FEM 4100

Topic 2BRAIN ANATOMY

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• Two parts of a nervous system – Central Nervous System (CNS)

• Brain (in the skull)• Spinal Cord (in the spine)

– Peripheral Nervous System (PNS)• Located outside of the skull and spine• Connects the central nervous system to all other

parts of the body • Serves to bring information into the CNS and

carry signals out of the CNS

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THE NERVOUS SYSTEM

Central Nervous System

• Spinal cord– An extension of the brain, reaching from the base of the

brain through the neck and spinal column, that transmits messages between the brain and the peripheral nervous system

– Protected by bone and spinal fluid• Brain structures

– Hindbrain (brainstem)– Midbrain– Forebrain

Central Nervous System

• Brainstem– The structure that begins at the point where the spinal

cord enlarges as it enters the brain – Medulla

• The part of the brainstem that controls heartbeat, blood pressure, breathing, coughing, and swallowing

Central Nervous System

• Brainstem (continued)– Reticular formation

• A structure in the brainstem that plays a crucial role in arousal and attention and that screens sensory messages entering the brain

• Pons• A structure in the brainstem that plays a role in body movement

and even exerts an influence on sleep and dreaming

Central Nervous System

• Cerebellum– The brain structure that executes smooth, skilled body

movements and regulates muscle tone and posture

Central Nervous System

• Midbrain– The structures of this brain region act primarily as relay

stations through which the basic physiological functions of the hindbrain are linked to the cognitive functions of the forebrain

– Substantia nigra• The midbrain structure that controls unconscious motor

movements

Central Nervous System

• Thalamus– The structure, located above the brainstem, that acts as

a relay station for information flowing into or out of the higher brain centers

– Regulates sleep cycles• Hypothalamus

– A small but influential brain structure that controls the pituitary gland and regulates hunger, thirst, sexual behavior, body temperature, and a wide variety of emotional behaviors

Central Nervous System

• Limbic system– A group of structures in the brain, including the

amygdala and hippocampus, that are collectively involved in emotion, memory, and motivation

– Amygdala• A structure in the limbic system that plays an important role in

emotion, particularly in response to aversive stimuli

– Hippocampus• A structure in the limbic system that plays a central role in the

formation of long-term memories

Central Nervous System

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THE NERVOUS SYSTEM

Spinal cord Brain

Centralnervous system

Skeletal system

Sym patheticnervous system

Parasym pathetic nervous system

Autonom icnervous system

Peripheralnervous system

Nervous system

• Neuraxis– An imaginary line drawn through the center of

the length of the central nervous system, fromthe bottom of the spinal cord to the front of theforebrain.

– Anterior & posterior• Anterior

– With respect to the central nervous system, located near or toward the head.

• Posterior– With respect to the central nervous system, located near or

toward the tail.

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BASIC FEATURES OF THE NERVOUS SYSTEM

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• Rostral & caudal– Rostral

• “Toward the beak”; with respect to the central nervous system, in a direction along the neuraxis toward the front of the face.

– Caudal• “Toward the tail”; with respect to the central nervous system, in a

direction along the neuraxis away from the front of the face.• Dorsal & ventral

– Dorsal• “Toward the back”; with respect to the central

nervous system, in a direction perpendicularto the neuraxis toward the top of the head or the back.

– Ventral• “Toward the belly”; with respect to the central

nervous system, in a direction perpendicular tothe neuraxis toward the bottom of the skull or thefront surface of the body.

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• Lateral or medial– Lateral

• Toward the side of the body, away from the middle.

– Medial• Toward the middle of the body, away from the side.

• Ipsilateral or Contralateral– Ipsilateral

• Located on the same side of the body.

– Contralateral• Located on opposites side of the body.

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– Cross section or Frontal section• A transverse cut like a salami.• With respect to the central nervous system, a slice taken at

right angles to the neuraxis.• A slice through the brain parallel to the forehead.

– Horizontal section• A slice through the brain parallel to the ground.

– Sagittal section• A slice through the brain parallel to the neuraxis and

perpendicular to the ground.

– Midsagittal• The plane through the neuraxis perpendicular to the ground;

divides the brain into two symmetrical halves

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MENINGES, VENTRICLES & CSF

• CNS - encased in bone and covered by three meninges– Dura mater (“hard mother”)

• The tough outermost membrane of the meninges; flexible, unstretchable.

– Arachnoid membrane – • From the Greek arachne, meaning “spider”.• The weblike middle layer of the meninges, located between the

dura mater and the inner pia mater.

– Pia mater (“pious mother”)• The layer of the meninges adjacent to the surface of the brain; thin

and delicate. • Adheres to CNS surface

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Meninges, Ventricles, and CSF

– Subarachnoid space• The fluid-filled space that cushions the brain; located

between the arachnoid membrane and the pia mater.

– Cerebrospinal fluid (CSF)• A clear fluid, similar to blood plasma, that fills the

ventricular system of the brain and the subarachnoid space surrounding the brain and spinal cord.

• Fluid serves as cushion

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MENINGES, VENTRICLES & CSF

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The Five Major Divisions of the Brain

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The Five Major Divisions of the Brain

• Telencephalon– Cerebral cortex– Limbic system– Basal ganglia

• Diencephalon– Thalamus – sensory relay nuclei– Hypothalamus

Regulation of motivated behaviors Controls hormone release by the pituitary

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• Mesencephalon – Tectum (dorsal surface)

• Inferior colliculi – audition• Superior colliculi - vision

– Tegmentum (ventral) – 3 ‘colorful’ structures• Periaqueductal gray – analgesia• Substantia nigra – sensorimotor• Red nucleus– sensorimotor

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• Myelencephalon = medulla– Composed largely of tracts– Origin of the reticular formation

• Metencephalon– Many tracts– Pons – ventral surface– Cerebellum - coordination

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THE CENTRAL NERVOUS SYSTEM

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THE CENTRAL NERVOUS SYSTEM

• The forebrain-telencephalon• Cerebrum

– The largest structure of the human brain, consisting of the two cerebral hemispheres connected by the corpus callosum and covered by the cerebral cortex

– The most rostral of the three major divisions of the brain; includes the telencephalon and diencephalon.

– Convolutions serve to increase surface area.– Longitudinal fissure – a groove that separates right and left

hemispheres– Corpus callosum – largest hemisphere-connecting tract– The thick band of nerve fibers that connects the two cerebral

hemispheres and makes possible the transfer of information and the synchronization of activity between them

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THE CENTRAL NERVOUS SYSTEM

• The forebrain-telencephalon• Cerebrum

– Cerebral hemispheres• The right and left halves of the cerebrum, covered by the

cerebral cortex and connected by the corpus callosum• One of the two major portions of the forebrain, covered by the

cerebral cortex.– Cerebral cortex

• The gray, convoluted covering of the cerebral hemispheres that is responsible for higher mental processes including language, memory, and thinking

• Referred to as gray matter• Andreason and others

• Indicated that the amount of gray matter is positively correlated with human intelligence

• Convolutions• The numerous folds or wrinkles in the cortex

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• The forebrain-telencephalon• Cerebral cortex

– Three types of areas of the cerebral cortex• Sensory input areas: where vision, hearing, touch,

pressure, and temperature register• Motor areas: control voluntary movement• Association areas: house memories and are involved in

thought, perception, and language

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• The forebrain-telencephalon– Subcortical region

• The region located within the brain, beneath the cortical surface.• Contains the limbic system and the basal ganglia.

– Sulcus• A groove in the surface of the cerebral hemisphere, smaller than a

fissure.

– Fissure• A major groove in the surface of the brain, larger than a sulcus.

– Gyrus• A convolution of the cortex of the cerebral hemispheres, separated

by sulci or fissures.

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• The forebrain-telencephalon– Primary visual cortex

• The region of the posterior occipital lobe whose primary input is from the visual system.

– Calcarine fissure• A fissure located in the occipital lobe on the medial surface of

the brain; most of the primary visual cortex is located along its upper and lower banks.

– Primary auditory cortex• The region of the superior temporal lobe whose primary input is

from the auditory system.

– Lateral fissure• The fissure that separates the temporal lobe from the overlying

frontal and parietal lobes.

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• The forebrain-telencephalon– Primary somatosensory cortex

• The region of the anterior parietal lobe whose primary input is from the somatosensory system.

– Central sulcus• The sulcus that separates the frontal lobe from the parietal lobe.

– Primary motor cortex• The region of the posterior frontal lobe that contains neurons that

control movements of skeletal muscle.• The connections of this region are contralateral.• The left primary motor cortex controls the right side

of the body and vice versa.

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• The forebrain-telencephalon

– The Brain Lobes• Frontal lobe• Parietal lobe• Temporal lobe• Occipital lobe

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The Frontal Lobes• The anterior portion of the cerebral

cortex, rostral to the parietal lobe and dorsal to the temporal lobe. This includes everything in front of the central sulcus (front of the brain)

• Functions include– motor cortex : control voluntary body

movements, – Broca’s area : speech production– the frontal association areas: memory

search, reasoning thinking, motivation, planning for the future, impulse control, and emotional responses

• Phineas Gage

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• Motor cortex– The strip of tissue at the rear of the frontal

lobes that controls voluntary body movement– Discovered by Fritsch and Hitzig– Wilder Penfield

• Applied electrical stimulation to the motor cortex of conscious human patients undergoing neurosurgery

• Mapped the primary motor cortex in humans– Plasticity is maintained throughout life

• The capacity of the brain to adapt to changes such as brain damage

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The Parietal Lobes• The region of the cerebral cortex caudal

to the frontal lobe and dorsal to the temporal lobe (Top rear of the brain)

• The lobes that contain the somatosensory cortex and other areas that are responsible for – body awareness, – attention, – motor control and – spatial orientation

• Somatosensory cortex– The strip of tissue at the front of the

parietal lobe where touch, pressure, temperature, and pain register in the cerebral cortex

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The Temporal Lobes

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The region of the cerebral cortex rostral to the occipital lobe and ventral to the parietal and frontal lobes (in front of the ears)

The lobes that contain the primary auditory cortex, Wernicke’s area (hearing), and association areas for interpreting auditory information, vision, memory

Primary auditory cortex: The part of the temporal lobes

where hearing registers in the cerebral cortex

The Occipital Lobes• The region of the cerebral cortex

caudal to the parietal and temporal lobes.

• This is located posterior to the central sulcus (At the back of the head)

• The lobes that contain the primary visual cortex and association areas involved in the interpretation of visual information

• Primary visual cortex– The area at the rear of the occipital

lobes where vision registers in the cerebral cortex

– Each eye is connected to the primary visual cortex in both right and left occipital lobes

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What Became of Albert Einstein's Brain?

What Became of Albert Einstein's Brain?

• On April 18, 1955, the great mathematician and physicist Albert Einstein died. He was 76 years old.

• Einstein had requested that his body be cremated but that his brain be saved and studied for research.

• Scientists counted the number of neurons (nerve cells) and glial cells in four areas of Einstein’s brain: area 9 of the cerebral cortex on the right and left hemisphere and area 39 of the cerebral cortex on the right and left hemisphere.

• The ratios of neurons to glial cells in Einstein’s brain were compared to those from the brains of 11 men who died at the average age of 64.

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Investigation for Student Centered learning

Clues

• Area 9 is located in the frontal lobe (prefrontal cortex) and is thought to be important for planning behavior, attention and memory.

• Area 39 is located in the parietal lobe and is part of the "association cortex."

• Area 39 is thought to be involved with language and several other complex functions.

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• The forebrain-telencephalon– Sensory association cortex

• Those regions of the cerebral cortex that receiveinformation from regions of the primary sensorycortex. Perception takes place here and memoriesare stored here.

– Motor association cortex (premotor cortex)• The region of the frontal lobe rostral to the primary

cortex; also known as the premotor cortex. Controlsoverall motor behavior.

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• The forebrain-telencephalon– Prefrontal cortex

• The region of the frontal lobe rostral to themotor association cortex. This region is involvedin formulating plans and strategies.

– Corpus callosum• A large bundle of axons that interconnects

corresponding regions of the association cortexon each side of the brain.

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• The forebrain-telencephalon – Neocortex

• The phylogenetically newest cortex, includingthe primary sensory cortex, primary motor cortex,and association cortex.

– Limbic cortex• Phylogenetically old cortex, located at the medial

edge of the cerebral hemispheres; part of the limbicsystem.

– Cingulate gyrus• A strip of limbic cortex lying along the lateral

walls of the groove separating the cerebralhemispheres, just above the corpus callosum.

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• The forebrain-telencephalon• Subcortical structures - Limbic system

• Regulation of motivated behaviors • A group of brain regions including the anterior thalamic

nuclei, amygdala, hippocampus, limbic cortex, fornix, cingulate, septum, mammillary bodies and parts of the hypothalamus, as well as their interconnecting fiber bundles.

• These structures in the brain are collectively involved in emotion, memory, and motivation

– Hippocampus• A forebrain structure in the limbic system (in the temporal

lobe) that plays a central role in the formation of long-term memories

• Includes the hippocampus proper, dentate gyrus, and subiculum.

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• Limbic system– Fornix

• A fiber bundle that connects the hippocampus with– other parts of the brain, including the mammillary– bodies of the hypothalamus.

– Mammillary bodies• A protrusion of the bottom of the brain at the

posterior end of the hypothalamus, containingsome hypothalamic nuclei.

• Serve as relay stations in reflexes related to thesense of smell.

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• Limbic system– Basal ganglia motor system

• Part of the telencephalon, including the caudatenucleus, the globus pallidus, and the putamen.

• Parkinson’s disease is caused by degenerationof the caudate nucleus and putamen.

• Parkinson’s disease includes weakness, tremors,rigidity of the limbs, poor balance and difficulty initiatingmovements.

• Amygdala, striatum (caudate nucleus + putamen), globus pallidus

• Amygdala• A structure in the limbic system (in the interior of the rostral temporal

lobe), containing a set of nuclei.• plays an important role in emotion, particularly in response to aversive

stimuli54

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• The forebrain-diencephalon– Diencephalon

• Situated between the telencephalon and the mesencephalon.• A region of the forebrain surrounding the third ventricle. • The most important structures include the thalamus and the

hypothalamus.

– Thalamus (Greek thalamos, “inner chamber”)• The largest portion of the diencephalon, located above the

hypothalamus; contains nuclei that project information to specific regions of the cerebral cortex and receive information from it.

– Projection fiber• An axon of a neuron in one region of the brain whose

terminals form synapses with neurons in another region.

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• The forebrain-diencephalon

• Thalamus– The structure, located above the brainstem, that acts as a

relay station for information flowing into or out of the higher brain centers

– Regulates sleep cycles– Lateral geniculate nucleus

• A nucleus of the thalamus that receives fibers from the retina and projects fibers to the primary visual cortex.

– Medial geniculate nucleus• A nucleus of the thalamus that receives fibers from the auditory

system and projects fibers to the auditory cortex.

– Ventrolateral nucleus• A nucleus of the thalamus that receives inputs from

the cerebellum and sends axons to the primary motor cortex.58

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• The forebrain-diencephalon

• Hypothalamus• A group of nuclei in the diencephalon situated beneath the

thalamus.

• A small but influential brain structure that controls the pituitary gland and regulates hunger, thirst, sexual behavior, body temperature, and a wide variety of emotional behaviors

• Controls the autonomic nervous system.• Controls the anterior and posterior pituitary glands.• Organizes behavior such as fighting, feeding, fleeing, and

mating.• Includes:

• Optic chiasm• Anterior pituitary gland• Neurosecretory cell• Posterior pituitary gland

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• The forebrain-diencephalon: Hypothalamus

– Optic chiasm• A connection between the optic nerves where half of the fibers of the

optic nerve cross to the contralateral side– Anterior pituitary gland

• The “master gland”.• The anterior part of the pituitary gland; an endocrine gland whose

secretions are controlled by the hypothalamic hormones.– Neurosecretory cell

• A neuron that secretes a hormone or hormone-like substance.

– Posterior pituitary gland• The posterior part of the pituitary gland; an

endocrine gland that contains hormone-secretingterminal buttons of axons whose cell bodies liewithin the hypothalamus.

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• The midbrain-mesencephalon

– The midbrain; a region of the brain that surrounds the cerebral aqueduct; includes the tectum and tegmentum.

– The esencephalon; the central of the three major divisions of the brain.

– The structures of this brain region act primarily as relay stations through which the basic physiological functions of the hindbrain are linked to the cognitive functions of the forebrain

– Substantia nigra• The midbrain structure that controls

unconscious motor movements

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• The midbrain-mesencephalon

• Tectum (“roof”)– The dorsal part of the midbrain; includes the

superior and inferior colliculi.– Includes:

– Superior colliculi– Inferior colliculi– Brain stem

– Superior colliculi• Protrusions on top of the midbrain; part of the

visual system.• In mammals they are primarily involved in visual

reflexes and reactions to moving stimuli66

• The midbrain- mesencephalon• Tectum (“roof”)

– Inferior colliculi• Protrusions on top of the midbrain; part of the

auditory system.egmentum (“covering”)• The ventral part of the midbrain, includes the

periaqueductal gray matter, reticular formation,red nucleus, and substantia nigra.

– Brain stem• The stem of the brain, from the medulla to the

diencephalon, excluding the cerebellum.

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• The midbrain- mesencephalon

• Tegmentum– Periaqueductal gray matter

• The region of the midbrain surrounding the cerebral aqueduct; contains neural circuits involved in species-typical behaviors such as fighting and mating; involved in sensitivity to pain.

– Red nucleus• A large nucleus of the midbrain that receives inputs from the cerebellum

and motor cortex and sends axons to motor neurons in the spinal cord.– Substantia nigra (“black substance”)

• A darkly stained region of the tegmentum thatcontains neurons that communicate with thecaudate nucleus and putamen in the basal ganglia.

• Degeneration of the substantia nigra is involvedin Parkinson’s disease.

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• The hindbrain-metencephalon• The most caudal part of the brain; • includes the metencephalon and myelencephalon.

– Cerebellum (“little brain”)• A major part of the brain located dorsal to the pons,

containing the two cerebellar hemispheres, covered with the cerebellar cortex; important component of the motor system.

• The brain structure that executes smooth, skilled body movements and regulates muscle tone and posture

– Cerebellar cortex• The cortex that covers the surface of the cerebellum.

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• The hindbrain-metencephalon

– Deep cerebellar nuclei• Nuclei located within the cerebellar hemispheres;

receive projections from the cerebellar cortex andsend projections out of the cerebellum to other partsof the brain.

– Brainstem• The structure that begins at the point where the spinal

cord enlarges as it enters the brain

– Cerebellar peduncle• One of three bundles of axons that attach each cerebellar

hemisphere to the dorsal pons.71

• The hindbrain-metencephalon– Pons (“bridge”)

• The region of the metencephalon rostral to the medulla, caudal to the midbrain, and ventral to the cerebellum;

• A structure in the brainstem that plays a role in body movement and even exerts an influence on arousal, sleep and dreaming

– Reticular formation• A structure in the brainstem that plays a crucial role in arousal and

attention and that screens sensory messages entering the brain

– Medulla oblongata• The most caudal portion of the brain, located in the myelencephalon,

immediately rostral to the spinal cord.• The part of the brainstem that controls vital functions such as the

cardiovascular system, respiration, and skeletal muscle tone (breathing, coughing, and swallowing)

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Peripheral Nervous System

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Somatic Nervous System Afferent nerves (sensory) Efferent nerves (motor) controls organs under voluntary control (mainly

muscles)

Autonomic Nervous System Sympathetic and parasympathetic nerves

Sympathetic and parasympathetic nerves generally have opposite effects

Two-stage neural paths, neuron exiting the CNS synapses on a second-stage neuron before the target organ

regulates individual organ function and homeostasis, and for the most part is not subject to voluntary control

Peripheral Nervous System

• Peripheral nervous system (PNS)– The nerves connecting the central nervous system to

the rest of the body– Contains two subdivisions

• Somatic division• Autonomic division – contains two divisions

– Sympathetic division (activates)– Parasympathetic division (inhibits)

Peripheral Nervous System

Peripheral Nervous System

• Somatic division– Consists of all the sensory nerves, which transmit

information from the sense receptors—eyes, ears, nose, tongue, and skin—to the central nervous system

– Consists of all the motor nerves, which relay messages from the central nervous system to all the skeletal muscles of the body

Peripheral Nervous System

• Autonomic division– Operates without any conscious control or awareness on

your part– Transmits messages between the central nervous system

and the glands, the cardiac muscle, and the smooth muscles

Peripheral Nervous System

• Autonomic division (continued)– Divided into two parts

• Sympathetic nervous system– Mobilizes the body’s resources during stress, emergencies,

or heavy exertion, preparing the body for action– Named the fight-or-flight response by Walter Cannon

• Parasympathetic nervous system– Associated with relaxation and the conservation of energy;

the division that brings the heightened bodily responses back to normal following an emergency

• Sympathetic• Thoracolumbar• “fight or flight”• Second stage

neurons are far from the target organ

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Autonomic Nervous System

ParasympatheticCraniosacral“rest and restore”Second stage

neurons are near the target organ

Nam e each division of the nervous system and describe its role.

3. __________C onnect centra l system

to vo luntary m uscles

5. __________Arousing; red ies body

for activity; use of energy

6. __________C alm ing; readies body

for restroation of energy

4. __________C onnects centra l systemto nonvoluntary m uscles

and g lands

1. __________ Spinaland C rania l N erves

2. __________Brain

Spinal C ord

N ervous System

Copyright © Allyn & Bacon 2005

Answers• Peripheral nervous system• Central nervous system• Somatic division• Autonomic division• Sympathetic division• Parasympathetic division

Copyright © Allyn & Bacon 2005

• Spinal cord• The cord of nervous tissue that extends caudally from

the medulla, the base of the brain through the neck and spinal column, that transmits messages between the brain and the peripheral nervous system

• Protected by bone and spinal fluid

– Gray matter – inner component – primarily cell bodies

– White matter – outer – mainly myelinated axons– Dorsal – afferent, sensory– Ventral – efferent, motor

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Compare the relative amount of gray and white matter at each level of the spinal cord. In the cervical segment, there is a relatively large amount of white matter.

This pattern is caused by the many axons going up to the brain from all levels of the spinal cord AND there are many axons traveling from the brain down to different segments of the spinal cord.

In lower segments of the spinal cord, there is less white matter because there are fewer axons traveling to and from the brain.

There are also differences in the gray matter. In the cervical segment, the ventral horn (the lower half of the segment) is enlarged.

Also in the lumbar segment that is illustrated, the ventral horn is large.

These segments are those that contain motor neurons that control movement of the arms (cervical segment) and legs (lumbar segment).

The Spinal Cord

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The human spinal column is made up of 33 bones: 7 vertebrae in the cervical region, 12 in the thoracic region, 5 in the lumbar region, 5 in the sacral region and 4 in the coccygeal region.

However, in adults the bones in the sacral region join to form one bone called the sacrum; the bones in the cocygeal region join to form one bone called the coccyx.

• Spinal cord

– Spinal root• A bundle of axons surrounded by connective tissue that occur in pairs,

which fuse and form a spinal nerve.– Cauda equina

• A bundle of spinal roots located caudal to the end of the spinal cord.– Caudal block

• The anesthesia and paralysis of the lower part of the body produced by injection of a local anesthetic into the cerebrospinal fluid surrounding the cauda equina.

– Dorsal root• The spinal root that contains incoming (afferent) sensory fibers.

– Ventral root• The spinal root that contains the outgoing (efferent) motor fibers.

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• The Peripheral Nervous System• The spinal nerves

– Afferent axon• An axon directed toward the central nervous system, conveying sensory

information.– Dorsal root ganglion

• A nodule on a dorsal root that contains cell bodies of afferent spinal nerve neurons.

– Efferent axon• An axon directed away from the central nervous system, conveying

motor commands to muscles and glands.– Cranial nerves

• Twelve pairs of peripheral nerves attached directly to the brain that serve sensory and motor functions of the head, neck, and shoulders.

– Vagus nerve (“wandering”)• The largest of the cranial nerves, conveying efferent fibers of the

parasympathetic division of the autonomic nervous system to organs of the thoracic and abdominal cavities.

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• The Peripheral Nervous System

• The autonomic nervous system– Somatic nervous system

• The part of the peripheral nervous systemthat controls the movement of skeletal musclesor transmits somatosensory information to thecentral nervous system.

– Autonomic nervous system• The portion of the peripheral nervous system

that controls the body’s vegetative functions.

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• The Peripheral Nervous System

• The autonomic nervous system-sympathetic division– Sympathetic division

• The portion of the autonomic nervous system that controls functions that accompany arousal and expenditure of energy.

– Sympathetic ganglia• Nodules that contain synapses between preganglionic and postganglionic

neurons of the sympathetic nervous system.

– Preganglionic neuron• The efferent neuron of the autonomic nervous system whose cell body is

located in a cranial nerve nucleusor in the intermediate horn of the spinal gray matterand whose terminal buttons synapse uponpostganglionic neurons in the autonomic nervous system.

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• The Peripheral Nervous System

• The autonomic nervous system-sympathetic division– Postganglionic neuron

• Neurons of the autonomic nervous system that form synapses directly with their target organ.

– Adrenal medulla• The inner portion of the adrenal gland, located

atop the kidney, controlled by sympathetic nervefibers; secretes epinephrine and norepinephrine.

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• The Peripheral Nervous System

• The autonomic nervous system-parasympathetic division

• The portion of the autonomic nervous system that controls functions that occur during a relaxed state.

• Supports activities involved with increases in the body’s supply of stored energy including salivation, gastric and intestinal motility, secretion of digestive juices, and increased blood flow to the gastrointestinal system.

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Endocrine System

• Endocrine system– A system of ductless glands in various parts of the body

that manufacture and secrete hormones into the bloodstream or lymph fluids, thus affecting cells in other parts of the body

– Hormones• A substance manufactured and released in one part of the body

that affects other parts of the body

Endocrine System

Endocrine System

• Pituitary gland– The endocrine gland located in the brain and

often called the “master gland,” which releases hormones that control other endocrine glands and which also releases a growth hormone

– Thyroid gland– Produces the important hormone thyroxin,

which regulates the rate at which food is metabolized

Endocrine System

Endocrine System

• Pancreas– Regulates the body’s blood sugar levels by

releasing the hormones insulin and glucagon into the bloodstream

• Adrenal glands– A pair of endocrine glands that release

hormones that prepare the body for emergencies and stressful situations and also release small amounts of the sex hormones

Endocrine System

• Gonads– Sex glands; the ovaries in females and the testes

in males– Release the sex hormones that make

reproduction possible and that are responsible for the secondary sex characteristics