exam 2 (review slides)

Question 1

ways of asexual reproduction: budding, fission, fragmentation, & parthenogenesis

Answer 1

budding: tiny version of plant or animal that grows on the side of the parent plant or animal that eventually breaks off to become an independent organism
- simple form of asexual reproduction

fission: single organism splits into 2 separate organisms
- you had a pizza and suddenly that pizza becomes 2 pizzas

fragmentation: similar to fission, but instead of 2 equal parts, splits into many smaller pieces
- has to be accompanied by regeneration- regrowth of lost body parts

parthenogenesis: organism can produce offspring without needing a mate, clones
- development of a new individual from an unfertilized egg

Question 2

parts of the male reproductive system and the pathway of sperm

Answer 2

1. testis: produces sperm and sex hormones
2. epididymis: stores sperm as they mature
3. vas deferens: conducts and stores sperm
4. seminal vesicle: contributes secretions to semen
5. prostate gland: contributes secretions to semen
6. urethra: conducts sperm
7. bulbourethral glands: contributes secretions to semen
8. penis: organ of copulation

Question 3

hermaphroditism

Answer 3

an organism has both male and female reproductive organs

• evolutionary adaptation because sometimes it was hard to find a mate
• any 2 individuals can mate under this system and in some species, hermaphrodites can also self-fertilize
• can also change their sex under certain circumstances

Question 4

spermatogenesis & oogenesis

Answer 4

spermatogenesis: formation of sperm, is continuous and prolific (producing a lot)
- hundreds of millions of sperm are produced per day; each sperm takes about 7 weeks to develop

oogenesis: development of a mature egg, is a prolonged process
- immature eggs form in the female embryo but do not complete their development until years or decades later

Question 5

3 accessory glands that add to semen: seminal vesicles, prostate gland, bulbourethral gland

Answer 5

2 seminal vesicles: contribute about 60% of total volume of semen
- fluid is thick, yellowish and alkaline (basic)

prostate gland: secretes its products directly into urethra
- think, milky fluid contains anticoagulant (prevents clots) enzymes and citrate (sperm nutrient)

bulbourethral glands: secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in urethra

Question 6

the 3 ways that spermatogenesis differs from oogenesis

Answer 6

1. all 4 products of meiosis develop into sperm, while only 1 of the 4 becomes an egg: all 4 daughter cells of meiosis become functional sperm, whereas only 1 daughter becomes functional egg. the rest of the 3 daughter cells are called polar bodies and are degenerate
2. spermatogenesis occurs throughout adolescence (starting at puberty) and adulthood
   - factory that keeps running
3. sperm are producing continuously without the prolonged interruptions in oogenesis: long pauses between stages in oogenesis, especially during developmental stage before birth and during each menstrual cycle

both processes generate haploid gametes via meiotic divisions of a set of dedicated diploid cells

Question 7

mammalian reproduction is coordinated by hormones from which 3 organs?

Answer 7

hypothalamus, anterior pituitary, and gonads

Question 8

Gonandotropin-releasing hormone (GnRH)

Answer 8

messenger hormone that tells the body’s glands (the pituitary glands) to release other hormones that help with reproduction, boss telling the workers what to do

• directs release of FSH and LH from anterior pituitary
• secreted by hypothalamus

Question 9

3 functions of sex hormones

Answer 9

• gamete production
• sexual behavior
• development of primary and secondary sex characteristics

Question 10

FSH & LH

Answer 10

FSH (follicle-stimulating hormone): tells ovaries in females and testes in males to start making cells for reproduction, signal that starts engine
- one of the hormones released by the pituitary gland in response to GnRH
- stimulates Sertoli cells

LH (luteinizing hormone): helps regulate menstrual cycle in females and stimulates the testes to produce testosterone in males, supervisor that oversees the work and makes sure everything is going smoothly

Question 11

Sertoli & Leydig cells

Answer 11

Sertoli cells: cells found in testes of males (seminiferous tubules), provide support & nourishment for developing sperm cells - construction workers who build & maintain the structures needed for making sperm
- secrete hormone inhibin
- stimulated by FSH

Leydig cells: also in testes of males (located between seminiferous tubules), produce testosterone & other androgens (male hormones)
- stimulated by LH

Question 12

main sex hormones are ______ hormones

____________ is the main androgen

estrogen mainly consists of __________ and __________

Answer 12

steroid (easily pass through cell membranes)

testosterone

estradiol and progesterone

Question 13

2 negative feedback mechanisms of testosterone and inhibin

Answer 13

Testosterone:
- when levels are too high, hypothalamus detects this and signals pituitary gland to reduce production of LH

Inhibin:
- when inhibin levels rise, acts on anterior pituitary gland to decrease production of FSH

negative feedback loop maintains balance

Question 14

steps of the ovarian cycle

Answer 14

• begins when hypothalamus released GnRH

1. Follicular phase: GnRH stimulates anterior pituitary gland to secrete small amounts of FSH and LH → FSH stimulates follicle growth → follicles make estradiol (initiates buildup of uterine lining) → when estradiol begins to rise steeply, FSH and LH levels increase
   estradiol exerts a positive feedback on hypothalamus to secrete more GnRH
2. Ovulation: dominant follicle releases mature egg that travels down the fallopian tube, caused by the sudden rise in LH
3. Luteal Phase: empty follicle that released the egg transforms into a structure called the corpus luteum (which produces hormones like progesterone and some estrogen- *negative feedback on hypothalamus and pituitary to greatly reduce LH and FSH secretion, preventing maturation of another egg)
   - if fertilization doesn’t occur, corpus luteum disintegrates → decrease in estradiol and progesterone removing negative feedback on hypothalamus and pituitary → endometrium (lining of the uterine wall) sheds → menses

Question 15

2 phases of the uterine (menstrual) cycle

Answer 15

proliferative phase:
- occurs during first half of cycle, just after menstruation (bleeding)
- steroid hormones stimulate uterus to prepare for support of an embryo (estradiol secreted by follicles signals the endometrium to thicken)
-
follicular phase of ovarian cycle is coordinated with the proliferative phase of the uterine cycle

secretory phase:
- second half of cycle, after ovulation
- this phase prepares uterus to receive and nourish a fertilized egg is fertilization occurs
- estradiol and progesterone secreted by corpus luteum stimulate maintenance & development of uterine lining

luteal phase of ovarian cycle is coordinated with the secretory phase of the uterine cycle

once corpus luteum has disintegrated, the rapid drop in ovarian hormones causes a shedding of the endometrial tissue

Question 16

endometriosis

Answer 16

cells of uterine lining migrate to an abnormal location outside of the uterus → tissue breaks down every month but nowhere for blood to go → pelvic pain and bleeding into the abdomen

Question 17

menstrual vs. estrous cycle

Answer 17

menstrual cycle: characteristic of only humans and some primates, shedding of uterine lining if no fertilization
- females can potentially conceive throughout most of the cycle, even during menstruation, even though fertility highest during ovulation

estrous cycle: occurs in most mammals, no shedding of uterine lining, uterine lining (endometrium) is reabsorbed instead
- females only receptive to mating (in heat) during specific times of their cycle, known as estrus
- length and frequency of estrous cycles vary from species to species

Question 18

process of implantation before embryo development + cleavage definition & blastocyst definition

Answer 18

1. ovulation
2. fertilization in the oviduct
3. cleavage begins (cleavage= resulting zygote begins to divide by mitosis)
4. Cleavage continues
5. implantation of a blastocyst in the endometrium (blastocyst=ball of cells with a central cavity)

Question 19

briefly describe major accomplishments during the first, second, and third trimesters

Answer 19

first: development of body organs
- all major structures are present by 8 weeks, and embryo is called a fetus

second: placenta takes over the production of progesterone, the hormone that maintains the pregnancy

third: fetus grows and fills the space within the embryonic membranes

Question 20

set order of the common stages of embryonic development between many animal species

Answer 20

1. Fertilization
* Formation of a diploid zygote from a haploid egg and sperm
* When sea urchins release their gametes into the water, the jelly coat of
egg exudes soluble molecules that attract sperm to egg

2. Cleavage
* A series of cell divisions that divide or cleave the embryo into many cells
* Rapid divisions and lack accompanying cell growth, generate a hollow ball
of cells called a blastula

3. Gastrulation
* Blastula folds in on itself, rearranging into a multilayered embryo, the gastrula

4. Organogenesis
* Local changes in cell shape and large-scale changes in cell location generate the rudimentary organs

Question 21

acrosomal reaction & depolarization

Answer 21

• acrosome: tip of the sperm that releases hydrolytic enzymes when it touches the egg (allows it to penetrate the egg)
• depolarization: sodium ions diffuse into egg and cause depolarization (decrease in charge difference across plasma membrane)

depolarization is a fast block to polyspermy

• polyspermy: entry of multiple sperm into the egg

Question 22

fast block of polyspermy vs slow block of polyspermy

Answer 22

fast - depolarization

slow - formation of fertilization envelope

Question 23

the cortical reaction

Answer 23

• reaction involves release of certain substances from egg’s outer layer (the cortex), which cause changes in structure of egg’s membrane and forms a fertilization envelope
• prevents other sperm from entering the egg
• slow block to polyspermy

Question 24

3 steps of what happens when the sperm hits the egg

Answer 24

1. sperm-egg fusion and depolarization of egg membrane (fast block to polyspermy)
2. cortical granule release (cortical reaction)
3. formation of fertilization envelope (slow block to polyspermy)

Question 25

cleavage pattern in frogs

Answer 25

In frogs and many other land animals, cleavage is asymmetric due to distribution of yolk (stored nutrients)

• Displacing effect of yolk persists in subsequent divisions, causing blastocoel to form entirely in animal hemisphere

Question 26

holoblastic vs meroblastic cleavage

Answer 26

holoblastic cleavage: entire egg is divided into smaller cells with each division
- in animals that have less yolk like echinoderms (sea urchins), frogs, mammals, and annelids

meroblastic cleavage: only part of the egg is divided into smaller cells with each division
- in animals with large yolky eggs like birds and reptiles

Question 27

gastrulation in frogs

Answer 27

• beings when a group of cells on the top side of blastula being to invaginate (close in on each other) creating an indented crease called the blastopore
• opposite to the position where sperm entered egg

Question 28

gastrulation in chicks

Answer 28

• begins with the formation of a structure called the primitive streak (midline thickens) on the surface of the blastodisc, which is a disc-shaped layer of cells that sits on top of the yolk
• cells migrate inward from the primitive streak to form the three germ layers:
  move downward = ectoderm
  move laterally = mesoderm
  left behind on surface = endoderm

Question 29

gastrulation in humans

Answer 29

• blastocyst is the human equivalent of the blastula
• inner cell mass: cluster of cells at one end of the blastocyst
• trophoblast: outer layer of cells surrounding the inner cell mass
• helps initiate implantation
• inner cell mass then forms a disk with an inner layer of cells called the epiblast and an outer layer of cells called the hypoblast
• epiblast: gives rise to the embryo proper, including the three germ layers (ectoderm, mesoderm, and endoderm) and ultimately all the tissues and organs of the fetus
• hypoblast: contributes to the development of extra-embryonic tissues, including the yolk sac, which plays a role in early nutrient transfer to the developing embryo
• gastrulation involves inward movement from epiblast through primitive streak, similar to chick embryo

after gastrulation, embryonic germ layers have formed

Question 30

4 extra embryonic membranes that form around embryo in amniotes (animals that have amniotic sacs)

Answer 30

chorion: functions in gas exchange

amnion: encloses amniotic fluid, which physically protects the developing embryo

allantois: waste storage, incorporated into umbilical cord

yolk sac: site of early formation of blood cells, which later migrate into embryo proper

Question 31

axis formation in the frog

Answer 31

anterior-posterior axis (horizontal) of frog embryo is determined during oogenesis

animal-vegetal asymmetry dictates where
anterior-posterior axis forms

animal vegetal are names of the poles, top and bottom

dorsal-ventral axis (vertical) is determined at random by wherever sperm enters in animal hemisphere

Question 32

The ”Organizer” of Spemann and Mangold

Answer 32

• they took a piece of tissue of one embryo (the dorsal lip) and put it in another animal and it started gastrulation in the host!!
• was a pretty big deal!!

from slides:
the transplanted dorsal lip of the blastopore triggered a second gastrulation in host

• Dorsal lip functions as an organizer of the embryo’s body plan
• Inducing changes in surrounding tissues to form notochord, neural tube, and so on

Question 33

blastopore

Answer 33

basically a small opening or dent that forms during gastrulation, which is one of the earliest stages of embryonic development

• blastopore marks the beginning of the formation of the digestive tract
• in many animals, including humans, the blastopore eventually develops into either the mouth or the anus, depending on the species

Question 34

resting membrane potential + what channel is open/closed

Answer 34

baseline slightly negative electrical charge (inside) that exists across the membrane of a cell when it’s not actively sending signals or doing anything special

default setting of a cell’s electrical state when it’s just chilling out

• in resting state, K+ channels are open and gates for Na+ channels are mostly closed so Na+ is outside and K+ is inside

K+ diffuses out of cell through leak channels which are always open

Question 35

action potential

Answer 35

when the neuron starts firing due to stimuli

results from changes in membrane potential as ions move through voltage-gated channels

(otherwise at resting potential these gated channels are closed)

Question 36

voltage-gated ion channels

Answer 36

open or close in response to a change in voltage across plasma membrane of a neuron

• don’t just open and/or close randomly

Question 37

hyperpolarization and depolarization

Answer 37

hyperpolarization: “temporary chill mode” making neuron less likely to fire
- after firing (action potential), neuron needs to reset
- K+ channels open and K+ diffuses out to make inside more negative

depolarization: “turning on the neuron’s activity” making it more likely to fire
- Na+ channels open and let Na+ into the cell to make it more positive

Question 38

refractory period

Answer 38

after an action potential when a second action potential cannot be initiated

refractory period is a result of a temporary inactivation of Na+ channels
- occurs during falling phase and early part of undershoot

Question 39

rising and falling phase of action potential

Answer 39

1. some voltage-gated Na+ channels open, and Na+ flows into cell
2. rising phase: rapid increase in electrical charge inside the neuron, begins when neuron receives enough stimuli to cross threshold
   - Na+ rush in making the inside more positive = positive feedback cycle
3. falling phase: after rising phase, neuron returns to rest, becoming more negative inside
   - voltage gated Na+ channels close stopping inflow of Na+
   - voltage-gated K+ channels open to let K+ out of cell

Question 40

facts about how action potential is conducted

Answer 40

• frequency of action potential (rate of AP) is proportional to the strength of the signal
• all-or-none and travel only toward synaptic terminals
• as the impulse travels down, the Na+ channels behind the zone of depolarization prevent the action potential from traveling backwards

Question 41

chemical synapses + steps of communication

Answer 41

communication bridges between neurons (where they talk)

1. action potential depolarizes membrane at synaptic terminal which opens voltage gated Ca 2+ channels
2. Ca+ channels diffuse in
3. the increase in Ca2+ concentrations causes synaptic vesicle (small sacs) to fuse with the terminal membrane and release neurotransmitter
4. the neurotransmitter diffuses across the synaptic cleft and is received by postsynaptic cell (the neighboring neuron)
5. on the surface of the postsynaptic cell, there are receptors that can recognize and bind to these neurotransmitters. when the neurotransmitter binds to its specific receptor, it activates it, which can lead to changes in the electrical state of the postsynaptic neuron (ligand-gated ion channel)

Question 42

EPSPs and IPSPs

Answer 42

thumbs down and thumbs up signals that a neuron can receive from its neighboring neurons

EPSPs- Excitatory Postsynaptic Potentials: thumbs-up signal, little boosts of positive charge that make a neuron more likely to fire an action potential

• when neighboring neurotransmitters bind to receptors on the receiving neuron, they can cause slight depolarization of neuron’s membrane = brings neuron closer to its threshold for firing

IPSPs- Inhibitory Postsynaptic Potentials: thumbs-down signal, gentle pushes in the opposite direction

• neighboring neurotransmitters bind to receptors causing slight hyperpolarization which moves neuron further away from the threshold

Question 43

summation + temporal/spatial summation

Answer 43

a single EPSP is usually too small to trigger an action potential but can combine to produce a larger potential in a process called summation

temporal summation: neuron receiving repeated signals from the same presynaptic neuron in a short amount of time
multiple whispers from the same friend

spatial summation: neuron receiving signals from multiple presynaptic neurons at different locations on its dendrites
- slide says: “second EPSP arises before postsynaptic membrane potential returns to its resting value”

both of these can collectively cause the neuron to reach threshold for firing

Question 44

reflex

Answer 44

body’s rapid, automatic, involuntary response to a stimulus

Question 45

order of a reflex

Answer 45

reflex taps tendon connected to the muscle → sensors detect and sensory neurons convey information to the spinal cord → in response, motor neurons convey signals to the muscle causing it to contract → interneurons also receive signals from the sensory neurons → motor neurons are inhibited by the interneurons to prevent other contractions

Question 46

autonomic nervous system + 2 divisions

Answer 46

autonomic nervous system: regulates smooth and cardiac muscle and is involuntary

sympathetic division: fight or flight response, regulates arousal and energy generation, ex.
- heart rate increases
- digestion is inhibited
- liver converts glycogen to glucose
- adrenal medulla increases secretion of epinephrine

parasympathetic division: rest and digest response, antagonistic effects on target organs and promotes calming, ex.:
- heart rate decreases
- digestion is enhanced
- glycogen production increases

Question 47

preganglionic and postganglionic neurons + difference in sympathetic and parasympathetic systems

Answer 47

• follows the same pathway in both parasympathetic and sympathetic systems, just differs in hormone production

preganglionic neurons: messengers that carry info from CNS (brain and spinal cord) to ganglia (nerve cell bodies)
release acetylcholine as a neurotransmitter

postganglionic neurons: next step in the relay of info, take signals from preganglionic neurons in ganglia and carry them to their final destination (organs, muscles, or glands)
in parasympathetic, release acetylcholine and in sympathetic release norepinephrine

Question 48

glial cells + many types

Answer 48

support staff of the nervous system - provide structural support, insulation, clean-up
- not as flashy as neurons but still essential for nervous system

2 types in embryo:
radial glia - form tracks along which newly formed neurons migrate from neural tube

astrocytes - formation of blood brain barrier (BBB) which restricts entry of must substances into the brain

in the CNS:
- ependymal cells: promote circulation of cerebrospinal fluid
- astrocytes
- oligondendrocytes: myelinate axons in the CNS (increases conduction speed)
- microglia: immune cells in the CNS that protect against pathogens

in the PNS:
- shwann cells: myelinate axons in the PNS

Question 49

cerebrum

Answer 49

controls skeletal muscle contraction

• center for learning, emotion, memory, and perception

Question 50

Broca’s and Wernicke’s

Answer 50

Brocas is speech
- damage to this causes patients to understand language but cannot speak

Wernickes is language comprehension
- damage to this causes patients to not understand language but still speak

Question 51

thalamus and hypothalamus

Answer 51

thalamus: main input center for sensory information going to cerebrum (cops thal and Amos that direct traffic)

hypothalamus: control center that includes body’s thermostat and central biological clock
- regulation of pituitary gland, regulates hunger and thirst, plays role in sexual and mating behaviors, initiates fight or flight response

Question 52

what happens to people who suffer damage to their hippocampus

Answer 52

they are unable to form new lasting memories but can freely recall events from before their injury

• lack of normal hippocampal function traps them in their past (aww this is so sad flash typa stuff)

Question 53

long-term potentiation

Answer 53

process where repeated firing of neurons strengthens the connection b/w them improving their ability to communicate with each other over the long term

• means that next time one neuron fires, the other neuron is more likely to fire as well

slide says: “involves presynaptic neuron that releases excitatory neurotransmitter glutamate” :

• basically when neuron fires, it release glutamate into the synapse
• the glutamate then binds to specific receptors on the postsynaptic neuron called NMDA receptors which are otherwise blocked by Mg2+ ions
• so when depolarization happens, it allows the magnesium to move allowing Ca2+ ions to enter triggering biochemical changes that lead to the strengthening of the connection

glutamate →NMDA receptor → removes Mg2+ blockade → allows Ca2+ in → strengthens bonds → #besties4lyfe

Question 54

what causes Alzheimer’s disease

Answer 54

associated with the formation of amyloid plaques and neurofibrillary tangles in the brain (made of tau protein)

• plaques are aggregates of B-amyloid (insoluble peptide cleaved from extracellular portion of a membrane protein found in neurons) = B-amyloid accumulates in plaques outside neurons

Question 55

Parkinson’s disease

Answer 55

progressive motor disorder caused by death of dopamine-secreting neurons in midbrain that synapse in the basal nuclei

Question 56

sensory transduction and how sensory receptors work + receptor potential

Answer 56

sensory transduction - opening or closing of ion channels in response to stimulus

sensory receptors work by interacting with stimuli → results in opening/closing of ion channels → alter of membrane potential

receptor potential: change in membrane potential produced by activation of a sensory receptor

Question 57

how does size of receptor potential affect intensity of the stimulus

Answer 57

the greater the size, the greater the intensity of the stimulus

• electrical signal produced by a sensory receptor gets stronger when the stimulus it detects becomes more intense
• allows body to differentiate between weak and strong stimuli

Question 58

sensory adaptation

Answer 58

tendency of sensory neurons to become less sensitive when they are stimulated repeatedly

• decrease in responsiveness to continued stimulation

Question 59

how do we hear sounds

Answer 59

we rely on hair cells inside our ears which are sensory cells with hairlike projections that detect motion (vibrating objects create pressure waves in air)

Question 60

whole long process of how you are able to hear

Answer 60

1. sound waves hit ears and create ripples in the water pool
2. waves push down on cochlear duct and basilar membrane → causes them to vibrate like a trampoline
3. as basilar membrane vibrates, hair cells (sit on top of it) move side to side swaying in the wind
4. hair cells bending causes ion channels to open or close
5. cause depolarization → neurotransmitter release
6. signals go to brain
7. finally sound waves reach end of tympanic canal where they’re dampened by round window - which resets ear for the next vibrations that arrive

Question 61

how does ear capture info about volume and pitch

Answer 61

volume: determined by amplitude (height) of sound wave

• larger amplitude = more vigorous vibration of basilar membrane → greater bending of hair cells → more action potential in afferent neuron that transmit into to brain

pitch: determined by frequency of sound wave (# of vibrations per unit time)

Question 62

2 main types of photoreceptor cells

Answer 62

rods: more sensitive to light, but do not distinguish colors

cones: provide color vision, but contribute very little to night vision
- think c for color

Question 63

pathway of sensory transduction in eye

Answer 63

light converts cis-retinal to trans-retinal in rods and cones →cGMP breaks down → Na+ channels close → hyperpolarization of cell

Question 64

lateral inhibition

Answer 64

like adjusting the brightness of a spotlight to make the edges between light and dark areas stand out more
- sharpens edges and enhances contrast in an image

slide says: “when a rod or cone stimulates a horizontal cell and horizontal cell inhibits more distant photoreceptors and bipolar cells”

Question 65

how does focusing of the eyes occur

Answer 65

by changing the shape of the lens

• ciliary smooth muscles control shape of lens
• bends light and focuses it on retina

**when focusing on close object = lens become spherical

when focusing on far object = lens flatten**

Question 66

changes for near vision and distant vision

Answer 66

near vision: ciliary muscle contract, pulling border of choroid toward lens, suspensory ligaments relax → lens becomes thicken and rounder → focusing on more objects

distance vision: ciliary muscles relax, border of choroid moves away from lens, suspensory ligaments pull against lens → lens become flatter, focusing on distant objects

Question 67

process of stimulus leading to contraction of muscle fiber (neuromuscular joint?)

Answer 67

1. arrival of action potential at synaptic terminal releases acetylcholine (ACh)
2. ACh binds to receptors → depolarization that initiates an action potential
3. APs travel to interior of muscle fiber along transverse (T) tubules
4. AP spreads along T tubules causes sarcoplasmic reticulum (SR) to release Ca2+ into cytosol
5. Ca2+ binds to troponin complex
6. muscle fiber contraction is initiated

Question 68

smooth muscle contraction

Answer 68

Ca2+ regulates smooth muscle contraction but there’s no troponin complex or T tubules and SR (sarcoplasmic reticulum) is not well developed

During an AP,
* Ca2+ enters cytosol through plasma membrane
* Binds to cytosolic protein calmodulin
* Ca2+- calmodulin complex activates an enzyme that phosphorylates
myosin head, enabling cross-bridge activity → contraction

Question 70

axon hillock

Answer 70

region where the plasma membrane generates nerve impulses