late night finds AUG 8th

Question 1

glial cells

Answer 1

cells that support the neurons
- structurally and support - astrocytes (BBB), microglia (phagocytic), oligodendrocytes (produce mylein), ependymal ( produce spinal fluid)

Question 2

potassium equilibrium in and out of the cell?

Answer 2

140mM inside and 4mM outside

so due to concentration gradient K leaks out, but then bc inside is negative, K+ is also pulled in —> this finds a equilibrium so overall no net movement

Question 3

equilibrium potential of potassium

Answer 3

-90mV (negative bc + ion is leaving)

Question 4

equilibrium potential of sodium

Answer 4

12mM inside and 145mM outside so concentration leaks Na into the cell (positive ion inside) —> 60mV

Question 5

net resting potencial is

Answer 5

70mV`

Question 6

two types of summation

Answer 6

temporal (one neuron) and spatial (many neurons)

Question 7

temporal summation

Answer 7

several from one neuron over time

Question 8

spatial summation

Answer 8

several impulses from many different neurons

Question 9

after threshold is met what ion flows in

Answer 9

Na+ influx

Question 10

after action potencial isreached what repolarizes it

Answer 10

K+ flows out

Question 11

what casues sodium to go into the cell if threshold is reached

Answer 11

strong electrochemcal gradient - voltage gated channels open

• electrical - inside is more negative
• chemical - flows down concentration gradient ( there is less sodium inside the cell)

Question 12

impulse propagation

Answer 12

when an action potencial travels down anaxon

Question 13

if an axon is wider what is the resulting impulse propagation speed?

Answer 13

it is faster!! bc greater cross-sectional area means less resitence

Question 14

does length or area affect impulse propagation speed more sigificantly?

Answer 14

area! bigger area= faster impulse

longer length= higher resistence= slower conduction

Question 15

why does myelien speed up transduction

Answer 15

bc it insulates the axons so well to prevent dissapation of electric energy- so well that the membrane is only permeable at nodes de ravier- thus signal hops = saltatory conduction

Question 16

incereased intensity of stimuli results in ?

Answer 16

increase f of firing

Question 17

whats the dif between electrical and chemical transmission

Answer 17

electrical is down a neuron in AP and chemical is across a synapse - with NT

Question 18

how at NT released

Answer 18

when AP reaches, voltage-gated Ca open and let in Ca- triggers release of vesicles- eocytosis

Question 19

spinal cord is protected with

Answer 19

vertebral column

Question 20

spinal crd divided into ( from top to bottom)

Answer 20

cervical, thoracic, lumbar, sacral

Question 21

dorsal root ganglia

Answer 21

contains the cell bodies of sensory neurons - in the spinal cord - so central NS
- pain, mechanical stim, first order neurons, reflex arch

• The term ‘ganglion’ means a collection of neuronal cell bodies present in the peripheral nervous system. A ganglion consists of cell bodies of neurons present in the peripheral parts of the body. Hence, a ganglion is a part of the peripheral nervous system.
• One of the several types of ganglia present in the peripheral nervous system is dorsal root ganglion.

Question 22

somatic NS

Answer 22

joints, skin and muscle- sensory and motor neurons/opposite of autonomic

Question 23

the main difference between to somatic and the autonomic NS

Answer 23

is that the autonomic NS contains two neurons and a synapse in the peripheral part

• first is the preganglionic neuron (soma is in CNS)
• second is postganglionic

but inthe somatic, motor neurons go directly from spinal cord to muscle without synapsing

Question 24

which system has 2 neurons in PNS

Answer 24

the autonomic NS

Question 25

two types of reflex arch

Answer 25

monosynaptic and polysynaptic

Question 26

monosynaptic reflex arch

Answer 26

there is a single synapse between the sensory neuron the perceives it and the motor that pulls back - so no interneuron (knee-jerk)

Question 27

polysynaptic reflex arch

Answer 27

there is atleast one interneuron (withdrawal reflex - stepping on a nail)

Question 28

penetrance vs expressivity

Answer 28

penetrance = proportion of individuals in a pop carrying the allele that actually express the phenotype expressivity= the differnt manifestations of the same genotype acrooss a population - the varying phenotypes despite identical genetypes

Question 29

example of penetrance

Answer 29

hungtintons disease - ppl with 40 repeat cycles will have full penetrance - 100% of ppl with this genotype will have symptoms - individuals with less sequences show high penetrance

Question 30

expressivity constant

Answer 30

then all ppl with saem genotype = same phenotype

Question 31

expressivity variable

Answer 31

same genotype but different expressivity (variability in individual) - example in one dominant allele- but multiple different symptoms

Question 32

genetic leakage

Answer 32

a flow of genes between species - mate to produce hybrid offspring such as a mule - cant reproduce bc odd number of chromosomes

Question 33

a mule is an example of

Answer 33

genetic leakage

Question 34

genetic drift

Answer 34

change of composition of the gene pool due to change(no enviromental explanation it is due to chance!) - is a change in the frequency of an allele within a population over time. This change in the frequency of the allele or gene variation must occur randomly in order for genetic drift to occur. There are no environmental influences that cause genetic drift to occur. Examples of genetic drift are more evident in smaller populations of organisms. - The American Bison was hunted to near extinction and even today as the population has recovered, the result is a population of bison with little genetic variation

Question 35

founder effect

Answer 35

more extreme case of genetic drift, where a small partof a population finds itelf in reproductive isolation as a result of natural barriers or other bottlenecks that drastically and suddenly reduce the size of pop available for breeding- results in inbreeeding

Question 36

inbreeding results in

Answer 36

homozygosity- increases the prevalence of homozygous for dom and rec mutations/genotypes

Question 37

examples of genetic drift

Answer 37

The American Bison was hunted to near extinction and even today as the population has recovered, the result is a population of bison with little genetic variation A certain type of plant can produce blue or yellow flowers. During a fire, many yellow flowers are destroyed and now since blue is the dominant allele, the plant reproduces plants that only produce blue flowers. -A population of rabbits can have brown fur and white fur with brown fur being the dominant allele. By random chance, the offspring may all be brown and this could reduce or eliminate the allele for white fur. A mother with blue eyes and a father with brown eyes can have children with brown or blue eyes. If brown is the dominant allele, even though there is a 50% chance of having blue eyes, they might have all children with brown eyes by chance. A bird may have an allele for two different beak sizes. Depending on which alleles show up in the offspring, genetic drift could cause one of the beak sizes to disappear from the population thus reducing the genetic variation of the birds gene pool