Physiology Unit 1 Exam

Human physiology

study of human body function

cell

smallest living unit

tissue

collections of cells performing similar function

organ

2+ tissues combine to make a structure that performs specific function

system

collection of organs that combine to perform certain functions

ICF-Intracellular

fluid within cells

ECF-extracellular

fluid outside cells-but within body

plasma

fluid surrounding blood cells

interstitial

fluid “between” other cells

homeostasis

ability to maintain a relatively constant/uniform internal enviornment

negative feedback

major physiological mechanism used to maintain homeostasis, it goes in the opposite direction

receptor

molecular sensors (proteins) that detect stimuli

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ex: thermoreceptors, chemoreceptors

integrating center

orchestrates appropriate response (brain)

effector organs

tissues/organs responsible for appropriate body responses (muscles, glands)

afferent

from body to the CNS

efferent

from CNS back to the body

hyperthermia

increased body temp

hypothermia

decreased body temp

positive feedback

cause rapid change (burst) away from the set point. There needs to be a termination point

what are the 4 major categories of cells

epithelial, muscle, connective, and neurons

epithelial cells

form sheet-like layers of cells that function as a barrier. they line the external body surfaces and hollow organs

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ex: skin, lungs, glands, stomach, intestines, blood vessels

muscle cells

specialized cells designed to contract(shorten)

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voluntary: flexing bicep

involuntary: pumping of blood, mixing of food in the stomach

skeletal muscle cells

attached to bones and tendons

smooth muscle cells

surround blood vessels

cardiac muscle cells

pumps blood when it contracts

connective tissues

diverse set of cells that connect or “link” body structures

connective tissue types

bone, tendons, fat, and blood

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(many have extracellular matrix)

neurons

communicate with each other and other body cells

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they have branches to receive(dendrites) or send (axons) signals. significant neuronal processing occurs in brain and spinal cord.

What are the 5 levels of a cell?

1. Small organic molecules
2. macromolecules
3. supramolecular structures (cell wall, membrane, chromosome)
4. organelles and other structures (chloroplast, nucleus, mitochondria)
5. the cell

What are the 4 marcomolecules?

Proteins, nucleic acids, polysaccharides, lipids

Lipid

Fats that are not soluble in water because of heterogeneous chemical structure

What do lipids (good) function in?

1. membrane structure
2. energy storage
3. signaling: intracellular (ex: DAG) and intercellular (ex: steroids)

What are some characteristics of lipids?

1. some have very long hydrophobic tails
2. some may also have a hydrophilic head group (because of the phosphate)

what do cell membranes contain?

bilayers of Amphipathic phospholipids which makes it a barrier for water-soluble substances: ions, glucose, and amino acids…they also contain associated proteins

Characteristics of saturated FA

They are straight and can pack together tightly, and make a more stable portion of plasma membrane

characteristics of unsaturated FA

are kinked and do not pack together tightly

triglycerides

a major form of energy storage, and it is a type of fat found in the blood that comes from the food we eat

Steriods

Derived from cholesterol and are major signaling molecules. The cholesterol also helps from the plasma membrane

Polysaccharides/ Carbohydrates

the most abundant class of organic molecules found in nature. It is derived from photosynthesis. They are also polar so they dissolve in water!

What are the functions of carbohydrates?

1. Building blocks of other macromolecules
2. Energy source (glucose)
3. modify structure/function of other macromolecules (ex:proteins)

Monosaccharides

they serve as energy sources for cells and are building blocks for other macromolecules such as polysaccharides and nucleotides. they often exist in a ring-shaped structure

How are Polysaccharides formed?

Monosaccharides join via glycosidic bonds to form polymers

Glycogen

common “early use” energy store composed of many linked glucoses

Polysaccharide function of energy

Glucose-major input to ATP production

Polysaccharide function of modifying structure/function of other macromolecules:

Glycolipids: outside membrane-adhesion

Glycoproteins: posttranslational-affects trafficking/folding

What are the templates for proteins?

Nucleic acids

Transcription

 **the process of making an RNA copy of a gene's DNA sequence**

Translation

**the process of translating the sequence of a messenger RNA (mRNA) molecule to a** sequence of amino acids during protein synthesis

DNA

typically a right handed double helix (B-DNA) that “stores” the genetic code in the nucleus, can be a template for transcription and replication

What makes up a nucleotide?

A phosphate, some type of sugar(D-deoxyribose in DNA or D-ribose in RNA) and some type of base (adenine, guanine, thymine, cytosine or uracil (in RNA))

What are the complementary base pairings?

A=T and G=C

What do nucleic acids do?

they store and “express” genetic code

DNA Vs. RNA

DNA: nuclear “storage” of code, double stranded, antiparallel, complementary

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RNA: “expression” of code, single stranded, uses “U”, and functions in cytoplasm

Energy transfer nucleotides:

Adenosine di(tri)phosphate ADP/ATP

Adenine+ribose+2 or 3 phosphates

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Guanosine di(tri)phosphate GDP/GTP

proteins perform most cellular functions, what are some examples?

enzymes, structural proteins, regulatory proteins, transport proteins, hormonal proteins, defensive proteins, etc…

R-group chemistry

dictates amino acid interactions and ultimate protein folding

peptide bonds

strong covalent bonds that link amino acids

primary structure

 the sequence of amino acids linked together to form a polypeptide chain

secondary structure

ocal folded structures that form within a polypeptide due to interactions between atoms of the backbone

tertiary structure

the overall three-dimensional arrangement of its polypeptide chain in space

quaternary structure

the association of several protein chains or subunits into a closely packed arrangement

what happens if there is a minor modification to the protein shape?

can dramatically affect its function

chymotrypsin

breaks down peptide bonds so it breaks down proteins into individual proteins

kinesin

they “walk” along a microtubule track uses ATP as energy to move

tubulin

multiple important cellular functions such as structural support, pathway for transport and force generation in cell division

some proteins function as enzymes!

they speed up chemical reactions

characteristics of enzymes

\-are typically proteins (ase)

\-some require ATP-other enzymes do not

\-enzymes increase likelihood of chemical (don’t allow “new” reactions)

\-are not changed/consumed during reaction

\-stabilize “transition state” intermediate-allowing faster reaction

Anabolic chemical reactions

synthesize large molecules from small, energy is stored as “potential” energy

catabolic reactions

they release energy and break down large molecules into smaller products, they occur spontaneously but are “sped up” by enzymes

chemical reactions are reversible

law of mass action determines direction of reaction

what factors affect enzyme reaction rates?

\-temperature

\-pH

enzyme/substrate concentration

\-affinity (strength of association)

\-allosteric reactions

enzymes catalytic rate

how fast enzyme functions (assuming 100% active site occupancy)

allosteric interactions

chemical modulator binds enzyme at different location than active site, which changes enzyme conformation

enzyme functions are often affected by covalent modifications

typically post-translational modification, often these modifications are reversible

organelles

specialized structures living in a cell

what is the structure of the plasma membrane?

bilayer composed primarily of amphipathic lipids (ex: phospolipids) and proteins

what carries out many plasma membrane functions?

proteins

as the plasma membrane forms a semipermeable barrier what is required?

protein transports are required to aid in moving most substances in/out of cells

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ex: amino acids, glucose, ions need “help” crossing biological membranes

cAMP

is an important intracellular second messenger molecule regulated in many physiological processes

cadherins

an example of a protein that helps cells adhere to each other to form tissues/organs

tight junctions

forms impermeable barriers in epithelial tissues that line special organ structures such as GI tract, kidney, and BBB

what proteins form intercellular ridges?

Claudin and Occludin, they do not allow passage of solutes between cells, so they must pass through epithetical cell plasma membrane

gap junctions

allow for rapid intercellular transport, quick communication allows tissue to function as a “unit”

Connexins

they form channels/pores so that small molecules can quickly diffuse to neighboring cell

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ex: common in the heart, smooth muscle and neurons

nucleus

information center of the cell that stores/protects DNA blueprint, this is where DNA replication and transcription takes place

nucleolus

site of ribosome synthesis

histone proteins

packages DNA

after processing where is mRNA released

cytoplasm

nuclear pores

allow movement of large particles (mRNA, ribosomes, etc…) into/out of membrane bound nucleus

What happens when ribosomes attach to mRNA?

It gets translated into protein. Ribosomes “read” triplet nucleotide code, and bring one amino acid in for every 3 nucleotides-attach amino acids via peptide bond

Initation stage of translation

starts at 5’ AUG (consensus sequence)

Elongation stage of translation

AA shuttled in by tRNA’s and linked via peptide bond (N-terminus to C-terminus)

Termination stage of translation

“UAG” stop codon reached and protein factor releases polypeptide

destination of polypeptide translated in cytosol

short amino acid stretches in nascent polypeptide determines where the protein should traffic to in cell

secretory pathway polypeptide have a special signal sequence that sends them to ER for further processing

ER-Transport vesicle-golgi-secretory vesicle-plasma membrane

Endoplasmic reticulum (ER)

network of flat membranous sacs contagious with nuclear envelope

transport vesicle

facilitates the movement of specific molecules across a vesicle's membrane

rough ER

ribosomes synthesize secretory pathway (plasma membrane) proteins, initial processing of proteins occurs in rough ER (glycosylation, folding, etc…)

smooth ER

lipid synthesis, Ca++ storage, and looks smooth because there are no membrane bounded ribosomes

Golgi complex

\-processing/sorting station for membrane bound and secretory proteins

\-close proximity to ER

\-membranous complex with vesicles fusing and being released

\-synthesis of complex polysaccharides

\-glycosylation