Bio240-Exam4

Functions of Nervous System

overall, facilitates communication between cells. Does this via 4 ways

• detect stimuli (internal or external)

• conduct stimuli

• process stimuli

• cause a response

How is the nervous system divided

CNS: brain adn spinal cord

Peripheral NS: peripheral nerves. these have sensory receptors, collect information, sends it to CNS, and CNS sends this information to motor portion of NS

• motor NS:

  • somatic: this is the skeletal muscle

  • automatic: this is smooth muscle, cardiac muscle, and glands

HOw can the autonomic NS be further divided

this is noe of the division of motor NS. THis autonomic can be further divided.

• Parasympathetic: rest and digest

• sympathetic: flight/flight - regulated by epi/norepi

What is the basic unit of the nervous system, and what is its structure like?

Neuron! (nerve cell)

• cell body: “soma” contains nucleus, has dendrites coming off it (finger-like projections)

• Axon = tail

• axon part has domains: nodes of ranvier and myelin sheath

• synapse: this is at the end of the cord, oppostie cell body. the synapse of one will connect to the cell body of another

Electrical signal within neuron

electrical signal = action potential

myelin sheath provides insulation which allows for electrical signals to move faster, nodes of ranvier have no insulation

chemcial signal within neuron

synapse: this is the space/junction between two neurons, which allows for different neurons to communcate with eachother.

neurotransmitters: chemical signals released at the synpase

Generating action potential (Na, K)

Neurons are suspended in extracellular fluid

extracellular fluid: high in Na, low in K ions

inside the neuron: low in Na, high in K

Neuron resting membrane potential

this occurs when there are more positive ions outside the cell than inside the cell

the result is that inside the neuron is more negative, and outside is more positive. THis difference is an electrical potential called the resting membrane potential, and RMP is usually around -70mV

What 3 channels occur at the Nodes of Ranvier

These three channels are all existant in the neuron cell membrane, more specifically at NOR

1) potassium channel: a pore in the membrane allows K thorugh the membrane via diffusion. When the cell is at rest, K ions leak out of the cell throguh K channels.

2) sodium channel: pore in the membrane allows Na thorugh the membrane via diffusion. When the cell is at rest, Na channels are closed and pretty much no/very little Na moves.

3) Na/K pump: this maintains resting potential by pumping Na and K against their concentration gradient. This helps to maintain balance.

Action potential

this is communcation between cells. The -55 and 30 thresholds must occur, or nothing happens. its not like a -45 will fire a little bit.

1) cell recieve a stimulus: this can be an external stimulus like loud sounds or a stimulus from another neuron (internal) in the form of a neurotransmitter. -55 activation.

2) Na channels open widely. This allows Na to rush into the cell, which resutls in the inside of the cell being + charged in comparison to outside the cell. electrical potential rises to +30mV

• the first two steps cause depolarization.

3) Na channels close after about 1 millisecond. There is then a refractory period, which is a temporary shutdown. Na channels cannot open again until the cell resets.Cell is very + inside.

4) K channels open compeltely. K ions rush out of cell. THis causes the electrical potential to go back to -70mV.

• these two steps (3 and 4) are the repolarization process. There is now a lot of Na in cell and a lot of K outside of cell. Imbalanced.

5) Na/K pump restores rsting membrane potential. it continues to maintain balance by pumping Na out and K in.

• once Na/K pump restores the RMP, the cell is now ready for the next stimulus

How is action potential/cell commucation transmitted throughout the neuron

the myelin sheath and NOR transmit the signals in waves.

Some NORs are +, some are -

overall, axon of presynapses neuron, then synapse, then dendrite of postsynpastic neuron

• the typical nueron can form between 1000 and 10,000 synapse connections with other neurons.

How does communication occur from 1 cell to another

The action potential much cross the synapses

1) action potential reaches the synaptic terminal

2) Triggers calcium channels to open

3) Ca 2+ reaches into cells and stimulates the synaptic vesicles

4) neurtramsitters are released into synapses

Different neurotransmitters

dopamine, seretonin, acetylcholine, norepinephrine, etc

Sponge NS

no brain, no neurons

starfish

no brain, does have neurons, does have nerve ring

flatworm

ganglia (cluster of neurons). this flatworm is where we see the first division of the CNS and the PNS

Arthropod NS

this is where we see ganglia (cluster of neurons) form into a structure (brain). Central ganglia. we also see segmented ganglia

Mollusks

officially see brain, nerves, other ganglia. octopus!

vertebrate NS

CEREBRUM:

we see cerebrum (linear not folded) begin to enlargen.beginst o enlargen even more upon us moving on land beause there is more texture, surroundings, etc on land, so need larger brain to compensate.

cerebrum becomes folded in apes (including us) for inprove ognitive ability.

birds have a porportionatly very large cerebrum because they use tools, must coordinate with their wings for flight, etc.

Cerebellum: motor movement

this is large among fish and sharks because they need to escape and hunt

largest among birds and mammals because we need to coordinate our arms, legs, etc more than swimming animals.

HOw mant enurons does the human brain have

100 million

what brain structures does a human have

two cerebral hemispheres (left and right)

brainstem

diencephalon

cerebellum

hippocampus (latin for seahorse)

amygdala

Cerebrum in humans

this part if folded to increase surface area

has sulcus(despression) and gyrus (ridge that sticks out). different on people except for central

two hemispheres make this up: connected by corpus callosum. two hemispheres function differently.

Lobes of cerebrum

Frontal:

• motor and prefrontal cortex

• prefrontal = problem solving, decisoon making, last part of brain to develop. more connections happen after puberty

• motor cortex controls voluntary msucles. different parts control different areas of your body.

Parietal: sensory reception. different aprts control different areas of body

occipital: visual infomration with visual recognition (how soft is this, how far away, etc)overall visual processing

temporal: audio: does this sound threatening, concerning, comforting

what seperates the motor cortex and the sensory cortex of parietal lobe

central sulcus

Left cerebral hemisphere

language processing

1) visual cortex reads

2) Angular gyrus: a specific gyrus transforms visual representation into auditory code

3) wernickies area: interprets auditory code/places code into correct order to make sense. damage to this area means that you wont be able to make sense of words

4) Brocas area: interacts with motor cortex to control speech msucles so you can speak. damage to this area impairs speech, not understanding. motor cortex helps with pronounciations.

Diencephalon

this area relays sensory infromation between brain regions and works to maintain homeostasis

three areas come together to make this process happen

1) thalamus: recieves signals and sends info where it needs to be (from spinal cord to cerebrum, otehr area. also from area to spinal cord)

2) hypothalamus: homrones released to maintain homeostasis. the hypothalamus recieves “im hunry, cold, etc” signals and alerts us of this situation

3) pineal gland: circadian rhythm.

cerebellum

this area contrls movement coordination, balance, and equilibrium

“this muscle needs to be switched on now, then this one, then these 2, then all 4 off” helps us move, like pick up food with fork and into mouth

Brainstem

connects brain to spinal cord. this controls primitive function like breathing, heart rate, consciousness, reflexes.

three parts: midbrain, medulla, and pons

Hippocampus

this is responsible for turning short term memory into long term memory

when learning something, connections in hippocampus form. the more you do something, the stronger those connections grow. there comes a point wehre the connections are so strong that they grow into cerebrum and are long term memory.

• this part of the first one affected when someone had alzheimers

• important in spatial information (where is this in relation to this, etc)

Amygdala

emotional processing (puts emotional significance to sensory input)

attached to hippocampus, which makes sense because memories often have emotional signifcance, and our emotions regarding new events may be a result of prior experiences/memories

Do we only use 10% of our brain

NO!

What is the difference between varying action potentials

all AP are the same, the difference is only what is sending the AP and who is receieving it

Types of sensory receptos

this is based onhow they fucntion (8)

touch

pressure

sound

motion

temperature

pain

chemicals

electromagnetic radiation

Touch and pressure receptors

this are run by mechanoreceptors, wich are receptors that are physicallty stimulated. 3 types

Meissners Corpuslces: type of mechanoreceptor. modified dentries that are enar surface of skin, therefore being affected by vibrations

Merkels disks: modified dendrites thta are near the surface and area affected by light touch

pacinian corpuscles: modifid dentrites that are deep in skin layers, being affected by deep pressure

Temperature receptors

thermoreceptors detect hot and cold to help reguate body temp

ruffinis end organs: stimulated by heat

end bulbs of kraus: stimulated by cold

Pain receptors

nocireceptors: naked dendrties (free nerve endings) that detect excessive heat, pressure, and chemicals

nocireceptors detect pain, itch, and temps

Motion and sound

stretch receptors: found within muscles that change in length

hair cells: these are specialized cilia in hair that transform sound vibrations in fluid of cochlea int electrical signals that are relayed to auditory nerve of brain

Che

Chemcial

chemoreceptors: stimulated by chemicals. they transmit information about total solute concentration of a solution like air, fluid, etc

two examples

• gustatory receptors: taste

• olfactory receptors: smell

electromaginetic radiation receptors

photoreceptors: type of nerve cell that recieves light in form of electromagnetic radiation. can be visible or non-visible (infrared)

• rods and cones

three layers of the visual system

outer fibrous tunic

middle vas tunic

inner tunic

Outer fibrous tunic

cornea and sclera

Middle vascular tunic

choroid, ciliar body, lens, iris, pupil

we are able to change the shape or our lens for better view

lens becomes rounded if obect close, fat with object further away

refraction

abaility to bend light in order to focus it on a point on the retina. cornea and lens bend the light

if eye is too long, this is myopia/near-sightedness. concave lens fixes this

if eye is too short/tall, this leads to farsightedness (hyperonia). convex lens fixes this

if lens stiffens with age, this can cause blurry vision. presbyopia

if the cornea distorts the focal point of the light in front of and/or behind retina, this is astigmatism

Iris

the iris is responsible for light regulation, does this via dilation/contriction

dim is dilation to have access to more light, bright is constriction to keep some of it out.

Inner tunic

retina, foveam opticalise

the rtina has two types of photoreceptor cells that send impulses to brain

• rods are for monochrome (all byt fovea and blind spot)

• cones are for color (fovea)

• neither rods nor cones at blind spot (this is why it is blind)

Aqueous chamber of eye

anterior chamber of eye is filled with water-like humor (before cornea very front of eye)

vitreous chamber/posterioir chamber is filled with vitreous (jelly-like) humor (back compartment of eye)

Mammalian eye-sight

most mammals are nocturnal. They have evolved to have a well-developed night vision but poor color vision (NOT the same as colorblindness)

to enhance night vision, many mammals have reflective layer called tapetum that reflects light back into retina to allow for further photoreceptor action via more light exposure

primates are the exception: we are diurnal. we have well developed color vision via a large abundance of cone cells

Sense of taste

this sense coems from taste cells (gustatory cells) whcih are located on taste buds

these gustatory cells are sensitive to 5 primary tastes (sweet, salty, bitter, sour, and unami)

microvilli pick up dossilved chemicals into saliva

• gustatory receptor cellsare concentrated in groups called tastes buds/pores

Sense of smell

400 different olfactory receptors bind odorant

• chemcials are dissolved in mucus cause dendrites to fire

• olfraction: receptor cells are located in roof of nasal cavity

• different odors trigger different combinations of receptor cellls

  • not limited to 5 messages like taste, smell is capable of a lot!

Parts of mammalian ears

Outer Ear:

• external pinna and auditory canal

Middle Ear:

• Tumpanic membrane and 3 small bones (smallest in body)

  • three small bones. malleus, incus, stapes

• function: conducts sound waves by vibration

• Eustachian tube connects middle ear to back of throat, which helps to equalize pressure and drain fluid. Opens with yawning, swallowing, and chewing

Inner Ear:

• cochlea: snail shaped complex organ for hearing and balance

• oval window: membrane covered opening in cochlea where stapes from other ear attaches

• sound vibrations from middle ear are transferred to cochlea at the oval window

Parts of cochlea (6)

1) two large chambers

• upper (vestibular canal) and lower (tympanic canal) chamber. Both chambers are full of fluid called perilymph

2) 1 small chamber called cochlear duct. filled with endolymph

3) organ of corti: structure in cochlear duct that contains receptor cells for hearing

4) hair cells: sensory cells for hearing in organ of corti

5) tectorial membrane: membrane in cochlear duct suspended over hairs (attached to the top of hair cells)

6) Auditory nerve: attached to the base of hair cells

Hearing steps

1) soudn vibrations transmitted through middle ear (via bones) to oral window of inner ear

2) vibrations of oval window cause pressure waves of cohclear fluid. THis causes vibrations of the basilar/base membrane, and promoties hair cells against the tectorial membrane

3) Hair cells bend and depolarize. An action potential starts and is sent to auditory nerve

• difference hair cells are stimulated by different sound frequencies in different parts of cochlea

  • cochlea uncoils, which ends vibrations from tympanic membrane

Parts of inner ear used for balance (2)

1) semicircle canals: there are three of these. each has enlarged end called a vestibule (ampula) which is filled with endolymph

2) cupula: gelatin-like mass in each vestibule. cluster of hair cells are embedded in the gelatin of cupula.

Balance steps

1) as the head moves, endolymph in each semicircle canal moves and puts more pressure on different cupula

2) the above step bends the hair cells, causing depolarization and ana ction potential that gest sent to the brain via vestibular nerve

3) When the head position changes, endolymph moves away from cupula and pressure eases. Hair cells return to normal.

What are the three ourposed of the skeleton

support, protection, and leverage. the skeleton is what is being moved upon movement

muscles work to do what (2)

maintain posture (body position)

produce heat (shivering)

Three characteristics of muscle tissue

excitability: can receive and respond to stimuli

contractability: can contract (become shorter and thicker, which creates a force to do work)

extensability: ability to stretch back when relaxed

Anatomy of skeletal muscles

sarcomeres make up myofibrils, which make up msucle fibers, which form bundles. These bundles of mucle fibers come together to form muscle

Sarcomere: Actin/thin filaments on m lines. Myosin/thick filaments in middle. H zone is middle where the actin filament is not. This H zone becomes less wide upon contraction. I band is only actin. sarcoplasmic reticulum arrounds sarcomere. A band is the whole area that includes the myosin filament.

Myosin filament and actin filament structure

Myosin filament: thick. has two heads which ATP bind to. Each ahd has a tail. the two tails intertwine. The heads bind to actin, specifically the cups, and the heads “walk” on actin via cup binding.

Actin filament: thing/ has cups during rest. also has troponin, which is a Ca2+ bidning protein. also has tropomyosin, which prevents myosin from having access to actin.

Steps of nerves and muscle contraction

1) Neuron triggers Ach release at neuromuscular junction

• Neurons send a signal (AP-electrical in nature) to neuromuscular junction

• electrical signal stimulates production of neurotransmitter (Ach)

• Ach is released into the space (synapse) between the neuron (cell) and myofibri (muscle fiber) (Ach geos out of cell and into space ebtween this cell and myofibril/muscle fiber)

2) Ach transfers electrical signal to myofibril, which triggers Ca2+ release

• ach triggers AP, which goes through myofibril

• AP triggers Ca2+ release from storage into the myofibril

• Ca2+ binds to troponin, which shifts tropomyosin and exposes actin cups.

3) Sliding of filaments: requires ATP

• myosin head binds to actin, creating a crossbirdge

• myosin pulls actin filaments when muscle contracts. this is the powerstroke. to release this, atp is necessary. this sliding in sarcomere causes muscle contraction (whole muscle contracts when many sarcomeres have this sliding happen at once)

Parthogenesis

unfertilized egg growing into embryo. form of asex rep

fragmentation/fission

form of asex reproduction when mature organism splits into different parts (fission) or they break small piece off, and that small piece grows to maturity. Starfish, plants, some inverts.

What is the result of asex

clone via mitosis

Sex reproduction

two sexes: fusuon of genetic material from 2 different individuals to form an offspring. meiosis. this results in genetic variety

Three general systems of mammalian reproduction

1) prodction: gonads are invovled here, gonads being structures that produce gametes

• gametogenesis: production of haploid gametes via meiosis

2) transport: ducts, tubes, accessory glands are invovled here

3) development: includes uterus, egg with birds (not female egg, burd egg case), amnion for amphibians

External vs internal testes

many mammals have external testes

• external testes: outside of body cavity within scrotum. This is because the body cavity may be too warm to make viable sperm. testes suually do grow in body cavity, then drop later in fetal development

• gubernaculum: this is a fibrous rope that is attached to the testes. at 2 months gestation, gubernaculum pulls testes down. testes pass through inguinal cavity to developing scrotum, then eventually reach scrotum at 8 months gestation. The gubernaculum disintegrates.

• muscles in scrotum contract or relax to control temperature of tstes. the two muscles that do this are cremaster muscle and dartos muscle.

Male gonads

testes in male. testes = pairs gonad where gametes are produced

• semiiniferous tubules (SIT) are tightly coiled tubules where sperm is produced. the coiling allows for more sperm.

  • spermatogenesis (production of sperm cells) occurs in the lining of the SIT.

• Cells of leydig are cells in the testes that secrete male hormones like testosterone. this testosterone is important for bone density, physical appearance. testosterone also makes sure sperm is viable.

Duct System in males

1) epididymis: coiled tubules attaches to testes. this transports sperm. The transportation fo sperm through epididymis can take 3 weeks, during whcih time the sperm becomes mature and is now self-mobile.

2) Vas deferens: this is a long tube that extends from scrotum into body cavity to acrry mature sperm.

• vas deferns is further contained ina tube called spermatic cord. this cord also contains blood vessels and nerves that stimulate peristalsis to help move sperm and toehr stuff

• vas deferens joins with urethra eventually

3) Urethra: connected to vas deferences and urinary bladder. transprots semen and urine

Accessory glands for males

glands which produce seminal fluid (support fluid for sperm).

• sperm + siminal fluid = semen

• seminal vesicles are paired glands that produce the bulk of seminal fluid (about 60%) and it contains fructose, which is the energy source for sperm ebcause fructose can be used to make ATP

  • sperm uses fructose to make ATP and spterm uses this ATP to swim

• Prostate: single gland that surrounds urethra and secretes 15-30% of the seminal fluid. also helps to activate sperm.

  • hypothesis: prostate is cancerous because receives a lot of testosterone, and testosterone causes rapid cell division. not 100% sure

• bulbourethral (cowpers): Paris glands that sit below prostate, they secerte alkaline fluid that helps to neutralize vagina since ivagina is naturally acidic. helps sperm to survive, because sperm wont usually survive severe pH.

Two fucntions of ovaries

produce sex hormones

produce eggs (oocytes = immature egg)

• follicles: fluid filled sacs that hold oocytes

Function of 3 female reproductive organs

1) Uterine tube: transports oocyte to site of fertilization. extends from ovary to uterus. also called oviduct.

• there are two uterine tubes, one for each ovary. both attach to the uterus

2) Uterus: supports developing fetus

• usually, if egg is fertilzied in uterine tube as it should be, the egg will embed in the uterus

3) Birth canal: cervix and vagina. L and D occur through here

Ovarian Cycle

3 stages

1) Primary/primordial: this happens to the fetus before it is born. stem cells in ovary divide and produce primary follicles. about 3-5 million are produced, but most disintegrate. 500,000 are left at birth. This means that females have a finite number of eggs because each follicle carries one egg. Eggs are 2n (diploid)

2) Secondary: growing: when puberty occurs, primary follicles enter this secondary phase. follicle grows and is released once a month during ovulation. 2n cell goes through meiosis to become haploid.there are now two sets of chromosomes. Only one is needed, other becomes polar body.

• the oocyte and the follicle grow in size to create a gap/antrum/space.

3) Mature/Graafian stage: during ovulation, the follicle grows so large that it pushes against the edge of the ovary wall. the oocyte then bursts out of the ovary.

• the ovarian cycle occurs outside of the ovary, the middle of the ovary contains BV and nerves. these primary follicles sit on the outside and eventually go through the different phases of the ovarian cycle.

Follicle stimulating hormone and luterinizing hormone

Gonadtropin rleasing hormone (GnRH) is released by the hypothalamus, goes to anterior pituitary, nd then causes nt pit to release FSH and LH

FSH: involved in secondary phase because FSH helps to grow antrum.

LH: improtant for moving follicle toward ovary wall to make the follicle wall and ovary wall fuse. this fusion allows for the antum to burst.

• LH is only really present before ovulation because that when the follicle needs to move toward the ovary wall. Ovulation testing sticks test for LH

twins/triplets occur how?

when more than one egg is fertlizled. relatviely random as to whether or not wgg will be released from L or R ovary. Maybe on egg from each ovary, if both fertilized, twins! if more than three eggs are rleased and fertilized, then more than twins!

Secondary oocyte and polar body

at secondary phase of ovarian cycle, the primary oocyte goes through meiosis to come haploid. this results in two sets of chromosomes, but we only need one. Secondary oocyte is kept (ahving one set), and the other set becomes a polar body. the polar body disintegrates.

corpus luteum

corpus luteum releases hormones if there is fertilization. Doesnt do anyhting if no fertilization. this is made by old follicles that were never fertilized and empty follicles that became empty after egg released

Hormone secreting parts of female anatomy

graafian follcile: final structure in ovary where oocyte develops

• secretes estrogen before ovulation

corpus luteum: empty follicle after oocyte release. this releases estrogen and progestrone after ovulation

Ovulation

Follicle is already fused to ovary wall and then the oocyte forces way into ovary.

the secondary oocyte bursts from follicle and travels from ovary, into space between ovary and UT, then into UT. Ut opening is the infundambulum. this is the widest end that has fumbriae, which are hair-like extensions of the infundibulum. these beat to enourage the oocyte to get into UT tube.

fertilization usually occurs in UT. sperm travels through cervix, thorugh uterus, and into UT (L or R) and reaches egg. this secondary oocyte now is fertilized (now blastocyte) and cell division occurs. this fertilized

• ovary not attach to anything really. tehre is a ligament holding it in place, but thats it.

L

Ligaments in female rep system

ovarian ligament: uterus to ovary. ovary not directly attached to uterus

round ligament: uterus to pelvis

broad ligament: sheets of ligaments from peritoneum that support uterus

• ovarian and round ligament are remanents of gubernaculum, which exists in both males and females

Uterus recieving embryo/blastocyte

uterus recieves blastocyte.

the uterus supports the balstrocyte developing

• blastocyte, into embryo, into fetus, into baby

cervix is the muscular opening of uterus that stays clsoed during pregnany. there is a mucus plug in cervix to pretect against infection.

Three layers of uterus

endometrium, myometrium, and perimetrium

• endometrium is the innermost layer. this is the layer thata thickens and is shed during period. it sheds if there is no embryo impanted

• blastocyte usually embeds in body of uterus, depth being into the endometrium (so not really deep, still in surface of body)

  • endometriosis: endometrium tissue forms on outside of uterus by sneaking through space between UT and ovary or actually just builds up inside UT. it thickens and sheds to cause bleeding build up, hich aplies pressure to uterus and causes pain.

Estrogen and progesterone in ovarian cycle

estrogen: hgihest before ovualtion. this peak stimulates fimbrae to act. there is another estrogen peak later (weaker though) to coorespond with progestrone

progesterone: released by corpus letium (as is second wave of estrogen). This and estrogen peak after ovulation to stimulate endometrium growth

uterine/mentral cycle

this si when the mature follicle becomes secondary follicle via FSH. This change from Mature to secondary releases estrogen

LH stimulates ovulation and corpus luteum releases progestrone and estrogen. Lh also helps to mature follicle

what does a pregnancy test measure

human chorionic gonadotropin (hcg). this hcg hormone is rleased by developing embryo, and hcg is only present after fertilixation.. this si still released with ectopics

ectopic pregnancy

fetilzation occurs outside of UT. this causes the fetus to not implant in uterus, therefore resulting in a non-viable pregnancy. it amy implant and develop in UT, body cavity (not uterus body), or cervix, none of which are viable. not enough space and blood vessel availability for viability. still see hcg, so may not know its ectopic until first ultrasound ☹

three stages of pregnancy

1) fertilizatoin: 300-400 million sperm in female rep tract, only few 100 make it to oocyte, onlt one fertilizes egg to form zygote.

• fraternal/not Identical twins: two different fertilized eggs

• identifical twins: one zygote splits into two. cool!

• occurs in UT. zygote goes through mitosis in 36 hours to make 2 cells, then speeds up cell diviison to have 16 in 72 hours

2) implantation: 7-8 days after fertilization, zygote implants unto uterine wall. until implantation, zygote is nourshed by ovum itself

3) Labor and delivery: final stages :-o

• effacement: thinning of cervix/initial labor stages where cervix thins. fully effaced is when cervix is 1cm thick

• dilation: the opening of the cervix is how large? 10 cm means baby acoming! baby-birthing time! 😄