HPO 5-7.pptx - The Nervous System PDF

LECTURE 5 The Nervous System Part I – Structure & Anatomy 1 LECTURE OUTLINE Introduction Divisions of nervous system CNS, PNS, SNS & ANS Structure of Neuron Classification of neurons Structural Functional...

LECTURE 5 The Nervous System Part I – Structure & Anatomy 1 LECTURE OUTLINE Introduction Divisions of nervous system CNS, PNS, SNS & ANS Structure of Neuron Classification of neurons Structural Functional Neuroglia Neuroglia of CNS Neuroglia of PNS Anatomy of Brain Anatomy of Spinal cord 2  Nervous System Master control and communicating system of the body. Sensory input Sensory receptor Integration Motor Output Effector 3 Introduction Two organ systems, the endocrine system and the nervous system, provide the necessary regulation in the body. They work together to control important aspects of body function and maintains homeostasis. Most endocrine responses develop more slowly but last much longer than responses of the nervous system. The nervous system provides faster but generally briefer responses to stimuli by temporarily modifying the activities of other organ systems. The modifications may appear in a matter of milliseconds, but the effects disappear soon after neural activity ceases. 4 Introduction Nervous system consists of Brain, Spinal cord and Nerves. A master & more complex system of the body Nervous system constitutes about 3% of the total body weight Divided into: (1) Central Nervous System (CNS) (2) Peripheral Nervous System (PNS) - Somatic Nervous System (SNS) - Autonomic Nervous System (ANS)  Nervous System 1. Central Nervous System (CNS) Composed of Brain & Spinal Cord 2. Peripheral Nervous System (PNS) Branches out in pairs from spinal cord to the rest of the body. Composed Cranial nerves & spinal nerves. Cranial nerves (12 pairs) – connected to the brain Spinal nerves (31 pairs) – attached to the spinal cord. Carry nerve impulses to and from the spinal cord to body parts not served by the cranial nerves. 6 3. Somatic Nervous System (SNS) Controls skeletal muscle contractions (voluntary) and carry nerves to joints and skin. 4. Autonomic Nervous System (ANS) or Visceral Motor System Controls cardiac and smooth muscles contractions and glandular secretion at some levels (involuntary)  Peripheral Nervous System involuntary voluntary Somatic Autonomic Enteric nervous Nervous Nervous system System System Smooth muscles, Skeletal muscles GI Tract Cardiac muscle, glands 8  The Brain  Contains ~ 100 billion nerve cells (neurons) and trillions of "support Cranial cells” called glia. nerves  In the average adult human, the brain weighs 1.3 to 1.4 kg. The Spinal Cord  About 43 cm long in adult women and 45 cm long in adult men and Spinal weighs about 35-40 gm. nerves  The vertebral column (back bone) that houses the spinal cord, is about 70 cm long. 9 Vertebral Column 10 1. Cervical region is connected to the head, neck, upper body, arms, and hands 2. Thoracic region is connected to the hands, fingers, chest, and abdominal muscles 3. Lumbar region is connected to the hips, knee, ankles, and toe muscles 4. Sacral region is connected to the legs, toes, bladder, and anal muscles 5. Coccygeal region is connected to the skin 11  Central Nervous System (CNS) Peripheral Nervous System (PNS) Autonomic Nervous System Somatic Nervous System (ANS) (SNS) Sympathetic Parasympathetic “Fight or “Rest and Flight” Digest” S: Salivation (SLUDGE) L: Lacrimation U: Urination D: Defecation G: Gastric disturbance E: Emesis (vomiting) 12  Autonomic Nervous System (ANS) The autonomic system controls muscles in the heart, the smooth muscle in internal organs such as the intestine, bladder, and uterus. Controls 2 opposing (antagonistic) actions 1. Sympathetic division – fight or flight 2. Parasympathetic division - relax E.g. Sympathetic system causes your heart to beat faster; the parasympathetic system reverses this effect. 13  Major Components of Nervous System 1. Neurons or nerve cell - Neurons are the basic structural and functional unit of the nervous system. - Neurons can be grouped by structure or by function. - Consists of an axon, dendrites and a cell body. Each neurone has only 1 axon. - Function: Transmit nerve impulses. Nerve impulses only travel in 1 direction, from the receptive area (dendrites), to the cell body and down the length of axon. 2. Neurotransmitters - Chemical substance which travels across a synaptic junction to act on a target cell. 3. Effector organs - Specific tissues stimulated by the nervous system 14 Structure of a Neuron Dendrite Axon terminal Cell body (or) SomaNode of Ranvier Impulse direction Schwann cells Myelin sheath Axon hillock Nucleus http://en.wikipedia.org/wiki/Axon_terminal 15 Nerve and Ganglion A nerve is large bundle of axons wrapped in connective tissue. The cell bodies attached to the axons of a nerve are grouped together as a ganglion. 16  Neuron - Vocabulary Cell body Central part of the neuron Contains the nucleus and other cell organelles and components for various purposes Cytoplasm release neurotransmitter for cell-to-cell communication. Mitochondria generate energy to meet the high energy demands of active neurons. Dendrites Receives incoming signals from other neurons. Axons A single tube-like structure that transmits an electrical impulse along its length to other neurons. Thicker and longer than the dendrites of a neuron Axon hillock The base or initial segment of the axon attached to the thickened region of the cell body. 17 Neuron - Vocabulary Myelin sheath A fatty white insulating substance which surrounds around the axon. It helps to increases the impulse propagation rate along the axon. Node of Ranvier Non-insulated regions between the myelin sheath that allows faster transmission of electrical impulse Schwann cells or neurilemma cells Found only in PNS, form a sheath around peripheral axon The outer surface of Schwann cell is called neurilemma. Plays an important role in the regeneration of cut or injured axons. Axon terminal The end of the axon. Send signal to the dendrite of another neuron 18 The gap between Schwann cells is known as the Node of Ranvier, and serves as points along the neuron for regenerating a signal. 19 Types of Neurons by Structural Classification 20 http://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter12/medialib/CH12/fig_html/fig12_4.html Types of Neurons by Structural Classification Neurons are classified on the basis of the relationship of the dendrites to the cell body and the axon: 1. Anaxonic: - small and have no anatomical clues to distinguish dendrites from axons; all the cell processes look alike. - located in the brain and in special sense organs. - functions are poorly understood. 2. Bipolar: - have two distinct processes—one dendritic process that branches extensively at its distal tip, and one axon, with the cell body between them. - rare but occur in special sense organs, where they relay information about sight, smell, or hearing from the receptor cells to other neurons. - smaller than unipolar or multipolar neurons 21 Types of Neurons by Structural Classification 3. Unipolar, or pseudounipolar neuron: - the dendrites and axon are continuous, basically fused and the cell body lies off to one side. - Most sensory neurons of the peripheral nervous system are unipolar. 4. Multipolar: - have two or more dendrites and a single axon. - most common type of neuron in the CNS. For example, all the motor neurons that control skeletal muscles are multipolar neurons. - axons can be as long as those of unipolar neurons. 22 Different Neurons and their Functions Sensory neurons (afferent) carry signals from the outer parts of your body into the central nervous system Inter-neurons connect various neurons within the brain and spinal cord Motor neurons (efferent) carry signals from the central nervous system to the outer parts (muscles, skin, glands) of your body 23 Types of Neurons by Functional Classification 1. Sensory neuron - Afferent Send nerve impulses to the spinal cord and brain from all over the body. www.dmacc.edu/.../Chapter_8_Nervous_System.htm 24  Types of Neurons by Functional Classification 2. Motor neuron – Efferent Carries impulses away from the spinal cord and brain to muscles and glands. www.dmacc.edu/.../Chapter_8_Nervous_Syste m.htm 3. Interneuron or Connecting Neuron Transmits nerve impulses from one neuronal dendrite to the axon of another neuron. Connects various neurons within the brain and spinal cord All are found only in the gray matter of the brain or spinal cord. 25  Neuroglia (Glial Cell) Neuroglia are nerve supporting cells. Neuroglia are cells in the nervous system that are not neurons. They account for about half of the volume of nervous system. Support, nourish and protect the neurons. Uncontrolled growth of glial cells results in brain tumors. Neuroglial cells found in CNS -Astrocyte, Oligodendrocyte, Microglia & Ependymal cells Neuroglial cells found in PNS -Schwann cells and Satellite cells 26 Neuroglial Cells 27 http://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter12/medialib/CH12/html/ch12_4.html Lateral view of Human Brain showing Different Lobes 28 Watch this: https://youtu.be/5_vT_mnKomY Parts of Human Brain www.dmacc.edu/.../Chapter_8_Nervous_System.htm 29 The Brain Hindbrain - controls basic, automatic and vital task Midbrain Helps coordinates muscle groups and responses to sights and sounds Forebrain Receives and integrates sensory input from the external environment and determine most of our more complex behaviour 30  The Brain A. Brain Stem 1. Consist of a two-way conduction pathway between the brain and other body regions. a. Sensory fibers bring nerve impulse from the spinal cord to the brain. b. Motor fibers carry nerve impulses down from the brain to the spinal cord. 2. Brain stem components: a. Medulla oblongata The two-way conduction pathways associated with the cardiac, respiratory and vasomotor control centers. b. Pons The word, “pons” means bridge Its two-way conduction pathway connects the spinal cord with the brain and parts of the brain with each other. c. Midbrain The two-way conduction pathway for relaying visual and auditory nerve impulses.  The Brain B. Cerebellum 1. Functions: a. Muscular coordination required for normal movements b. Maintains equilibrium c. Sustain normal posture C. Diencephalon 1. Hypothalamus a. The posterior pituitary gland is an extension of the hypothalamus. It produces many hormones (chemicals) that regulate or help control the functioning of every cell in the body. b. Neurons of hypothalamus produce many kinds of hormones. Eg. ADH or Antidiuretic Hormone that maintains the body's water balance by affecting the volume of urine excreted c. Functions:- Regulate body temperature, some metabolic processes and the ANS. The Brain 2. Thalamus a. A section of gray matter located superior to the hypothalamus b. Functions: - Helps produce sensations by acting as a relay between the body’s sense organs and the cerebral cortex. - Assists in sensory perception. - Regulation of motor functions. - Control of sleep and wake cycles  The Brain D. Cerebrum 1. Largest part of the brain that has a. Ridges called convolutions b. Grooves called Sulci or Fissures (deepest grooves) - Divide cerebrum into a right and left half. 2. Cerebral cortex- a thin layer of gray matter that composes the surface of the cerebrum 3. Below the cerebral cortex is white matter that contains a few islands of gray matter known as cerebral nuclei or basal ganglia. 4. Functions: produce automatic movement and postures. Image source: http://www.alzheimer-riese.it/index.php/contributi-dal- mondo/ricerche/4701-la-distinzione-iniziale-tra-alzheimer-e- 35 demenza-frontotemporale Ross and Wilson. Anatomy and Physiology in Health and Illness. Tenth Image source: https://askabiologist.asu.edu/what-your-brain-doing 36  Different Regions of Human Spinal cord Cross section of Spinal cord http://upload.wikimedia.org/wikipedia http://i256.photobucket.com/albums/hh175/bioblogs/spinal_cord.gif 37 Spinal Cord 1. Gray matter Sensory nuclei in gray matter receive and pass sensory information from peripheral receptors. Motor nuclei in gray matter give motor command to peripheral effectors. 2. White matter Carries information from place to place (brain to spinal cord and vice versa). Dorsal root nerves bring stimuli to the spinal cord. Ventral root nerves control somatic and visceral effectors.  Neuronal Connection with Spinal Cord 39 http://www.bio.miami.edu/~cmallery/150/neuro/c7.48.4.kneejerk.jpg Knee Jerk Reflex (Patellar Reflex) Reflexes are rapid, predictable & involuntary responses to stimuli. Imagine you hit your knee with something hard Receptors send a signal into the spinal cord through sensory neuron. The sensory neuron passes the message to a motor neuron that controls your leg muscles. Nerve impulses travel down the motor neuron and stimulate the leg muscle to contract 40 Reflex action - is a stereotyped (involuntary) motor response elicited by a defined stimulus Sensory cells (receptors) in the stimulated body part send signals to the spinal cord along a sensory nerve cell. Within the spine a reflex arc switches the signals straight back to the muscles of the body (in this case the arm or the leg) (effectors) via an intermediate nerve cell and then a motor nerve cell; Contraction of the leg occurs, and the muscle contracts (the arm or leg jerks upwards). Only three nerve cells are involved, and the brain is only aware of the response after it has taken place. 41 Neural Processes Reception See Red Light Information Transmission delivery Integration information processed Transmission Information delivery Actual Response Step on brakes 42  Did you know….? Neurons are the oldest and longest cells in the body! You have many of the same neurons for your whole life. Although other cells die and are replaced, many neurons (especially in brain) are never replaced when they die. 43 What you need to know Be able to label and discuss the structure & anatomy of 1. Different types of nerve cells and neuroglial cells 2. Brain 3. Spinal cord 44  LECTURE 6 THE NERVOUS SYSTEM PART II – NEUROPHYSIOLOGY 45 LECTURE OUTLINE · Functional overview of nervous system · Structure of synapse · Neurotransmitters · Neuromodulators · An overview of neural activities (Action potential) · Different Gated Channels · Function of Central Nervous System · Function Peripheral Nervous System - Somatic Nervous System - Autonomic Nervous System · Nerve reflexes · Monitoring brain activity - Electroencephalogram · Clinical connection · Parkinson Disease 46  Functions of Nervous System Vision Hearing Taste Touch Smell Thinking Balance Co-ordination Mood Memory Sleeping Temperature and so on… 47  Functions of The Nervous System: 1. SENSORY FUNCTION - Gathers information both from the outside world and from inside the body. 2. TRANSMISSION FUNCTION - Transmits the information to the processing area of the brain and spinal cord. 3. INTEGRATIVE FUNCTION - Processes the information to determine the best response. 4. MOTOR FUNCTION - Sends information to muscles, glands, and organs (effectors) so they can respond correctly. Muscular contraction or glandular secretions.  Neurophysiology - Vocabulary Neurotransmitter – chemical compound released by the end of one neuron to pass the impulse to another neuron. Neuromodulator – a compound released by a neuron that adjust the sensitivities of another neuron to specific neurotransmitter. Synapse – the site of communication between a nerve cell and some other cell. Transmembrane potential – the potential difference (mv) measured across plasma membrane that results from the uneven distribution of positive and negative ions. 49 Neurophysiology - Vocabulary Resting potential – the transmembrane potential of a normal cell without any stimulus (or) its homeostatic state. Action potential – a propagated change in the resting/transmembrane potential of cells, initiated by a change in membrane permeability to sodium ions. Depolarization – a change in resting/transmembrane potential from a negative value (-70 mv) to towards 0 mv. 50 Neurophysiology - Vocabulary Repolarization is the return of the membrane potential to their previous resting state, which corresponds with relaxation of the cell. Hyperpolarization is a change in a cell’s membrane potential that makes it more negative. It is the opposite of a depolarization. Reflex – a rapid, automatic response to stimulus. 51 Electrical Activity in Axons THE ACTION POTENTIAL 52  Resting Membrane Potential When a neuron is not sending a signal, it is said to be "at rest.” When a neuron is at rest, the inside of the neuron is negative relative to the outside, due to uneven distribution of charged ions. At rest, there are relatively more sodium ions outside the neuron and more potassium ions inside that neuron. 53 Resting Membrane Potential The resting membrane potential of a neuron is about - 70 mV (mV=millivolt) This means that the inside of the neuron is 70 mV less than the outside. 54 Action Potential (or Nerve Impulse) Action potential is a sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restore it to the resting state. Neurons are “excitable”- that is they convert stimuli to action potentials. A stimulus is anything in the cell’s environment that changes the resting potential. If a stimulus causes the membrane to depolarize beyond a critical level or threshold, then action potential arises. 56 All-or-nothing rule If the neuron does not reach this critical threshold level, then no action potential will fire. When the threshold level is reached, an action potential of a fixed sized will always fire For any given neuron, the size of the action potential is always the same. Refer to Slide 5 for the neurophysiology terms 57  The structure of typical synapse Synapse: A specialized site where the neuron communicates with another cell. Two cells meet at every synapse: (1) the presynaptic cell, which has the synaptic terminal and sends a message, and (2) the post-synaptic cell, which receives the message as shown in the figure. The communication between cells at a synapse most commonly involves the release of chemicals called neurotransmitters by the synaptic terminal. The neurotransmitters are typically packaged in synaptic vesicles. 58 http://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter12/medialib/CH12/fig_html/fig12_3.html  An overview of Neural Activities Resting potential (or) Transmembrane potential: Neuron membrane potential at resting stage (no action) Graded potential: A Stimulus that disturb resting potential and cause temporary and localized change in resting potential of neuron. Action potential: If the graded potential is sufficiently large, 59 it produces an action potential in the membrane of the axon.  Polarisation At resting membrane potential, the membrane is said to be POLARISED. One side is really negatively charged and the other side is really positively charged Neuron at rest is already polarised at -70 mV Depolarisatio n  Depolarisation Change in membrane potential induces Na+ channels to open  Na+ ions flood into the cell The membrane depolarises (becomes less negative) due to influx of positively charged ions 63 Na+ channels open, allowing Na+ to flood in down its concentration gradient and leading to a positive potential inside the neuron. K+ channels are closed, keeping K+ in, so there is now 65 Repolarisation  Repolarisation Na+ channels close when potential reaches +30mV [Na+] decreases as Na+ / K+ ATPase works to restore membrane potential K+ channels open  K+ ions flood out of cell “Repolarise” – become more negative again Na+ channels rapidly close, and [Na+] decreases, as Na+ ions are no longer entering the cell but instead are being actively transported out by the Na+/K+ pump. K+ channels open now, letting K+ flow 69 down its concentration gradient out of the cell  Membrane potential 70 Hyperpolarisation  Hyperpolarisation K+ channels are slow to close  too many K+ ions flood out of cell Causes negative membrane potential to temporarily exceed the resting membrane potential K+ channels eventually close and Na+ / K+ ATPase restores resting potential K+ channels are slower to close than Na+ channels  Excess K+ ions exit the cell, causing a temporary hyperpolarization as the potential inside becomes more negative than at resting potential. Once K+ channels close, the resting potential returns to Action potential: Channels 74 Depolarization, Hyperpolarization & Repolarization Depolarization: any shift from the resting potential (-70 mv) towards the 0 mV. Repolarization: Back to the normal resting potential (-70 mv) Hyperpolarization: An increase in negativity of the resting potential, i.e.> -70 mv. http://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter12/medialib/CH12/html/ch12_5_3.html 75  76 http://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter12/medialib/CH12/fig_html/tab12_3.html  A. Neurotransmitters Acetylcholine (ACh), the most widespread (and best-studied) neurotransmitter, is released at 1. all neuromuscular junctions involving skeletal muscle fibers 2. many synapses in the CNS 3. all neuron-to-neuron synapses in the PNS, and 4. all neuromuscular and neuroglandular junctions of the parasympathetic division of the ANS 77  A. Neurotransmitters Other neurotransmitter: 1. Norepinephrine - widely distributed in the brain and in portions of the autonomic nervous system (ANS) - Also called noradrenaline. 2. Dopamine - CNS neurotransmitter released in many areas of the brain. - Eg. inadequate dopamine production and release in brain can lead to the overstimulation of neurons that control skeletal muscle tone, resulting Parkinson's disease. 78  A. Neurotransmitters 3. Serotonin - CNS neurotransmitter. - Inadequate serotonin production can have widespread effects on attention and emotional states and may be responsible for many cases of severe chronic depression. 4. Gamma aminobutyric acid, or GABA - Generally has an inhibitory effect. - Its release appears to reduce anxiety, and some anti- anxiety drugs work by enhancing these effects. 79  B. Neuromodulators Compounds that can change the rate of neurotransmitter release or response of post-synaptic neuron to specific neurotransmitter. Neuromodulators called opioids have effects similar to those of the drugs opium and morphine. Three classes of opioids are identified in the CNS: (1) the endorphins (2) the enkephalins (3) the dynorphins. Primary function of opioids: Pain relief. Pain relief occurs through the inhibition of the release of neurotransmitter at synapses that relay pain sensations. 80 Sympathetic System “Fight or Flight?” Functions automatically to regulate body functions. Most active when you feel threatened or stressed Goals of the Sympathetic Division 1. To help the body cope quickly with situations that may disrupt homeostasis (like being killed!) Heart pounds, rapid breathing, dilated eyes, more blood to the skeletal muscles………… 81 Parasympathetic System “Rest and Digest” Most active when body is at rest/non-threatened state Goals of the Parasympathetic Division 1. To promote normal digestion Secretions of stomach, liver (bile), small intestine increased, bladder constricted (urination), etc 2. Conserve body energy Decrease demands on cardiovascular system 82  Sympathetic Parasympathetic Speed things up so the body is prepared for the activity. Increase pulse, metabolism, respiration etc… Progressively slow things down to relax. Decrease pulse, metabolism, 83 respiration etc.. http://www.eruptingmind.com/basic-functions-nervous-system/ Monitoring Brain Activity Electroencephalogram (EEG) (Courtesy of Dr K Ng) It is a measurement of the electrical activity of the brain measured from an array of electrodes set on the scalp. When is it used? Diagnose epilepsy, stroke, suspected lesions of brain for tumour, inflammation, etc.. The assessment of impaired consciousness or altered mental state To evaluate cognitive impairment and dementia. Sleep disorders such as narcolepsy. To monitor brain activity when a person is under general anaesthesia., etc... 84 Monitoring Brain Activity Electroencephalograph (EEG) (Beta waves) (Alpha waves) The waveforms in the EEG are generated by impulses near the communication between neurons or nerves in the brain. (Theta waves) They are picked up by the electrodes on the surface of the scalp. (Delta waves) Four types of brainwaves are associated with different levels of arousal: www.answers.com/topic/ electroencephalogram 85  Four Types of Brainwaves 1. Alpha waves are associated with wakefulness, and relaxed. 2. Beta waves with excitement, concentration on tasks, stress and tension. 3. Theta waves occur transiently during sleep in normal adults, but most often observed in children and frustrated adults. Theta waves presence may also indicate brain disorder, eg tumour 4. Delta waves associated with deep sleep and they are generally low-frequency waves. 86 Uses of Electroencephalograph (EEG) 1. To monitor the effects of exercise since there is a close correlation between certain EEG wave patterns and fatigue or overtraining. 2. To determine the extent of injuries inflicted to the head (for example, after a knockout in boxing). 87 Clinical Connection - Parkinson’s Disease Action of Neurotransmitters Some neurotransmitters cause an action potential (i.e. stimulatory). Others prevent an Action Potential (i.e. inhibitory ) – usually by increasing threshold. Parkinson's disease - deficiency of the neurotransmitter dopamine, due to progressive death of brain cells  causing tremors, rigidity and unstable posture. Dopamine acts as inhibitory factor preventing these tremors. 88 Clinical Connection - Parkinson’s Disease Parkinson's disease is a progressive disorder of the nervous system that affects movement. Parkinson ’s disease is noted by the degeneration and damage to the dopamine-producing cells in the brain. Dopamine enables the smooth and coordinated movements of the body’s muscles. Symptoms: The primary symptoms of Parkinson’s include tremors, slowness of movement, rigidity, and a difficulty with balance. Parkinson’s can also induce small, cramped handwriting, stiff facial expressions, shuffling when walking, muffled 89 What You Need To Know Functions of CNS & PNS Neurotransmitters & Neuromodulators Action potential Functions of sympathetic and parasympathetic systems Encephalogram (EEG) 90  LECTURE 7 The Endocrine System LECTURE OUTLINE Exocrine vs. Endocrine Glands Hormone Basics Hypothalamus-Pituitary Relationship Hormones of the Pituitary Thyroid Gland Parathyroid Gland Clinical connection - Goiter - Diabetes mellitus What does “endocrine” mean? “Endo” – within or inside “-crine” – to secrete “Exo” is the opposite of “Endo” 93  What is the Endocrine System? The endocrine system is composed of glands and specialized tissues that produce and secrete hormones into the bloodstream. Functions closely with the nervous system in regulating and integrating body processes. *Exocrine glands are those that secrete their products via a duct. Eg. Sweat glands, salivary glands, mammary glands and many glands of the digestive system  Exocrine vs. Endocrine Glands Endocrine glands are made of secretory cells that release Exocrine glands secrete their their products (hormones) products into ducts. These ducts into the blood stream. either empty outside of the body or inside the body. Eg: thyroid, pituitary, pancreas Eg: sweat, sebaceous glands,  Many Organs Have Mixed Endocrine and Exocrine Functions Major Endocrine Glands that Other Organs with Endocrine also have Exocrine Functions Functions Pancreas also secretes Stomach enzymes Small Intestine Ovary and testes- Placenta Human Chorionic produce ova and Gonadotropin (HCG) sperms, respectively Estrogen and Progesterone Heart Atrial Natriuretic Hormone Kidney Erythropoietin Renin  What are Hormones? Chemical messengers that are secreted by cells into the bloodstream (via the capillary network) and regulate the activities of other cells in the body. When released into the blood, the hormone circulates freely throughout the body. However, a hormone will only affect the activity of its target cells. Cells with receptors for that particular hormone. Once the hormone binds to the receptor, a chain of events is initiated that leads to the target cell’s 3 Major Group of Hormones The chemical groups affect a hormone’s distribution, the type of receptors it binds to, and other aspects of  Hormone Types Lipid Soluble Water Soluble Steroid Hormones Non-steroid amino- acid Synthesized from based hormones and cholesterol. protein based hormones Ovaries, Testes, Protein-based -Insulin, Adrenals secrete Glucagon, ADH, Oxytocin steroid hormones AA-based – epinephrine, histamine, serotonin Organs and Hormones of the Endocrine System 101 The Pituitary The Master Endocrine Gland Located near the brain. (Size of a pea) Controls the activities of many other endocrine glands. The production and secretion of hormones of the pituitary gland are regulated by the hypothalamus. Two Lobes Anterior Pituitary Posterior Pituitary The main difference between anterior and posterior pituitary gland is that the action of the anterior pituitary gland is regulated through vessels connected to the hypothalamus whereas the action of the posterior pituitary gland is regulated through nerves connected to the hypothalamus.  (1) Anterior Pituitary Hormones Hormone Action Growth Hormone Stimulates growth (Esp. bones and (GH) muscles) and metabolism Prolactin Stimulates milk production Follicle-stimulating Stimulate production of ova and sperm hormone (FSH) Luteinizing hormone Stimulates ovaries and testes (LH) Thyroid stimulating Stimulates thyroid gland hormone (TSH) Adrenocorticotropic Stimulate adrenal cortex to secrete hormone (ACTH) glucocorticoids (glucose metabolism.) Hormones of Anterior Pituitary Think “FLAT PiG!” FSH Follicle stimulating hormone LH Luteinizing hormone Adrenocorticotropic Hormone Thyroid Stimulating Hormone Prolactin ignore Growth Hormone  (2) Posterior Pituitary Hormones Hypothalamus also produces 2 hormones which are stored in and secreted from the posterior lobe of the pituitary gland. 1. Oxytocin Stimulating uterine contractions of childbirth Stimulates milk production from mammary glands 2. Antidiuretic Hormone (ADH) or Vasopressin Causes kidneys to reabsorb more water Urinate less Conserves body water  Anterior Posterior 1. Known as 1. Known as adenohypophysis neurohypophysis 2. Mainly involved in regulating 2. Mainly involved physiological in creating functions such as positive feedback growth, reproduction, loops in the body lactation and stress 3. Releases oxytocin 3. Releases ACTH, TSH, and vasopressin FSH, LH, growth factor, prolactin and beta-endorphin (3) Thyroid and Parathyroids Thyroid Thyroxine (T4) Stimulate basal metabolic rate Thyroid Calcitonin Reduces blood calcium levels Parathyroid Parathyroid hormone Increases blood (PTH) calcium levels 107 Thyroid Gland Produces and secretes thyroxine (T4), the main thyroid hormone Secretes T4 when stimulated by the thyroid-stimulating hormone (TSH), from the anterior pituitary T4 stimulates metabolic rate and promotes growth Dietary Iodine is required to produce active thyroid hormones. See next slide: Goiter  Thyroxine (T4) T4 stimulates metabolism and promotes growth T4 stimulates synthesis and use of ATP, cells use more oxygen to produce more ATP, gives off more heat, raises body temp Hyperthyroidism  increased basal metabolic rate, weight loss, low heat tolerance T4 is required for normal foetal CNS development Hypothyroidism in fetus may lead to severe mental retardation 109  Hypothalamus Control of Anterior Pituitary Hormones Hypothalamus Regulation of the secretion of Thyroxine Thyroxine (T4) is responsible for Thyrotropin Release proper growth and development Hormone (TRH) (esp of CNS, in foetus and up to 6mths after birth) and controls the basal metabolic rate (BMR). Anterior Pituitary The secretion of T4 is controlled by negative feedback: the response is opposite to the Thyroid Stimulating stimulus. Hormone (TSH) (-) negative feedback Fall in T4  Ant. Pituitary is more responsive to TRH  more TSH Thyroid secreted more T4 Rise in T4 Ant. Pituitary is less responsive to TRH less TSH Thyroxine less T4. 110  Clinical Connection: Goiter Abnormal enlargement of the thyroid gland Associated with hypo- or hyper-secretion A cause is iodine deficiency Iodine is required for the production of thyroid hormone Low iodine intake (deficiency) decrease thyroid hormone in blood increase secretion of TSH thyroid gland enlarges goiter 111  Thyroid Gland Also releases calcitonin. Stimulates removal of calcium from blood. Calcium is deposited into bone. Helpful Hint: Remember that calcitonin tones down calcium in the blood Parathyroid Glands Embedded in the connective tissue that surrounds the thyroid gland Produce the parathyroid hormone (PTH) PTH increases the levels of calcium in the blood Increases reabsorption and reduce excretion of Ca2+ in Parathyroid kidneys gland Increases dissolving of Ca2+ from bones Parathyroid hormone Negative (PTH) feedback Increase blood Ca2+ level  Calcitonin and PTH have OPPOSITE Effects Calcitonin: Tones down blood calcium. PTH: Raises blood calcium. (4) Pancreas - Islets of Langerhans Exocrine secretion of pancreatic enzymes 115  Pancreas - Islets of Langerhans These are clusters of cells in the pancreas that secrete the hormones insulin and glucagon (and other hormones/peptides) (1) Insulin (secreted by beta cells) Reduces blood sugar concentrations Stimulates uptake of glucose from blood into the cells, especially skeletal muscle fibers and liver cells (2) Glucagon (secreted by alpha cells) Raises blood [glucose] Stimulates liver cells to convert glycogen to glucose 116  (5) Adrenal Glands Located on top of each kidney Two independent regions of tissue 1. Adrenal cortex (outer layer) Steroid hormones (e.g. cortisol) 2. Adrenal medulla (inner layer) Epinephrine (adrenaline) and norepinephrine – fright, fight and flight http://www.yourdictionary.com/adrenal-gland 117  Adrenal Cortex - Steroid Hormones Cortisol Helps adapt the body to long-term stress Essential for glucagon to raise blood sugar (glucose) level effectively Also reduces inflammation and inhibit allergic reaction Aldosterone Maintain sodium and potassium balance in kidneys Increases sodium reabsorption in the distal tubule of kidney nephrons to maintain blood pressure  Adrenal Medulla Hormones Epinephrine (adrenaline) & norepinephrine (noradrenaline) Increase heart, respiratory and metabolic rate Increase alertness, blood pressure Increase blood flow to skeletal muscles Stimulate conversion of glycogen to glucose 119  (6) Ovary Hormones Estrogens Stimulates development of secondary sex characteristics Stimulates growth of sex organs at puberty Prompt monthly preparation of uterus for pregnancy Progesterone Completes preparation of uterus for pregnancy Stimulates breast development for milk production  (7) Testes Testosterone Stimulates development of secondary sex characteristics and growth spurt at puberty Stimulates development of sex organs Stimulates sperm production Case Study 1 What happens after an ice-cream binge? When blood glucose level is high 1. β cells in pancreas detect it Release insulin 2. Enhance membrane transport of glucose into muscle cells. 3. Uptake of sugar by muscle cells 4. Glycogen formation in liver 5. Lowers blood sugar level Hypoglycemic effect Case Study 2 What happens when you starve? When blood glucose level is low 1. α cells in pancreatic cells detect it Secrete glucagon 2. Glycogen breakdown in liver cells 3. Raises blood sugar level Hyperglycemic effect Clinical Connection: Diabetes Mellitus Due to lack of insulin Insulin stimulates the cells to absorb glucose In diabetes mellitus, the cells does not absorb enough glucose glucose remains in the blood eventually appear in the urine NERVOUS SYSTEM versus ENDOCRINE SYSTEM Comparison of Nervous and Endocrine control/co-ordination Differences Nervous System Endocrine System Communication Impulses across By chemical Hormones synapses by chemical (means) through and electrical means circulatory system Transmission faster slower Response Faster & localized Slower & widespread throughout the body Target Pathway Specific (through Hormones broadcast to nerves) to specific target cells everywhere cells Action Causes glands to Causes changes to secrete or muscle to metabolic activity contract What you need to know Basics: Difference between endocrine and exocrine gland What are hormones How nervous and endocrine systems are different Hormones secreted by Pituitary Thyroid and Parathyroid Hormones How are blood calcium levels maintained? Hormones of Adrenal cortex, Ovary & Testes Comparison of nervous and endocrine control Clinical connection What causes goiter? Diabetes mellitus  Anterior Pituitary Hormones Hormone Action Human Growth Stimulates growth (Esp. bones and Hormone (HGH) muscles) and metabolism Prolactin Stimulates milk production Follicle-Stimulating Stimulate production of ova and Hormone (FSH) sperm Luteinizing Stimulates ovaries and testes Hormone (LH) Thyroid- Stimulates thyroid gland Stimulating Hormone (TSH) Adrenocorticotropi Stimulate adrenal cortex to c Hormone (ACTH) secrete glucocorticoids (glucose metabolism.) 130  Hormone Action Oxytocin Stimulates smooth muscle contraction of (Posterior) uterus and breasts (milk secretion) Anti-Diuretic Hormone Increases permeability of collecting duct (ADH) aka of kidney nephrons to water Vasopressin (Posterior) Thyroxine (T4) Stimulates metabolic rate (Thyroid) Calcitonin Inhibits osteoclast activity; increases (Thyroid) renal Ca2+ excretion 131  Hormone Action Parathyroid Hormone Indirectly stimulates osteoclasts; (Parathyroid) enhances renal and digestive Ca2+ absorption Insulin Decreases blood sugar (Pancreas) Glucagon Increases blood sugar (Pancreas) Cortisol Helps to regulate metabolism during (Adrenal) times of stress by increasing blood sugar; immunosuppressive Aldosterone Increases Na+ reabsorption in distal (Adrenal) tubule and collecting duct of kidney nephron; crucial for maintaining blood pressure Epinephrine Stimulate sympathetic nervous system; Norepinehrine increases heart, respiratory, metabolic (Adrenal) rates; see slide for more functions 132  Hormone Action Estrogens and Progesterone Stimulate development of female (Ovary) secondary sex characteristics and prepare the body for childbirth Testosterone Stimulates development of male (Testes) secondary sex characteristics and sperm production