The Nervous system- -is the complex arrangement throughout the body of highly specialized cells, the neurons, which acts as a communication system, enabling the organism to respond to external and internal stimuli.
Senseorgans are sensitive nerve endings located in certain body parts. Its attributes are: A.) Sensitivity and Irritability: The Power to react to stimulus B.) Conductivity: The power to conduct nerve impulses C.) Specificity: the attribute of reacting to particular stimulus D.) Adaptability: the power to become used to a particular stimulus.
A.)Extroceptors-found in the eyes, ears, nose, mouth, skin and are sensitive to external stimulus. B.) Interoceptors- sense organs in the respiratory tract, digestive and genito-urinary tract. C.) Proprieoceptors- are embeded in muscles, tendons and joints.
A.Muscles of three kinds: Voluntary Involuntary Cardiac or heart
Voluntary Muscles Voluntary muscles:Muscles that move and work when we want them to Examples: Arm muscles Leg muscles Neck muscles
Involuntary Muscles Involuntary muscles: Muscles that keep workingwhether we think about them or not Examples: Stomach Lungs Muscles in the heartThe Nervous system along with other chemicals in the body controls our involuntary muscles
Attached to bones by strong fibers called tendons Muscles work in pairs to move the bones: Example: biceps (relaxes and stretches) and triceps (contract and pull up the elbow) Muscle is long, round, and crossstriped
Can be found only inthe HEART Muscle contracts and relaxesabout 70 times a minute withoutstopping or getting tired Muscle is strained bothcrossways and longways
Found in many differentorgans throughout the bodyExamples: esophagus,stomach, and intestines Muscle is slender andsmooth without cross stripes.
Fun FactsThe main purpose of the Muscular System is for allthe muscles to work together to create movement! Muscles make up almost 50% of our body weightThere are more than 600 muscles in the human body
Contractility-power of muscles to shorten.Tonicity- power to be in partial contraction.Extensibility-power to stretchElasticity-power to resume to its original shape.
Functions 1. To lend shape to the body as the skeletal or voluntary muscles of the arms and legs do 2. To propel food and waste product along the intestinal pathway as smooth muscles in the digestive tract do 3. For movement as when the arms and legs move or when we move the mouth to form the sounds of speech 4. To control the flow of blood, automatically opening and closing the blood vessels in response to body needs. 5. To convert mechanical energy to mechanical work
B.Glands- are special secreting organs which pour their secretions either directly or indirectly to the bloodstream. -have ducts or canals thru which they pour out their secretions. These includes lachrymal(tear) glands, sebaceous (sweat);salivary, gastric, sex and mammary glands.
Pituitary gland is located beneath hypothalamus
Stores & releases 2 hormones Hypothalamus produced in hypothalamus: Antidiuretic hormone (ADH/vasopressin) which Neurosecretory cells of the Axon promotes H20 conservation by hypothalamus kidneys Oxytocin which stimulates Posterior pituitary contractions of uterus during Anterior pituitary parturition & contractions of mammary gland alveoli for milk-ejection reflex HORMONE ADH Oxytocin TARGET Kidney tubules Mammary glands, uterine muscles
Secretes 6 trophic hormones that maintain size of targets High blood levels cause target to hypertrophy Low levels cause atrophy
Growth hormone (GH) promotes growth, protein synthesis, & movement of amino acids into cells Thyroid stimulating hormone (TSH) stimulates thyroid to produce & secrete T4 & T3 Adrenocorticotroph ic hormone (ACTH) stimulates adrenal cortex to secrete cortisol, aldosterone
Follicle stimulating hormone (FSH) stimulates growth of ovarian follicles & sperm production Luteinizing hormone (LH) causes ovulation & secretion of testosterone in testes Prolactin (PRL) stimulates milk production by mammary glands
Other hormones/products of the pituitary gland include: MSH - influences skin pigmentation in some vertebrates and fat metabolism in mammals Endorphins - inhibit the sensation of pain
Releasing & inhibiting hormones from hypothalamus are released from axon endings into capillary bed in median eminence Carried by hypothalamo- hypophyseal portal system directly to another capillary bed in A. Pit. Diffuse into A. Pit. & regulate secretion of its hormones
Hypothalamus receives input from higher brain centers that can affect Pituitary secretion E.g. psychological stress affects circadian rhythms, menstrual cycle, & adrenal hormones
Siton top of kidneys outer cortex inner medulla
Adrenal Cortex Mineralocorticoids Aldosterone which stimulate kidneys to reabsorb Na+ and secrete K Glucocorticoids Cortisol which inhibits glucose utilization & stimulates gluconeogenesis. Inhibits inflammation, Supresses the immune system
Secretes Epinephrine and Norepinephrine "fight or flight" response causes: Increased respiratory rate Increased HR & cardiac output General vasoconstriction which increases venous return Glycogenolysis & lipolysis Etc, etc, etc
Cushing’s disease Hyperadrenocorticism widened face with acne and flushing fatty deposits over back of neck stretch marks, easy bruising, hair overgrowth diabetes mellitus muscle loss and fatigue depression and psychosis moon-like face, Addison’s disease Hypoadrenocorticism Hyperpigmentation, weight loss
Islocated just below the larynx Secretes T4 & T3 which set BMR & are needed for growth, development Also secretes Calcitonin which lowers blood calcium levels
Hypothyroidism People with inadequate T4 & T3 levels are hypothyroid Have low BMR, weight gain, lethargy, cold intolerance Hyperthyroidism Autoimmune disease where antibodies act like TSH & stimulate thyroid gland to grow & oversecrete = hyperthyroidism Characterized by exopthalmos, weight loss, heat intolerance, irritability/anxiety, high BMR, rapid heart rate
Graves disease is a form of hyperthyroidism that often presents with exopthalmos
On the surface of thyroid gland Secrete Parathyroid hormone (PTH) Elevates blood Ca2+ levels
Two antagonistic Calcitonin Thyroid gland releases calcitonin. hormones, Reduces Stimulates Ca2+ uptake parathyroid Ca2+ deposition in bones in kidneys hormone (PTH) and calcitonin STIMULUS: Blood Ca2+ play the major Rising blood level declines Ca2+ level to set point role in calcium Homeostasis: (Ca2+) Blood Ca2+ level (about 10 mg/100 mL) homeostasis in Blood Ca2+ level rises STIMULUS: Falling blood Ca2+ level to set point mammals Stimulates Ca2+ release Parathyroid gland from bones PTH Increases Ca2+ uptake in intestines Stimulates Ca2+ Active uptake in kidneys vitamin D
Diabetes mellitus is the best-known endocrine disorder Is caused by a deficiency of insulin or a decreased response to insulin in target tissues Is marked by elevated blood glucose levels Type I diabetes mellitus (insulin-dependent diabetes) Is an autoimmune disorder in which the immune system destroys the beta cells of the pancreas Type II diabetes mellitus (non-insulin-dependent diabetes) Is characterized either by a deficiency of insulin or, more commonly, by reduced responsiveness of target cells due to some change in insulin receptors
Alphassecrete glucagon in response to low blood glucose during periods of fasting Stimulates glycogenolysis & lipolysis Increases blood glucose
Gonads (testes & ovaries) secrete steroid hormones The testes primarily synthesize androgens, the main one being testosterone Which stimulate the development and maintenance of the male reproductive system Estrogens, the most important of which is estradiol Are responsible for the maintenance of the female reproductive system and the development of female secondary sex characteristics Progestins, which include progesterone Are primarily involved in preparing and maintaining the uterus in mammals
Testosterone causes an increase in muscle and bone mass and is often taken as a supplement to cause muscle growth
Placenta secretes estrogen, progesterone, hCG which maintains pregnancy,prev ents eggs from ripening in the ovary, and numerous polypeptide hormones
A.The Neuron is the basic conducting unit of the nervous system. It has 3 principal parts: Dendrites-are specialized signal- receiving structures where the impulse (input)enters ; the cell body (central region) which integrates input and output and the axon where the output is discharged.
According to speed According to basic function a. Sensory Neurons (afferent fibers) -conduct impulses to the nervous system. b. Association Neurons -central and connecting conduct impulses with in the nervous system. c. Motor Neurons (efferent fibers) -conduct impulses away from the nervous system
The skull is a rounded layer ofbone designed to protect the brainfrom penetrating injuries.
The base of the skull isBony ridges rough, with many bony protuberances. These ridges can result in injury to the temporal lobe of the brain during rapid acceleration. Injury from contact with skull
The brain requires a rich blood supply, and the space between the skull and cerebrum contains many blood vessels. These blood vessels can be ruptured during trauma, resulting in bleeding.Groove for middlemeningeal artery
The human brainrequires a constantsupply of oxygen. Alack of oxygen of justa few minutes resultsin irreversible damageto the brain.
Dendrites: Collects information from other neurons. Cell Body Axon: Transmits information to other neurons.Click image to play or pause video
The meninges are layersof tissue that separate theskull and the brain. Skull Dura mater Arachnoid Layer Pia Mater Brain
The largest portion of the brainis the cerebrum. It consists oftwo hemispheres that areconnected together at thecorpus callosum. Corpus callosumThe cerebrum is often dividedinto five lobes that areresponsible for different brainfunctions.
NeocortexThe cerebrum’s surface—theneocortex—is convoluted intohundreds of folds.The neocortex is where all thehigher brain functions take place.
The cerebral cortex is a thin layer of cells about 1.5 to4 mm thick.The cortex provides the connections and pathwaysfor the highest cognitive functions, such as languageand abstract thinking.The cerebral cortex contains about 25 billion neurons,more than 62,000 miles of axons, and300,000,000,000,000 synapses. Neocortex layer The thin layer of the neocortex is dense with neurons.
The frontal lobe is the area ofthe brain responsible forhigher cognitive functions.These include:• Problem solving• Spontaneity• Memory• Language• Motivation• Judgment• Impulse control• Social and sexual behavior.
The temporal lobe plays arole in emotions, and isalso responsible forsmelling, tasting,perception, memory,understanding music,aggressiveness, andsexual behavior.The temporal lobe alsocontains the languagearea of the brain.
The parietal lobe plays arole in our sensations oftouch, smell, and taste. Italso processes sensoryand spatial awareness,and is a key componentin eye-hand co-ordinationand arm movement.The parietal lobe alsocontains a specializedarea called Wernicke’sarea that is responsiblefor matching writtenwords with the sound ofspoken speech.
The occipitallobe is at therear of thebrain andcontrols visionandrecognition.
The limbic lobeis located deepin the brain,and makes upthe limbicsystem.
The limbic system is thearea of the brain thatregulates emotion andmemory. It directlyconnects the lower andhigher brain functions.A. Cingulate gyrusB. FornixC. Anterior thalamic nucleiD. HypothalamusE. Amygdaloid nucleusF. Hippocampus
The cerebellum is connected to thebrainstem, and is the center forbody movement and balance.
Thalamus means “inner room” in Greek,as it sits deep in the brain at the top ofthe brainstem.The thalamus is called the gateway tothe cerebral cortex, as nearly allsensory inputs pass through it to thehigher levels of the brain.
The hypothalamus sits under the thalamus atthe top of the brainstem. Although thehypothalamus is small, it controls many criticalbodily functions:• Controls autonomic nervous system• Center for emotional response and behavior• Regulates body temperature• Regulates food intake• Regulates water balance and thirst The hypothalamus is• Controls sleep-wake cycles shaded blue. The pituitary• Controls endocrine system gland extends from the hypothalamus.
The medulla oblongata mergesseamlessly with the spinal cord andcreates the base of the brainstem.The medulla is primarily a controlcenter for vital involuntary reflexessuch as swallowing, vomiting,sneezing, coughing, and regulation ofcardiovascular and respiratory activity.The medulla is also the origin of manycranial nerves.
The pons is the roundedbrainstem region between themidbrain and the medullaoblongata. In fact, pons means“bridge” in Latin.The main function of the pons isto connect the cerebellum to therest of the brain and to modify therespiratory output of the medulla.The pons is the origin of severalcranial nerves.
The ventricles are a complexseries of spaces and tunnelsthrough the center of the brain.The ventricles secretecerebrospinal fluid, whichsuspends the brain in the skull.The ventricles also provide aroute for chemical messengersthat are widely distributed throughthe central nervous system. Click image to play or pause video
Cerebrospinal fluid is a colorlessliquid that bathes the brain and spine.It is formed within the ventricles of thebrain, and it circulates throughout thecentral nervous system.Cerebrospinal fluid fills the ventriclesand meninges, allowing the brain to“float” within the skull. Click image to play or pause video
The brainstem is the mostprimitive part of the brain andcontrols the basic functions oflife: breathing, heart rate,swallowing, reflexes to sight orsound, sweating, bloodpressure, sleep, and balance.The brainstem can be divided Click image to play or pause videointo three major sections.Detailed brainstem anatomy.
The visual cortexresides in the occipitallobe of the brain.Sensory impulsestravel from the eyes viathe optic nerve to thevisual cortex.Damage to the visualcortex can result inblindness.
The gustatory complex(green circle) is the partof the sensory cortex(purple area) that isresponsible for taste.
The prefrontal cortex isinvolved with intellect,complex learning, andpersonality.Injuries to the front lobecan cause mental andpersonality changes.
Prefrontal cortexEmotions are an extremelycomplex brain function. Theemotional core of the brain is thelimbic system. This is wheresenses and awareness are firstprocessed in the brain.Mood and personality aremediated through the prefrontalcortex. This part of the brain isthe center of higher cognitive andemotional functions. Limbic system
Broca’s AreaBroca’s area is where weformulate speech and thearea of the brain that sendsmotor instructions to themotor cortex.Injury to Broca’s area cancause difficulty in speaking.The individual may knowwhat words he or she wishesto speak, but will be unableto do so.
Auditory Association AreaWernicke’s area is aspecialized portion of theparietal lobe that recognizesand understands written andspoken language.Wernicke’s area surrounds theauditory association area.Damage to this part of thebrain can result in someonehearing speech, but notunderstanding it. Wernicke’s Area
There are two auditoryareas of the brain:• The primary auditoryarea (brown circle) is whatdetects sounds that aretransmitted from the ear. Itis located in the sensorycortex.• The auditory associationarea (purple circle) is thepart of the brain that isused to recognize thesounds as speech, music,or noise.
The motor portion of thecerebrum is illustrated here. Thelight red area is the premotorcortex, which is responsible forrepetitive motions of learnedmotor skills. The dark red area isthe primary motor area, and isresponsible for control ofskeletal muscles.Different areas of the brain areassociated with different parts ofthe body.Injury to the motor cortex canresult in motor disturbance in theassociated body part.
The sensory portion of thecerebrum is illustrated here.Different areas of the brain areassociated with different parts ofthe body, as can be seen below.Injury to the sensory cortex canresult in sensory disturbance inthe associated body part.
The brainstem controlsthe basic functions of life.Damage to these areasof the brain are usuallyfatal:•The pons plays a critical Ponsrole in respiration. Medulla Oblongata•The medulla oblongatais responsible forrespiration andcardiovascular functions.