Year 9 Science - Maintaining Balance Vocabulary

Vocabulary flashcards reviewing core key terms, body systems, reproductive modes, and anatomical structures from Year 9 Science Maintaining Balance notes.

Homeostasis

The maintenance of stable internal conditions despite changes in the external environment.

Set point

The target value or narrow normal range that the body attempts to maintain for a given variable (e.g., core body temperature set point of approximately $37\,^\circ\text{C}$).

Negative feedback

A mechanism in which a stimulus initiates a response that counteracts and reverses the initial change, bringing a variable back toward its set point.

Stimulus

A detectable physical or chemical change in the internal or external environment.

Receptor

Specialized sensory cells or organs that detect a stimulus.

Control Centre

The processing hub (typically the brain or spinal cord) that receives information from receptors and determines the appropriate response.

Effector

A muscle or gland that executes the physical response sent by the control centre.

Vasodilation

The dilation of blood vessels near the skin to radiate heat during an overheating response.

Vasoconstriction

The constriction of peripheral blood vessels to conserve heat during a chilling response.

Central Nervous System (CNS)

Comprises the brain and spinal cord, acting as the central processing unit to integrate information and make decisions.

Peripheral Nervous System (PNS)

Comprises all nerves outside the CNS, acting as the communication network connecting the CNS to sensory organs, limbs, and internal organs.

Somatic Nervous System

The part of the peripheral nervous system that regulates voluntary control of skeletal muscle movements.

Autonomic Nervous System

The part of the peripheral nervous system that regulates involuntary, automatic bodily functions such as heart rate, digestion, and breathing rate.

Sympathetic Division

The division of the autonomic nervous system that activates the 'fight or flight' response during stress, danger, or exercise.

Parasympathetic Division

The division of the autonomic nervous system that drives the 'rest and digest' state during calm conditions to conserve energy.

Sensory Neurons

Neurons that transmit nerve impulses from sensory receptors toward the Central Nervous System.

Interneurons

Neurons located within the Central Nervous System that process, integrate, and pass signals between sensory neurons and motor neurons.

Motor Neurons

Neurons that transmit nerve impulses away from the Central Nervous System to effectors (muscles or glands).

Dendrites

Branched extensions of a neuron that receive signals and convert them into electrical impulses.

Cell Body

The part of a neuron that contains the nucleus and organelles.

Axon

The elongated portion of a neuron that carries electrical impulses through the length of the cell.

Myelin Sheath

An insulating layer wrapped around the axon that helps to increase signal transmission speed.

Axon Terminals

Specialized ends of a neuron that release chemical messengers (neurotransmitters) into the synaptic gap to communicate with target cells.

Labelled Neuron

A nerve cell consisting of dendrites, cell body, nucleus, axon, myelin sheath, and axon terminals.

Synapse

A tiny gap between the axon terminal of one neuron and a target cell.

Neurotransmitter

A chemical messenger that moves across a synapse to transmit a signal from a neuron to a target cell.

Reflex Action

A fast, automatic response to a stimulus that occurs without conscious thought by the brain.

Reflex Arc

The pathway of a reflex response consisting of Receptor -> Sensory Neuron -> Interneuron (in Spinal Cord) -> Motor Neuron -> Effector.

Endocrine System

A system that coordinates slow, long-term processes using chemical messengers called hormones secreted into the bloodstream.

Hormone

A chemical messenger produced by a gland that travels through the bloodstream to send signals to specific target cells.

Target Cells

Cells that carry out responses as instructed by a specific hormone.

Insulin

A hormone released by the pancreas in response to high blood glucose, stimulating muscle and liver cells to take up glucose and store it as glycogen.

Glucagon

A hormone released by the pancreas in response to low blood glucose, signaling liver and muscle cells to break down stored glycogen into glucose.

Type 1 Diabetes

An autoimmune condition where immune cells destroy cells in the pancreas, preventing insulin production.

Type 2 Diabetes

A condition where pancreas cells produce insulin, but body cells become resistant to its action, leading to chronic high blood glucose levels.

Gut Microbiome

A complex ecosystem of trillions of microorganisms inhabiting the digestive tract that aid digestion and protect against harmful pathogens.

Gut-Brain Axis

A multi-directional pathway between microbes in the digestive system and the brain influencing digestion, immunity, mood, and cognitive health.

Asexual Reproduction

A form of reproduction requiring only one parent, producing offspring that are genetically identical clones of the parent.

Sexual Reproduction

A form of reproduction requiring two parents and the fusion of specialized sex cells (gametes), producing genetically unique offspring.

Budding

An asexual reproduction technique where an offspring develops as an outgrowth or bud on the parent body and eventually detaches.

Fragmentation

An asexual reproduction technique where the parent body splits into distinct fragments, each regenerating into a complete new organism.

Binary Fission

An asexual reproduction technique where a single parent cell replicates its genetic material and divides equally into two identical cells.

Vegetative Reproduction

An asexual reproduction process where specialized non-reproductive plant structures produce new cloned plants.

Parthenogenesis

An asexual reproduction process where an unfertilized egg cell develops into a viable embryo without sperm fertilisation.

Gametes

Specialized sex cells (sperm and egg) containing half the species' genetic chromosome count.

Ovulation

The monthly release of a mature egg cell from an ovary into the fallopian tube.

Fertilisation

The fusion of a male sex cell with a female egg cell to form a zygote.

Menstruation

The monthly shedding of the blood-rich uterine lining (endometrium) through the vagina when fertilisation does not occur.

Gestation

The growth and development period of the embryo and fetus within the uterus from fertilisation to birth (approximately $38\text{--}40\,\text{weeks}$ in humans).

Human Female Reproductive System

The anatomical structures involved in female reproduction, including ovaries, fallopian tubes, uterus, endometrium, cervix, and vagina.

Human Male Reproductive System

The anatomical structures involved in male reproduction, including testes, scrotum, epididymis, vas deferens, seminal vesicles, prostate gland, urethra, and penis.

Anther

The structure in a flower that produces and releases pollen grains containing male gametes.

Stigma

The sticky top surface of the female structure in a flower that captures pollen.

Style

The supportive tube in a flower connecting the stigma down to the ovary.

Ovary (Plant)

The swollen base of the carpel that protects ovules and matures into fruit after fertilisation.

Ovule

The structure inside a plant ovary that houses the female egg cell and develops into a seed after fertilisation.

Labelled Flower

A plant reproductive organ containing stamen (anther and filament) and carpel (stigma, style, ovary, and ovule).

Pollination

The physical transfer of pollen grains from the anther to a receptive stigma.

Natural Selection

The process where certain traits are selected for based on environmental conditions such as temperature, diseases, and predators.

Selective Breeding

The process where certain traits are selected for by humans in order to produce desirable traits in offspring.

Cloning

The laboratory process of producing a genetically identical organism from a single parent.