General Biology 116 Exam 2 Study Notes

GENERAL BIOLOGY 116 EXAM 2 NOTES

Follicular Phase of the Menstrual Cycle

  • Sequence of Events:
        1. Gonadotropin Releasing Hormone (GnRH) is secreted by the hypothalamus.
        2. Estradiol secretion begins to increase as the follicle develops.
        3. Estradiol is secreted at low levels initially.
        4. Luteinizing Hormone (LH) is secreted at high levels.
        5. Both LH and Follicle Stimulating Hormone (FSH) are secreted at low levels.

  • Diagnostic Questions:
        - A woman unable to become pregnant with normal FSH but low LH likely experiences:
            - Ovulation not occurring due to insufficient LH.
        - A couple with healthy gametes but sperm unable to fertilize the egg could indicate:
            - Sperm lack enzymes in the acrosome or the secondary oocyte lacks sperm receptors.

Functions of Egg Coverings in Humans

  • Egg coverings protect and facilitate processes but do not provide nutrients or directly facilitate movement through the oviduct.

Developmental Stages

  • Archenteron and Endoderm Development:
        - Occurs during the gastrula stage of development.

  • Cortical Granule Synthesis:
        - A chemical preventing synthesis of cortical granules would primarily affect:
            - Acrosomal reaction leading to polyspermy.

Phylogenetic Trees and Taxa

  • Phylogenetic trees illustrate relationships based on shared derived characters such as the amniotic egg and neurulation characters.

Fertilization Events

  • Triggering Egg Activation:
        - Direct egg activation is triggered by a wave of Ca²⁺ ions.

True Statements about Gametes

  • Only eggs are larger than sperm, both contribute a haploid genome to the zygote, and sperm trigger egg activation.

Early Embryonic Development Stages

  • Correct Sequence:
        1. Epiblast and hypoblast form
        2. Gastrulation begins
        3. Blastocyst implants
        4. Cleavage stage completes

Hypersecretion Effects of Adrenal Medulla Hormones

  • Symptoms can include less blood flow to the digestive system, and increased breathing and metabolic rates.

Thyroid Stimulating Hormone (TSH)

  • TSH:
        - Secreted from the anterior pituitary (not the hypothalamus).
        - Stimulates the production of Thyroid Releasing Hormone (TRH).

Tropic Hormones Definition

  • A tropic hormone: signals a gland to release another hormone.

Addison's Disease Symptoms

  • Symptoms of Addison's disease include:
        - Blood sugar drops and chronic dehydration, suppressed immune system and water imbalances.

Hormones from Pituitary Gland

  • Hormones released by the anterior pituitary include TSH; those released by the posterior pituitary are oxytocin and ADH (Antidiuretic Hormone).

Inhibin in Male Reproductive System

  • Inhibin secretion functions to:
        - Suppress FSH secretion in the pituitary.

Spermatogenesis Sequence

  • Order:
        1. Spermatogonium
        2. Primary Spermatocyte
        3. Secondary Spermatocyte
        4. Spermatid
        5. Mature Sperm Cell

Hormonal Pathway in Male Reproductive System

  • High levels of Androgen Binding Protein relate to:
        - Hyposecretion of inhibin from Sertoli cells.

Leydig Cells and Testosterone

  • Damage to Leydig cells will lead to:
        - Decreased testosterone production.

Hormone Receptor Blockage Consequences

  • Blocking all hormone receptors on male gonad cells would prevent action of:
        - Follicle Stimulating Hormone (FSH).

Nervous System Comparison

  • CNS vs PNS:
        - CNS contains interneurons, sensory neurons, and motor neurons.
        - PNS consists of sensory and motor pathways.

Information Flow in Nervous System

  • Correct Sequence:
        1. Stimuli
        2. Afferent neurons
        3. Sensory receptors
        4. Information processing
        5. Efferent neurons

Peripheral Nervous System Types

  • Input into the peripheral nervous system can be:
        - Visceral or somatic.

Neural Tube and Crest Cells

  • Discovery of a neural tube indicates:
        - Classification in the Phylum Chordata, possibly bilateral organisms.

Damage to Peripheral Motor System

  • Damage would impede:
        - Communication from the central nervous system to skeletal muscles.

Glial Cells and Myelin

  • Oligodendrocytes are glial cells containing abundant myelin.

Reflex Pathway Components

  • Reflex arcs involve:
        - Motor neurons, spinal cord, and sensory neurons.

Sodium and Potassium Channels

  • Potassium voltage-gated channels open during certain membrane potentials indicating ion transitions at different points.

Nerve Impulse Transmission

  • Exposure to chemicals impairing lipid synthesis affects resting potentials and action potentials across neurons.

Na+ Voltage-Gated Channels in Saltatory Conduction

  • Located at nodes of Ranvier in myelinated axons.

Sperm Cell Structure

  • The head region of mature sperm cells contains:
        - Acrosome and nucleus, vital for fertilization but does not provide energy or hormone secretion.

Citric Acid in Semen

  • If citric acid is low, the prostate gland may not be functioning properly.

Oogenesis Sequence

  • End of prophase I in oogenesis results in a primary oocyte and a polar body (2n).

Functions of Female Reproductive System

  • Key functions include:
        - Nourishing the developing embryo, producing gametes, lactation, and receiving sperm.

Hormones in Uterine Secretory Phase

  • Primarily Responsible:
        - Progesterone stimulates the secretory phase in the uterus.

Corpus Luteum Formation

  • The corpus luteum originates from the follicle located in the ovary.

Menstrual Cycle Sequence

  • Correctly sequencing from day 1 includes release of GnRH triggering increases in estradiol and the ovulation process following.

Early Human Development Sequence

  • Correct order includes:
        1. Karyogamy
        2. Acrosomal reaction
        3. Calcium wave
        4. Blastula formation

Hormones and Corpus Luteum Maintenance

  • Hormones that maintain the corpus luteum include:
        - Luteinizing hormone (LH) and human chorionic gonadotropin (HCG).

Correct Sequence of Development Stages

  • The correct order starting from fertilization involves:
        1. Fertilization
        2. Cleavage
        3. Gastrulation
        4. Neural plate formation
        5. Crest cells migration.

Types of Cleavage

  • Unequal cleavage occurs when the furrow passes through but uneven division happens resulting in different embryo development patterns.

Stages in Fertilization

  • Steps include acrosomal reaction, cortical reaction, karyogamy, and blastulation.

Germ Layers

  • The notochord develops from the mesoderm germ layer in embryonic development.

Unique Structures in Mammals

  • The trophoblast is a structure found uniquely in mammals, important for early development processes.

Negative Feedback Example

  • Maintaining body temperature in birds illustrates true negative feedback regulation.

Hormonal Signal Disruption Consequence

  • Binding of the hormone to the receptor will still occur even with disruption to adenyl cyclase's activation, implying basic signaling can persist despite disturbances.

Neural Pathways for Hormones Released by Hypothalamus

  • Hormone release signaling can occur through neuroendocrine signaling.

Positive Feedback Regulation

  • Results in increasing the magnitude of a stimulus, as seen during events like childbirth with oxytocin release.

Comparison of Water-Soluble and Lipid-Soluble Hormones

  • Water-soluble hormones influence immediate signaling (e.g. exocytosis), while lipid-soluble hormones often affect gene expression directly.

Water-Soluble Hormone Pathway Sequence

  • Sequence includes hormone travel in bloodstream, binding to receptors, activation of G proteins, and production of secondary messengers such as cAMP.

Glucagon and Liver Interaction

  • Glucagon does not diffuse across membranes but acts through receptors on liver cells.

Final Position of Hormone After Signaling

  • After signaling involving water-soluble hormones, the hormone would still be bound to receptor proteins on the plasma membrane after signal transduction completion.

Thyroid Hormone Pathway Sequence

  • Correct sequence following a decrease in blood T3/T4 levels begins with hypothalamic response to restore normal levels through TSH signaling to the thyroid gland.

Calcium Homeostasis Sequence

  • To restore calcium levels, the steps initiated by low blood calcium involve the parathyroid hormone and subsequent signaling to bones and kidneys.