<< Chapter < Page Chapter >> Page >

Thalamus

The thalamus    (Greek for “inner chamber”), illustrated in [link] , acts as a gateway to and from the cortex. It receives sensory and motor inputs from the body and also receives feedback from the cortex. This feedback mechanism can modulate conscious awareness of sensory and motor inputs depending on the attention and arousal state of the animal. The thalamus helps regulate consciousness, arousal, and sleep states. A rare genetic disorder called fatal familial insomnia causes the degeneration of thalamic neurons and glia. This disorder prevents affected patients from being able to sleep, among other symptoms, and is eventually fatal.

Illustration shows parts of the limbic system. The thalamus and hypothalamus are located in the cavity in the center of the cerebral cortex. The cingulate gyrus is part of the cerebral cortex that wraps around the upper part of the basal ganglia. The hippocampus is part of the cerebral cortex located beneath the thalamus. The amygdala is located at the end of the basal ganglia.
The limbic system regulates emotion and other behaviors. It includes parts of the cerebral cortex located near the center of the brain, including the cingulate gyrus and the hippocampus as well as the thalamus, hypothalamus and amygdala.

Hypothalamus

Below the thalamus is the hypothalamus    , shown in [link] . The hypothalamus controls the endocrine system by sending signals to the pituitary gland, a pea-sized endocrine gland that releases several different hormones that affect other glands as well as other cells. This relationship means that the hypothalamus regulates important behaviors that are controlled by these hormones. The hypothalamus is the body’s thermostat—it makes sure key functions like food and water intake, energy expenditure, and body temperature are kept at appropriate levels. Neurons within the hypothalamus also regulate circadian rhythms, sometimes called sleep cycles.

Limbic system

The limbic system    is a connected set of structures that regulates emotion, as well as behaviors related to fear and motivation. It plays a role in memory formation and includes parts of the thalamus and hypothalamus as well as the hippocampus. One important structure within the limbic system is a temporal lobe structure called the amygdala    (Greek for “almond”), illustrated in [link] . The two amygdala are important both for the sensation of fear and for recognizing fearful faces. The cingulate gyrus    helps regulate emotions and pain.

Cerebellum

The cerebellum    (Latin for “little brain”), shown in [link] , 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.

Brainstem

The brainstem    , illustrated in [link] , connects the rest of the brain with the spinal cord. It consists of the midbrain, medulla oblongata, and the pons. Motor and sensory neurons extend through the brainstem allowing for the relay of signals between the brain and spinal cord. Ascending neural pathways cross in this section of the brain allowing the left hemisphere of the cerebrum to control the right side of the body and vice versa. The brainstem coordinates motor control signals sent from the brain to the body. The brainstem controls several important functions of the body including alertness, arousal, breathing, blood pressure, digestion, heart rate, swallowing, 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    , shown in [link] . 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 bones of the vertebrate 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, as illustrated in [link] . Myelinated axons make up the “white matter” and neuron and glial cell bodies make up the “gray matter.” Gray matter is also composed of interneurons, which connect two neurons each located in different parts of the body. Axons and cell bodies in the dorsal (facing the back of the animal) spinal cord convey mostly sensory information from the body to the brain. Axons and cell bodies in the ventral (facing the front of the animal) 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 United States, there around 10,000 spinal cord injuries each year. Because the spinal cord is the information superhighway connecting the brain with the body, damage to the spinal cord can lead to paralysis. The extent of the paralysis depends on the location of the injury along the spinal cord and whether the spinal cord was completely severed. For example, if the spinal cord is damaged at the level of the neck, it can cause paralysis from the neck down, whereas damage to the spinal column further down may limit paralysis to the legs. Spinal cord injuries are notoriously difficult to treat because spinal nerves do not regenerate, although ongoing research suggests that stem cell transplants may be able to act as a bridge to reconnect severed nerves. Researchers are also looking at ways to prevent the inflammation that worsens nerve damage after injury. One such treatment is to pump the body with cold saline to induce hypothermia. This cooling can prevent swelling and other processes that are thought to worsen spinal cord injuries.

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 axons).

Section summary

The vertebrate central nervous system contains the brain and the spinal cord, which are covered and protected by three meninges. The brain contains structurally and functionally defined regions. In mammals, these include the cortex (which can be broken down into four primary functional lobes: frontal, temporal, occipital, and parietal), basal ganglia, thalamus, hypothalamus, limbic system, cerebellum, and brainstem—although structures in some of these designations overlap. While functions may be primarily localized to one structure in the brain, most complex functions, like language and sleep, involve neurons in multiple brain regions. The spinal cord is the information superhighway that connects the brain with the rest of the body through its connections with peripheral nerves. It transmits sensory and motor input and also controls motor reflexes.

Questions & Answers

Parkinson's disease is a caused by the degeneration of neurons that release
birabwa Reply
why is it so hard to get to the questions
Eric Reply
why is it so hard to get to questions?
Eric
what types of proteins which are found in hair,hooves and tendons?
Kapalu Reply
what is blood cells
Isaac Reply
It's cells of the blood
Kaique
can biology be also be define has a scientific study that deal with life?
Stanley Reply
do you care asking you a question
Afolayan Reply
name the gas that diffuses into the plants leaves on a bright, sunny day
Tuhemwe Reply
explain why this gas diffuses into the plant's leaves
Tuhemwe
name two gases that diffuses out of the plant's leaves on a bright sunny day
Tuhemwe
Biology olympaid
Khan
what is ecosystem
Rondy Reply
why does a car move yet it is not a living thing?
Sserujja
this is because of the engine and fuel placed on
Gift
I also think it because force has been apply to it.
Stanley
It is aplace where organísms live and associate with each other.
Nasib
what is the reason of swelling due to fracture
Ejaz Reply
Sngy alaka
Khan
how do animals reproduce
Kelvin Reply
be specific because there are so many types of animals and how they reproduce are different
Sheillah
yeah
Chinwendu
just be specific with a particular animal
Stanley
what happens when you sneeze
Asuquo Reply
The sneeze center sends out a signal to tightly close your throat, eyes and mouth. Your chest muscles contract and compress your lungs while your throat muscles relax. All of that means air, saliva and mucus is forced out of your nose and mouth. AAAAAHHHH-CHOOOO.
Hassan
how are you
Ayouba
hy
Ejaz
hii
Ishitha
hello
mahesha
Hello
Madu
Am fine
Abavon
how far
Abavon
hello
Sheillah
with why
Sheillah
with what
Sheillah
I have a question plzz
Sheillah
what is globsl warming
Rondy
Global warming is the overall rise in temperature of the Earth itself which is caused by multiple factors. Such factors include: greenhouse gases, the burning of fossil fuels and other forms of human activity.
Maryam
It's overall effects are known as climate change.
Maryam
thanks
Rondy
good
Haider
No problem.
Maryam
Thank you.
Maryam
what is creatinine?
Haider
Creatinine is a waste product produced in the body during muscle metabolism. This waste product is expelled from the body through urine. Here is it's formula:  C4H7N3O
Maryam
Formula: C4H7N3O
Maryam
ok
Haider
ok
Stephen
Outline the process of cell in the body interms of it's function.
Aliruku Reply
what communication method used mainly by plants
Jerda Reply
what is biology
james Reply
Biology is the study of life
Omoloju
yah
John
Biology is natural science that studies life and living orgasms.
Hilda
any questions from colleague
Sheillah
define nerve impulse
Karlin Reply
A nerve impulse is the way nerve cells (neurons) communicate with one another. Nerve impulsesare mostly electrical signals along the dendrites to produce a nerve impulse or action potential. The action potential is the result of ions moving in and out of the cell.
Sam

Get the best Biology course in your pocket!





Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Biology' conversation and receive update notifications?

Ask