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The cerebellum    (cerebellum = “little brain”) sits at the base of the brain on top of the brainstem. The cerebellum controls balance and aids in coordinating movement and learning new motor tasks. The cerebellum of birds is large compared to other vertebrates because of the coordination required by flight.

The brainstem    connects the rest of the brain with the spinal cord and regulates some of the most important and basic functions of the nervous system including breathing, swallowing, digestion, sleeping, walking, and sensory and motor information integration.

Spinal cord

Connecting to the brainstem and extending down the body through the spinal column is the spinal cord. The spinal cord is a thick bundle of nerve tissue that carries information about the body to the brain and from the brain to the body. The spinal cord is contained within the meninges and the bones of the vertebral column but is able to communicate signals to and from the body through its connections with spinal nerves (part of the peripheral nervous system). A cross-section of the spinal cord looks like a white oval containing a gray butterfly-shape ( [link] ). Myelinated axons make up the “white matter” and neuron and glia cell bodies (and interneurons) make up the “gray matter.” Axons and cell bodies in the dorsal spinal cord convey mostly sensory information from the body to the brain. Axons and cell bodies in the ventral spinal cord primarily transmit signals controlling movement from the brain to the body.

The spinal cord also controls motor reflexes. These reflexes are quick, unconscious movements—like automatically removing a hand from a hot object. Reflexes are so fast because they involve local synaptic connections. For example, the knee reflex that a doctor tests during a routine physical is controlled by a single synapse between a sensory neuron and a motor neuron. While a reflex may only require the involvement of one or two synapses, synapses with interneurons in the spinal column transmit information to the brain to convey what happened (the knee jerked, or the hand was hot).

In the cross section the gray matter forms an X inside the oval white matter. The legs of the X are thicker than the arms. Each leg is called a ventral horn, and each arm is called a dorsal horn.
A cross-section of the spinal cord shows gray matter (containing cell bodies and interneurons) and white matter (containing myelinated axons).

The peripheral nervous system

The peripheral nervous system (PNS)    is the connection between the central nervous system and the rest of the body. The PNS can be broken down into the autonomic nervous system    , which controls bodily functions without conscious control, and the sensory-somatic nervous system    , which transmits sensory information from the skin, muscles, and sensory organs to the CNS and sends motor commands from the CNS to the muscles.

The autonomic nervous system is divided into sympathetic and parasympathetic systems. In the sympathetic system, the soma of the preganglionic neurons is usually located in the spine while in the parasympathetic system the soma is usually in the brainstem or sacral, at the bottom of the spine. In both systems, the preganglionic neuron releases the neurotransmitter acetylcholine into the synapse. Postganglionic neurons of the sympathetic system have somas in a sympathetic ganglion, located next to the spinal cord. Postganglionic neurons of the parasympathetic system have somas in ganglions near the target organ. Postganglionic neurons of the sympathetic system release norepinephrine into the synapse, while postganglionic neurons of the parasympathetic system release acetylcholine or nitric oxide.
In the autonomic nervous system, a preganglionic neuron (originating in the thoraco-lumbar region of the spinal cord) synapses to a neuron in a ganglion that, in turn, synapses on a target organ. Activation of the sympathetic nervous system causes release of norepinephrine on the target organ. Activation of the parasympathetic nervous system causes release of acetylcholine on the target organ. ...............................................................................................................................................................................................................

Questions & Answers

different between human being and animals
Habeeb Reply
what is fat soluble drugs
Acho Reply
drugs that dissolve mostly in fatty tissues
shea
what is cell
Sesay Reply
cell is the basic unit of life.
ibtisam
how many double bond present in arachidonic acid?
Rekha
what is the source of the homologous chromosomes and the importance of its event?
Tani Reply
what is biology
Habeeb
chemical, cellular, tissue, organ, organ system, organisms
Saleema Reply
chemical, tissue, cellular, organ, organism, organ system
Saleema
yes, both parts are apart of the reproductive and endocrine system because they function in both
Saleema
du antigen
gambo
what is antigenic
gambo
how many bones are there in a human
Tih Reply
206
Shivani
206 when they fused together
gambo
206 bones
Kate
206bones
R0se
206
Mahmmad
define ornithology
Aniowo
ornithology is the study of birds in every aspect.
Hemamalene
chemical which makes a person to lose appetite
milton Reply
name the matrix from which bone is made?
Vaibhav Reply
hydroxyapatite
Tani
whats the nuclear pore ?
Tani Reply
tell me about the nuclear pore or nuclear membrane I don't quite understanding
Tani
The nuclear pore is a protein-lined channel in the nuclear membrane that regulates the transportation of molecules between thenucleus and the cytoplasm.
Jack
The nuclear pore is a protein lined channel in the nuclear membrane (nuclear envelope) that regulates the transportation of molecules between the nucleus and the cytoplasm.
Jack
Thank you...
Tani
what is cell?
Shashi Reply
cell is a small building block that make everything in the body. Other words known as the smallest unit of life
Cheryl
cell is the basics unit of life, in words it's enablement of life process
Dumbari
what is diffusion
kambani
diffusion is the net movement of a particles from an area of high concentration to an area of low concentration down a concentration gradient
linadora
What is the meaning of the word cell?
hafsa Reply
unit
Samiullah
who discovered cell and in what year.
Jonathan
Robert hook discovered cell in 1665.
Alisohai
what is biology
gambo
bioLoGy is tHe bRanCH oF SCIENce, anD iTs dEals witH tHe stUdy oF liFe ..
Alisohai
what happened when the hand accidentally touches a hot abject
Tumbu Reply
quickly removes its hand
hafsa
a stimuli is sent to the central nervous system by neurons which in turn send back a response which makes that person to quickly remove his hand from the hot object.
Ofang
what is cell
Ernest Reply
cell can be defined as the smallest unit of life
alhassan
what is a hormone
Michael Reply
hormones are the body's chemical messengers and are part of the endocrine system,.
Nisa
hormone are the chemical messanger that are produce by ductless gland to act on a target organ.
Luqman
why are the pictures showing
Anasili Reply
I don't get your question well
Prophet

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Source:  OpenStax, Human biology. OpenStax CNX. Dec 01, 2015 Download for free at http://legacy.cnx.org/content/col11903/1.3
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