Nervous System

regulation

an organism's ability to deal with the effects of a disruption by controlling its own inherent dynamics in response to changes in its internal and external environments.

response

the behavior that is manifested by a living organism which is the result of an external or internal stimulus.

actions of the body: muscle contractions, gland secretions, or brain actions.

stimulus

anything that causes you to react, for example, the smell of food and your mouth watering.

Nervous Regulation

the ability to move flexibly between different states of arousal in response to stressors. This means that when we encounter a change in our environment, like a stressful situation, we can adapt so that we are not overwhelmed.

Neuron

the fundamental units of the brain and nervous system, the cells responsible for receiving sensory input from the external world, for sending motor commands to our muscles, and for transforming and relaying the electrical signals at every step in between.

Impulse

The movement of action potential along a nerve fiber in response to a stimulus (such as touch, pain, heat or cold)

Cell body / Cyton

the spherical part of the neuron that contains the nucleus. The cell body connects to the dendrites, which bring information to the neuron, and the axon, which sends information to other neurons.

Dendrites / Receptors

the finger-like cells present on the end of a neuron. They are short, branching fibres extending from the cell body of the nerve cell. This fibre increases the surface area available for receiving incoming information. Dendrites are the receiving or input portions of a neuron.

Axon

portion of a nerve cell (neuron) that carries nerve impulses away from the cell body. A neuron typically has one axon that connects it with other neurons or with muscle or gland cells.

Schwann’s Cells

the major glial cell type in the peripheral nervous system. They play essential roles in the development, maintenance, function, and regeneration of peripheral nerves.

Myelin Sheath

an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. This myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cells.

Terminal Branches

the tiny, tree-like ends of a neuron that send messages to other neurons.

Synapse

a small gap at the end of a neuron that allows a signal to pass from one neuron to the next

Neurotransmitters

endogenous chemicals that allow neurons to communicate with each other throughout the body. They enable the brain to provide a variety of functions, through the process of chemical synaptic transmission.

Sensory Neurons

the nerve cells that are activated by sensory input from the environment - for example, when you touch a hot surface with your fingertips, the sensory neurons will be the ones firing and sending off signals to the rest of the nervous system about the information they have received.

Interneurons

neurons that connect to brain regions

Motor Neurons

cells in the brain and spinal cord that allow us to move, speak, swallow and breathe by sending commands from the brain to the muscles that carry out these functions.

Effectors

a bodily tissue, structure, or organ (as a gland or muscle) that becomes active in response to stimulation.

Sodium Potassium Pump

a specialized type of transport protein found in your cell membranes. The cell membrane is the semi-permeable outer barrier of many cells. The NaK pump's job is to move potassium ions into the cell while simultaneously moving sodium ions out of the cell.

Nerve Net

a simple, decentralized, multipolar multipolar nervous system found in animals like jellyfish

Central Nervous System

made up of the brain and spinal cord:

• The brain controls how we think, learn, move, and feel.

• The spinal cord carries messages back and forth between the brain and the nerves that run throughout the body.

Ganglia

clusters of nerve cell bodies found throughout the body. They are part of the peripheral nervous system (PNS) and carry nerve signals to and from the central nervous system (CNS)

Peripheral Nervous System

consists of nerves and ganglia, which lie outside the brain and the spinal cord.

Sense Organs

a body part (as an eye or ear) that receives stimuli (as light or sound) in such a way as to excite nerve cells to send information to the brain.

Human Nervous System

a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body.

Brain

The organ inside the head that controls all body functions of a human being. Made up of billions of nerve cells, the brain is protected by the cranium (the bones that form the head). It is made up of three major parts: the cerebrum, the cerebellum, and the brain stem.

Cerebrum

The largest part of the brain. It is divided into two hemispheres, or halves, called the cerebral hemispheres. Areas within the cerebrum control muscle functions and also control speech, thought, emotions, reading, writing, and learning.

Cerebellum

The portion of the brain in the back of the head between the cerebrum and the brain stem. The cerebellum controls balance for walking and standing, and other complex motor functions.

Medulla

the lowest part of the brain present at the base of the brainstem. It is responsible for various brain activities that involve the autonomic nervous response, such as heart rate and respiration process.

Spinal Cord

• the long, cylindrical structure that connects your brain and lower back.

• It contains tissues, fluids and nerve cells.

• A bony column of vertebrae surrounds and protects your spinal cord.

• Your spinal cord helps carry electrical nerve signals throughout your body.

Reflexes

an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus.

Somatic Nervous System

a component of the peripheral nervous system associated with the voluntary control of the body movements via the use of skeletal muscles.

Autonomic Nervous System

The part of the nervous system that controls muscles of internal organs (such as the heart, blood vessels, lungs, stomach, and intestines) and glands (such as salivary glands and sweat glands).

Parasympathetic Nervous

The part of the nervous system that slows the heart, dilates blood vessels, decreases pupil size, increases digestive juices, and relaxes muscles in the gastrointestinal tract.

Sympathetic Nervous System

The part of the nervous system that increases heart rate, blood pressure, breathing rate, and pupil size. It also causes blood vessels to narrow and decreases digestive juices.

The effects of drugs

Drugs interfere with the way neurons send, receive, and process signals via neurotransmitters. Some drugs, such as marijuana and heroin, can activate neurons because their chemical structure mimics that of a natural neurotransmitter in the body. This allows the drugs to attach onto and activate the neurons.

Stimulants

a class of drugs that speed up messages travelling between the brain and body. They can make a person feel more awake, alert, confident or energetic. Stimulants include caffeine, nicotine, amphetamines and cocaine.

Depressants

drugs that lower neurotransmission levels, or depress or reduce arousal or stimulation in various areas of the brain.

Hallucinogens

can potentially change the way people see, hear, taste, smell or feel, and also affect mood and thought.

Meningitis

an infection and inflammation of the fluid and membranes surrounding the brain and spinal cord.

Cerebral Palsy

a group of conditions that affect movement and posture. It's caused by damage that occurs to the developing brain, most often before birth. Symptoms appear during infancy or preschool years and vary from very mild to serious. Children with cerebral palsy may have exaggerated reflexes

Polio

• A virus that may cause paralysis and is easily preventable by the polio vaccine.

• Polio is transmitted through contaminated water and food or contact with an infected person.

• Many people who are infected with the poliovirus don't become sick and have no symptoms. However, those who do get sick develop paralysis, which can sometimes be fatal.

• Treatment includes bed rest, pain relievers, and portable ventilators.

Endocrine Regulation

regulates how much of each hormone is released. This can depend on levels of hormones already in the blood, or on levels of other substances in the blood, like calcium. Many things affect hormone levels, such as stress, infection, and changes in the balance of fluid and minerals in blood.

Target Tissue

The biological tissue(s) most adversely affected by exposure to a chemical substance.

Endocrine Gland

An organ that makes hormones that are released directly into the blood and travel to tissues and organs all over the body.

Hormones

a regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action.

Hypothalamus

The area of the brain that controls body temperature, hunger, and thirst.

Pituitary Gland

makes, stores and releases hormones

Thyroid Stimulating Hormone

a pituitary hormone that stimulates the thyroid gland to produce thyroxine, and then triiodothyronine which stimulates the metabolism of almost every tissue in the body.

Follicle Stimulating Hormone

A hormone made in the pituitary gland.

Growth Hormone

a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in human development.

Hyposecretion

when the amount of hormones that are released is too low.

Hypersecretion

when the amount of hormones that are released is too high.

Thyroid Gland

produces hormones that regulate the body's metabolic rate, growth and development. It plays a role in controlling heart, muscle and digestive function, brain development and bone maintenance.

Thyroxine

The thyroid gland in your neck makes a hormone called thyroxine. Thyroxine controls how much energy your body uses (the metabolic rate). It's also involved in digestion, how your heart and muscles work, brain development and bone health.

Goiter

Enlargement of the thyroid gland

Parathyroid Gland

The parathyroid glands lie behind the thyroid. They produce parathyroid hormone, which plays a role in regulating the body's blood level of calcium and phosphorus.

Parathormone

Parathyroid hormone (PTH) is a hormone that your parathyroid glands make and release to control the level of calcium in your blood, not your bones.

Adrenal Glands

Adrenal glands, also known as suprarenal glands, are small, triangular-shaped glands located on top of both kidneys. Adrenal glands produce hormones that help regulate your metabolism, immune system, blood pressure, response to stress and other essential functions.

Adrenaline

a hormone secreted by the adrenal glands, especially in conditions of stress, increasing rates of blood circulation, breathing, and carbohydrate metabolism and preparing muscles for exertion.

Cortisol

Cortisol is a steroid hormone that is produced by your 2 adrenal glands, which sit on top of each kidney. When you are stressed, increased cortisol is released into your bloodstream. Having the right cortisol balance is essential for your health, and producing too much or too little cortisol can cause health problems.

“Fight or Flight”

A physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival.

Steroids

A man-made version of hormones normally produced by the adrenal glands which are 2 small glands found above the kidneys.

Islets of Langerhans / Pancreas

Functional units of the endocrine pancreas and have a paramount role in maintaining glucose homeostasis.

Insulin

• Produced by beta cells in the pancreatic islets

• Insulin is a hormone your body makes that helps it control your blood sugar level and metabolism

• Your pancreas makes insulin and releases it into your bloodstream.

• Insulin helps your body use blood sugar, also called blood glucose, for the energy it needs.

Glucagon

A peptide hormone secreted from the alpha cells of the pancreatic islets of Langerhans

Diabetes

A chronic disease that occurs either when the pancreas does not produce enough insulin or when the body cannot effectively use the insulin it produces.

Gonads

an organ that produces gametes; a testis or ovary.

Ovaries

One of a pair of female glands in which the eggs form and the female hormones estrogen and progesterone are made. These hormones play an important role in female traits, such as breast development, body shape, and body hair. They are also involved in the menstrual cycle, fertility, and pregnancy.

Estrogen

A group of hormones that play an important role in the normal sexual and reproductive development in women. They are also sex hormones. The woman's ovaries make most estrogen hormones, although the adrenal glands and fat cells also make small amounts of the hormones.

Secondary Sex Characteristics

Physical feature related to the sex of an organism that emerges during puberty, or the phase of sexual maturity. Examples of secondary sex characters in humans include the development of breasts in females and pigmented facial hair in males.

Progesterone

An endogenous steroid hormone that is commonly produced by the adrenal cortex as well as the gonads, which consist of the ovaries and the testes.

Testes

an organ which produces spermatozoa (male reproductive cells).

Testosterone

Primary male hormone responsible for regulating sex differentiation, producing male sex characteristics, spermatogenesis, and fertility. Testosterone's effects are first seen in the fetus.

Negative Feedback

A normal biological response in which the effects of a reaction slow or stop that reaction. A negative feedback loop helps regulate health by ensuring that a reaction is appropriate and that the systems of the body are in a constant state of equilibrium, also known as homeostasis

Exoskeleton

A skeleton that is on the exterior of an animal to both support the body shape and protect the internal organs

Endoskeleton

An internal skeleton, such as the bony or cartilaginous skeleton of vertebrates.

Bones muscles: skeletal, cardiac & smooth

Skeletal muscle is an organ that primarily controls movement and posture.

Cardiac muscle

Cardiac muscle encompasses the heart, which keeps the human body alive.

Smooth muscle

Smooth muscle is present throughout the gastrointestinal, reproductive, urinary, vascular, and respiratory systems.

Tendons

A fibrous connective tissue that attaches muscle to bone.

Ligaments

Ligaments are fibrous connective tissue that connect bones to bones and serve to hold structures together

Cartilage

A strong, flexible connective tissue that protects your joints and bones