Life Sciences: Human Reproduction, Nervous System, and Plant Responses

A comprehensive set of vocabulary flashcards covering human reproduction, the nervous system, sensory organs, homeostasis, and plant growth responses based on the lecture transcript.

Spermatogenesis

The process occurring under the influence of testosterone in the seminiferous tubules of the testes where germinal epithelium undergoes meiosis to produce four haploid spermatids that mature into spermatozoa.

Oogenesis

The process under the influence of FSH where the germinal epithelium of the ovary undergoes mitosis to form follicles, eventually leading to one cell undergoing meiosis to form a single mature ovum.

Graafian follicle

A structure in the ovary, developed under FSH, containing a mature ovum and producing oestrogen to prepare the uterus for attachment.

Ovulation

The process occurring approximately every $4\,\text{weeks}$ where the Graafian follicle ruptures to release a mature ovum into the fallopian tube.

Corpus luteum

A structure formed from the empty Graafian follicle under the influence of luteinising hormone that secretes progesterone to maintain pregnancy.

Endometrium

The lining of the uterus that becomes thicker, more vascular, and more glandular to prepare for the attachment of a fertilised ovum.

Fertilisation

The fusion of a haploid sperm cell nucleus with a haploid ovum nucleus in the fallopian tube to form a diploid zygote.

Acrosome

The part of the sperm cell containing enzymes used to penetrate the egg cell membrane.

Morula

A solid ball of cells formed by the mitotic division of a zygote.

Blastocyst

A hollow ball of cells that develops from the morula and attaches to the endometrial lining of the uterine wall.

Chorionic villi

Projections developed by the chorion that embed into the uterine wall and, along with the endometrium, form the placenta.

Amniotic fluid

Fluid that fills the amnion sac to protect the foetus against temperature fluctuations, dehydration, and mechanical injuries by acting as a shock absorber.

Umbilical vein

The blood vessel that carries oxygen and absorbed nutrients from the mother to the foetus.

Umbilical artery

The blood vessel through which carbon dioxide and waste diffuse from the foetal blood into the maternal blood.

Autonomic nervous system

A collection of motor neurons that controls involuntary events through two sets of antagonistic nerves to maintain homeostasis.

Sympathetic nerves

Nerves that stimulate responses to prepare the body for "fight or flight" situations, such as increasing the heartbeat.

Parasympathetic nerves

Nerves that inhibit responses to bring about a relaxed or rest state, thereby conserving energy.

Reflex action

An involuntary response to a stimulus where an impulse travels from a receptor through sensory, interneuron, and motor neurons to an effector.

Organ of corti

The structure in the inner ear that converts pressure waves in the perilymph or endolymph into nerve impulses.

Cristae

Receptors in the semi-circular canals stimulated by changes in the speed or direction of movement to help maintain balance.

Accommodation

The process by which the ciliary muscles and suspensory ligaments change the convexity of the lens to form a clear image on the retina.

Pupillary mechanism

The process where circular and radial muscles of the iris adjust the size of the pupil to regulate the amount of light entering the eye.

ADH (Antidiuretic Hormone)

A hormone secreted by the pituitary gland that increases the permeability of the distal and collecting tubules to water for re-absorption.

Osmoregulators

Cells located in the hypothalamus that detect changes in the volume of water in the blood to regulate ADH secretion.

Vasoconstriction

The narrowing of blood vessels in the skin on cold days to reduce blood flow to the surface and minimize heat loss.

Vasodilation

The widening of blood vessels in the skin on hot days to increase blood flow to the surface and maximize heat loss through radiation and sweat evaporation.

Auxins

Plant hormones produced at the tips of stems and roots that move downward or upward to regulate growth and tropisms.

Phototropism

The growth of a plant stem towards light caused by the movement of auxins to the darker side, promoting faster growth on that side.

Geotropism

The growth response of a plant to gravity, where high concentrations of auxins inhibit growth on the lower side of roots, causing them to bend downwards.