Zygote Development: Ovulation and Fertilization

Questions and Answers

What are the two main types of immune responses to infections?

Innate immunity and acquired immunity

What is the function of antibodies in the blood?

To transport oxygen

To fight bacterial infections (correct)

To carry nutrients

To clump foreign antigens (correct)

What is a blastocyst?

A hollow ball of about 100 cells.

Is type O blood considered a universal donor?

True Signup and view all the answers

What are the primary functions of the placenta? (Select all that apply)

Exchange site between the embryo and mother Signup and view all the answers

Mixing the wrong blood type can cause clumping of red blood cells.

True Signup and view all the answers

What does human chorionic gonadotropin (hCG) do?

Keeps corpus luteum active. Signup and view all the answers

What are the two types of gonads in humans?

Testes and ovaries Signup and view all the answers

The genetic sex of an individual is determined by the combination of ______ chromosomes.

X and Y Signup and view all the answers

Which hormone triggers uterine contractions during labor?

Oxytocin Signup and view all the answers

What is parturition?

The birth process. Signup and view all the answers

Match the following terms related to blood types:

Type A = Has A antigens Type B = Has B antigens Type AB = Has A and B antigens Type O = Has no antigens Signup and view all the answers

What is the SRY gene responsible for?

Determining male sex characteristics Signup and view all the answers

Cervical stretch does not play a role in initiating uterine contractions.

False Signup and view all the answers

The hormonal control of milk secretion and release requires ______.

Oxytocin Signup and view all the answers

Bipotential tissues can differentiate into either male or female organs.

True Signup and view all the answers

Which of the following is a role of the endocrine system in relation to the immune system?

Modulating immune responses Signup and view all the answers

What occurs during menopause?

Cessation of a woman's reproductive cycle Signup and view all the answers

What is the difference between menarche and andropause?

Menarche is the first menstrual period in females, while andropause refers to lower testosterone levels in aging men. Signup and view all the answers

What is the first phase of the ovarian cycle?

Follicular phase Signup and view all the answers

What occurs during the ovulation phase?

Ripened follicles release oocyte(s) into the fallopian tube. Signup and view all the answers

What does the corpus luteum secrete?

Estrogen Signup and view all the answers

The menses phase occurs when a woman is pregnant.

False Signup and view all the answers

The hormone that initiates ovulation is called _____ (abbreviation).

LH Signup and view all the answers

Which of the following is NOT a contraceptive method?

Fertilization Signup and view all the answers

What is capacitation in fertilization?

The final maturation step of the sperm that enables it to swim rapidly and fertilize the egg. Signup and view all the answers

The cortical reaction prevents more than one sperm from fertilizing an egg.

True Signup and view all the answers

What is the role of FSH in the menstrual cycle?

Stimulates follicle growth in the ovary. Signup and view all the answers

What does the SRY gene produce?

SRY protein Signup and view all the answers

What are the functions of Sertoli cells?

Secrete anti-Müllerian hormone (AMH) Signup and view all the answers

Which hormone causes the Müllerian ducts to regress?

Anti-Müllerian hormone (AMH) Signup and view all the answers

What is gametogenesis?

Gamete production Signup and view all the answers

At what stage of development are women born with all their eggs?

At birth Signup and view all the answers

Germ cells of the embryonic gonads undergo meiosis before mitotic divisions.

False Signup and view all the answers

What is the primary function of Leydig cells?

Produce testosterone Signup and view all the answers

Which hormones control gonadal secretions in both sexes?

Hypothalamic and anterior pituitary hormones Signup and view all the answers

The __________ produces progesterone and estrogen in women.

ovary Signup and view all the answers

What is the main estrogen hormone produced in men?

Estradiol Signup and view all the answers

Match the following structures with their functions:

Testis = Sperm production Ovary = Egg production Uterus = Where fertilized eggs implant Prostate = Secretes antibacterial fluid Signup and view all the answers

What does the uterine endometrium do during the menstrual cycle?

Its thickness varies Signup and view all the answers

What is the primary function of FSH?

Initiate/maintain gametogenesis Signup and view all the answers

What are the three primary functions of the immune system?

All of the above Signup and view all the answers

Autoimmune diseases occur when the immune system fails to recognize self cells.

True Signup and view all the answers

Which type of pathogen is targeted by the immune system?

All of the above Signup and view all the answers

What are the two lines of defense in the body's immune system?

Physical and chemical barriers; immune defenses. Signup and view all the answers

What are the primary lymphoid tissues?

Thymus and bone marrow Signup and view all the answers

What type of immunity is characterized by the body's ability to remember pathogens?

Acquired immunity Signup and view all the answers

What are antibodies also known as?

Immunoglobulins. Signup and view all the answers

B lymphocytes differentiate into _______ cells that secrete antibodies.

plasma Signup and view all the answers

What is the role of cytokines in the immune response?

Attract other immune cells Signup and view all the answers

What type of cells are leukocytes?

White blood cells. Signup and view all the answers

Match the following antibody classes with their functions:

IgG = Most abundant in adults and provides immunity to infants IgA = Found in external secretions like saliva and breast milk IgE = Associated with allergic reactions IgM = Associated with primary immune response Signup and view all the answers

Study Notes

Immune System Overview

The immune system protects the body against pathogens, removes dead or damaged cells, and identifies abnormal cells.
It differentiates between "self" and "non-self" cells to target specific invaders.

Functions of the Immune System

Protects from various pathogens, including parasites, bacteria, and viruses.
Plays a role in eliminating dead and damaged cells.
Aims to recognize and eliminate abnormal cells.

Immune System Pathologies

Autoimmune diseases, like Type 1 diabetes, arise when the immune system mistakenly attacks the body's own cells.
Allergies result from overactive immune responses to benign substances.
Immunodeficiency diseases, such as AIDS, occur when immune system components fail to function properly, leading to increased illness.

Pathogen Characteristics

Bacteria lack cell walls and can survive intracellularly, while viruses rely on host cells for replication.

Body Defenses

Two lines of defense:
- Physical and Chemical Barriers: The first line includes skin, epithelial linings, mucous, and lysozymes that prevent pathogen entry.
- Immune Defenses: The second line involves innate (nonspecific) and acquired (specific) immune responses responding to pathogens.

Immune System Anatomy

Composed of lymphoid tissues and various immune cells, primarily white blood cells (WBCs).
Primary lymphoid tissues: Bone marrow and thymus, where immune cells develop and mature.
Secondary lymphoid tissues: Lymph nodes and spleen, where mature immune cells interact with pathogens.

Innate Immunity

Excludes pathogens through physical barriers; if unsuccessful, the innate immune system employs leukocytes that act nonspecifically against foreign materials.
Phagocytes, including macrophages and neutrophils, eliminate invaders through phagocytosis.

Inflammatory Response

Triggered by cytokines released from macrophages to recruit additional immune cells.
Functions to attract immune cells, create a physical barrier to infection, and promote tissue repair.

Acquired Immunity

Characterized by its specificity to antigens, primarily involving T-cells and B-cells.
T-cells differentiate into helper T cells (which regulate immune responses) and cytotoxic T cells (which target infected cells).
B-cells differentiate into plasma cells (producing antibodies) and memory cells (long-lived, enabling quick response upon re-exposure).

B Lymphocytes and Humoral Immunity

B lymphocytes enhance immune responses by secreting antibodies (immunoglobulins) during infections.
Memory cells facilitate faster responses during subsequent exposures to antigens.

Antibody Classes

IgG: Most abundant in adults; provides passive immunity to infants.
IgA: Present in secretions such as saliva and breast milk; disables pathogens.
IgE: Related to allergic reactions.
IgM: Associated with the initial immune response.
IgD: Found on B lymphocyte surfaces; role is less understood.

Functions of Antibodies

Antibodies bind to antigens to neutralize pathogens and enhance phagocytosis.
They facilitate clustering of antigens, making it easier for phagocytes to recognize and destroy them.

Antigen-Presenting Cells

Antigen-presenting cells use MHC receptors to display processed antigens, enabling T-helper cells to bind and initiate further immune responses.### Immune Response to Infections
The body has multiple defense layers against infections, including first and second lines of defense.
First line includes immediate barriers, while second line involves immune activation and inflammatory responses.
For bacterial infections:
- White blood cells (WBCs) are attracted to infection sites to tag invaders, leading to effective killing of bacteria.
- Vasodilation facilitates increased blood flow to the infected area.
For viral infections:
- Normal cells can be sacrificed to prevent virus replication.
- Immune complexes form to signal more help from immune cells, enhancing defense mechanisms.

ABO Blood Types

Blood type is determined by antigens present on red blood cells (RBCs).
Type O is known as the universal donor due to the absence of A and B antigens, reducing the risk of reactions.
Type AB is the universal recipient, as individuals with this type have no antibodies to A or B antigens.
Mixing incompatible blood types can cause clumping (agglutination) of RBCs, impairing circulation.

Autoimmune Diseases

Autoimmune diseases occur when the immune system mistakenly attacks the body's own cells.
Notable examples include conditions that destroy muscle functionality and disrupt normal immune responses.

Neuro-Endocrine-Immune Interaction

The brain and immune system interact, influencing health and recovery.
Mental and emotional states can impact immune function, supported by neuroimmunomodulation studies.
Common signaling molecules and overlapping responses illustrate the connection between nervous, endocrine, and immune systems.

Reproductive Processes and Development

Humans exhibit sexual dimorphism; males and females have distinct sexual organs and reproductive roles.
Gonads (testes and ovaries) are responsible for gamete production (sperm and eggs).
Internal genitalia consist of glands and ducts connecting the gonads to the exterior.
Each nucleated body cell has 46 chromosomes, including one pair of sex chromosomes (X and Y).
The presence of a Y chromosome typically indicates male development, due to the sex-determining region (SRY).

Sexual Differentiation

Early embryonic tissues are bipotential, able to develop into either male or female organs.
If the SRY gene is present, bipotential gonads develop into testes; in its absence, they form ovaries.
Two pairs of accessory ducts (Wolffian and Müllerian) guide the development of male and female internal structures.

Development of Internal and External Organs

Lack of testosterone causes regression of male internal structures, while its presence promotes development of male organs.
Dihydrotestosterone (DHT) plays a crucial role in forming male external genitalia.
External and internal organ differentiation begins around 6 weeks of gestation, influenced by the presence or absence of specific hormones.### Embryonic Development: Males
SRY gene produces SRY protein, essential for testis development.
Testis contains Sertoli cells that secrete Anti-Müllerian hormone (AMH) causing Müllerian ducts to regress.
Leydig cells in the testis secrete androgens, primarily testosterone and dihydrotestosterone (DHT).
Testosterone converts Wolffian ducts to male accessory structures and migrates testes to the scrotum.
DHT is responsible for the development of external genitalia and prostate.

Embryonic Development: Females

Absence of SRY gene leads to the development of ovarian tissue from the cortex of biopotential gonads.
Without AMH, Müllerian ducts develop into internal female structures: upper vagina, uterus, and fallopian tubes.
Wolffian ducts degenerate in the absence of testosterone.
Absence of DHT leads to female characteristics in external genitalia.

Gametogenesis

Gametogenesis refers to the production of gametes (eggs in females, sperm in males).
Females are born with a finite number of oocytes; males continuously produce sperm.
Each germ cell undergoes mitotic divisions in utero, preparing for meiosis to form gametes.

Oogenesis

Oogonia present at birth complete mitosis but remain arrested in prophase of meiosis until puberty.
At puberty, primary oocytes resume meiosis, continuing maturation until fertilization occurs.

Hormonal Regulation in Reproduction

Gonadal secretions of steroids are controlled by hormones from the hypothalamus and pituitary gland.
Both men and women produce androgens and estrogens, but in different proportions and pathways.
In women, the ovaries produce progesterone and estrogen, while in men, the testis produces most testosterone.

Steroid Hormone Synthesis

All steroid hormones originate from cholesterol.
Aromatase converts testosterone into estradiol, the primary estrogen in males.

Reproductive Hormones

Gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the anterior pituitary to release LH and FSH.
LH stimulates testosterone production in males, while FSH works with sex hormones to support gametogenesis.
Gonads secrete inhibins and activins to regulate FSH secretion.

Male Reproductive Structures

External genitalia comprise the penis and scrotum, containing the testes.
The urethra serves as a pathway for both sperm and urine.
Accessory glands include the prostate, seminal vesicle, and bulbourethral gland, contributing to seminal fluid.

Spermatogenesis

Takes place in seminiferous tubules within the testes, where Sertoli cells provide nourishment and regulate sperm development.
Germ cells undergo meiotic division, developing into sperm while losing excess cytoplasm during maturation.

Spermatozoa Structure

Spermatozoa consist of a head (acrosome and nucleus), midpiece (mitochondria), and tail (flagellum).
Development relies on energy from mitochondria to support swimming toward the egg.

Regulation of Spermatogenesis

Pulsatile release of GnRH regulates LH and FSH, influencing testosterone production and spermatocyte maturation.
Inhibin and activin modulate FSH release, providing feedback in the regulatory pathways.

Female Reproductive Structures

Sperm enters the female reproductive tract via the cervix, moving through the uterine lumen to the fallopian tubes for potential fertilization.
The uterus has three layers: connective tissue covering, myometrium (muscle layer), and endometrium (epithelial layer).

Phases of the Menstrual Cycle

The menstrual cycle lasts approximately 24-35 days and is defined by ovarian phases:
Follicular phase: Growth of follicles and maturation of eggs.
Ovulation: Release of mature oocyte into fallopian tube.
Luteal phase: Prepares the body for potential pregnancy, lasting about 14 days unless fertilization occurs.

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Description

Explore the stages of zygote development from ovulation to implantation. This quiz covers key processes such as cell division and the formation of the blastocyst. Test your knowledge on embryonic development and its significance.