Human Body Systems

Front

Homeostasis Noun

---

[hoh-mee-oh-stay-sis]

Back

Homeostasis

---

The process by which an organism maintains a stable internal environment despite changes in external conditions.

---

Example: This balanced scale represents homeostasis, showing how a body maintains a stable, steady internal state, just like keeping the two sides of a scale even.

Front

Negative Feedback Noun

---

[neg-uh-tiv feed-bak]

Back

Negative Feedback

---

A control mechanism that counteracts a change, bringing a variable back towards its set point.

---

Example: A speed hump provides negative feedback to a driver, causing them to slow down and reduce the car's speed to a safer level.

Front

Positive Feedback Noun

---

[poz-i-tiv feed-bak]

Back

Positive Feedback

---

A control mechanism that amplifies a change, pushing a variable further from its set point to complete a process.

---

Example: This diagram shows a positive feedback loop: uterine contractions cause the brain to release oxytocin, which in turn makes the contractions even stronger.

Front

Neuron Noun

---

[noor-on]

Back

Neuron

---

A specialized cell that transmits electrical and chemical signals, serving as the basic unit of the nervous system.

---

Example: This diagram shows a nerve cell (neuron) and labels its main parts, including the dendrites, soma (cell body), nucleus, axon, and myelin sheath.

Front

Axon Noun

---

[ak-son]

Back

Axon

---

The long, slender projection of a neuron that conducts electrical impulses away from the cell body.

---

Example: This diagram shows the axon as the long, cable-like part of a neuron that transmits signals away from the cell body to other cells.

Front

Dendrite Noun

---

[den-dryt]

Back

Dendrite

---

The branched, tree-like extensions of a neuron that receive signals from other neurons.

---

Example: This image shows a dendrite as the part of a nerve cell that has receptors to receive signals from another nerve cell's axon.

Front

Synapse Noun

---

[sin-aps]

Back

Synapse

---

The small gap between two neurons where signals are passed from one cell to the next.

---

Example: This diagram shows a synapse, the tiny gap where a signal passes from one neuron to the next using chemical messengers called neurotransmitters.

Front

Neurotransmitter Noun

---

[noor-oh-trans-mit-er]

Back

Neurotransmitter

---

A chemical messenger that transmits signals across a synapse from one neuron to another target cell.

---

Example: This image shows neurotransmitters, which are chemical messengers, being released from one nerve cell and crossing a gap to send a signal to another.

Front

Sympathetic Nervous System Noun

---

[sim-puh-thet-ik nur-vuhs sis-tuhm]

Back

Sympathetic Nervous System

---

The division of the autonomic nervous system responsible for the body's 'fight or flight' response.

---

Example: This diagram shows the 'fight-or-flight' response, which is controlled by the sympathetic nervous system to prepare the body for intense activity.

Front

Parasympathetic Nervous System Noun

---

[par-uh-sim-puh-thet-ik nur-vuhs sis-tuhm]

Back

Parasympathetic Nervous System

---

The division of the autonomic nervous system responsible for the body's 'rest and digest' functions.

---

Example: This diagram shows how the parasympathetic nervous system controls 'rest and digest' functions, like slowing the heartbeat, stimulating digestion, and constricting pupils.