Winter Test 1 (Ch. 4, 16,11,12) Flashcards
Purines
double ring
Adenine (A)
Guanine (G)
Pyrimidines
single ring
Cytosine (C)
Thymine (T)
DNA structure breakdown
DNA –> histones –> nucleosomes –> chromatid –> chromosome
process of DNA synthesis
DNA –> mRNA –> protein
transcription
step from DNA to mRNA
occurs in the nucleus where DNA is located
translation
step from mRNA to protein
most occurs in cytoplasm
Peptide formation
1) DNA double helix
2) 7 base triplets on template strand of DNA
3) mRNA transcribed
4) Anticodons of tRNA bind to mRNA codons
5) Amino acids carried by 6 tRNA molecules
6) Amino acids linked into a peptide chain
Cell cycle
G1 phase- get materials needed to replicate DNA
S phase- DNA replication
G2 phase- synthesize enzymes for cell division and repairs DNA replication errors
M phase- mitosis
G1, S, G2 are called interphase
Cells stop dividing when
snugly contact neighboring cells
when nutrients or growth factors are withdrawn
contact inhibition – no more space
Cells divide when
they have enough cytoplasm for two daughter cells
they have replicated their DNA
adequate supply of nutrients
are stimulated by growth factors
Polygenetic inheritance
genes at two or more loci, or even different chromosomes, contribute to a single phenotypic trait (skin and eye color, alcoholism, mental illness, cancer, and heart disease)
Pleitropy
one gene produces multiple phenotypic effects
Penetrance
% of population inhibiting expected phenotype
Modality of Receptors
Thermoreceptors- heat and cold Photoreceptors- eyes/light Nociceptors- pain Chemoreceptors- chemicals: odor, fluids, tastes Mechanoreceptors- vibrations, pressure
Duration of receptors
phasic- burst of action potentials, quickly adapt and sharply reduce or stop
tonic- adapt slowly, generate nerve signals more steadily
Intensity of receptors
3 ways:
which fibers are sending signals
how many fibers are doing so
how fast these fibers are firing
Origin of stimuli of receptors
exteroceptors- external stimuli
interoceptors- internal stimuli
proprioceptors- body position
Distribution of receptors
general (somesthetic) senses- widely distributed
special senses- vision, hearing, equilibrium, taste, and smell
Uncapsulated nerve endings
lack connective tissue wrapping (free nerve endings)
Tactile (Merkel) discs- tonic receptors for light touch
Hair receptors
Encapsulated nerve endings
wrapped by glial cells or connective tissue
enhances sensitivity/selectivity of response
Project pathways of sensory neurons
3 nerve orders:
1st- afferent, body to spinal cord
2nd- spinal cord to thalamus
3rd- thalamus to cerebrum
Papillae of the tongue
filliform- no taste buds (for texture)
fungiform- tips and sides of tongue
vallate (circumvallate)- 50% of taste buds
2 mechanisms of taste
Salty (Na+) and Sour (acidic)- depolarizes and change membrane potential
Umami (amino acids), Bitter (alkaloids), Sweet- 2nd messenger system
Outer ear
auricle
auditory canal- temporal bone to tympanic membrane
external acoustic meatus
Middle ear
tympanic membrane- eardrum
auditory ossicles- malleus, incus, stapes
Inner ear
bony labyrinth
membranous labyrinth- endolymph and perilymph
cochlea
Cochlea
scala vestibuli- superior chamber, oval window –> apex
scala tympani- inferior chamber, apex –> round window
scala media- triangular middle chamber, endolymph
Equilibrium
static- orientation of the head when the body is stationary
dynamic- perception of motion pr acceleration
Vestibule
Saccule and utricle:
macula sacculi- vertical on wall of saccule
macula utricully- horizontally of floor of utricle
conjunctiva
a transparent mucous membrane that lines eyelids and covers anterior surface of eyeball, except cornea
Tunics of the eyeball
tunica fibrosa- outer fibrous layer (sclera and cornea)
tunica vasculosa- middle vascular layer (choroid, ciliary body, iris)
tunica interna- retina
Characteristics of muscle
responsiveness (excitability) conductivity contractility extensibility elasticity
Connective tissues of muscles
endomysium- around the muscle cells
perimysium- around the muscle fascicles
epimysium- around the entire muscle
sarcomeres
functional contractile unit of the muscle fiber
muscle shortens because individual sarcomeres shorten
pulls z discs closer to each other
Resting membrane potential
in muscle cells about -90mV
maintained by Na-K pump
Active muscle fiber/nerve cell
ion gates open in the plasma membrane
Na+ instantly diffuses down its concentration gradient into the cell
depolarization - inside of the plasma membrane becomes briefly positive
immediately, Na+ gates close and K+ gates open
K+ rushes out of cell
loss of positive potassium ions turns the membrane negative again (repolarization)
excitation-contraction coupling
preparing a muscle to contract
Excitation of muscles
nerve signal opens voltage-gated calcium channels in synaptic knob calcium stimulates exocytosis of ACh from synaptic vesicles ACh released into synaptic cleft two ACh molecules bind to each receptor protein, opening Na+ and K+ channels. voltage change (EPP) in end-plate region opens nearby voltage-gated channels producing an action potential that spreads over muscle surface.
Contraction of muscles
need ATP
Bent actin bound to ATP
Power stroke- sliding of thin filament (actin)
Relaxation of muscles
nerve stimulation & ACh release stop
AChE breaks down ACh & fragments reabsorbed into synaptic knob
stimulation by ACh stops
Isometric muscle contraction
same length of muscle, changes in load of weight
Isotonic muscle contraction
changes in length of muscle, same load of weight
Anaerobic fermentation
enables cells to produce ATP in the absence of oxygen
yields little ATP and toxic lactic acid, a major factor in muscle fatigue
aerobic respiration
produces far more ATP
less toxic end products (CO2 and water)
requires a continual supply of oxygen
phosphagen system
provides nearly all energy used for short bursts of intense activity
slow oxidative (SO), slow-twitch, red, or type I fibers
abundant mitochondria, myoglobin and capillaries - deep red color
adapted for aerobic respiration and fatigue resistance
fast glycolytic (FG), fast-twitch, white, or type II fibers
fibers are well adapted for quick responses, but not for fatigue resistance
rich in enzymes of phosphagen and glycogen-lactic acid systems generate lactic acid causing fatigue
poor in mitochondria, myoglobin, and blood capillaries which gives pale appearance
Central nervous system (CNS)
brain and spinal cord enclosed in bony coverings
Peripheral nervous system (PNS)
all the nervous system except the brain and spinal cord
composed of nerves and ganglia
sensory (afferent) division
carries sensory signals from various receptors to the CNS
somatic sensory division
carries signals from receptors in the skin, muscles, bones, and joints
visceral sensory division
carries signals from the viscera of the thoracic and abdominal cavities
heart, lungs, stomach, and urinary bladder
sympathetic nervous system
tends to arouse body for action
accelerating heart beat and respiration, while inhibiting digestive and urinary systems
parasympathetic nervous system
tends to have calming effect
slows heart rate and breathing
stimulates digestive and urinary systems
interneurons (association) neurons
CNS; process, store, and retrieve information and ‘make decisions’ that determine how the body will respond to stimuli
motor (efferent) neuron
motor because most of them lead to muscles
efferent neurons conduct signals away from the CNS
multipolar neuron
one axon and multiple dendrites
most common
most neurons in the brain and spinal cord
bipolar neuron
one axon and one dendrite
olfactory cells, retina, inner ear
unipolar neuron
single process leading away from the soma
sensory from skin and organs to spinal cord
anaxonic neuron
many dendrites but no axon
help in visual processes
