Uab 124 Final Exam (Gibbons)

What is the target of an endocrine signal?

Any cell with a receptor for that hormone.

What is the target of a nervous signal?

The cell on the other end of the axon (e.g., neuron, muscle cell).

Which system has a faster response—nervous or endocrine?

Nervous system.

Which system has a longer-lasting response—nervous or endocrine?

Endocrine system.

What are the five types of intercellular communication?

Endocrine, paracrine, autocrine, synaptic, neuroendocrine.

What is endocrine signaling?

Hormones are secreted into extracellular fluid and travel via the bloodstream to target cells.

What is paracrine signaling?

Local regulators act on nearby target cells by diffusion.

What is autocrine signaling?

The target cell is the same as the secreting cell.

What is synaptic signaling?

Neurons release neurotransmitters at synapses, which bind to receptors on target cells.

What is neuroendocrine signaling?

Neurosecretory cells release neurohormones into the bloodstream to reach target cells.

Which type of signaling involves a cell sending messages to itself?

Autocrine signaling.

What are pheromones?

Chemical signals used to communicate with other individuals of the same species.

What are the three major classes of hormones?

Polypeptides, steroids, amines.

Are steroid hormones water-soluble or lipid-soluble?

Lipid-soluble.

How do water-soluble hormones travel?

Freely in the bloodstream.

How do lipid-soluble hormones travel?

Bound to transport proteins in the bloodstream.

Where do water-soluble hormones bind?

To receptors on the cell surface.

Where do lipid-soluble hormones bind?

To receptors inside the cytoplasm or nucleus of the cell.

What is the response to water-soluble hormones?

Signal transduction pathways leading to changes in cytoskeleton, enzyme activation, or gene expression.

What is the response to lipid-soluble hormones?

Gene expression regulation.

How do water-soluble hormones initiate a response?

They bind to cell-surface receptors, initiating a signal transduction pathway.

Give an example of a water-soluble hormone response.

Epinephrine activates enzymes in liver cells to break down glycogen and release glucose.

How do lipid-soluble hormones initiate a response?

They bind to cytosolic receptors, forming a hormone-receptor complex that acts as a transcriptional regulator in the nucleus.

Give an example of a lipid-soluble hormone response.

Estradiol in female birds activates genes for egg yolk production.

What is the difference between endocrine and exocrine glands?

Endocrine glands release hormones into the bloodstream; exocrine glands release substances through ducts.

Name some endocrine glands.

Pituitary gland, pineal, thyroid, thymus, parathyroid, ovaries, testes, pancreas, adrenal

What is a negative feedback loop?

A process where the response reduces the initial stimulus to maintain homeostasis.

What is a positive feedback loop?

A process where the response reinforces the initial stimulus until completion.

Which feedback loop is most important for maintaining homeostasis?

Negative feedback loops.

Give an example of a process regulated by a positive feedback loop.

Childbirth or milk release during nursing.

How does the hypothalamus interact with the pituitary gland?

Through neurosecretory cells connecting to the posterior pituitary or releasing hormones to the anterior pituitary.

What does the posterior pituitary release?

ADH (vasopressin) and oxytocin; Neurohormones directly into the bloodstream.

What does the anterior pituitary release?

FSH, LH, ACTH, TSH, Prolactin, Growth Hormone, MSH (melanocyte stimulating hormone) ; Hormones, including tropic hormones, which act on other endocrine glands.

What is a hormone cascade pathway?

A series of hormonal signals where one hormone triggers the release of another.

Describe the thyroid hormone cascade.

1. Hypothalamus releases TRH.

2. Anterior pituitary releases TSH.

3. Thyroid releases thyroid hormone (T3 and T4).

4. Thyroid hormone inhibits TRH and TSH release via negative feedback.

What happens if there is insufficient iodine in the diet?

Low thyroid hormone levels lead to excessive TSH secretion, causing goiter.

The hypothalamus has a physical extension which forms the:

Posterior pituitary

Tropic hormones

Hormones produced int the anterior pituitary that cause release of another hormones

What is asexual reproduction?

the reproduction of offspring without the fusion of gametes.

What is sexual reproduction?

Reproduction by combining gametes (sperm and egg).

What are the advantages of asexual reproduction?

Faster process.

Takes less energy.

No need to find a mate.

Produces exact copies of successful genomes.

Less likelihood of errors.

Why reproduce sexually if asexual reproduction is more efficient?

Sexual reproduction increases genetic diversity, making populations more adaptable to changing environments.

What is fragmentation and regeneration in asexual reproduction?

Body breaks into pieces, and pieces grow into new individuals.

What are examples of animals that use fragmentation to reproduce?

Sponges, echinoderms, corals, worms.

What is budding in asexual reproduction?

offspring is created from the body (outgrowth) of the parent.

What are examples of animals that use budding as a form of reproduction?

Hydra, coral polyps.

What is parthenogenesis?

the development of an egg into an embryo without fertilization

What are examples of animals that use parthenogenesis as a form of reproduction?

Daphnia, six-lined racerunner lizards, some insects.

What is hermaphroditism?

When an organism has both male and female reproductive structures.

What are the types of hermaphroditism?

Simultaneous & Sequential.

What are simultaneous hermaphrodites?

individuals that possess male and female reproductive functions at the same time. Ex: earthworms, snails.

What are sequential hermaphrodites?

Born as one sex and can change to the other sex at some point during their life. This usually occurs if reproductive success is much greater by being the other sex. Ex: Clownfish

What is external fertilization?

Gametes are released into the environment where fertilization occurs (e.g., fish, amphibians).

What is internal fertilization?

Sperm is deposited in the female reproductive tract, where fertilization occurs (e.g., mammals, reptiles).

What is the function of the testis?

produce sperm and release of testosterone

What is the pathway of sperm?

"SEVEN UP"

Seminiferous tubules

Epididymis

Vas deferens

Ejaculatory duct

(Nothing)

Urethra

Penis

What is the function of the accessory glands (seminal vesicles, prostate)?

Release secretions that make up semen, providing nutrients and a medium for sperm to swim.

What is the function of the ovary?

Egg production and release of sex hormones.

What is the pathway of the egg?

Ovary (follicle) → Fallopian tube → Uterus → Cervix → Vagina.

What is the pathway of sperm if fertilizing an egg?

Seminiferous tubules → Epididymis → Vas deferens → Urethra → Vagina → Cervix → Uterus → Fallopian tube.

What is spermatogenesis?

Continuous production of sperm in males.

What is oogenesis?

Prolonged process of egg development in females.

How does spermatogenesis differ from oogenesis?

-Spermatogenesis produces 4 sperm per meiosis; oogenesis produces 1 egg.

-Spermatogenesis is continuous after puberty; oogenesis begins in the embryo and pauses until puberty.

What hormone does the hypothalamus release to regulate reproduction?

Gonadotropin-releasing hormone (GnRH)

What hormones does the anterior pituitary release regarding reproduction?

Follicle-stimulating hormone (FSH).

Luteinizing hormone (LH).

What does FSH do in males?

Stimulates Sertoli cells in the testes to nourish sperm.

What does LH do in males?

Stimulates Leydig cells in the testes to produce testosterone.

What role does testosterone play in males?

Promotes spermatogenesis and provides negative feedback to regulate GnRH, FSH, and LH.

What are the two cycles in females?

-Ovarian cycle (changes in ovaries).

-Uterine cycle (changes in the uterus).

What happens during the ovarian cycle?

1. Follicle grows and releases estradiol (raises estrogen levels).

2. LH surge causes ovulation.

3. Corpus luteum forms and releases progesterone.

What is estradiol?

Raises estrogen levels to reduce symptoms of menopause by improving vaginal health, reducing bone loss, and helping regulate body temperature

What is progesterone? ("pregnancy" hormone)

Prepares the endometrium (lining of your uterus) for a fertilized egg to implant and grow

What happens during the uterine cycle?

- Estradiol and progesterone thicken the endometrium.

- If no embryo implants, the endometrium is shed (menstruation).

What is menopause?

Cessation of ovulation and menstruation after ~400-500 cycles in females.

Why might menopause have evolved?

To allow mothers to provide better care for existing children or grandchildren.

What are the three categories of contraceptive methods?

1. Preventing release of eggs or sperm.

2. Keeping sperm and egg apart.

3. Preventing implantation of an embryo.

What are examples of contraceptive methods for males?

Vasectomy or condom

What is a vasectomy?

Cuts vas deferens to prevent sperm transport.

What does a condom do?

Prevents sperm from entering the vagina.

What are examples of contraception methods on females?

Birth control pill, tubal ligation, or IUD.

Birth control pills...

Prevent ovulation with hormones.

Tubal ligation...

cuts fallopian tubes to prevent egg transportation.

an IUD (Intra-Uterine Device)...

Prevents implantation of an embryo.

What is the main advantage of internal fertilization?

Reproduction does not need to be tied to water.

What structure produces progesterone after ovulation?

Corpus luteum.

What is fertilization?

The formation of a diploid zygote from a haploid egg and sperm.

What is the purpose of the acrosomal reaction during fertilization in sea urchins?

The acrosome releases enzymes that break through the egg's protective jelly coat, allowing sperm to reach the egg membrane.

What is the fast block to polyspermy?

Depolarization of the egg membrane immediately after sperm fusion, preventing additional sperm from entering.

What is the cortical reaction (slow block to polyspermy)?

Cortical granules release contents that form a fertilization envelope, hardening the vitelline layer and preventing additional sperm from binding.

What are the differences between fertilization in sea urchins and mammals?

-Mammals have internal fertilization.

-Sperm must travel through follicle cells and the zona pellucida in mammals.

-Mammals do not have a fast block to polyspermy.

-First cell division occurs 12-36 hours after fertilization in mammals (compared to 90 minutes in sea urchins).

What is cleavage?

A period of rapid cell division without growth following fertilization.

What is a blastula?

A hollow ball of cells with a fluid-filled cavity called the blastocoel.

What are blastomeres?

The smaller cells formed by cleavage of the fertilized egg.

What is morphogenesis?

the process by which an animal takes shape

What is gastrulation?

The movement of cells from the blastula surface to the interior, forming a three-layered embryo called a gastrula

What are the three germ layers formed during gastrulation?

Ectoderm, Mesoderm, and Endoderm

The ectoderm is the...

Outer layer (e.g., skin, nervous system).

The mesoderm is the...

Middle layer (e.g., muscles, circulatory system).

The endoderm is the...

Inner layer (e.g., digestive tract lining).

What is the fate of the ectoderm?

Forms the epidermis of skin, nervous system, and sensory organs.