Biology Unit 4

Thyroid gland disorders

Among the most common endocrine disorders - affect all major body systems

reciprocal innervation

An arrangement, in which the components of a neural circuit simultaneously cause contraction of one muscle and relaxation of its antagonists. - prevents conflict between opposing muscles and is vital in coordinating body movements.

tickle

Free nerve endings and lamellated corpuscles are thought to mediate the tickle sensation

Cranial Nerve VI

Abducens Nerve Major function: Control some of the muscles moving the eyeballs

Cranial Nerve XI

Accessory Nerve Major function: Control head and shoulder muscles

Acini

Clusters of pancreatic cells - produce digestive enzymes which flow into the gastrointestinal tract through a network of ducts

Localization of Pain

Fast pain is very precisely localized to the stimulated area

brachial plexus

Formed by the roots (anterior rami) of spinal nerves C5-C8 and T1 - extends inferiorly and laterally on either side of the last four cervical and first thoracic vertebrae - passes above the first rib posterior to the clavicle and then enters the axilla. - supplies the shoulder and upper limbs.

cervical plexus

Formed by the roots (anterior rami) of the first four cervical nerves (C1-C4), with contributions from C5. There is one on each side of the neck alongside the first four cervical vertebrae. The cervical plexus supplies the skin and muscles of the head, neck, and superior part of the shoulders and chest and diaphragm.

hemispheric lateralization - anatomy

Functional asymmetry - Although the brain is almost symmetrical on its right and left sides, subtle anatomical differences between the two hemispheres exist. For example, in about two-thirds of the population, the planum temporale, a region of the temporal lobe that includes Wernicke's area, is 50% larger on the left side than on the right side. This asymmetry appears in the human fetus at about 30 weeks of gestation. Physiological differences also exist; although the two hemispheres share performance of many functions, each hemisphere also specializes in performing certain unique functions.

Adaptation in sensory receptors

Generator potential or receptor potential decreases in amplitude during a maintained, constant stimulus. - This causes the requency of nerve impulses in the first-0rder neuron to decrease. - The perception of a sensation may fade or disappear even though the stimulus persists (think stepping into a hot bath)

Hormone receptors

Hormones influence their target cells by chemically binding to these.

Homeostasis and Endocrine system

Hugely connected. Blood and calcium levels, for ex. regulated by the glands. Also blood glucose control, which are controlled by islets of Langerhans.

circadian rhythm

Humans sleep and awaken in this 24-hour cycle - established by the suprachiasmatic nucleus of the hypothalamus

Cranial Nerve XII

Hypoglossal nerve Major function: Control tongue muscles

Congenital hypothyroidism

Hyposecretion of thyroid hormones that is present at birth - Must be treated promptly to avoid devastating consequences -

Up-regulation

If a hormone is deficient, the number of receptors may increase, making a target cell more sensitive to a hormone. This is called...

Down-regulation

If a hormone is present in excess, the number of target cell receptors will decrease. This is called...

cranial reflex

If integration occurs in the brain stem rather than the spinal cord, the reflex is called a... An example is the tracking movements of your eyes as you read this sentence.

Tactile sensations

Include touch, pressure, vibration, itch and tickle. - we perceive them differently but they arise by activation of some of the same types of receptors.

Water-soluble hormones

Include: - amine hormones - peptide hormones and protein hormones - eicosanoid hormones

Lipid-soluble hormones

Include: - steroid hormones - thyroid hormones - nitric oxide

Actions of T3 and T4

Increase basal metabolic rate, stimulate synthesis of proteins, increase use of glucose and fatty acids for ATP production, increase liplysis, enhance cholesterol excretion, accelerate body growth and contribute to development of the nervous system.

conus medullaris

Inferior to the lumbar enlargement, the spinal cord terminates as a tapering, conical structure - ends at the level of the intervertebral disc between the first and second lumbar vertebrae in adults

Pancreas

Is both an endocrine gland and an exocrine gland. - a flattened organ located in the curve of the duodenum - consists of a head, a body and a talk.

decussation of pyramids

Just superior to the junction of the medulla with the spinal cord, 90% of the axons in the left pyramid cross to the right side, and 90% of the axons in the right pyramid cross to the left side. - explains why each side of the brain controls movements on the opposite side of the body.

Typically, a person goes from stage 1 to stage 4 of NREM sleep in how long?

Less than 1 hour.

2 chemical classes of hormones

Lipid-soluble and water-soluble

Action of lipid-soluble hormones

Lipid-soluble steroid hormones and thyroid hormones affect cell function by altering gene expression.

Paracrine

Local hormones that act on neighboring cells

Autocrine

Local hormones that act on the same cell that secreted them.

Cranial Nerve 'zero'

Located anterior to the first nerves - Innervate the vomeronasal organs, which may have a function in detecting pheromones, chemical signals passed subconsciously from one individual to another. - Pheromones have effects on reproductive and social behaviours.

Thymus

Located behind the sternum between the lungs. - plays a role in immunity.

monosynaptic reflex arc

A reflex pathway having only one synapse in the CNS - More often, the integrating center consists of one or more interneurons, which may relay impulses to other interneurons as well as to a motor neuron.

Stress response (or general adaptation syndrome)

A sequence of bodily changes that occur under a variety of stressful conditions. - controlled mostly by hypothalamus. Occurs in three stages: 1. flight or fight response 2. a slower resistance reaction 3. exhaustion

Where does a spinal nerve divide into several branches?

A short distance after passing through its intervertebral foramen

Pineal gland

A small endocrine glad attached to the roof of the third centrical of the brain at the midline. - consists of pinealocytes

Adrenal glands

A pair of glands, each of which lies superior to each kidney - have a flattended pyramidal shape - 3 -5cm in height -

Integrative cerebral functions of Wakefulness vs Sleep

A person who is awake is in a state of readiness and is able to react consciously to various stimuli. -the cerebral cortex is very active during wakefulness; fewer impulses arise during most stages of sleep.

Integrating centre

One or more regions of gray matter within the CNS play this role.

Target cells

Only these cells for a given hormone have receptors that bind and recognize that hormone.

Cranial Nerve II

Optic nerve Major function: Vision

Stress and disease

Stress can lead to particular diseases by temporarily inhibiting certain components of the immune system.

The brain

The portion of the central nervous system contained within the cranium.

memory consolidation.

The reinforcement that results from the frequent retrieval of a piece of information

Cranial Nerve V

Trigeminal Nerve Major function: Carry nerve impulses associated with head sensations and chewing muscles

Cranial Nerve IV

Trochlear nerve Major function: Control some of the muscles moving the eyeballs

roots

Two bundles of axons that connect each spinal nerve to a segment of the cord.

medullary rhythmicity area of the respiratory center

adjusts the basic rhythm of breathing.

Parafollicular cells

aka C cells - lie between thyroid follicles - produce calcitonin which helps to regulate calcium homeostasis.

Direct motor pathways

provide input to lower motor neurons via axons that extend directly from the cerebral cortex - Direct motor pathways in which signals initiated by the primary motor area in the right hemisphere control skeletal muscles on the left side of the body

spinal cord reflex

quick, automatic response to certain kinds of stimuli that involves neurons only in the spinal nerves and spinal cord

Cranial Nerve III

Oculomotor nerve Major function: Control some of the muscles moving the eyeballs, changes in size of pupil and shape of lens

Tracts VS Nerves

Tracts: bundles of axons in the CNS Nerves: bundles of axons in the PNS

what activates fight-or-flight response?

"E situations" such as exercise, emergency, excitement, and embarrassment

Somatic sensory impulses entering the spinal cord ascend to the cerebral cortex via two general pathways:

(1) the posterior column-medial lemniscus pathway and (2) the anterolateral (spinothalamic) pathways

2 layers of cranial dura mater

(spinal dura mater has only one) 2 dural layers around the brain are fused together except where they separate to enclose the dural venous sinuses that drain venous blood from the brain and deliver it into the internal jugular veins.

Substances that do cross the BBB

- A few water soluble substances, such as glucose, cross by active transport - others, such as creatine, urea and most ions cross very slow - lipid soluble substances: oxygen, carbon dioxide , alcohol and most anesthetic agents easily cross the barrier.

blood-cerebrospinal fluid barrier

- Because the ependymal cells are joined by tight junctions, materials entering CSF from choroid capillaries cannot leak between these cells; instead, they must pass through the ependymal cells. - This barrier permits certain substances to enter the CSF but excludes others, protecting the brain and spinal cord from potentially harmful blood-borne substances.

cerebellum

- Compares intended movements with what is actually happening to smooth and coordinate complex, skilled movements. - Regulates posture and balance. - May have a role in cognition and language processing. - second only to the cerebrum in size - occupies the inferior and posterior aspects of the cranial cavity. - posterior to the medulla and pons and inferior to the posterior portion of the cerebrum - In superior or inferior views, the shape of the cerebellum resembles a butterfly

Giantism

- Hypersecretion of hGH during childhood - Abnormal increase in the length of long bones. - Grows to be very tall; body proportions are about normal.

Pituitary dwarfism

- Hyposecretion of Human Growth Hormone during the growth years slows bone growth. - The epiphyseal plates close before normal height is reached. - Other organs of the body also fail to grow. Body proportions are childlike. - Requires administration of hGH during childhood before plates close.

components of an autonomic reflex arc

- Receptor: Like the receptor in a somatic reflex arc, the receptor in an autonomic reflex arc is the distal end of a sensory neuron, which responds to a stimulus and produces a change that will ultimately trigger nerve impulses. Autonomic sensory receptors are mostly associated with interoceptors. - Sensory neuron: Conducts nerve impulses from receptors to the CNS. - Integrating center: Interneurons within the CNS relay signals from sensory neurons to motor neurons. The main integrating centers for most autonomic reflexes are located in the hypothalamus and brain stem. Some autonomic reflexes, such as those for urination and defecation, have integrating centers in the spinal cord. - Motor neurons: Nerve impulses triggered by the integrating center propagate out of the CNS along motor neurons to an effector. In an autonomic reflex arc, two motor neurons connect the CNS to an effector: The preganglionic neuron conducts motor impulses from the CNS to an autonomic ganglion, and the postganglionic neuron conducts motor impulses from an autonomic ganglion to an effector - Effector: In an autonomic reflex arc, the effectors are smooth muscle, cardiac muscle, and glands.

Somatic senses

- Tactile sensations (touch, pressure and vibration) - Thermal sensations (warm and cold) - Pain sensations - Proprioceptive sesnations (allow the perception of static and moving positions of body parts)

Reflex arc Step 1: Sensory receptor

- The distal end of a sensory neuron (dendrite) or an associated sensory structure serves as a sensory receptor. - It responds to a specific stimulus by producing a graded potential called a generator (or receptor) potential - If a generator potential reaches the threshold level of depolarization, it will trigger one or more nerve impulses in the sensory neuron.

Cerebrospinal fluid

- a clear, colorless liquid that protects the brain and spinal cord from chemical and physical injuries. It also carries oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia. - CSF continuously circulates through cavities in the brain and spinal cord and around the brain and spinal cord in the subarachnoid space (between the arachnoid mater and pia mater).

principal plexuses

- cervical plexus - brachial plexus - lumbar plexus - sacral plexus

medulla oblongata

- is continuous with the superior part of the spinal cord; it forms the inferior part of the brain stem - begins at the foramen magnum and extends to the inferior border of the pons, a distance of about 3 cm (1.2 in.). - The medulla's white matter contains all sensory (ascending) and motor (descending) tracts that extend between the spinal cord and other parts of the brain. - Relays sensory input and motor output between other parts of the brain and the spinal cord. - Vital centers regulate heartbeat, blood vessel diameter, and breathing (together with pons) - Other centers coordinate swallowing, vomiting, coughing, sneezing, and hiccupping. - Contains nuclei of origin for cranial nerves VIII, IX, X, XI, and XII.

Sympathetic trunk ganglia

- lie in a vertical row on either side of the vertebral column. - These ganglia extend from the base of the skull to the coccyx - Because the sympathetic trunk ganglia are near the spinal cord, most sympathetic preganglionic axons are short. - Postganglionic axons from sympathetic trunk ganglia mostly innervate organs above the diaphragm. Examples of sympathetic trunk ganglia are the superior , middle, and inferior cervical ganglia

two types of cholinergic receptors

- nicotinic receptors - muscarinic receptors Both bind ACh

perception of slow pain

-begins a second or more after a stimulus is applied. - It then gradually increases in intensity over a period of several seconds or minutes. - Impulses for slow pain conduct along small-diameter, unmyelinated C fibers. - This type of pain, which may be excruciating, is also referred to as chronic, burning, aching, or throbbing pain. - Slow pain can occur both in the skin and in deeper tissues or internal organs. - An example is the pain associated with a toothache.

crossed extensor reflex

-causes contraction of muscles that extend joints in the limb opposite a painful stimulus. -helps you maintain balance just before you undergo a flexor/withdrawal reflex - contralateral reflex arc - reciprocal innervation

All monosynaptic reflexes

... they are all ipsilateral reflexes

Spinal nerves and the nerves that branch from them are part of the ...

... they're part of the peripheral nervous system.

Somatic slow pain also is well localized....

....but more diffuse (involves large areas); it usually appears to come from a larger area of the skin.

Free fraction

0.1 - 10% of the molecules of a lipid-soluble hormone are not bound to a transport protein. This fraction diffuses out of capillaries, binds to receptors and triggers responses.

Pancreatic islets

1 - 2 million tiny clusters of endocrine tissue that are scattered among the exocrine acini aka islets of Langerhans

Cell types in pancreatic islets

1. Alpha cells (A cells) - constitute about 17% of pancreatic islet cells. Secrete glucagon. 2. Beta cells (B cells) - constitute about 70% of pancreatic islet cells. Secrete insulin. 3. Delta cells (D cells) - constitute about 7% of pancreatic islet cells. Secrete somatostatin. 4. F cells constitute the remainder of pancreatic islet cells. Secrete pancreatic polypeptide.

Operation of a tendon reflex

1. As the tension applied to a tendon increases, the tendon organ (sensory receptor) is stimulated (depolarized to threshold). 2. Nerve impulses arise and propagate into the spinal cord along a sensory neuron. 3. Within the spinal cord (integrating center), the sensory neuron activates an inhibitory interneuron that synapses with a motor neuron. 4. The inhibitory neurotransmitter inhibits (hyperpolarizes) the motor neuron, which then generates fewer nerve impulses. 5. The muscle relaxes and relieves excess tension.

How much of an adults sleep time is REM?

25%

The two motor neurons in ANS pathways

1. Has cell body in CNS - its myelinated axon extends from the CNS to an autonomic ganglion 2. Has its cell body in the same autonomic ganglion - its unmyelinated axon extends directly from the ganglion to the effector (smooth muscle, cardiac muscle, or a gland)

The CSF contributes to homeostasis in three main ways

1. Mechanical protection CSF serves as a shock-absorbing medium that protects the delicate tissues of the brain and spinal cord from jolts that would otherwise cause them to hit the bony walls of the cranial and vertebral cavities. The fluid also buoys the brain so that it "floats" in the cranial cavity. 2. Chemical protection CSF provides an optimal chemical environment for accurate neuronal signaling. Even slight changes in the ionic composition of CSF within the brain can seriously disrupt production of action potentials and postsynaptic potentials. 3. Circulation CSF allows exchange of nutrients and waste products between the blood and nervous tissue.

The posterior pituitary hormones

1. Oxytocin 2. Antidiuretic hormone

Three types of effects of hormonal interactions

1. Permissive 2. Synergistic 3. Antagonistic

During a typical 7- or 8-hour sleep period, there are how many episodes of REM sleep?

3 - 5

Process of sensation - 4 steps

1. Stimulation of the sensory receptor 2. Transduction of the stimulus 3. Generation of nerve impulses 4. Integration of sensory input.

Cerebellar function involves four activities

1. The cerebellum monitors intentions for movement 2. The cerebellum monitors actual movement by receiving input from proprioceptors in joints and muscles that reveals what actually is happening (blue lines). These nerve impulses travel in the anterior and posterior spinocerebellar tracts. 3. The cerebellum compares the command signals (intentions for movement) with sensory information (actual movement performed). 4. If there is a discrepancy between intended and actual movement, the cerebellum sends out corrective feedback to upper motor neurons. As movements occur, the cerebellum continuously provides error corrections to upper motor neurons, which decreases errors and smoothes the motion. - It also contributes over longer periods to the learning of new motor skills.

Transport proteins - three functions

1. They make lipid-soluble hormones temporarily water soluble, thus increasing their solubility in blood 2. They retard passage of small hormone molecules through the filtering mechanism in the kidneys, thus slowing the rate of hormone loss in the urine. 3. They provide a ready reserve of hormone, already present in the bloodstream.

How much of a 2 yr old's sleep time is REM?

35%

reflex

A fast, automatic, unplanned sequence of actions that occurs in response to a particular stimulus. - Some reflexes are inborn, such as pulling your hand away from a hot surface before you even feel that it is hot. - Other reflexes are learned or acquired. For instance, you learn many reflexes while acquiring driving expertise

Local hormones

Act locally on neighboring cells or on the same cell that secreted them without first entering the bloodstream.

fight-or-flight response

Activation of the sympathetic division and release of hormones by the adrenal medullae set in motion this series of physiological responses

Slowly adapting receptors

Adapt slowly and continue to trigger nerve impulses as long as the stimulus persists ex: receptors associated with pain, body position, and chemical composition of blood.

Rapidly adapting receptors

Adapt very quickly. - specialized for signaling changes in a stimulus ex: receptors associated with pressure touch and smell.

four types of brain waves

Alpha, beta, theta and delta

septum pellucidum

Anteriorly, the lateral ventricles are separated by a thin membrane

Two regions of the adrenals

Are structurally and functionally different 1. adrenal cortex: large and peripherally located. Comprises 80 - 90% of the gland. 2. adrenal medulla: small and centrally located

Somatic sensations

Arise from stimulation of sensory receptors embedded in the skin or subcutaneous layer, in mucous membranes of the mouth, vagina and anus; in muscles, tendons and joints, and the inner ear. - sensory receptors for somatic sensations are distributed unevenly... some parts of the body surface are densely populated with receptors, and others contain only a few.

filum terminale

Arising from the conus medullaris - an extension of the pia mater that extends inferiorly and anchors the spinal cord to the coccyx.

melatonin

As more melatonin is liberated during darkness than in light, this hormone is thought to promote sleepiness. Melatonin also appears to contribute to the setting of the body's biological clock.

Diabetes Insipidus

Associated with dysfunction of the posterior pituitary - Due to defects in antidiuretic hormone receptors or an inability to secrete ADH. - Treatment involves hormone replacement, usually for life.

Infundibulum

Attaches the hypothalamus and pituitary.

Chemoreceptors

Basis of classification: type of stimulus detected. Description: Detect chemicals in mouth (taste), nose (smell) and body fluids.

Free nerve endings

Basis of classification: Microscopic features Description: Bare dendrites association with pain, thermal, tickle, itchand some touch sensations.

Encapsulated nerve endings

Basis of classification: Microscopic features Description: Dendrites enclosed in a connective tissue capsule, such as a corpuscle of touch.

cauda equina

Because the spinal cord is shorter than the vertebral column, nerves that arise from the lumbar, sacral, and coccygeal regions of the spinal cord do not leave the vertebral column at the same level they exit the cord. - The roots of these spinal nerves angle inferiorly in the vertebral cavity from the end of the spinal cord like wisps of hair.

lateral gray horns

Between the anterior and posterior gray horns - present only in the thoracic, upper lumbar, and sacral segments of the spinal cord. - contain autonomic motor nuclei that regulate the activity of smooth muscle, cardiac muscle, and glands.

Normal sleep consists of two components

Non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep

Portal system

Blood flows from one capillary network into a portal vein and then into a second capillary network without passing through the heart.

Two types of cells of parathyroid glands

Both are types of epithelial cells 1. Chief (principal) cells - produce parathyroid hormone. Are the more numerous. 2. Oxyphil cells - function unknown.

Oxygen and glucose use by the brain

Brain only makes up 2% of total body weight but consumes about 20% of the oxygen and glucose used, even at rest. Neurons synthesize ATP almost exclusively from glucose via reactions that use oxygen. Almost no glucose is stored in the brain, so the supply must be continuous. If blood entering the brain has a low level of glucos, mental confusion, dizziness, convulsion and loss of consciousness may occur.

arachnoid villi

CSF is gradually reabsorbed into the blood through these fingerlike extensions of the arachnoid that project into the dural venous sinuses

Perception

Conscious awareness and interpretation of sensations - primarily a function of the cerebral cortex. - if we have no perception of a sensation, it's because it never reached the cerebral cortex.

Sensation

Conscious or subconsious awareness of changes in the external or internal environment.

Brain stem

Continuous with the spinal cord and consists of the medulla oblongata, pons and midbrain

Cranial meninges

Continuous with the spinal meninges - have the same basic structures - bear the same names: 1. outer dura mater 2. middle arachnoid mater 3. inner pia mater

Adrenal glands

Control quick response. 2 types: Medulla: involved in flight or fight response... adrenaline Adrenal cortex: long term stress and its effects.

Thyroid gland, simplified

Controls metabolism. Increased T3 and T4 speeds up metabolism and vice versa. On throat.

Protective coverings of the brain

Cranium and the cranial meninges - surround and protect the brain

Hypoglycemia

Decreased blood glucose level - Excess insulin stimulates too much uptake of glucose by body cells. - The resulting hypoglycemia stimulates the secretion of epinephrine, glucagon and human growth hormone. - Results in anxiety, sweating, tremor, increased heart rate, hunger and weakness. - When blood glucose falls, brain cells are deprived of the steady supply of glucose they need to function effectively.

Parathyroid glands

Normally 4 of them - embedded in the posterior surface of the thyroid gland. - composed of small rounds masses of tissue.

Similarities between direct and indirect motor pathways

Direct and indirect pathways both govern generation of nerve impulses in the lower motor neurons, the neurons that stimulate contraction of skeletal muscles.

Posterior pituitary

Does not synthesize hormones. Instead stores and releases them.

gyri

During embryonic development, when brain size increases rapidly. Thus, the gray matter of the cortex enlarges much faster than the deeper white matter As a result, the cortical region rolls and folds upon itself. These are the folds. aka convolutions

Sympathetic Responses

During physical or emotional stress, the sympathetic division dominates the parasympathetic division - High sympathetic tone favors body functions that can support vigorous physical activity and rapid production of ATP. At the same time, the sympathetic division reduces body functions that favor the storage of energy. - Besides physical exertion, a variety of emotions—such as fear, embarrassment, or rage—stimulate the sympathetic division.

Connective Tissue Coverings of Spinal Nerves

Each spinal nerve and cranial nerve consists of many individual axons and contains layers of protective connective tissue coverings

Note: transduction of the stimulus

Each type of sensory receptor exhibits selectivity: it can transduce only one kind of stimulus. i.e. smelly molecules in the air stimulate only the olfactory receptors in the nose, which then transduce the molecules' chemical energy into electrical energy in the form of a graded potential.

Sensory modality

Each unique type of sensation: - touch, pain, vision, hearing

Longevity of effects of sympathetic stimulation vs. parasympathetic stimulation

Effects are longer in sympathetic stimulation because: - (1) Sympathetic postganglionic axons diverge more extensively; as a result, many tissues are activated simultaneously. (2) Acetylcholinesterase quickly inactivates acetylcholine, whereas norepinephrine lingers in the synaptic cleft for a longer period. (3) Epinephrine and norepinephrine secreted into the blood from the adrenal medulla intensify and prolong the responses caused by NE liberated from sympathetic postganglionic axons.

Sensory receptor

Either a specialized cell or the dendrites of a sensory neuron.

Autonomic nervous system stimulation does what to its effectors?

Either excites or inhibits its effectors (which are called visceral effectors)

Reflex arc Step 4: Motor Neuron

Impulses triggered by the integrating center propagate out of the CNS along a motor neuron to the part of the body that will respond.

reticular formation

In addition to the well-defined nuclei already described, much of the brain stem consists of small clusters of neuronal cell bodies (gray matter) interspersed among small bundles of myelinated axons (white matter). - The broad region where white matter and gray matter exhibit a netlike arrangement - extends from the upper part of the spinal cord, throughout the brain stem, and into the lower part of the diencephalon.

Parasympathetic Responses

In contrast to the "fight-or-flight" activities of the sympathetic division, the parasympathetic division enhances "rest and digest" activities. - Parasympathetic responses support body functions that conserve and restore body energy during times of rest and recovery. In the quiet intervals between periods of exercise, parasympathetic impulses to the digestive glands and the smooth muscle of the gastrointestinal tract predominate over sympathetic impulses. This allows energy-supplying food to be digested and absorbed. At the same time, parasympathetic responses reduce body functions that support physical activity.

Follicle-stimulating hormone

In females, initiates development of oocytes and induces ovarian secretion of estrogens. In males, stimulates testes to produce sperm.

Luteinizing hormone

In females, stimulates secretion of estrogens and progesterone, ovulation and formation of corpus luteum. In males, stimulates testes to produce testosterone.

nuclei (in spinal cord)

In the gray matter of the spinal cord and brain, clusters of neuronal cell bodies form functional groups called...

Thyroid follicles

Microscopic spherical saces that make up most of the thyroid gland - made up of follicular cells that secrete the thyroid hormones

Graves disease

Most common form of hyperthyroidism - 7-10x more common in females - An autoimmune disorder in which the person produces antibodies that mimic the action of TSH - These antibodies continually stimulate the thyroid gland to grow and produce thyroid hormones.

How hormones circulate

Most enter interstitial fluid and then the bloodstream. The circulating blood delivers hormones to cells throughout the body. They exert their effects by binding to receptors on/in target cells.

Hormone transport in the blood

Most water-soluble hormones circulate in the water blood plasma in a free form whereas most lipid-soluble hormone molecules are bound to transport proteins.

The stages of sleep, with REM and NREM combined

NREM Stage 1 NREM Stage 2 NREM Stage 3 NREM Stage 4 NREM Stage 3 NREM Stage 2 REM NREM Stage 2 NREM Stage 3 etc... ... repeated

posterior column-medial lemniscus pathway

Nerve impulses for conscious proprioception and most tactile sensations ascend to the cerebral cortex along this pathway

somatic motor pathways

Neurons in four distinct but highly interactive neural circuits, collectively termed this - participate in control of movement by providing input to lower motor neurons

reticular activating system

Neurons within the reticular formation have both ascending (sensory) and descending (motor) functions. - This part of the reticular formation consists of sensory neurons that project to the cerebral cortex - helps maintain consciousness and is active during awakening from sleep - The reticular formation's main descending function is to help regulate muscle tone, the slight degree of contraction in normal resting muscles.

Oxytocin

Neurosecretory cells of hypothalamus secrete this in response to uterine distention and stimulation of nipples. - Stimulates contraction of smooth muscle cells of uterus during childbirth - stimulates contraction of myoepithelial cells in mammary glands to cause milk ejection.

Testes

Oval gonads that lie in the scrotum. - produce testosterone, a male sex hormone - also produce inhibin

Superficial somatic pain

Pain that arises from stimulation of receptors in the skin

Ovaries

Paired oval bodies located in the female pelvic cavity - produce several steroid hormones including 2 estrogens and progesterone, which regulate the menstruate cycle, maintain pregnancy and prepare the mammary glands for lactation

phantom limb sensation

Patients who have had a limb amputated may still experience sensations such as itching, pressure, tingling, or pain as if the limb were still there

Pituitary

Pea-shaped structure that lies in the hypophyseal fossa of the sella turcica of the sphenoid bone. - attached to the hypothalamus by the infundibulum and has two anatomically and functionally separate lobes.

Endocrine glands - example

Pituitary, thyroid, parathyroid, adrenal and pineal glands.

Location of Cerebellum

Posterior to brain stem

primary somatosensory area

Precise localization of somatic sensations occurs when nerve impulses arrive here - Each region in this area receives sensory input from a different part of the body. - Note that some parts of the body—chiefly the lips, face, tongue, and thumb—provide input to large regions in the somatosensory area. - Other parts of the body, such as the trunk and lower limbs, project to much smaller cortical regions. The relative sizes of these regions in the somatosensory area are proportional to the number of specialized sensory receptors within the corresponding part of the body.

Parasympathetic Ganglia

Preganglionic axons of the parasympathetic division synapse with postganglionic neurons in terminal (intramural) ganglia.

Myxedema

Produced by adult hypothyroidism - Hallmark is edema that casuses the facial tissues to swell and look puffy. - Slow heart rate, low body temp, sensitivity to cold, dry hair and skin, muscular weakness, lethargy and tendency to gain weight easily. - 5x more common in females than in males

Cushing's syndrome

Produced by hypersecretion of cortisol by the adrenal cortex. - Caused by a tumour either of the adrenal glad or another tumor that secretes adrenocorticotropic hormone. - Characterized by breakdown of muscle proteins and redistribution of body fat: spindly arms and legs with a moon face, buffalo hump on the back and pendulous abdomen.

Receptor potentials

Produced by sensory receptors in response to a stimulus - DO NOT generate action potentials. Ex: hair cells, gustatory receptor cells and photoreceptors <--- their graded potentials trigger release of neurotransmitter through exocytosis of synaptic vesicles.

Generator potential

Produced by sensory receptors in response to a stimulus - when generator potential is large enough to reach threshold, it triggers one or more nerve impulses in the axon of a first-order sensory neuron. - Generator potentials generate action potentials.

Control of secretion by anterior pituitary

Regulated in two ways: 1. Neurosecretory cells in hypothalamus secrete five releasing hormones, which stimulate secretion of anterior pituitary hormones and two inhibiting hormones, which suppress secretion of anterior pituitary hormones 2. Negative feedback in the form of hormones released by target glands decreases secretions of three types of anterior pituitary cells.

Pineal gland, simplified

Regulates daily rhythms. Think melatonin in the middle of the night. Situated in the brain. Third eye.

Testosterone

Regulates production of sperm and stimulates the development and maintenance of male secondary sex characteristics

Parathyroid hormone

Regulates the homeostasis of calcium, magnesium and phosphate ions by increasing blood calcium and magnesium levels and decreasing blood phosphate levels. - secretion is controlled by the level of calcium in the blood.

5 parasympathetic responses

SLUDD - salivation (S) - lacrimation (L) - urination (U) - digestion (D) - defecation (D).

Central canal

Small space that extends the entire length of the spinal cord and is filled with cerebrospinal fluid

Special senses

Smell, taste, vision, hearing and equilibrium (balance)

Cutaneous sensation

Somatic sensations that arise from stimulating the skin surface.

Human Growth hormone

Stimulates liver, muscle, cartilage, bone and other tissues to synthesize and secrete insulinlike growth factors, which promote growth of body cells, protein synthesis, tissue repair, lipolysis and elevation of blood glucose concentration.

Adrenocorticotropic hormone

Stimulates secretion of glucocorticoids by adrenal cortex.

Thyroid-stimulating hormone

Stimulates synthesis and secretion of thyroid hormones by thyroid gland

preganglionic neuron

The first of the two motor neurons in any autonomic motor pathway - Its cell body is in the brain or spinal cord, and its axon exits the CNS as part of a cranial or spinal nerve. The axon of a preganglionic neuron is a small-diameter, myelinated type B fiber that usually extends to an autonomic ganglion

delta waves

The frequency of these waves is 1-5 Hz. Delta waves occur during deep sleep in adults, but they are normal in awake infants. When produced by an awake adult, they indicate brain damage.

beta waves

The frequency of these waves is between 14 and 30 Hz. Beta waves generally appear when the nervous system is active—that is, during periods of sensory input and mental activity.

Reflex arc Step 2: Sensory neuron

The nerve impulses propagate from the sensory receptor along the axon of the sensory neuron to the axon terminals, which are located in the gray matter of the spinal cord or brain stem.

Gonads

The organs that produce gametes

cerebral cortex

The outer rim of gray matter of the cerebrum - 2-4 mm thick - contains billions of neurons. - Deep to the cerebral cortex lies the cerebral white matter.

Epineurium

The outermost covering over the entire nerve

Reflex arc Step 5: Effector

The part of the body that responds to the motor nerve impulse, such as a muscle or gland - Its action is called a reflex

reflex arc (reflex circuit)

The pathway followed by nerve impulses that produce a reflex

cerebellar cortex

The superficial layer of the cerebellum - consists of gray matter in a series of slender, parallel ridges called folia

anterior (ventral) white columns, (2) posterior (dorsal) white columns, and (3) lateral white columns

The white matter, like the gray matter, is organized into regions. The anterior and posterior gray horns divide the white matter on each side into three broad areas - Each column, in turn, contains distinct bundles of axons having a common origin or destination and carrying similar information.

gamma motor neurons

These motor neurons terminate near both ends of the intrafusal fibers and adjust the tension in a muscle spindle to variations in the length of the muscle

alpha waves

These rhythmic waves occur at a frequency of about 8-13 cycles per second. (The unit commonly used to express frequency is the hertz [Hz]. One hertz is one cycle per second.) Alpha waves are present in the EEGs of nearly all normal individuals when they are awake and resting with their eyes closed. These waves disappear entirely during sleep.

Touch

These sensations usually result from stimulation of tactile receptors in the skin or subcutaneous layer. includes crude touch and fine touch.

theta waves

These waves have frequencies of 4-7 Hz. Theta waves normally occur in children and adults experiencing emotional stress. They also occur in many disorders of the brain.

Functions of the spinal nerves and the nerves that branch from them

They connect the CNS to sensory receptors, muscles, and glands in all parts of the body.

The anterior and medial parts of the hypothalamus control

They control the parasympathetic division. - Stimulation of these areas results in a decrease in heart rate, lowering of blood pressure, constriction of the pupils, and increased secretion and motility of the gastrointestinal tract.

Subsequent REM periods last how long?

They gradually increase in length, with the final one lasting up to 50 minutes.

Prolactin

Together with other hormones, promotes milk secretion by the mammary glands.

Pneumotaxic area and apneustic area

Together with the medullary rhythmicity area, they help control breathing.

Diabetes and Endocrine, simplified

Too much glucose in urine - so, glucose we can't use. 2 types: Type 1 - autoimmune disorder where cells in pancreas are attacked and insulin is not made correctly Type 2 - less to do w/ insulin and more to do with cells, which are not sure what to do with all the glucose. To do with lack of exercise and dietary problems

Somatic Sensory Pathways to the Cerebellum

Two tracts in the spinal cord—the posterior spinocerebellar tract (spī-nō-ser-e-BEL-ar) and the anterior spinocerebellar tract —are the major routes proprioceptive impulses take to reach the cerebellum. - Although they are not consciously perceived, sensory impulses conveyed to the cerebellum along these two pathways are critical for posture, balance, and coordination of skilled movements.

What surrounds and protects the delicate nervous tissue of the spinal cord?

Two types of connective tissue coverings: 1. bony vertebrae 2. tough, connective tissue meninge - plus a cushion of cerebrospinal fluid (produced in the brain)

How much of an infants' sleep time is REM?

Up to 50%! (So, they dream a lot!)

Primary motor area

a major control region for planning and initiating voluntary movements.

Corpuscles of touch

aka Meissner corpuscles - receptors for fine touch that are located in the dermal papillae of hairless skin. - each one is an egg-shaped mass of dendrites enclosed by a capsule of connective tissue. - rapidly adapting receptors, thus they generate nerve impulses mainly at the onset of touch. - abundant in the fingertips, hands, eyelids, tip of the tongue, lips, nipples, soles, clit and tip of the penis.

Anterior pituitary

aka adenohypophysis - accounts for 75% of total weight of the gland

Arousal

aka awakening from sleep - involves increased activity in the RAS - For arousal to occur, the RAS must be stimulated - Many sensory stimuli can activate the RAS: painful stimuli detected by nociceptors, touch and pressure on the skin, movement of the limbs, bright light, or the buzz of an alarm clock. Once the RAS is activated, the cerebral cortex is also activated, and arousal occurs.

Posterior pituitary

aka neurohypophysis - contains axons and axon terminals of more than 10,000 neurons whose cell bodies are located in the supraoptic and paraventricular nuclei of the hypothalamus.

lamellated corpuscle

aka pacinian corpuscle a large oval structure composed of a multilayered connective tissue capsule that encloses a dendrite - adapt rapidly - widely distributed in the body

The autonomic nervous system and homeostasis

autonomic nervous system responds to subconsciously perceived visceral sensations and excites or inhibits smooth muscle, cardiac muscle, and glands.

Structurally, the ANS includes

autonomic sensory neurons, integrating centers in the CNS, and autonomic motor neurons

long-term potentiation (LTP)

believed to underlie some aspects of memory - transmission at some synapses within the hippocampus is enhanced (potentiated) for hours or weeks after a brief period of high-frequency stimulation.

Adrenergic receptors

bind both norepinephrine and epinephrine. - The norepinephrine can be either released as a neurotransmitter by sympathetic postganglionic neurons or released as a hormone into the blood by the adrenal medullae; epinephrine is released as a hormone.

common integrative area

bordered by somatosensory, visual, and auditory association areas. - receives nerve impulses from these areas and from the primary gustatory area, primary olfactory area, the thalamus, and parts of the brain stem. - integrates sensory interpretations from the association areas and impulses from other areas, allowing the formation of thoughts based on a variety of sensory inputs. It then transmits signals to other parts of the brain for the appropriate response to the sensory signals it has interpreted.

The white matter consists primarily of

bundles of myelinated axons of neurons.

posterior (dorsal) gray horns

contain somatic and autonomic sensory nuclei

anterior (ventral) gray horns

contain somatic motor nuclei, which provide nerve impulses for contraction of skeletal muscles.

anterior (ventral) root

contains axons of motor neurons, which conduct nerve impulses from the CNS to effector organs and cells.

posterior (dorsal) root

contains only sensory axons, which conduct nerve impulses from sensory receptors in the skin, muscles, and internal organs into the central nervous system.

lateral and anterior spinothalamic tracts

convey nerve impulses for sensing pain, warmth, coolness, itching, tickling, deep pres-sure, and a crude, poorly localized sense of touch.

The lateral spinothalamic tract

conveys sensory impulses for pain and temperature

association areas

deal with more complex integrative functions such as memory, emotions, reasoning, will, judgment, personality traits, and intelligence. - consist of some motor and sensory areas, plus large areas on the lateral surfaces of the occipital, parietal, and temporal lobes and on the frontal lobes anterior to the motor areas. - Association areas are connected with one another by association tracts

Sleep deprivation

impairs attention, learning, and performance

in many instances of visceral pain, the pain is felt?

in or just deep to the skin that overlies the stimulated organ, or in a surface area far from the stimulated organ. - This phenomenon is called referred pain

frontal eye field area

in the frontal cortex; is sometimes included in the premotor area -controls voluntary scanning movements of the eyes—like those you just used in reading this sentence.

motor areas

initiate movements -Motor output from the cerebral cortex flows mainly from the anterior part of each hemisphere

cholinergic receptors

integral membrane proteins in the postsynaptic plasma membrane.

The receptors for the neurotransmitters involved in autonomic responses

integral membrane proteins located in the plasma membrane of the postsynaptic neuron or effector cell.

somatic reflexes

involve contraction of skeletal muscles.

polysynaptic reflex arc

involves more than two types of neurons and more than one CNS synapse.

Norepinephrine aka noradrenaline

released by adrenergic neurons in the ANS

Sensory and motor tracts of the spinal cord are continuous with ....

sensory and motor tracts of the brain.

muscle spindles

sensory receptors in the muscle

central sulcus

separates the frontal lobe from the parietal lobe.

lateral cerebral sulcus (fissure)

separates the frontal lobe from the temporal lobe.

parieto-occipital sulcus

separates the parietal lobe from the occipital lobe

Each muscle spindle consists of

several slowly adapting sensory nerve endings that wrap around 3 to 10 specialized muscle fibers, called intrafusal muscle fibers

Sulci

shallower grooves between folds of gyri

posterior median sulcus

shallower, narrow furrow on the posterior (dorsal) side of the white matter of the spinal cord.

cerebrum

the "seat of intelligence." - provides us with the ability to read, write, and speak; to make calculations and compose music; and to remember the past, plan for the future, and imagine things that have never existed before. - Sensory areas are involved in the perception of sensory information; motor areas control muscular movement; and association areas deal with more complex integrative functions such as memory, personality traits, and intelligence. -Basal ganglia coordinate gross, automatic muscle movements and regulate muscle tone. Limbic system functions in emotional aspects of behavior related to survival.

Learning

the ability to acquire new information or skills through instruction or experience.

Immediate memory

the ability to recall ongoing experiences for a few seconds. - It provides a perspective to the present time that allows us to know where we are and what we are doing

craniosacral outflow

the axons of the parasympathetic preganglionic neurons

thoracolumbar outflow

the axons of the sympathetic preganglionic neurons

autonomic tone

the balance between sympathetic and parasympathetic activity - regulated by the hypothalamus

preganglionic neuron cell bodies of the SYMPATHETIC division are in...

the lateral horns of the gray matter in the 12 thoracic segments and the first two (and sometimes three) lumbar segments of the spinal cord - thus, the sympathetic division is also called the thoracolumbar division

longitudinal fissure

the most prominent fissure in the brain - divides the brain into L and R hemispheres.

postganglionic neuron

the second neuron in the autonomic motor pathway - the postganglionic neuron lies entirely outside the CNS - Its cell body and dendrites are located in an autonomic ganglion, where it forms synapses with one or more preganglionic axons - s entirely outside the CNS. Its cell body and dendrites are located in an autonomic ganglion, where it forms synapses with one or more preganglionic axons. The axon of a postganglionic neuron is a small-diameter, unmyelinated type C fiber that terminates in a visceral effector.

Sympathetic ganglia

the sites of synapses between sympathetic preganglionic and postganglionic neurons.

muscle tone

the small degree of contraction present while the muscle is at rest.

Short-term memory

the temporary ability to recall a few pieces of information for seconds to minutes - One example is when you look up an unfamiliar telephone number, cross the room to the phone, and then dial the new number. If the number has no special significance, it is usually forgotten within a few seconds.

basal ganglia and cerebellum influence movement through?

their effects on upper motor neurons. -

meninges

three connective tissue coverings that encircle the spinal cord and brain

The main function of muscle spindles

to measure muscle length —how much a muscle is being stretched

arbor vitae

tracts of white matter deep to the grey matter of the cerebellar cortex

alpha (α) receptors and beta (β) receptors

two main types of adrenergic receptors - found on visceral effectors innervated by most sympathetic postganglionic axons

sympathetic division of ANS

usually sends nerve impulses that excites an organ

parasympathetic division of ANS

usually sends nerve impulses that inhibit or calm an organ/activity.

fight-or-flight response steps

- The pupils of the eyes dilate. - Heart rate, force of heart contraction, and blood pressure increase. - The airways dilate, allowing faster movement of air into and out of the lungs. - The blood vessels that supply the kidneys and gastrointestinal tract constrict, which decreases blood flow through these tissues. The result is a slowing of urine formation and digestive activities, which are not essential during exercise. - Blood vessels that supply organs involved in exercise or fighting off danger—skeletal muscles, cardiac muscle, liver, and adipose tissue—dilate, allowing greater blood flow through these tissues. - Liver cells perform glycogenolysis (breakdown of glycogen to glucose), and adipose tissue cells perform lipolysis (breakdown of triglycerides to fatty acids and glycerol). - Release of glucose by the liver increases blood glucose level. - Processes that are not essential for meeting the stressful situation are inhibited. For example, muscular movements of the gastrointestinal tract and digestive secretions slow down or even stop.

Inhibin

Also produced by ovaries - inhibits secretion of FSH

a spinal nerve is classified as? Why?

- a mixed nerve. - Because the posterior root contains sensory axons and the anterior root contains motor axons

The Role of the Reticular Activating System in Awakening

- a portion of the reticular formation is known as the reticular activating system (RAS) - When this area is active, many nerve impulses are transmitted to widespread areas of the cerebral cortex, both directly and via the thalamus. The effect is a generalized increase in cortical activity.

deep somatic pain

- caused by stimulation of receptors in skeletal muscles, joints, tendons, and fascia

stretch reflex

- causes contraction of a skeletal muscle (the effector) in response to stretching of the muscle. - This type of reflex occurs via a monosynaptic reflex arc. - The reflex can occur by activation of a single sensory neuron that forms one synapse in the CNS with a single motor neuron. - Stretch reflexes can be elicited by tapping on tendons attached to muscles at the elbow, wrist, knee, and ankle joints.

Two functional classifications of autonomic neurons

- cholinergic - adrenergic

Basal ganglia

- control automatic movements of skeletal muscles and muscle tone. - Deep within each cerebral hemisphere - three nuclei (masses of gray matter) that are collectively termed this - receive input from the cerebral cortex and provide output back to motor parts of the cortex. - the nuclei of the basal ganglia have extensive connections with one another. - A major function is to help regulate initiation and termination of movements. - help initiate and terminate some cognitive processes, such as attention, memory, and planning, and may act with the limbic system to regulate emotional behaviors.

3 decreases of the parasympathetic system

- decreased heart rate - decreased diameter of airways (bronchoconstriction) - decreased diameter (constriction) of the pupils.

tracts

- distinct bundles of axons in the CNS having a common origin or destination and carrying similar information, located in the columns of white matter - may extend long distances up or down the spinal cord

midbrain or mesencephalon

- extends from the pons to the diencephalon - is about 2.5cm long - The cerebral aqueduct passes through the midbrain, connecting the third ventricle above with the fourth ventricle below. Like the medulla and the pons, the midbrain contains both tracts and nuclei. - Relays motor output from the cerebral cortex to the pons and sensory input from the spinal cord to the thalamus. - Superior colliculi coordinate movements of the eyeballs in response to visual and other stimuli, and the inferior colliculi coordinate movements of the head and trunk in response to auditory stimuli. Most of substantia nigra and red nucleus contribute to control of movement. - Contains nuclei of origin for cranial nerves III and IV.

lumbar plexus

- formed by the roots (anterior rami) of spinal nerves L1-L4 - On either side of the first four lumbar vertebrae, the lumbar plexus passes obliquely outward, posterior to the psoas major muscle and anterior to the quadratus lumborum muscle. It then gives rise to its peripheral nerves. - supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs.

sacral plexus

- formed by the roots (anterior rami) of spinal nerves L4-L5 and S1-S4 - This plexus is situated largely anterior to the sacrum. - supplies the buttocks, perineum, and lower limbs. The largest nerve in the body—the sciatic nerve—arises from this plexus.

autonomic (visceral) reflexes

- generally are not consciously perceived. - involve responses of smooth muscle, cardiac muscle, and glands. - body functions such as heart rate, digestion, urination, and defecation are controlled by the autonomic nervous system through autonomic reflexes.

direct pathways

- include the lateral corticospinal, anterior corticospinal, and corticobulbar tracts. They convey nerve impulses that originate in the cerebral cortex and are destined to cause precise, - voluntary movements of skeletal muscles.

Indirect pathways

- include the rubrospinal, tectospinal, and vestibulospinal tracts - convey nerve impulses from the brain stem and other parts of the brain that govern automatic movements and help coordinate body movements with visual stimuli. - also maintain skeletal muscle tone, maintain contraction of postural muscles, and play a major role in equilibrium by regulating muscle tone in response to movements of the head.

Broca's speech area

- located in the frontal lobe close to the lateral cerebral sulcus, is involved in the articulation of speech. - In most people, Broca's speech area is localized in the left cerebral hemisphere. - Neural circuits established between Broca's speech area, the premotor area, and primary motor area activate muscles of the larynx, pharynx, and mouth and breathing muscles. - The coordinated contractions of your speech and breathing muscles enable you to speak your thoughts.

Modulation of Movement by the Cerebellum

- maintaining proper posture and balance - active in both learning and performing rapid, coordinated, highly skilled movements such as hitting a golf ball, speaking, and swimming

Warm receptors

- not as abundant as cold receptors -located in the dermis and are attached to small-diameter, unmyelinated C fibers; they are activated by temperatures between 32° and 48°C (90-118°F)

perception of fast pain

- occurs very rapidly, usually within 0.1 second after a stimulus is applied -this is because the nerve impulses propagate along medium-diameter, myelinated A fibers. - This type of pain is also known as acute, sharp, or pricking pain. Ex: The pain felt from a needle puncture or knife cut to the skin - Fast pain is not felt in deeper tissues of the body.

ANS nerve pathway

- preganglionic neurons convey nerve impulses from the CNS to autonomic ganglia - postganglionic neurons relay the impulses from autonomic ganglia to visceral effectors.

Hypothalamus

- receives input from the limbic system, cerebral cortex, thalamus and reticular activating system. - receives sensory signals from internal organs and from retina. - controls autonomic nervous system and regulates body temp, thirst, hunger, sexual behaviour and defensive reactions such as fear and rage. - important regulatory centre in nervous system as well asa crucial endocrine gland.

Somatic sensory pathways

- relay information from the somatic sensory receptors to the primary somatosensory area in the cerebral cortex and to the cerebellum. - The pathways to the cerebral cortex consist of thousands of sets of three neurons: a first-order neuron, a second-order neuron, and a third-order neuron.

Control of hormone secretion

- release of most hormones occurs in short bursts, with little or no secretion between bursts. Regulated by: 1. signals from the nervous system 2. chemical changes in the blood 3. other hormones

Basal ganglia

- suppress unwanted movements by their inhibitory effects on the thalamus and superior colliculus - influence muscle tone - also influence many aspects of cortical function, including sensory, limbic, cognitive, and linguistic functions.

arachnoid mater

- the middle meninx - an avascular covering - called the arachnoid mater because of its spider's web arrangement of delicate collagen fibers and some elastic fibers. - It is deep to the dura mater and is continuous with the arachnoid mater of the brain.

Nociceptors

- the receptors for pain - free nerve endings found in every tissue of the body except the brain - Intense thermal, mechanical, or chemical stimuli can activate nociceptors - Tissue irritation or injury releases chemicals such as prostaglandins, kinins, and potassium ions (K+) that stimulate nociceptors

Acromegaly

-Hypersecretion of hGH during adulthood. - At this point, hGH cannot produce further lengthening of long bones, b/c epiphy. plate is closed, the bones of the hands, feet, cheeks and jaws thicken and other tissues enlarge. - also, eyelids, lips, tongue and nose enlarge. - skin thickens and develops furrows, esp on the forehead and soles.

3 Physiological efects of the ANS

1. autonomic tone 2. sympathetic responses (fight or flight) 3. parasympathetic responses

4 major parts of the adult brain

1. brain stem 2. cerebellum 3. diencephalon 4. cerebrum

The anterior pituitary hormones

1. hGH - Human growth hormone 2. TSH - Thyroid-stimulating hormone 3. FSH - Follicle-stimulating hormone 4. LH - Luteinizing hormone 5. PRL - Prolactin 6. ACTH - Adrenocoricotropic hormone 7. Melanocyte-stimulating hormone

4 somatic motor pathways

1. local circuit neurons 2. upper motor neurons 3. basal gnaglia neurons 4. cerebellar neurons

Two parts of anterior pit

1. pars distalis (larger portion) 2. parts tuberalis (forms a sheath around the infundibulum)

Two parts of posterior pit

1. pars nervosa (larger bulbar portion) 2. infundibulum

Five functional components of a reflex arc

1. sensory receptor 2. sensory neuron 3. integrating centre 4. motor neuron 5. effector

Four modalities of somatic sensation

1. tactile 2. thermal 3. pain 4. proprioceptive

four important somatic spinal reflexes

1. the stretch reflex 2. the tendon reflex 3. the flexor (withdrawal) reflex 4. the crossed extensor reflex.

First REM period lasts how long?

10 minutes

Neurons and neuroglia #'s in the brain

100 billion neurons and 10 - 50 trillion neuroglia

autonomic ganglia - 3 groups

2 sympathetic ganglia: - sympathetic trunk ganglia - prevertebral ganglia 1 parasympathetic ganglia: - terminal ganglia

plasticity

A capability for change associated with learning - For an experience to become part of memory, it must produce persistent structural and functional changes that represent the experience in the brain. - Nervous system plasticity underlies our ability to change our behavior in response to stimuli from the external and internal environments. It involves changes in individual neurons—for example, synthesis of different proteins or sprouting of new dendrites—as well as changes in the strengths of synaptic connections among neurons.

Relaxin

A hormone produced by the ovaries and placenta during pregnancy - increases flexibility of the pubic symphysis during pregnancy - helps dilate uterine cervix during labour and delivery.

Hormone

A mediator molecule - released in one part of the body but regulates the activity of cells in other parts of the body.

electroencephalogram (EEG)

A record of brain waves - Brain waves generated by neurons close to the brain surface, mainly neurons in the cerebral cortex, can be detected by sensors called electrodes placed on the forehead and scalp.

Goiter

An enlarged thyroid gland. May be associated with hyperthyroidism, hypothyroidism and euthyroidism (normal TSH).

Separate cells

Basis of classification: Microscopic features Description: Receptor cells synapse with first-order sensory neurons; located in the retina of the eye (photoreceptors), inner ear (hair cells) and taste buds of the tongue (gustatory receptor cells)

Exteroreceptors

Basis of classification: location of receptor and activating stimuli Description: Located at or near body surface - sensitive to stimuli originating outsode body - provide info about external environment - convey visual, smell, taste, touch, pressure, vibration, thermal and pain sensations

Interoreceptors

Basis of classification: location of receptor and activating stimuli Description: Located in blood vessels, visceral organs and nervous system - provide information about internal environment - impulses produced usually are not consciously perceived but occasionally may be felt as pain or pressure

Proprioreceptors

Basis of classification: location of receptor and activating stimuli Description: Located in muscles, tendons, joints and inner ear - provide information about body position, muscle length and tension, position and motion of joints and equilibrium (balance).

Thermoreceptors

Basis of classification: type of stimulus detected Description: Detect changes in temperature

Photoreceptors

Basis of classification: type of stimulus detected Description: Detect light that strikes the retina of the eye.

Mechanoreceptors

Basis of classification: type of stimulus detected Description: Detect mechanical pressure - provide sensations of touch, pressure, vibration, proprioception, and hearing and equilibrium - monitor stretching of blood vessels and internal organs

Nocireceptors

Basis of classification: type of stimulus detected Description: Respond to painful stimuli resulting from physical or chemical damage to tissue.

Osmoreceptors

Basis of classification: type of stimulus detected Description: Sense the osmotic pressure of body fluids.

Hormones, simplified

Chemicals secreted by glands.

subarachnoid space

Between the arachnoid mater and the pia mater - contains cerebrospinal fluid

subdural space

Between the dura mater and the arachnoid mater - contains interstitial fluid

rami

Branches that spinal nerves divide into

language areas

Broca's speech area, Wernicke's area, and other language areas are located in the left cerebral hemisphere of most people, regardless of whether they are left-handed or right-handed. Injury to language areas of the cerebral cortex results in aphasia (a-FĀ-zē-a; a- = without; -phasia = speech), an inability to use or comprehend words

Thyroid gland

Butterfly-shaped - located just inferior to the larynx - composed of R and L lateral lobes, connection by an isthmus. - normal mass: 30g - highly vascularized - receives 80 - 120 ml of blood/minute

Endrocine vs. Nervous System control

Endocrine - slower and longer acting. Acts on virtually all types of body cells. Nervous - faster, briefer and acts on specific muscles and glands.

limbic system

Encircling the upper part of the brain stem and the corpus callosum is this ring of structures on the inner border of the cerebrum and floor of the diencephalon - sometimes called the "emotional brain" because it plays a primary role in a range of emotions, including pain, pleasure, docility, affection, and anger

Importance of brain blood flow

Even a brief slowing of brain blood flow may cause unconsciousness.

Melanocyte-stimulating hormone

Exact role in humans in unknown by may influence brain activity; when present in excess, can cause darkening of skin.

Somatic nervous system stimulation does what to its effectors?

Excites them (always) (which are skeletal muscle fibers)

Cranial Nerve VII

Facial Nerve Major function: Carry nerve impulses associated with taste, salivation and muscles of facial expression

Cranial Nerve IX

Glossopharyngeal Nerve Major function: Carry nerve impulses association with swallowing, salivation and taste

fascicles

Groups of axons with their endoneurium are arranged in these bundles

Addison's disease

Hyposecretion of glucocorticoids and aldosterone - aka 'chronic adrenocortical insufficiency') - due to autoimmune disorders in which antibodies cause adrenal cortex destruction or block binding of ACTH to its receptors. - Symptoms only appear once 90% of the adrenal cortex has been destroyed: mental lethargy, anorexia,, nausea, vomiting, weight loss, hypoglycemia and muscular weakness.

Relationship btwn hypothalamus and pituitary

Hypothalamus is master of pit. - Hypothalamus is major link between nervous and endocrine systems

long-term memory

Information in short-term memory may later be transformed into a more permanent type of memory - lasts from days to years - Information in long-term memory usually can be retrieved for use whenever needed

Flight or fight response

Initiated by nerve impulses from the hypothalamus to the sympathetic division of the autonomic nervous system - mobilizes the body's resources for immediate physical activity. - brings huge amounts of glucose and oxygen to the organs that are most active in warding off danger: the brain, skeletal muscles and the heart.

incompletely understood function of the cerebrum

Integration, the processing of sensory information by analyzing and storing it and making decisions for various responses. The integrative functions include cerebral activities such as sleep and wakefulness, learning and memory, and emotional responses.

The brain areas involved in long term memory

Long-term memories for information that can be expressed by language, such as a telephone number, apparently are stored in wide regions of the cerebral cortex. Memories for motor skills, such as how to serve a tennis ball, are stored in the basal ganglia and cerebellum as well as in the cerebral cortex.

Actions of Calcitonin

Lowers blood levels of Ca2+ and HPO4 by inhibiting bone resorption by osteoclasts and by accelerating uptake of calcium and phosphates into bone matrix.

Pinealocytes

Masses of neuroglia and secretory cells

Terminal (intramural ganglia)

Most of these ganglia are located close to or actually within the wall of a visceral organ. - Because the axons of parasympathetic preganglionic neurons extend from the CNS to a terminal ganglion in an innervated organ, they are longer than most of the axons of sympathetic preganglionic neurons. - Examples of terminal ganglia include the ciliary ganglion, pterygopalatine ganglion, submandibular ganglion, and otic ganglion

Epidural space around brain?

No, no space around brain

Pneumonic for Cranial Nerve numbers

Oh, Oh, Oh, To Touch and Feel Very Green Vegetables, AH!

Cranial Nerve I

Olfactory nerve Major function: Smell

Thymus gland, simplified

On top of heart. Involved in immune system - makes T-lymphocytes. More important in immunity in younger years.

Mineralocorticoids

One of the secretions of the adrenal cortex. - increase sodium and water reabsorption - decrease potassium reabsorption

Glucocorticoids

One of the secretions of the adrenal cortex. - promote protein breakdown, gluconeogenesis and lipolysis - help resist stress - serve as anti-inflammatory substances

Androgens

One of the secretions of the adrenal cortex. - stimulate the growth of axillary and pubic hair - aid the prepubertal growth spurt - contribute to libido

Triiodothyronine

One of the thyroid hormones. - aka T3 because it contains three atoms of idoine.

Thyroxine

One of the thyroid hormones. -aka tetraiodothyronine or T4 (because it contains 4 atoms of iodine)

Reflex arc Step 3: Integrating centre

One or more regions of gray matter within the CNS act as an integrating center. - In the simplest type of reflex, the integrating center is a single synapse between a sensory neuron and a motor neuron.

Breakdown of the BBB

Possible by trauma, toxins and inflammation

Pituitary Gland, simplified

Posterior - secretes oxytocin and ADH Anterior - secretes a number of hormones w/diff. effects. (Controls things from thyroid to endorphins)

Blood-brain barrier - function and anatomy

Protects brain cells from harmful substances and pathogens by preventing passage of many substances from blood into brain tissue - consists mainly of tight junctions that seal together the endothelial cells of brain capillaries, along with a thick basement membrane around the capillaries. - then, the processes of many astrocytes press up against the capillaries and secrete chemicals that maintain the permeability characteristics of the tight junctions.

Visceral senses

Provide information about conditions within interal organs

General senses

Refer to both somatic and visceral senses

Circulating hormones

Refers to most hormones. They pass from the secretory cells that make them into interstitial fluid and then into the blood.

Comparison of SNS + ANS: Neurotransmitters & Hormones

SNS: All somatic motor neurons release ACh. ANS: All preganglionic axons release acetylcholine (ACh); most sympathetic postganglionic neurons release norepinephrine (NE); those to most sweat glands release ACh; all parasympathetic postganglionic neurons release ACh; adrenal medullae release epinephrine and norepinephrine.

Comparison of SNS + ANS: Responses

SNS: Contraction of skeletal muscle. ANS: Contraction or relaxation of smooth muscle; increased or decreased rate and force of contraction of cardiac muscle; increased or decreased secretions of glands.

Comparison of SNS + ANS: Motor neuron pathway

SNS: One-neuron pathway: Somatic motor neurons extending from CNS synapse directly with effector. ANS: Usually two-neuron pathway: Preganglionic neurons extending from CNS synapse with postganglionic neurons in an autonomic ganglion, and postganglionic neurons extending from ganglion synapse with a visceral effector. Alternatively, preganglionic neurons may extend from CNS to synapse with cells of adrenal medullae.

Comparison of SNS + ANS: Effectors

SNS: Skeletal muscle. ANS: Smooth muscle, cardiac muscle, and glands

Comparison of SNS + ANS: Sensory input

SNS: Special senses and somatic senses. ANS: Mainly from interoceptors; some from special senses and somatic senses.

Comparison of SNS + ANS: Control of motor output

SNS: Voluntary control from cerebral cortex, with contributions from basal ganglia, cerebellum, brain stem, and spinal cord ANS: Involuntary control from limbic system, hypothalamus, brain stem, and spinal cord; limited control from cerebral cortex.

Resistance reaction

Second stage in the stress response. A longer lasting response. - releases a series of hormones that help the body continue fighting a stressor long after the fight or flight response dissipates.

Exocrine glands - definition

Secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ or to the otuer surface of the body.

Endocrine glands - definition

Secrete their products into the interstitial fluid surrounding the secretory cells rather than into ducts. From the inters. fluid, hormones diffuse into capillaries and blood carries them to target cells throughout the body.

Melatonin

Secreted by pineal gland - an amine hormone derived from serotonin

Adrenal medulla

Secretes epinephrine and norepinephrine, which are released during stress and produce effects similar to sympathetic responses.

Anterior pit and release of its hormones

Secretes hormones that regulate a wide range of bodily activities. - release of ant pit hormones is stimulated by releasing hormones and suppressed by inhibiting hormones.

Adrenal cortex

Secretes mineralocorticoids, glucocorticoids and androgens.

contralateral reflex arc

Sensory impulses enter one side of the spinal cord and motor impulses exit on the opposite side. - Thus, a crossed extensor reflex synchronizes the extension of the contralateral limb with the withdrawal (flexion) of the stimulated limb.

pyramids

Some of the white matter forms bulges on the anterior aspect of the medulla. - These protrusions are formed by the large corticospinal tracts that pass from the cerebrum to the spinal cord

Neurosecretory cells

Specialized neurons that synthesize the hypothalamic releasing and inhibiting hormones in their cell bodies and package the hormones inside vesicles, which reach the axon terminals by axonal transport.

Functional Organization of the Cerebral Cortex

Specific types of sensory, motor, and integrative signals are processed in certain regions of the cerebral cortex

Exocrine glands - example

Sudoriferous, sebaceous, mucous and digestive glands.

Location of diencephalon

Superior to brain stem. - consists of thalamus, hypothalamus and epithalamus

Cerebrum

Supported on the diencephalon and brain stem - largest part of the brain

extrafusal muscle fibers

Surrounding muscle spindles are ordinary skeletal muscle fibers called... - supplied by large-diameter A fibers called alpha motor neurons

Calcitriol

Synthesized by the kidneys, this is the active form of Vit D. Parathyroid hormed stimulates the kidneys to synthesize this.

Transport proteins - location of synthesization

Synthesized in the liver

Pain sensations

Temperatures below 10°C and above 48°C primarily stimulate pain receptors, rather than thermoreceptors, producing painful sensations - Pain is indispensable for survival - It serves a protective function by signaling the presence of noxious, tissue-damaging conditions - Pain may persist even after a pain-producing stimulus is removed because pain-mediating chemicals linger, and because nociceptors exhibit very little adaptation

cranial nerves

The 12 pairs of cranial nerves are so-named because they pass through various foramina in the bones of the cranium. - Like the 31 pairs of spinal nerves, they are part of the peripheral nervous system (PNS). Each cranial nerve has both a number, designated by a roman numeral, and a name (see Figure 14.5). The numbers indicate the order, from anterior to posterior, in which the nerves arise from the brain. The names designate a nerve's distribution or function.

Permissive effect

The action of some hormones on target cells require a simultaneous or recent exposure to a second hormone. The second hormone is said to have this effect.

intercostal or thoracic nerves.

The anterior rami of spinal nerves T2-T12 do not enter into the formation of plexuses and these nerves are known as ... These nerves directly connect to the structures they supply in the intercostal spaces.

Dermatomes

The area of the skin that provides sensory input to the CNS via one pair of spinal nerves or the trigeminal (V) nerve -The nerve supply in adjacent dermatomes overlaps somewhat. - Knowing which spinal cord segments supply each dermatome makes it possible to locate damaged regions of the spinal cord. If the skin in a particular region is stimulated but the sensation is not perceived, the nerves supplying that dermatome are probably damaged.

vermis

The central constricted area of the cerebellum

fissures

The deepest grooves between folds of gyri

Antagonistic effect

The effect when one hormone opposes the actions of another hormone.

Synergistic effect

The effect when two hormones acting together is greater or more extensive than the effect of each hormone acting alone.

horns

The gray matter on each side of the spinal cord is subdivided into regions called....

The brain areas involved in immediate and short term memory

The hippocampus, the mammillary bodies, and two nuclei of the thalamus (anterior and medial nuclei)

endoneurium

The innermost layer - covers individual axons within a nerve, whether myelinated or unmyelinated

pia mater

The innermost meninx - a thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain - consists of interlacing bundles of collagen fibers and some fine elastic fibers - Within the pia mater are many blood vessels that supply oxygen and nutrients to the spinal cord.

Autonomic sensory neurons

The main input to the ANS comes from here - these sensory signals are not consciously perceived most of the time, although intense activation of interoceptors may produce conscious sensations - these neurons are associated with interoceptors, which are sensory receptors located in blood vessels, visceral organs, muscles, and the nervous system that monitor conditions in the internal environment. Examples of interoceptors are chemoreceptors that monitor blood CO2 level and mechanoreceptors that detect the degree of stretch in the walls of organs or blood vessels.

Hypophyseal Portal system

The means through which hypothalamic hormones reach the anterior pituitary. Blood flows from capillaries in the hypothalamus into portal veins that carry blood to capillaries of the anterior pituitary.

cardiovascular center

The medulla also contains several nuclei, masses of gray matter where neurons form synapses with one another. Several of these nuclei control vital body functions. - The cardiovascular center regulates the rate and force of the heartbeat and the diameter of blood vessels.

Diabetes Mellitus

The most common endocrine disorder - Caused by an inability to use or produce insulin - Insulin in unavailable to aid transport of glucose into body cells, so blood glucose level is high and glucose spills into the urine (glucosuria). - Hallmarks: excessive urine, excessive thirst and excessive eating.

dura mater

The most superficial of the three spinal meninges - composed of dense, irregular connective tissue - forms a sac from the level of the foramen magnum in the occipital bone, where it is continuous with the dura mater of the brain, to the second sacral vertebra.

The brain + learning and memory

The parts of the brain known to be involved with memory include the association areas of the frontal, parietal, occipital, and temporal lobes; parts of the limbic system, especially the hippocampus and amygdala; and the diencephalon. The primary somatosensory and primary motor areas in the brain also exhibit plasticity. If a particular body part is used more intensively or in a newly learned activity, such as reading Braille, the cortical areas devoted to that body part gradually expand.

Prevertebral ganglia

The second group of sympathetic ganglia - lies anterior to the vertebral column and close to the large abdominal arteries. - In general, postganglionic axons from prevertebral ganglia innervate organs below the diaphragm. Examples of prevertebral ganglia are: - celiac ganglion - superior mesenteric ganglion - inferior mesenteric ganglion

Spinal cord and nerves and homeostasis

The spinal cord and spinal nerves contribute to homeostasis by providing quick, reflexive responses to many stimuli. The spinal cord is the pathway for sensory input to the brain and motor output from the brain.

The posterior and lateral parts of the hypothalamus control

They control the sympathetic division. - Stimulation of these areas produces an increase in heart rate and force of contraction, a rise in blood pressure due to constriction of blood vessels, an increase in body temperature, dilation of the pupils, and inhibition of the gastrointestinal tract

Exhaustion

Third stage in the stress response. Prolonged exposure to high levels of cortisol and other homones involves in the resistance reaction causes wasting of muscle, suppression of the immune system, ulceration of the gastrointestinal tract and failure of pancreatic beta cells.

Fissure and sulcus of spinal cord

Two grooves penetrate the white matter of the spinal cord and divide it into right and left sides

Patellar reflex

This reflex involves extension of the leg at the knee joint by contraction of the quadriceps femoris muscle in response to tapping the patellar ligament - This reflex is blocked by damage to the sensory or motor nerves supplying the muscle or to the integrating centers in the second, third, or fourth lumbar segments of the spinal cord. It is often absent in people with chronic diabetes mellitus or neurosyphilis, both of which cause degeneration of nerves. It is exaggerated in disease or injury involving certain motor tracts descending from the higher centers of the brain to the spinal cord.

Babinski reflex

This reflex results from gentle stroking of the lateral outer margin of the sole. - The great toe dorsiflexes, with or without a lateral fanning of the other toes. - This phenomenon normally occurs in children under 1½ years of age and is due to incomplete myelination of fibers in the corticospinal tract. - A positive Babinski sign after age 1½ is abnormal and indicates an interruption of the corticospinal tract as the result of a lesion of the tract, usually in the upper portion.

The function of REM sleep in infants and children

Thought to be maturation of the brain. During REM sleep, brain blood flow and oxygen use is higher than when awake during periods of intense mental/physical activity!

Formation, storage and release of thyroid hormones

Thyroid gland is the only endocrine gland that stores its secretory product in large quantities, normally approx 100-day supply. - hormones are synthesized from iodine and tyrosine within thyroglobulin. - they are transported in the blood bound to plasma proteins. - secretion is controlled by TRH from the hypothalamus and TSH from the anterior pit.

Cranial Nerve X

Vagus Nerve Major function: Carry nerve impulses to and from many organs in the thoracic and abdominal cavities

Cranial Nerve VIII

Vestibulocochlear Nerve Major function: Carry nerve impulses associated with hearing and equilibrium

Action of water-soluble hormones

Water-soluble hormones alter cell function by activating plasma membrane receptors, which elicit production of a second messenger that activates various enzymes inside the cell.

spinal reflex

When integration takes place in the spinal cord gray matter, the reflex is called a ... An example is the familiar patellar reflex (knee jerk).

corpus callosum

a broad band of white matter that containing axons that connects the cerebral hemispheres. Extends between them. (sits deep inside the brain)

Stimulus

a change in the internal or external environment

ganglion

a collection of neuronal cell bodies outside the CNS

transverse fissure

a deep groove, which along with the tentorium cerebelli, separates the cerebellum from the cerebrum

anterior median fissure

a deep, wide groove on the anterior (ventral) side of the white matter of the spinal cord

activate or block specific cholinergic or adrenergic receptors

a large number of drugs and natural products can do this

precentral gyrus

a major gyrus - located immediately anterior to the central sulcus - contains the primary motor area of the cerebral cortex

postcentral gyrus

a major gyrus - located immediately posterior to the central sulcus - contains the primary somatosensory area of the cerebral cortex.

premotor area

a motor association area that is immediately anterior to the primary motor area. - Neurons in this area communicate with the primary motor cortex, the sensory association areas in the parietal lobe, the basal ganglia, and the thalamus. The premotor area deals with learned motor activities of a complex and sequential nature. It generates nerve impulses that cause specific groups of muscles to contract in a specific sequence, as when you write your name. The premotor area also serves as a memory bank for such movements.

Two types of proprioceptors

a muscle spindle and a tendon organ

third ventricle

a narrow cavity along the midline superior to the hypothalamus and between the right and left halves of the thalamus

plexus

a network of axons from the anterior rami of spinal nerves that do not go directly to the body structures that supply and instead form networks on both the left and right sides of the body by joining with various numbers of axons from anterior rami of adjacent nerves.

acetylcholine (ACh)

a neurotransmitter releases by cholinergic neurons - stored in synaptic vesicles and released by exocytosis. - It then diffuses across the synaptic cleft and binds with specific cholinergic receptors

ipsilateral reflex

a reflex arc in which sensory nerve impulses enter the spinal cord on the same side from which motor nerve impulses leave it.

flexor or withdrawal reflex

a reflex involving a polysynaptic reflex arc that results when, for instance, you step on a tack. In response to such a painful stimulus, you immediately withdraw your leg - ipsilateral reflex arc - polysynaptic - reciprocal innervation

hypothalamus

a small part of the diencephalon located inferior to the thalamus. It is composed of a dozen or so nuclei in four major regions - Controls and integrates activities of the autonomic nervous system and pituitary gland. - Regulates emotional and behavioral patterns and circadian rhythms. - Controls body temperature and regulates eating and drinking behavior. - Helps maintain the waking state and establishes patterns of sleep. - Produces the hormones oxytocin and antidiuretic hormone (ADH).

epidural space

a space between the dura mater and the wall of the vertebral cavity - contains a cushion of fat and connective tissue that protects the spinal cord

Sleep

a state of altered consciousness or partial unconsciousness from which an individual can be aroused - Although it is essential, the exact functions of sleep are still unclear

consciousness

a state of wakefulness

receptor agonist

a substance that binds to and activates a receptor, in the process mimicking the effect of a natural neurotransmitter or hormone.

Pressure

a sustained sensation that is felt over a larger area than touch, occurs with deformation of deeper tissues. Receptors that contribute to sensations of pressure include corpuscles of touch, type I mechanoreceptors, and lamellated corpuscles

posterior (dorsal) root ganglion

a swelling in each posterior dorsal root which contains the cell bodies of sensory neurons.

pineal gland

about the size of a small pea and protrudes from the posterior midline of the third ventricle - onsidered part of the endocrine system because it secretes the hormone melatonin

Naming of the 31 pairs of spinal nerves

according to the region and level of the vertebral column from which they emerge

Wernicke's area

aka posterior language area a broad region in the left temporal and parietal lobes, interprets the meaning of speech by recognizing spoken words. - It is active as you translate words into thoughts. The regions in the right hemisphere that correspond to Broca's and Wernicke's areas in the left hemisphere also contribute to verbal communication by adding emotional content, such as anger or joy, to spoken words.

Antidiuretic hormone

aka vasopressin - Neurosecretory cells of hypothalamus secrete ADH in response to elevated blood osmotic pressure, dehydration, loss of blood volume, pain or stress - release inhibited by lower blood osmotic pressure, high blood volume and alcohol. - conserves body water by decreasing urine volume - decreases water loss through sweating - raises blood pressure by constricting arterioles.

Proprioceptive sensations

allow us to know where our head and limbs are located and how they are moving even if we are not looking at them, so that we can walk, type, or dress without using our eyes.

Type I cutaneous mechanoreceptors

also known as Merkel discs - function in fine touch - merkel discs are saucer-shaped, flattened free nerve endings that contact Merkel cells of the stratum basale - these mechanoreceptors are plentiful in the fingertips, hands, lips, and external genitalia.

spinal cord

although roughly cylindrical, is flattened slightly in its anterior-posterior dimension - In adults, it extends from the medulla oblongata, the inferior part of the brain, to the superior border of the second lumbar vertebra - Thus, the spinal cord does not extend the entire length of the adult vertebral column.

prefrontal cortex (frontal association area)

an extensive area in the anterior portion of the frontal lobe that is well-developed in primates, especially humans - This area has numerous connections with other areas of the cerebral cortex, thalamus, hypothalamus, limbic system, and cerebellum. - concerned with the makeup of a person's personality, intellect, complex learning abilities, recall of information, initiative, judgment, foresight, reasoning, conscience, intuition, mood, planning for the future, and development of abstract ideas

craniosacral division

another name for the parasympathetic division of ANS - due to the location of preganglionic neuron cell bodies in the cranial nerves and in the sacral segment of the spine.

thoracolumbar division

another name for the sympathetic division of ANS - due to location of preganglionic neuron cell bodies in thoracic and lumbar segments.

anterolateral or spinothalamic pathways

are composed of three-neuron sets - conveys impulses for tickle, itch, crude touch, and pressure - The first-order neurons connect a receptor of the neck, trunk, or limbs with the spinal cord - The axons of the second-order neurons cross to the opposite side of the spinal cord - Then, they pass upward to the brain stem in either the lateral spinothalamic tract or the anterior spinothalamic tract - The axons of the second-order neurons end in the ventral posterior nucleus of the thalamus, where they synapse with the third-order neurons. - The axons of the third-order neurons project to the primary somatosensory area on the same side of the cerebral cortex as the thalamus.

primary visual area

located at the posterior tip of the occipital lobe mainly on the medial surface - receives visual information and is involved in visual perception.

insula

cannot be seen at the surface of the brain because it lies within the lateral cerebral sulcus, deep to the parietal, frontal, and temporal lobes

Two distinct thermal sensations

coldness and warmth - mediated by different receptors - both adapt rapidly at the onset of a stimulus, but as noted earlier in the chapter they continue to generate impulses at a lower frequency throughout a prolonged stimulus.

First-order neurons

conduct impulses from somatic receptors into the brain stem or spinal cord. - From the face, mouth, teeth, and eyes, somatic sensory impulses propagate along cranial nerves into the brain stem. - From the neck, trunk, limbs, and posterior aspect of the head, somatic sensory impulses propagate along spinal nerves into the spinal cord.

Second-order neurons

conduct impulses from the brain stem and spinal cord to the thalamus - Axons of second-order neurons decussate (cross over to the opposite side) in the brain stem or spinal cord before ascending to the ventral posterior nucleus of the thalamus. - Thus, all somatic sensory information from one side of the body reaches the thalamus on the opposite side.

Third-order neurons

conduct impulses from the thalamus to the primary somatosensory area of the cortex on the same side.

Anatomical connection between hypothalamus and ANS

connected to both the sympathetic and parasympathetic divisions of the ANS by axons of neurons with dendrites and cell bodies in various hypothalamic nuclei.

motor (descending) tracts

consist of axons that carry nerve impulses from the brain.

Sensory (ascending) tracts

consist of axons that conduct nerve impulses toward the brain.

NREM sleep

consists of four gradually merging stages: 1. Stage 1: a transition stage between wakefulness and sleep that normally lasts 1-7 minutes. The person is relaxed with eyes closed and has fleeting thoughts. People awakened during this stage often say they have not been sleeping. 2. Stage 2 or light sleep is the first stage of true sleep. In it, a person is a little more difficult to awaken. Fragments of dreams may be experienced, and the eyes may slowly roll from side to side. 3. Stage 3 is a period of moderately deep sleep. Body temperature and blood pressure decrease and it is difficult to awaken the person. This stage occurs about 20 minutes after falling asleep. 4. Stage 4 is the deepest level of sleep. Although brain metabolism decreases significantly and body temperature drops slightly at this time, most reflexes are intact, and muscle tone is decreased only slightly. When sleepwalking occurs, it does so during this stage.

cerebral white matter

consists of myelinated and unmyelinated axons in three types of tracts: association tracts, commissural tracts and projection tracts

epithalamus

consists of the pineal gland and habenular nuclei.

association tracts

contain axons that conduct nerve impulses between gyri in the same hemisphere.

Commissural tracts

contain axons that conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other cerebral hemisphere. - Three important groups of commissural tracts are the corpus callosum (the largest fiber bundle in the brain, containing about 300 million fibers), anterior commissure, and posterior commissure.

Projection tracts

contain axons that conduct nerve impulses from the cerebrum to lower parts of the CNS (thalamus, brainstem, or spinal cord) or from lower parts of the CNS to the cerebrum.

The gray matter consists of

dendrites and cell bodies of neurons, unmyelinated axons, and neuroglia.

Motor output to skeletal muscles travels down the spinal cord in two types of descending pathways

direct and indirect

the three spinal meninges

dura mater, arachnoid mater and pia mater

brain waves

electrical signals involving brain neurons generating millions of nerve impulses (action potentials)

acetylcholinesterase

enzyme that inactivates acetylcholine

REM periods occur how often?

every 90 minutes

diencephalon

extends from the brain stem to the cerebrum and surrounds the third ventricle; it includes the thalamus, hypothalamus, and epithalamus.

two types of pain

fast and slow

gray commissure

forms the crossbar of the H. In the center of the gray commissure is a small space called the central canal

ventricles

four CSF-filled cavities within the brain

Thermoreceptors

free nerve endings that have receptive fields about 1 mm in diameter on the skin surface.

4 lobes of the cerebral hemisphere

frontal, parietal, temporal, and occipital lobes - named after the bones they sit under.

autonomic ganglion

ganglion of the autonomic system, located outside of CNS, which houses cell body and unmyelinated axon of the second part of the ANS pathway.

folia

gray matter of the cerebellar cortex made up of a series of slender, parallel ridges

typical spinal nerve

has two connections to the cord: a posterior root and an anterior root

somatosensory association area

just posterior to and receives input from the primary somatosensory area, as well as from the thalamus and other parts of the brain - This area permits you to determine the exact shape and texture of an object without looking at it, to determine the orientation of one object with respect to another as they are felt, and to sense the relationship of one body part to another. - Another role of the somatosensory association area is the storage of memories of past sensory experiences, enabling you to compare current sensations with previous experiences. For example, the somatosensory association area allows you to recognize objects such as a pencil and a paperclip simply by touching them.

alpha motor neurons

large-diameter A fibers

hemispheric lateralization - physiology

left hemisphere receives somatic sensory signals from and controls muscles on the right side of the body, whereas the right hemisphere receives sensory signals from and controls the left side of the body. In most people the left hemisphere is more important for reasoning, numerical and scientific skills, spoken and written language, and the ability to use and understand sign language. Conversely, the right hemisphere is more specialized for musical and artistic awareness; spatial and pattern perception; recognition of faces and emotional content of language; discrimination of different smells; and generating mental images of sight, sound, touch, taste, and smell to compare relationships among them.

fourth ventricle

lies between the brain stem and the cerebellum.

pons

lies directly superior to the medulla and anterior to the cerebellum and is about 2.5 cm (1 in.) long - consists of both nuclei and tracts - bridge that connects parts of the brain with one another; relays impulses from one side of the cerebellum to the other and between the medulla and midbrain. - These connections are provided by bundles of axons. Some axons of the pons connect the right and left sides of the cerebellum. Others are part of ascending sensory tracts and descending motor tracts. - some nuclei in the pons are the pneumotaxic area and the apneustic area - also contains nuclei associated with the following four pairs of cranial nerves: trigeminal (V) nerves, abducens (VI) nerves, facial (VII) nerves, and vestibulocochlear (VIII) nerves.

primary gustatory area

located at the base of the postcentral gyrus superior to the lateral cerebral sulcus in the parietal cortex - receives impulses for taste and is involved in gustatory perception.

Tendon organs

located at the junction of a tendon and a muscle - tendon organs protect tendons and their associated muscles from damage due to excessive tension - Each tendon organ consists of a thin capsule of connective tissue that encloses a few tendon fascicles (bundles of collagen fibers)

primary somatosensory area

located directly posterior to the central sulcus of each cerebral hemisphere in the postcentral gyrus of each parietal lobe. - extends from the lateral cerebral sulcus, along the lateral surface of the parietal lobe to the longitudinal fissure, and then along the medial surface of the parietal lobe within the longitudinal fissure. - receives nerve impulses for touch, proprioception (joint and muscle position), pain, itching, tickle, and temperature and is involved in the perception of these sensations. - A "map" of the entire body is present in the primary somatosensory area: Each point within the area receives impulses from a specific part of the body - the size of the cortical area receiving impulses from a particular part of the body depends on the number of receptors present there rather than on the size of the body part. - The primary somatosensory area allows you to pinpoint where sensations originate, so that you know exactly where on your body to swat that mosquito.

visual association area

located in the occipital lobe - receives sensory impulses from the primary visual area and the thalamus. - It relates present and past visual experiences and is essential for recognizing and evaluating what is seen. For example, the visual association area allows you to recognize an object such as a spoon simply by looking at it.

primary motor area

located in the precentral gyrus of the frontal lobe - Each region in the primary motor area controls voluntary contractions of specific muscles or groups of muscles - Electrical stimulation of any point in the primary motor area causes contraction of specific skeletal muscle fibers on the opposite side of the body - As is true for the primary somatosensory area, body parts do not "map" to the primary motor area in proportion to their size. More cortical area is devoted to those muscles involved in skilled, complex, or delicate movement. For instance, the cortical region devoted to muscles that move the fingers is much larger than the region for muscles that move the toes.

Cold receptors

located in the stratum basale of the epidermis and are attached to medium-diameter, myelinated A fibers, although a few connect to small-diameter, unmyelinated C fibers. - temperatures between 10° and 40°C (50-105°F) activate cold receptors

primary auditory area

located in the superior part of the temporal lobe near the lateral cerebral sulcus - receives information for sound and is involved in auditory perception.

primary olfactory area

located in the temporal lobe on the medial aspect - receives impulses for smell and is involved in olfactory perception.

auditory association area

located inferior and posterior to the primary auditory area in the temporal cortex - allows you to recognize a particular sound as speech, music, or noise.

thalamus

measures about 3 cm (1.2 in.) in length and makes up 80% of the diencephalon, consists of paired oval masses of gray matter organized into nuclei with interspersed tracts of white matter - Relays almost all sensory input to the cerebral cortex. - Provides crude perception of touch, pressure, pain, and temperature. - Includes nuclei involved in movement planning and control.

muscle stretch is followed by

muscle contraction, which relieves the stretching.

The stretch reflex operates as a feedback mechanism to control ?

muscle length by causing muscle contraction

The spinal cord has two principal functions in maintaining homeostasis

nerve impulse propagation and integration of information

lateral ventricle

one in each hemisphere of the cerebrum

tendon reflex

operates as a feedback mechanism to control muscle tension by causing muscle relaxation before muscle force becomes so great that tendons might be torn. - less sensitive than the stretch reflex, YET it can override the stretch reflex when tension is great, making you drop a very heavy weight, for example. - ipsilateral reflex arc - polysynaptic

dual innervation

organs receive impulses from both sympathetic and parasympathetic neurons. In general, nerve impulses from one division of the ANS stimulate the organ to increase its activity (excitation), and impulses from the other division decrease the organ's activity (inhibition)

All fascicles are wrapped in...

perineurium - the middle layer

Nicotinic receptors

present in the plasma membrane of dendrites and cell bodies of both sympathetic and parasympathetic postganglionic neurons and in the motor end plate at the neuromuscular junction. - They are so named because nicotine mimics the action of ACh by binding to these receptors.

Muscarinic receptors

present in the plasma membranes of all effectors (smooth muscle, cardiac muscle, and glands) innervated by parasympathetic postganglionic axons

joint kinesthetic receptors

present within and around the articular capsules of synovial joints

proprioceptors

proprioceptive sensations arise in receptors termed?

Indirect motor pathways

provide input to lower motor neurons from motor centers in the brain stem aka extrapyramidal pathways - include all somatic motor tracts other than the corticospinal and corticobulbar tracts. - Nerve impulses conducted along the indirect pathways follow complex, polysynaptic circuits that involve the motor cortex, basal ganglia, thalamus, cerebellum, reticular formation, and nuclei in the brain stem.

Hair root plexus

rapidly adapting crude touch receptors found in hairy skin; they consist of free nerve endings wrapped around hair follicles. Hair root plexuses detect movements on the skin surface that disturb hairs.

sensory areas

receive sensory information and are involved in perception, the conscious awareness of a sensation - Sensory information arrives mainly in the posterior half of both cerebral hemispheres, in regions behind the central sulci. - In the cortex, primary sensory areas have the most direct connections with peripheral sensory receptors.

Autonomic motor neurons

regulate visceral activities by either increasing (exciting) or decreasing (inhibiting) ongoing activities in their effector tissues (cardiac muscle, smooth muscle, and glands). - Changes in the diameter of the pupils, dilation and constriction of blood vessels, and adjustment of the rate and force of the heartbeat are examples of autonomic motor responses. - on and constriction of blood vessels, and adjustment of the rate and force of the heartbeat are examples of autonomic motor responses. Unlike skeletal muscle, tissues innervated by the ANS often function to some extent even if their nerve supply is damaged. i.e. The heart continues to beat when it is removed for transplantation into another person

adrenergic neurons in the ANS

release norepinephrine (NE), also known as noradrenalin - Most sympathetic postganglionic neurons are adrenergic. - Like ACh, NE is synthesized and stored in synaptic vesicles and released by exocytosis - Molecules of NE diffuse across the synaptic cleft and bind to specific adrenergic receptors on the postsynaptic membrane, causing either excitation or inhibition of the effector cell.

Cholinergic neurons

release the neurotransmitter acetylcholine (ACh) - In the ANS, the cholinergic neurons include (1) all sympathetic and parasympathetic preganglionic neurons, (2) sympathetic postganglionic neurons that innervate most sweat glands, and (3) all parasympathetic postganglionic neurons

Autonomic reflexes

responses that occur when nerve impulses pass through an autonomic reflex arc. - These reflexes play a key role in regulating controlled conditions in the body, such as: - blood pressure: by adjusting heart rate, force of ventricular contraction, and blood vessel diameter; - digestion: by adjusting the motility (movement) and muscle tone of the gastrointestinal tract; - defecation and urination: by regulating the opening and closing of sphincters.

parasympathetic responses are aka as

rest-and-digest activities

vibration

results from stimulation of free nerve endings by certain chemicals, such as bradykinin, often because of a local inflammatory response

Visceral pain

results from stimulation of nociceptors in visceral organs - If stimulation is diffuse (involves large areas), visceral pain can be severe

The gray matter of the spinal cord

shaped like the letter H or a butterfly and is surrounded by white matter

choroid plexuses

sites of CSF production - networks of capillaries (microscopic blood vessels) in the walls of the ventricles. The capillaries are covered by ependymal cells that form cerebrospinal fluid from blood plasma by filtration and secretion.

Nerve impulses from sensory receptors propagate up the spinal cord to the brain along two main routes on each side

spinothalamic tracts and the posterior columns

receptor antagonist

substance that binds to and blocks a receptor, thereby preventing a natural neurotransmitter or hormone from exerting its effect.

spinal meninges

surround the spinal cord and are continuous with the cranial meninges, which encircle the brain

autonomic plexuses

tangled networks of axons of both sympathetic and parasympathetic neurons in the thorax, abdomen, and pelvis

sensory receptors for tendon reflex

tendon (Golgi tendon) organs - lie within a tendon near its junction with a muscle

cerebellar hemispheres

the lateral wings/lobes of the cerebellum - Each hemisphere consists of lobes separated by deep and distinct fissures. - govern sub-conscious aspects of skeletal muscle movements. - contribute to equilibrium and balance.

The hypothalamus and the ANS

the major control and integration center of the ANS - receives sensory input related to visceral functions, olfaction (smell), and gustation (taste), as well as changes in temperature, osmolarity, and levels of various substances in blood. It also receives input relating to emotions from the limbic system. - Output from the hypothalamus influences autonomic centers both in the brain stem (such as the cardiovascular, salivation, swallowing, and vomiting centers) and the spinal cord (such as the defecation and urination reflex centers in the sacral spinal cord).

preganglionic neuron cell bodies of the PARASYMPATHETIC division are in...

the nuclei of four cranial nerves in the brain stem (III, VII, IX, and X) and in the lateral gray horns of the second through fourth sacral segments of the spinal cord

brain stem

the part of the brain between the spinal cord and the diencephalon; it consists of the (1) medulla oblongata, (2) pons, and (3) midbrain. - Extending through the brain stem is the reticular formation, a netlike region of interspersed gray and white matter.

Spinal nerves

the paths of communication between the spinal cord and the nerves supplying specific regions of the body

Kinesthesia

the perception of body movements

Memory

the process by which information acquired through learning is stored and retrieved. - occurs in stages over a period of time

Muscle spindles

the proprioceptors in skeletal muscles that monitor changes in the length of skeletal muscles and participate in stretch reflexes