Nervous System 11.1 Flashcards
Everything period.
Homeostasis
Stability within the body
What does the Human Nervous system do?
It responds to changes in body and external environment
It regulates body structures and is composed of many subsystems that work together to maintain homeostasis
It monitors and controls most body processes
What is the central Nervous System and what does it do?
It is the Brain and the Spinal cord
It processes and integrates information sent by nerves
What is the peripheral nervous system and what does it do?
Anything that is not in the centre (brain or spinal cord)
It sends sensory messages to CNS via nerves
It sends sensory information from CNS to muscles and glands
Sensory pathways?
Pathway that has nerves that carry sensory messages to the CNS
What is the motor pathway?
Pathway that has nerves that send sensory information from CNS to muscles and glands
Explain the Somatic Nervous System?
It is under conscious control - voluntary
Consists of sensory receptors in the head and extremities
Consists of nerves that send sensory information to CNS
Nerves that send instructions from CNS to skeletal muscles
Explain the Autonomic Nervous System?
Not under conscious control - involuntary
Controls glandular secretions - and the functioning of smooth and cardiac muscles
What are the categories under the Autonomic Nervous System and what do they do?
Sympathetic Nervous System and Parasympethic Nervous System
- They work in opposition to regulate the involuntary process of the body
Examples of Involuntary processes?
Breathing and heart rate.
The two main types of cells that compose the nervous system?
Neurons and glial cells
What are neurons?
They are macroscopic and the basic structural and functional units of the nervous system
Specialized the respond to physical and chemical stimuli to conduct electrochemical signals - release chemicals that regulate various body processes
What is the name of the tissue that neurons are organized into?
Nerves (covered by a connective tissue)
Where do nerves extend the neurons?
Through the peripheral nervous system.
What are glial cells?
They are a supporting framework that support neurons
They nourish the neurons, remove wastes, and defend neurons against infections
They account for half of the volume of the nervous system
What are the three main neurons that form basic-impulse pathways?
Sensory neurons, interneurons, and motor neurons
What are the three overlapping functions that make the nervous system?
Sensory Input, integration, and motor output?
Describe the sensory input.
Sensory neurons carry information from sensory receptors (senses) to CNS
Describe integration.
Found in CNS - act as a link between sensory and moto neurons -
Integrates and process incoming sensory information
Relays outgoing motor information
Describe motor output.
Motor neurons transmit information from CNS to effectors
What are reflexes?
sudden, unlearned, involuntary responses to to certain stimuli
What is a reflex arc?
a simple connection of neurons - results in reflex action in response to a stimulus
How many neurons do withdrawal reflexes use?
Depend on three neurons
Why do we not feel pain before we respond to stimuli?
The impulse is carried from the sensory neuron to interneuron in the spinal cord then to the motor neuron which instructs effectors to react
The sensory neurons do not pass the brain - There is not enough time for the brain to process this and involve itself with voluntary control
Brain processes what has happened after reflex - hence why we feel pain after
What four common features do neurons share?
Axons, dendrites, cell body (soma), and branching ends
Describe the dendrites appearance.
Highly branched, numerous, short,, branching terminals.
What benefit comes from dendrites being numerous and highly branched?
It increases the surface area to receive information
What do dendrites do?
They receive impulses from other neurons and sensory receptors - relay impulse to the cell body
Describe the appearance of the cell body?
It contains the nucleus - and is the site of the cell’s metabolic reactions
What does the cell body do?
It processes input from dendrites - if the input is large enough - relays it to the axon (where an impulse is initiated)
How long are axons?
They range in length depending on where in the body they are located (from 1mm to 1m)
What is a nerve in the body with a long length of axons?
Sciatic nerve - in leg
Contains neuronal axons that go from the spinal cord to foot (over 1m)
What do axons do?
Conduct impulses away from the cell body.
What does the terminal end of axons do?
Branches into many fibres.
What does the axon terminal do?
Releases chemical signals in the space between it and sensory receptors on other dendrites
Does this to communicate with adjacent neurons, glands, or muscles
How many axons per neuron?
One
Describe myelin sheath?
fatty, insulating layer that encloses the axons of some neurons
Gives axons white, glistening appearance
What does myelin sheath do?
It protects myelinated neurons - and speeds the rate of nerve impulse transmission!
What forms myelin?
Schwann cells
How do Schwann cells form myelin?
Schwann cells form myelin by wrapping itself around the axon.
What are myelinated neurons known as?
White matter
What are unmyelinated neurons known as?
Grey matter
Are most neurons in the PNS myelinated or not?
Mostly myelinated