are a major form of energy storage
adipose cells store/metabolize fatty acids to help maintain blood glucose/energy levels near homeostasis

Question 19

what are steroids

Answer 19

steroids are derived from cholesterol and are majoring signaling molecules
cholesterol also helps form the plasma membrane

Question 20

what are polysaccharides/carbohydrates

Answer 20

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

Question 21

what are monosaccharides

Answer 21

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

Question 22

what are polysaccharides function

Answer 22

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

Question 23

what are nucleic acids

Answer 23

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

Question 24

what is DNA

Answer 24

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

Question 25

what are nucleotides

Answer 25

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

Question 26

what are proteins

Answer 26

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)