G.C.E.(A/L) Biology - Animal Form and Function Practice Flashcards

These vocabulary flashcards cover the key systems, anatomical structures, and physiological processes of human and animal biology as detailed in the G.C.E. (A/L) Biology Resource Book.

Nerve net

The simplest nervous system found in cnidarians, composed of interconnected individual neurons.

Ganglia

Groups of neurons organized into clusters, often found in more complex animals like annelids and arthropods.

Central Nervous System (CNS)

The part of the nervous system in chordates consisting of the brain and the spinal cord.

Meninges

Three layers of protective tissues surrounding the CNS: the dura mater (outermost), arachnoid mater (middle), and pia mater (innermost).

Cerebrospinal fluid (CSF)

Fluid found in the ventricles and central canal that maintains uniform pressure, acts as a shock absorber, circulates nutrients, and removes waste.

Corpus callosum

A mass of white matter that connects the right and left cerebral hemispheres of the human brain.

Cerebral cortex

The superficial part of the cerebrum composed of grey matter (nerve cell bodies) showing many infoldings to increase surface area.

Thalamus

The main input center situated below the corpus callosum that sorts and directs sensory information to specific locations in the cerebral cortex.

Hypothalamus

A brain region that regulates body temperature, thirst, appetite, sleep cycles, and the autonomic nervous system, while also linking to the pituitary gland.

Pons Varolii

A part of the brain stem that forms a bridge between the two cerebellar hemispheres and helps regulate respiration.

Medulla oblongata

The lowest part of the brain stem that controls autonomic, homeostatic functions like breathing, heart activity, and involuntary reflexes like vomiting.

Afferent neurons

Sensory neurons that transmit information from sensory receptors toward the central nervous system.

Efferent neurons

Motor neurons that transmit instructions from the CNS to effector tissues such as muscles and glands.

Sympathetic division

A branch of the autonomic nervous system that prepares the body for stressful 'fight-or-flight' situations.

Parasympathetic division

A branch of the autonomic nervous system that promotes calming and 'rest and digest' functions.

Membrane potential

A voltage difference across the plasma membrane created by the attraction of opposite charges on the interior and exterior of a cell.

Resting potential

The membrane potential of a non-conducting neuron, typically between $-60\,mV$ and $-80\,mV$.

Action potential

A nerve impulse occurring due to a change in membrane potential above a threshold value involving depolarization, repolarization, and hyperpolarization.

Refractory period

The short time after an action potential during which a neuron cannot respond to another stimulus due to the inactivation of sodium channels.

Synapse

The junction where a presynaptic neuron communicates with a postsynaptic cell across a synaptic cleft.

Neurotransmitters

Chemical signaling molecules, such as acetylcholine or dopamine, released from synaptic terminals to trigger a response in a postsynaptic cell.

Sensory receptor

A specialized structure that detects a specific stimulus and converts its energy into a changing membrane potential.

Sensory adaptation

A decrease in responsiveness of sensory receptors following continuous stimulation.

Rods

Photoreceptors in the retina that are highly sensitive to light and enable night vision in black and white but do not distinguish colors.

Cones

Photoreceptors in the retina that provide color vision and sharp images in bright light but contribute little to night vision.

Accommodation

The adjustment of the lens's refractory power, controlled by ciliary muscles, to focus on near or distant objects.

Organ of Corti

The spiral organ on the basilar membrane of the cochlea containing hair cells with mechanoreceptors for hearing.

Otoliths

Small calcium carbonate particles in the vestibule of the inner ear that help perceive position with respect to gravity.

Epidermis

The outermost layer of skin consisting of stratified keratinized squamous epithelium and containing melanocytes.

Melanin

A dark pigment secreted by melanocytes in the deep germinative layer that protects against UV radiation and contributes to skin color.

Hormone

A specific signaling molecule secreted by endocrine glands that travels in the blood to act on specific target cells.

Tropic hormones

Hormones secreted by the anterior pituitary (such as TSH, ACTH, FSH, and LH) whose specific target site is another endocrine gland or cell.

Calcitonin

A hormone secreted by the thyroid gland that lowers blood calcium ion levels by promoting storage in bone and inhibiting kidney reabsorption.

Negative feedback

A regulatory mechanism where the accumulation of an end product slows a process, such as insulin release slowing as blood glucose levels drop.

Homeostasis

A steady state condition where the body's internal environment remains relatively constant within narrow physiological limits.

Asexual reproduction

A mechanism producing offspring genetically identical to the parent without the fusion of egg and sperm, relying on mitotic division.

Parthenogenesis

An unusual form of asexual reproduction where an egg develops into a complete individual without being fertilized.

Seminiferous tubules

Highly coiled loops within the testes where sperm are produced through spermatogenesis.

Sertoli cells

Supporting cells in the seminiferous tubules that nourish developing sperm and secrete the hormone inhibin.

Leydig cells

Cells located between seminiferous tubules that secrete testosterone to promote spermatogenesis.

Oogenesis

The process in females that produces mature oocytes, involving unequal cytokinesis to create one large egg and smaller polar bodies.

Corpus luteum

A glandular structure formed from a ruptured follicle after ovulation that secretes progesterone and estradiol to maintain the uterine lining.

Blastocyst

A stage of human development formed about five days after fertilization, consisting of an inner cell mass and an outer trophoblast.

Placenta

A disc-shaped organ formed by both fetal (chorionic villi) and maternal (endometrium) tissues that mediates material exchange between mother and fetus.

Sarcomere

The basic contractile unit of a striated muscle cell, repeating between two Z lines.

Sliding filament theory

The model of muscle contraction where thick (myosin) and thin (actin) filaments slide past each other, shortening the sarcomere while filaments remain a constant length.