Reproduction and human systems

Asexual Reproduction

A process where a single parent creates genetically identical offspring without using sex cells or gametes.

Binary Fission

A process where a single-celled organism copies its DNA and splits down the middle into two equal, identical cells (e.g., bacteria, amoebas).

Budding

A process where a small growth forms on the parent, grows, and eventually breaks off to live on its own (e.g., yeast, hydra).

Fragmentation

A process where the body of a parent breaks into pieces, and each piece grows into a brand-new, complete organism (e.g., starfish, planarians).

Vegetative Propagation

A process where new plants grow out of the roots, stems, or leaves of a parent plant without seeds or flowers (e.g., potato tubers, strawberry runners).

Spore Formation

A process where an organism creates tiny reproductive cells (spores) that release and grow into new individuals when conditions are good (e.g., fungi, ferns).

Parthenogenesis

A process where an unfertilized female egg cell develops directly into a new living animal without male sperm (e.g., bees, certain reptiles).

Apomixis

A type of seed production in plants that happens entirely without fertilization or pollination (e.g., dandelions).

Female Reproductive System

Produces ova (eggs) and supports the development of offspring throughout pregnancy.

Ovary

Primary female reproductive organ containing thousands of undeveloped ova.

Fallopian Tube

The canal through which the released ova travels to reach the uterus; typically the site of fertilization.

Uterus

Muscular organ where a fertilized egg implants and develops into a fetus.

Endometrium

Specialized inner lining of the uterus that nourishes a potential embryo or sheds during menstruation.

Cervix

Narrow neck connecting the bottom of the uterus to the top of the vagina.

Vagina

Elastic, muscular tube connecting the cervix to the outside of the female body.

Menstrual Cycle

A repeating series of biological changes in the female body preparing the reproductive system for pregnancy.

Average Menstrual Cycle Length

Typically around 28 days.

Ovulation

Release of a mature ova from the ovary into the fallopian tube, occurring around day 14 of the menstrual cycle.

Fertilization

Process occurring in the fallopian tube where a sperm cell meets and fuses with a released ova.

Zygote

The single-celled fertilized egg that results from the fusion of sperm and egg.

Blastocyst

The multi-celled structure that develops from the zygote on its way to implantation in the uterus.

Implantation

The process of the blastocyst embedding into the thickened endometrium of the uterus.

Testes

The male reproductive organs that produce sperm cells and testosterone.

Scrotum

Pouch of skin containing the testes, regulating their temperature for sperm viability.

Prostate Gland

A gland that secretes fluid into semen to nourish and protect sperm.

Epididymis

Coiled structure atop each testis where sperm cells mature and are stored.

Urethra

Tube that transports urine and semen out of the male body.

Semen

Fluid containing sperm and secretions from seminal vesicles and prostate gland.

Stages of Labour

The phases of childbirth: Stage 1 (Latent and Active Phase), Stage 2 (Delivery of the Baby), and Stage 3 (Delivery of the Placenta).

Placenta

Temporary organ formed during pregnancy that facilitates nutrient transfer from mother to fetus.

Testosterone

Primary male sex hormone responsible for male reproductive development and secondary sexual characteristics.

Circulatory System

A group of organs that work together to transport gases, nutrients, waste products, and heat throughout the body.

Heart

A pair of pumps composed of specialized cardiac muscle tissue that continuously contracts and relaxes.

Blood Vessels

A network of tubes that facilitate the physical movement and flow of blood to every part of the body.

Blood

A liquid organ that carries oxygen, water, and essential nutrients to cells while collecting carbon dioxide and waste products.

Atria

The two top chambers of the heart where blood enters.

Ventricles

The two bottom chambers of the heart that forcefully pump blood out of the heart.

Septum

A thick wall of tissue that separates the left side of the heart from the right side.

Valves

Four principal structures in the heart (tricuspid, pulmonary, mitral, and aortic) that ensure unidirectional blood flow.

Pulmonary Artery

Transports deoxygenated blood away from the heart to the lungs.

Pulmonary Vein

Returns oxygenated blood from the lungs back to the heart.

Aorta

The primary and largest artery that pumps oxygenated blood out to the entire body.

Vena Cava

Returns deoxygenated blood from the body tissues back to the heart, divided into superior and inferior parts.

Pulmonary Circulation

The pathway where deoxygenated blood is pumped from the right side of the heart to the lungs.

Systemic Circulation

The path of oxygenated blood from the left side of the heart to body tissues.

Arteries

Blood vessels that transport blood away from the heart under high pressure, characterized by thick elastic walls.

Veins

Blood vessels that return blood to the heart under lower pressure and contain one-way valves to prevent backward flow.

Capillaries

The smallest blood vessels whose thin walls allow for the exchange of nutrients, oxygen, and waste between blood and tissues.

Plasma

The clear liquid component of blood, constituting 55% of total blood volume, acting as a solvent for nutrients and waste.

Red Blood Cells (Erythrocytes)

Cells that carry oxygen and make up 45% of blood volume, containing hemoglobin.

White Blood Cells (Leukocytes)

Cells that defend the body against pathogens, comprising less than 1% of blood volume.

Platelets (Thrombocytes)

Cell fragments that help in blood clotting, preventing excessive bleeding.

Epiglottis

A flap that folds over the trachea during swallowing to prevent food from entering the lungs.

Diaphragm

A muscle that alters thoracic volume to aid in breathing by contracting and relaxing.

Fertilization

The biological process where a male sperm cell and female egg cell fuse to form a new organism.

Mammals

Warm-blooded vertebrates characterized by hair or fur, internal fertilization, and live birth.

Birds

Feathered vertebrates that lay hard-shelled eggs and utilize internal fertilization.

Reptiles

Cold-blooded vertebrates that lay soft, leathery eggs and typically utilize internal fertilization.

Amphibians

Vertebrates that undergo external fertilization, laying eggs in water.

Pollination

The transfer of pollen from the anther to the stigma, necessary for fertilization.

Pollinators

Animals that transfer pollen between flowers, often rewarded with nectar.

Petals

Colored structures of a flower that attract pollinators.

Sepals

Leaf-like structures that protect the floral bud before opening.

Stamen

The male reproductive organ of a flower, consisting of the anther and filament.

Carpel

The female reproductive organ of a flower, including the stigma, style, and ovary.

Vas Deferens

Tube sperm travels through

Function of the epiglottis

Closes over the larynx during swallowing to prevent food from entering the airway.

Primary function of alveoli

Tiny air sacs where rapid gas exchange (O2 and CO2) occurs with capillaries.

Diaphragm action during inhalation

Contracts and moves downward (flattens), creating a vacuum that pulls air into the lungs.

Surfactant function

A fluid that lowers surface tension in the alveoli, preventing them from collapsing during exhalation.

Respiratory System

Responsible for exchanging gases between the human body and the external environment.

Inhalation

Air entry into the lungs where oxygen moves into the blood.

Exhalation

Air leaving the lungs where carbon dioxide moves from the blood into the air.

Composition of Breathed Air

Air is composed of approximately 78% nitrogen, 21% oxygen, and 1% other gases.

Nostrils & Nasal Cavity

Air enters through the nostrils into the nasal cavity, which warms and moistens air.

Pharynx

The throat passage leading from the nasal cavity to the larynx.

Larynx

Known as the voice box, it vibrates vocal cords to enable speech.

Trachea

The windpipe that conducts air from the larynx into the chest.

Bronchi

The two primary branches of the trachea that enter each lung.

Bronchioles

Smaller tubes branching from the bronchi within the lungs.

Alveoli

Microscopic air sacs where gas exchange occurs with the bloodstream.

Epiglottis

A flap of cartilage preventing food and liquids from entering the trachea during swallowing.

Intercostal Muscles

Muscles between ribs that help move the rib cage during respiration.

Diaphragm

A muscle that forms the floor of the chest cavity and plays a major role in breathing.

Gas Exchange

The process by which oxygen is taken up and carbon dioxide is released in the alveoli.

Diffusion

The movement of matter from an area of higher concentration to an area of lower concentration.

Oxygen Transfer

The process where oxygen diffuses from alveolar air into the blood.

Carbon Dioxide Transfer

The process where carbon dioxide diffuses from the blood into the alveoli.

Mechanics of Breathing

Breathing relies on changes in chest volume and air pressure facilitated by muscles.

Inhalation Mechanism

Involves contraction of intercostal muscles and the diaphragm, increasing thoracic volume.

Exhalation Mechanism

Involves relaxation of intercostal muscles and diaphragm, decreasing thoracic volume.