Chapter 27, 28, 29

Front 1

27a. State the path that a human oocyte travels.

Back 1

Ovary, oviduct, uterus, cervix, vagina

Front 2

27b. Describe structure and function of scrotum and testes in the male reproductive system. State the path of sperm movement from testes to external environment.

Back 2

Scrotum: holds testes away from body (or closer to it) for optimal sperm production temp

Sperm Movement

- produced in testis

- epididymis: site of sperm maturation/storage

- vas deferens: takes sperm back into ejaculatory duct, then goes into urethra

Front 3

27c. State the function of the following structures: seminal vesicles, prostate gland, and bulbourethral gland

Back 3

Seminal vesicles: secrete fructose; energy for sperm

Bulbourethral gland: secretions increase mobility of sperm and clear out traces of acidic urine

Prostate gland: secretions nourish and protect sperm

Front 4

27d. Describe the fertilization stage of animal development.

Back 4

-Sperm contacts egg's outer coat, enzymes on top of sperm break through egg's coat

- proteins on sperm's head bind to protein receptors on vitelline layer of egg

- plasma membrane of sperm and egg fuse; sperm enters egg

- egg's outer layer hardens and separates (prevents entry of other sperm)

- sperm and egg nuclei fuse together and become a diploid zygote

Front 5

27e. Describe characteristics od cleavage stage of animal development. Define terms morula, blastula, and blastocoel.

***How is the interior of a zygote organized and how does this effect development?***

Back 5

- repeated mitosis; results in ball of cells

- when structure is a solid ball of many cells, it is called a morula

- structure is a blastula when cells enclose fluid filled cavity (the blastocoel)

- zygote, morula, and blastula are all same size (cells divide but no increase in their cytoplasm)

INTERIOR OF ZYGOTE

- Zygote cytoplasm has yolk and a variety of chemicals that control gene expression- these are not uniformly distributed

-affects cleavage patterns (the way the zygote divides)

- non equal distribution of certain chemicals affects fate of each cell/ what its function will be (by activating certain specific developmental genes)

Front 6

27f. Describe the events that occur in the gastrulation stage of animal development.

Back 6

- Rate of cell division slows down dramatically

- Cells begin to migrate and differentiate (ex blastocoel shrinks; simple digestive cavity starts forming)

-3 embryonic tissue layers form

- ectoderm: becomes nervous tissue and epidermis of skins

- endoderm: becomes epithelial lining of respiratory and digestive systems

- mesoderm: becomes everything else

- Now a gastrula

Front 7

27g. Describe the events that occur in the organ formation stage of animal development.

Back 7

- Cells chemically signal each other to change shape, migrate, and differentiate to form various tissues and organs

- Some cells are "programmed" to die (when their DNA creates certain proteins); helps to complete shape and function of some body parts (like fingers on hands)

- After this stage, organs increase in size and gradually assume their specialized functions

Front 8

27h. Explain events that take place in human development from ovulation to implantation.

Back 8

Implantation (about 7 days after fertilization)

- Blastocyst embeds in endometrium of uterus

Front 9

27 i. State the functions of extra embryonic membranes: amnion, yolk sac, chorion, and allantois

Back 9

- Amnion: surrounds embryo, holds amniotic fluid that protects embryo

-Yolk sac: Produces embryo's first blood cells

-Chorion: becomes part of placenta and secretes hCG (hormone that helps maintain endometrium thickens)

-Allantois: forms fetal part of umbilical cord

Front 10

27j. Describe the function and composition of the human placenta.

Back 10

- Embryonic tissues form

- Chorionic villi (outgrowths of chorion) are the start of placenta formation (yolk: first site red blood cell formation)

- Placenta fully developed a month after fertilization

- Combo of endometrium blood vessels and blood vessels of embryo's chorion/chorionic villi

- Wastes and nutrients diffuse between mother and embryo

- Mother's blood and embryo's blood do not mix

Front 11

27k. State the function of the following male hormones: GnRH, LH, FSH, and testosterone.

Back 11

Gonadotropin releasing hormone (GnRH): stimulates release of LH and FSH; released by hypothalamus

Lutenizing hormone (LH): promotes testosterone production and made in pituitary gland

Follicle stimulating hormone (FSH): stimulates sperm production

-Testosterone: stimulates sperm production

Sperm formation:

- diploid cell on wall of semiforous tubules divide by mitosis

- each resulting cell then divides by meiosis into 4 haploid cells; each of these haploid cells differentiates into sperm

- sperm gradually pushed into center of semiforous tubule, then go to epididymis for maturation and storage

- Parts of sperm: head (haploid nucleus with an enzyme rich cap), middle piece (mitochondria for ATP production), tail (flagellum)

Front 12

27l. Describe primary oocytes and follicles.

Back 12

Primary oocytes (immature egg)

- diploid ovary cells that have started and halted meiosis I

- about 2 million at birth; 300,000 at puberty

- only 400-500 mature into secondary oocytes and released during lifetime

Follicle: oocyte and surrounding cells

Front 13

27m. Describe the events that occur in the ovary during the pre-ovulatory phase and ovulation of female reproductive cycle.

Back 13

Hypothalamus secretes GnRH; pituitary secretes FSH and LH

causes: 1) follicle to grow in size, 2) glycoprotein deposit vitelline layer to form around oocyte, 3) cells outside vitelline layer to secrete estrogen

Blood estrogen levels cause a surge of LH from pituitary. This causes meiosis 1 to finish (now a secondary oocyte and polar body) and enzymes to degrade follicle wall

- Wall ruptures, fluid escapes and carries oocyte with it

Front 14

27n. Describe what occurs in the uterus during the pre-ovulatory phase.

Back 14

- Increase of estrogen

- This stimulates growth of endometrial tissue

- Increases blood vessel growth within endometrium

Front 15

27o. Describe the events that occur in ovary and uterus during post ovulatory phase of female reproductive cycle.

Back 15

- Corpus luteum forms from outer layers of ruptured follicle (glandular, secretes progesterone and some estrogen)

- Causes blood progesterone and estrogen levels to increase; which decreases FSH and LH secretion so no other follicles develop

- Endometrium kept at max. thickness (due to increase in estrogen and progesterone; makes it more receptive to implantation of blastocyst)

- Corpus luteum degrades if no blastocyst implants in endometrium

- progesterone and estrogen decrease which causes endometrium to break down; blood vessels rupture and endometrial cells and blood leave uterus as menstrual flow

Front 16

27p. During fertilization, how many sperm are deposited from male to female.

Back 16

-150 to 350 million sperm into vagina

- A few hundred reach oviduct

- secondary oocyte completes meiosis II only when a sperm penetrates it

- now a mature egg (ovum)

- forms a diploid zygote

Front 17

27q. Compare and contrast asexual and sexual reproduction.

Back 17

Asexual reproduction

- 1 parent gives all genes to offspring (all genetically identical)

- vegetative growth, budding, fission, fragmentation, and regeneration

Advantages:

- quick and not energetically expensive

- effective for organisms genetically well suited to given environment

Disadvantages:

- all offspring are genetically identical (all are affected equally when environmental conditions change)

Front 18

27q. Compare and contrast asexual and sexual reproduction.

Back 18

Sexual reproduction

- 2 parents (each contributes 1 copy of every gene to offspring)

Advantages:

- much genetic variation (likelihood some will survive in changing environmental conditions)

Disadvantages

-Lots of time and energy

- Attracts mates (by chemical means)

- body colors, structures, displays, defending territories

- gamete production and organs for fertilization

Front 19

27q. Describe why some animals reproduce sexually and asexually.

Back 19

- Some animals have both male and female reproductive systems

- Seen in non-mobile or solitary animals

- Many cannot self fertilize so increases chances of reproduction

- Produce asexually when there is ample food; warm/stable temps

-Produce sexually when conditions become less predictable and harsher

Front 20

27r. State the lengths of the embryonic and fetal periods of humandevelopment. Describe the major events that occur in each of the three trimesters of humandevelopment. State the characteristics of the embryo or fetus in each trimester.

EXTRA CREDIT

Back 20

27r. The embryonic period is 8-10 weeks and the fetal period is 7 months long.

First trimester: hormone levels change significantly, heart rate increases. Heart, brain, and lungs, arms, fingers, and legs form and heart starts beating.

Second trimester: facial features, eyelashes and nails form, heartbeat is heard. Fetus can kick, open, close its mouth and swallow and hears sounds

Third trimester: Arms and legs can move freely, eyes open, hair becomes longer. Body organs have developed the ability to function on their own

Front 21

27s. What are homeotic genes and homeoboxes? Describe howhomeotic genes are involved in animal development

EXTRA CREDIT

Back 21

Any group of genes that control the pattern of body formation during early embryonic development of organisms. These genes encode proteins called transcription factors that direct cells to form various parts of the body.

Front 22

28a. What is the difference between the central nervous system and the peripheral nervous system? State the structures that are found in each.

Back 22

CNS: Brain and spinal cord

PNS: Nerves in all other locations

Front 23

28b. What is a neuron? Describe the function and physical appearance of the three different regions of a neuron: axons, cell bodies, and dendrites.

Back 23

NEURON: NERVE CELL

Dendrites: numerous, short projections

Cell body: contains organelles

Axon: single, long projection; sends signals to other cells

Front 24

28c. State the functions and locations of sensory neurons, interneurons, and motor neurons. What is a sensory receptor?

Back 24

Sensory Neurons

- sensory receptor cells detect stimuli

- sensory neurons send signals from receptors to CNS

Interneurons

- located in CNS

- integrate info (from incoming or stored info)

- send info to other interneurons or motor neurons

Motor neurons

- send info from CNS to muscles or glands

Front 25

28d. Describe the electrical charges inside and outside a neuron when it is at rest (i.e., when it’s not sending an electrical signal). What causes these electrical charges?

Back 25

- At rest, neuron has a POSITIVE charge outside of plasma membrane and a NEGATIVE charge inside of cell

- caused of by differences in relative amounts of Na+ and K + ions

Front 26

28e. What is an action potential? Explain how an action potential is initiated, travels down a neuron,and ends.

Back 26

- a stimulus (light, pressure, heat, chemical signal from another neuron, etc.) causes Na+ channels to open → Na+ rush into neuron → the membrane polarity reverses (an action potential)

- This triggers nearby Na+ channels to open (like a domino effect) and Na+ rush into the next region of neuron (the area of reversed membrane polarity moves down the neuron)

- K+ behind the area of reversed membrane polarity rush out of neuron (this resets the original membrane polarity)

Front 27

28f. What is a synapse? Describe the events that occur at a synapse (i.e., how one neuron sends a signalto a neighboring neuron). What is a neurotransmitter?

Back 27

Synapse: the place where one neuron sends a signal to a neighboring neuron

1) action potential arrives

2) vesicles w/ neurotransmitter move to end of axon and fuse with plasma membrane

3) neurotransmitter released into synaptic cleft

4) neurotransmitter binds to receptors

5) ion channels open and action potentials are triggered in neighboring neuron

6) neurotransmitter released and ion channel closes (ends effect of neurotransmitter)

Front 28

28g. State the function of glia and explain how these cells are different from neurons. What effect doesa neuron’s myelin sheath have on action potentials? What is myelin made of, what types of cellsmake it, and how is it arranged around a neuron?

Back 28

Glial cells: do not conduct impulses; support, nourish, and assist neurons

- some secrete myelin (a lipid); myelin sheath makes action potentials travel faster

- signal can skip from one unsheathed node to the next

Front 29

28h. What is a nerve? Explain how the term nerve is different from the term neuron.

Back 29

axons and blood vessels bundled together by connective tissue

Front 30

29a. State the functions of the following types of sensory receptors: pain receptors, thermoreceptors,mechanoreceptors, stretch receptors, chemoreceptors, osmoreceptors, and photoreceptors.

Back 30

Pain receptors: respond to a variety of stimuli associated with tissue damage. The brain interprets the pain

Thermoreceptors: respond to changes in temperature

Mechanoreceptors: respond to stimuli which produce movement or change in shape of receptor; touch and pressure receptors.

Stretch receptors: mechanoreceptors responsive to distention of various organs and muscles, and are neurologically linked to the medulla in the brain

Chemoreceptors: respond to dissolved chemicals during sensations of taste and smell and to changes in internal body chemistry such as variations of O 2, CO 2, or H + in the blood

Osmoreceptors: Osmoreceptors are cells which are sensitized to osmotic pressure. Osmotic pressure changes with the concentration of solutes in the body.

Photoreceptors: respond to light, change them into electrical signals

Front 31

29b. Even though action potentials are all the same size, how can the brain perceive different stimulistrengths? Be able to describe a specific example of how this occurs.

Back 31

Stronger stimulus causes more neurotransmitters to be released from sensory receptor cells ( not all sensory receptors use neurotransmitters , some sometimes this is omitted) which means action potentials are sent more frequently to the brain

- you can tell the temperature of a surface by increasing number of action potentials

Front 32

29c. Describe sensory adaptations and what occurs when a stimulus lingers.

Back 32

- action potentials decline even if stimulus remains

- brain only notices changes in stimulus (ex. socks)