Chapter 13: Nervous System Flashcards
What is homeostasis
The body’s ability to keep physiological functions within normal limits despite fluctuations in the surroundings
Ex) Body temperature- sweating
What are the two systems that work together to ensure homeostasis
- Nervous system
- Endocrine system
What is the Nervous system
Rapid nerve impulses (fast and short)
What is the Endocrine System
Glands that release hormones into the bloodstream (slow and long)
What are the divisions of the Nervous System
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
What are the parts of the Central Nervous System
- Brain
- Spinal Cord
What does the CNS do
Acts as a coordinating centre for incoming and outgoing information
What are the parts of the Peripheral Nervous System
Everything else (NOT brain and spinal cord)
What does the PNS do
Carries information between the organs of the body and the central nervous system
The PNS is divided into 2 categories. What are they?
- Somatic Nerves (voluntary)
- Autonomic Nerves (involuntary)
What does CNS stand for
Central Nervous System
What does PNS stand for
Peripheral Nervous System
Characteristics of Somatic Nervous System
-Voluntary control (both motor and sensory neurons)
-These nerves lead to skeletal muscle
-Fast nerve transmission (myelinated neurons)
Characteristics of Autonomic Nervous System
-Involuntary
-Automatic
-Slower nerve transmission (Unmyelinated neurons)
-Controls: heart rate, blood pressure, breathing rate and more!
-Divided into 2 parts: parasympathetic and sympathetic
Characteristics of Parasympathetic
-REST AND DIGEST
-Nerves transmit impulses when returning to normal after a time of stress
-Slows functions (like heart rate and blood pressure)
-Nerves originate in the brain
Characteristics of Sympathetic
-FIGHT OR FLIGHT
-Nerves transmit impulses during times of stress
-Speeds up functions (like heart rate and blood pressure)
-Nerves originate in the spinal cord
What are Neurons
-The basic unit of the nervous system is the neuron
-A nerve is a bundle of neurons
-Neurons are specialized cells that conduct an electrical impulse
Dendrite structure and function
-Short, thin, thread-like
structures branching
from the cell body
-Receive stimuli
-Carry received
nerve impulses
toward the cell body
Cell body structure and function
-Contains the nucleus (control centre), mitochondria (energy production), other organelles
-Coordinates the neuron and produces chemical messengers (neurotransmitters)
Axon Hillock structure and function
-Swelling of the cell body connecting to the axon
-Originates or triggers nerve impulse (action potential)
Axon structure and function
-Long, thicker, single fibre extending
from the cell body
(Can be up to 1 metre in length)
-Carries the electrical component
of the nerve impulse away from the
cell body
-The larger the diameter, the faster the speed of the impulse
-Some axons are covered with an insulating myelin sheath
Myelin Sheath structure and function
-An insulating white coating produced by Schwann cells
-White color
-Allows for faster
movement of nerve impulse
-Prevents the
loss of charged ions from the nerve cell
-Nerves in the brain and spinal column:
White matter (myelinated)
Grey matter (unmylinated) {although more of a pink color}
Nodes of Ranvier structure and function
-Gaps between the myelin sheath (~1mm)
-Allows nerve impulses to travel faster down the axon, node to node (120m/s)
** 120 m/s = 432 km/h
-Multiple sclerosis (MS) causes hardened scar tissue to form on top of the myelin, disrupting nerve transmission
Synaptic Knobs (aka. motor end plates, terminal buttons) structure and function
-Bulb-like structure at the end of the nerve endings or terminal branches
-Transmits the nerve impulse to another neuron’s dendrites, a muscle or gland
-Releases chemical messengers (neurotransmitters)
