Human Body - I: Control and Coordination

Vocabulary flashcards covering key terms from the notes on the nervous system, reflexes, endocrine glands, hormones, and adolescence.

Stimulus

A change in the environment to which an organism responds.

Nervous system

Control system responsible for sending electrical messages (nerve impulses) throughout the body.

Endocrine system

Glands that secrete hormones directly into the bloodstream to coordinate body processes.

Neuron (nerve cell)

Structural and functional unit of the nervous system.

Cell body (cyton)

Central part of a neuron that contains cytoplasm and a nucleus.

Dendrites

Short extensions that receive impulses from other neurons and transmit them toward the cell body.

Axon

Long fibre that transmits impulses away from the cell body; end terminals form synaptic bulbs.

Myelin sheath

Protective fatty covering that insulates the axon.

Synapse

Junction between two neurons where neurotransmitters are released.

Neurotransmitter

Chemical messenger released at the synapse to transmit a signal to the next neuron.

Synaptic bulb

Bulb-like structure at axon terminals containing neurotransmitters.

Reflex action

Sudden involuntary response to a stimulus that is usually quick.

Reflex arc

Shortest path by which a nerve impulse travels from receptor to effector via a receptor, sensory neuron, association neuron, and motor neuron.

Receptor

Cell or nerve ending that receives a stimulus.

Effector

Muscle or gland that responds to a stimulus.

Central nervous system (CNS)

Brain and spinal cord; main processing centre.

Peripheral nervous system (PNS)

Nerves that extend from the CNS to the rest of the body (cranial and spinal nerves).

Autonomic nervous system (ANS)

Part of the PNS regulating involuntary functions; has sympathetic and parasympathetic divisions.

Sympathetic nervous system

Mobilizes the body for action (fight/flight); increases heart rate and energy availability.

Parasympathetic nervous system

Conserves energy and returns the body to normal after stress.

Cranial nerves

Nerves that originate from the brain; there are 12 pairs and they carry sensory and/or motor signals.

Spinal nerves

Nerves that originate from the spinal cord; 31 pairs and are mixed (sensory and motor).

Cerebrum

Largest part of the brain; involved in memory, thought, and voluntary actions; consists of left and right hemispheres.

Cerebellum

Part of the brain that coordinates balance and muscular activity.

Medulla oblongata

Lower part of the brainstem; controls involuntary actions like breathing and heartbeat.

Meninges

Three-layered protective coverings of the brain and spinal cord.

Cerebrospinal fluid

Fluid that cushions the brain and provides protection from shocks.

Sensory neuron

Carries impulses from sense organs to the brain or spinal cord.

Motor neuron

Carries impulses from the brain/spinal cord to muscles or glands.

Association neuron (mixed neuron)

Interconnects sensory and motor neurons within the brain and spinal cord.

Exocrine gland

Gland that secretes products through ducts to specific locations (e.g., sweat and salivary glands).

Endocrine gland

Gland that secretes hormones directly into the bloodstream.

Pituitary gland

Master gland at the base of the brain; secretes hormones that regulate other glands (e.g., GH, TSH, ACTH, ADH, prolactin, oxytocin).

Hypothalamus

Brain region that regulates pituitary activity and links nervous and endocrine systems.

Thyroid gland

Bilobed gland in front of the neck; secretes thyroxine to regulate metabolism and development.

Thyroxine

Hormone regulating basal metabolic rate, growth, and mental development.

Iodine

Mineral required for thyroxine synthesis.

Goitre

Enlargement of the thyroid due to iodine deficiency.

Cretinism

Stunted growth and mental retardation in infancy due to iodine deficiency during development.

Myxoedema

Severe hypothyroidism in adults; symptoms include slowed metabolism and swelling.

Adrenal glands

Glands above the kidneys; secrete adrenaline and corticosteroids.

Adrenaline

Emergency hormone that increases heart rate and blood flow to muscles.

Corticosteroids

Hormones that regulate metabolism and electrolyte balance.

Pancreas

Gland with both exocrine (pancreatic juice) and endocrine (insulin, glucagon) functions.

Insulin

Hormone that promotes glucose uptake and storage as glycogen; lowers blood glucose.

Glucagon

Hormone that converts glycogen to glucose in the liver; raises blood glucose.

Diabetes mellitus

Condition caused by insufficient insulin resulting in high blood sugar; symptoms include polyuria, thirst, weight loss, fatigue.

Ovaries

Glands that produce oestrogen and progesterone; regulate female reproductive development.

Estrogen

Female sex hormone; promotes female characteristics and regulates the reproductive cycle.

Progesterone

Hormone important for pregnancy; prepares the uterus for implantation and pregnancy.

Testosterone

Male sex hormone; drives male development and sperm production.

Puberty (Adolescence)

Period between ~11 and 19 years of age of hormonal changes leading to sexual maturation.

FSH (Follicle-stimulating hormone)

Hormone that stimulates ovarian development of eggs and spermatogenesis in males.

LH (Luteinising hormone)

Hormone that triggers ovulation and stimulates sex hormone production.

Adam's apple

Prominence on the neck due to enlargement of the larynx during male puberty.

Larynx

Voice box; enlarges in males during puberty causing deeper voice.