AVS 3350 Domestic Animal Physiology Review Final Exam PDF

AVS 3350 Domestic Animal Background design is of Cal Physiology Poly Pomona logo 1 Disclaimer This study guide is not all inclusive The instructor provides this as a guide slides Doesn’t assure...

AVS 3350 Domestic Animal Background design is of Cal Physiology Poly Pomona logo 1 Disclaimer This study guide is not all inclusive The instructor provides this as a guide slides Doesn’t assure that there will be no questions outside of this study slides You should study the course material 2 Study Guide -- Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 3  CNS Integrated Functions: Sensory Physiology 10 Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 4 Peripheral Nervous System Peripheral Nervous System (peripheral nerves and receptors) - Afferent Division (Sensory information IN) - Efferent Division (Motor responses) 5 The Vertebrate Nervous System Afferent Branch of Peripheral Nervous System Sensory pathways relay sensory information to the appropriate area of the cortex. Information from periphery to CNS – External environment - sensory – Special Sense (vision, hearing, taste, and smell) – Internal environment - visceral afferent 7 White Matter vs Gray Matter- Vocabulary Gray matter: non- myelinated material (cell bodies, dendrites, non- myelinated axons) - Nuclei: group of cell bodies in the CNS - Ganglia: group of cell bodies in the PNS White matter: myelinated axons - Tracts: bundle of axons in CNS - Nerves: bundles of axons in PNS 8 Sensory Processing- Vocabulary Sensory neurons - Are cells located in the Afferent Division of the Peripheral Nervous System - Receive information from peripheral sensory receptors Sensory nerves - Are bundles of sensory axons in the Peripheral Nervous System - Contact neurons in the CNS (spinal cord or brain) 9 Sensory Processing- Vocabulary Stimulus - Change which is detectable by the body Sensory Transduction - Conversion of stimulus energy into electrical energy - Example: light, heat, sound Receptor - Structure with an afferent neuron that responds to stimuli by producing depolarizing graded potentials- receptor potential 10 The Main Divisions Of Sensory Processing Somatic - body senses, skin, muscles, joints Special Senses - vision, hearing, equilibrium, taste, smell Visceral - organs, chemicals in blood, pH 11 Receptor Physiology Sensory receptors Transduction Adaptation 12 Receptor Physiology- Sensory Receptors Location As a specialized ending of a peripheral sensory neuron As a separate receptor cell - closely associated with the peripheral ending of a sensory neuron A sensory receptor that is specialized A sensory receptor that is a separate ending of an afferent neuron. cells from the afferent neuron. 13 Receptor Potential in Specialized Afferent Ending Receptor Potential in Separate Receptor Cell Receptor Potentials The stimulus acts on the sensory receptor by opening or closing ion channels, thereby producing a receptor potential Receptor Function Detects the Stimulus Respond to stimuli – by producing depolarizing graded potentials (receptor potentials) Converts the energy from the stimulus into electrical signals - Sensory Transduction 17 Transduction Conversion of stimulus energy into electrical energy Energy form of stimulus= Modality - Examples of modality: light waves, sound waves, pressure, temperature 18 Law of Specific Nerve Energies A given Sensory Receptor show specificity to a modality - Special cells in the eyes, photoreceptors detect light waves, but not sound waves Adequate stimulus= modality to which the sensory receptor responds best 19 Characteristics of Sensory Receptors Types 20 Sensory Pathways: Orders of Sensory Processing Third Order Sensory Neuron: - The neuron, 3rd in the chain of processing, in the CNS (thalamus) and will continue to the cortex Second Order Sensory Neuron: - The neuron 2nd in the chain of processing, usually in CNS (spinal cord or medulla oblongata, brainstem) First order Sensory Neuron: - The peripheral sensory neuron that first detects the stimulus 21 Somatosensory Pathways Two main pathways transmit information from peripheral somatosensory receptors to the central nervous system: 1- The dorsal column–medial lemniscal pathway - Fine touch, vibration, propioceptors 2- Spinothalamic tract - Lateral: Temperature and pain - Anterior: Crude touch and pressure 22 Somatosensory Pathways These pathways transmit different types of sensory information to: - the thalamus, and then to the primary somatosensory cortex. Both pathways enter the spinal cord on one side and cross to the other side before reaching the thalamus. - Somatosensory information from the right side of the body is perceived in the left somatosensory cortex, and vice versa 23 The Dorsal Column–Medial Lemniscal Pathway Transmits information from mechanoreceptors and proprioceptors to the thalamus It crosses to the other side of the CNS in the medulla oblongata The first-order neurons originate in the periphery and enter the dorsal horn of the spinal cord. Collaterals from the main axon may terminate in the spinal cord, communicating with interneurons The main branch of the axon ascends from the spinal cord to the ipsilateral brainstem in the dorsal columns The first-order neurons terminate in the medullary dorsal column nuclei where they form synapses with second-order neurons. The second-order neurons then cross over to the contralateral side of the medulla in a tract called the medial lemniscus and ascend to the thalamus. In the thalamus, the second-order neurons synapse with third-order neurons, which transmit information from the thalamus to the somatosensory cortex. 24 The Spinothalamic Tract The spinothalamic tract transmits information from thermoreceptors and nociceptors to the thalamus Crosses to the other side of the CNS within the spinal cord before it reaches the brain First-order neurons originate in the periphery at either thermoreceptors or nociceptors and enter the dorsal horn of the spinal cord. Here, first-order neurons form synapses with second order neurons in the dorsal horn. The second-order neurons cross over to the contralateral side of the spinal cord, ascend in the anterolateral quadrant of the spinal cord through the brainstem, and then terminate in the thalamus. In the thalamus, second-order neurons form synapses with third-order neurons that ascend to the somatosensory cortex. 25 Autonomic Nervous System 11 Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 26 The Vertebrate Nervous System The Somatic Nervous System Controls skeletal muscle - Coordinate the body involuntary functions- organs systems It is voluntary muscle movement and skeletal muscle reflexes The Somatic Nervous System A motor neuron travels from the CNS - to innervate skeletal muscle cells - corticospinal pathway is the major somatic efferent pathway Motor neurons originate in: - the ventral horn of the spinal cord Receive input from multiple sources - from afferents (for spinal reflexes) - the brainstem extrapyramidal tracts - and the cerebral cortex pyramidal tract The Somatic Nervous System A single motor neuron innervates - many muscle cells (called muscle fibers) - but each muscle fiber is innervated by only one motor neuron A motor neuron + all the muscle fibers it innervates - constitutes a motor unit When a motor neuron is activated: - it stimulates all the muscle fibers in its unit to contract Neuromuscular Junction The Autonomic Nervous System It about involuntary functions - Coordinate the body involuntary functions- organs systems - cardiovascular, respiratory, digestive, urinary, and reproductive functions - water, electrolyte, nutrients and gas concentration It has two branches: - Sympathetic and Parasympathetic Receives sensory information from: - specialized receptors (enteroreceptors) - which monitor the body’s internal and automatic functions Dual Innervation of the Autonomic Nervous System Primary function—regulate organs to maintain homeostasis Parasympathetic and sympathetic activities tend to oppose each other - Parasympathetic nervous system—cranial sacral- rest and digest - Sympathetic nervous system—thoraco lumbar - fight or flight response 33 Autonomic Nervous System Anatomy Parasympathetic: “Rest and digest” or cranio-sacral division - Axons emerge from the brainstem and the sacral segments of the spinal cord - and they innervate ganglia very close to (or within) target organs Sympathetic: “Fight or flight” or thoracolumbar division - Axons emerge from the thoracis and superior lumbar segments of the spinal cord - and innervate ganglia relatively close to the spinal cord Enteric Nervous System: is unique in the body - Made up of sensory, motor, and interneurons that are found in and around GI tract - They coordinate the activity of GI tract without CNS input - Sympathetic and parasympathetic influence the enteric but they don’t control it Anatomy of the Autonomic Nervous System The autonomic nervous system consists of efferent pathways containing two types of neurons These neurons communicate with one another through synapses located in peripheral structures called autonomic ganglia neurons that travel from CNS to the ganglia= Preganglionic neuron neurons that travel from the ganglia to the effector organs=Postganglionic neuron Terminology: autonomic ganglia= collection of cell nerves body found outside of CNS Within each ganglion: the axon terminal of preganglionic neurons and the cell bodies and dendrites of postganglionic neurons 35 Anatomy of Autonomic Pathways In autonomic pathways: The preganglionic neuron originates in the CNS and travels to a ganglion in the periphery, where it synapses with postganglionic neuron that innervates one of several types of effector organ. 36 Anatomy of the Sympathetic Nervous System Preganglionic neurons originate in thoracolumbar spinal cord General anatomy Short preganglionic neurons to sympathetic chain Long postganglionic neurons from chain to effector organs Ganglia linked together in sympathetic chain 37 Anatomy of Sympathetic Preganglionic and Postganglionic Neurons The preganglionic neurons originate in a region of gray matter called the lateral horn and exit the spinal cord in the ventral root Anatomical pathways of preganglionic and postganglionic neurons in the sympathetic nervous system. 38 Parasympathetic Nervous System Anatomy Preganglionic neurons originate in brainstem or sacral spinal cord (craniosacral division) Anatomy parasympathetic preganglionic neurons are relatively long terminate in ganglia located near the effector organ or within the effector organs in the ganglia, they form synapses with short postganglionic neurons that travel to the effector organ 39 Parasympathetic Nervous System Pathways 40 Quick Check Which of these organs listed below is not directly innervated by the autonomic nervous system? A- The hearts B- Sweat glands C- Smooth muscle D- Skeletal muscle E- Salivary glands Question Preganlionic fibers from the thoracic and lumbar segments of the spinal cord are part of the _______ division of the ANS A- Central B- Sympathetic C- Somatic motor D- Parasympathetic E- Ganglionic Neurotransmitters of the Autonomic Nervous System Preganglionic neurons of both the sympathetic and parasympathetic branches of the autonomic nervous system release Acetylcholine Parasympathetic postganglionic neurons Acetylcholine Sympathetic postganglionic neurons Norepinephrine and epinephrine NOTE: Acetylcholine is also the sole neurotransmitter of the somatic branch of the efferent nervous system 43 Autonomic Neurotransmitters Neurons that release the more commonly acetylcholine – are referred to as cholinergic Neurons that release norepinephrine – are referred to as adrenergic 44 Sympathetic Nervous System-Neurotransmitters and Receptors Neurotransmitters and receptors for three anatomical pathways of the sympathetic nervous system. In all cases, the preganglionic neuron releases acetylcholine which binds to the nicotinic cholinergic receptors on either postganglionic neurons or endocrine cells in the adrenal medulla. The postganglionic neurons release norepinephrine (NE) which binds to adrenergic receptors on the effector organs. Parasympathetic Nervous System-Neurotransmitters and Receptors Acetylcholine is released from both preganglionic and postganglionic neurons – it bind to nicotinic cholinergic receptors on the postganglionic neuron, – and to muscarinic cholinergic receptors at the effector organ 46 Autonomic Neuroeffector Junctions The synapse between an efferent neuron and its effector organ is called a neuroeffector junction. 47 Events at the Neuroeffector Junction 1. Action potential arrives at varicosity 2. Voltage-gated Ca2+ channels open 3. Ca2+ triggers exocytosis of neurotransmitter 4. Neurotransmitter binds with receptors on effector organ 5. Response in effector organ 6. Neurotransmitter degraded, diffuses away, reuptake 48 Anatomy of Neuroeffector Junctions in the Autonomic Nervous System 49 Central Control of the Autonomic Nervous System Hypothalamus Pons and medulla oblongata - Contain cardiovascular and respiratory regulatory centers - that control the heart, blood vessels, and smooth muscle in the respiratory airways - and regulate the automatic breathing patterns that do not require conscious thought - These areas of the brain receive input from hypothalamus, cerebral cortex, and limbic system - They also receive afferent information needed for reflex control of visceral function Brain Areas Exerting Control of Autonomic Functions This midsagittal section of the brain: the pons and medulla oblongata of the brainstem the hypothalamus 51 Comparison- Summary Slide Sympathetic: - Short preganglionic fiber - Sympathetic ganglia releases the neurotransmitter directly in the blood stream - Postganglionic fiber is long and releases epinephrine and norepinephrine at the target Parasympathetic: - Long preganglionic fiber - Ganglia is locater in or near the organ of effect - Preganglionic neuron release acetylcholine - Postganglionic fiber is short and releases acetylcholine at the target (black arrow) - Postganglionic neuron has nicotinic receptors - At the target we have muscarinic receptor Comparison- Summary Slide Stimulates metabolism Promotes relaxation Muscle Physiology I 13 Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 54 Structure of a Skeletal Muscle Bone Muscle body Tendon Structure of a Skeletal Muscle Inside the muscle fiber contains thousands of myofibrils - Myofibrils are bundles of protein filaments that contain the contractile elements Cylindrical shape Structure of a Skeletal Muscle Contract only when stimulated by central nervous system Called voluntary muscles Skeletal muscle contain: - Extensive vascular network Deliver oxygen and nutrients Remove metabolic waste Components of a Muscle Fiber- Terminology Muscle fibers surrounded by connective tissue= endomysium - Sarcolemma = plasma membrane of muscle fiber - Sarcoplasm = cytoplasm of the muscle fiber - Sarcoplasmic Reticulum (SR) = smooth ER (high in Calcium) Components and Structure of a Muscle Fiber Myofibrils - Lengthwise subdivisions within a muscle fiber - Responsible for muscle contraction - Made up of bundles of protein filaments (myofilaments) - Two types of myofilaments: Thin filaments - Composed of primarily actin- globular protein Thick filaments - Composed primarily of myosin- both fibrous and globular protein Components and Structure of a Muscle Fiber Components and Structure of a Muscle Fiber Sarcomere- The contractile Unit - Myofibrils are composed of a fundamental unit called sarcomere - Repeats over and over - Interactions between filaments produce contraction - Sarcomere is the contractile unit of a myofibril - Arrangement of filaments accounts for striated pattern of myofibrils Dark band (A bands) Light bands (I bands) Sarcomere Structure A Band - M line Located the center of A band Proteins stabilize position of thick filaments - H band On either side of M line Has thick filaments but no thin filaments - Zone of overlap Dark region Where thick and thin filaments overlap Sarcomere Structure I Band - Contains: Thin Filaments, but not thick filaments It has Z lines - Which bisect I bands - Mark boundaries between adjacent sarcomeres - Titin Elastic, support protein Extend from tips of thick filaments to the Z line Anchors thick filaments between M-line and Z-line Provides structural support and elasticity Aids in restoring resting sarcomere length Sarcomere Structure Sarcomere Structure H zone I bands I bands A bands A band - dark striations, thick filaments and thin filaments overlap I band - light striations, thin filaments only, no overlap H zone - thick only, no overlap Z disk – accessory proteins, anchoring point, link thin filaments M line – located in the center of A band, accessory proteins, link thick filaments Sarcomere - Z to Z Structure of a thin filament Thin filaments (also known as Actin) contain: – F actin, nebulin, tropomyosin, and troponin protein – Filamentous actin (F-actin) Made up of twisted strand composed of two rows of globular G-actin molecules Active sites on G- actin bind to myosin – Nebulin Holds F-actin strand together (gives stability) Structure of a Thin Filament Thin filaments are made up of two spirals of actin subunits 3 Proteins in thin filaments – Actin- contractile protein – Tropomyosin Regulatory – Troponin proteins Each G actin has a binding site for myosin Actin has binding sites for myosin Troponin Regulatory protein Complex of three proteins – Attaches to actin – Attaches to tropomyosin – Binds calcium reversibly Calcium binding to troponin regulates skeletal muscle contraction Structure of a thin filament Structure of a thin filament-cont - Tropomyosin Covers active sites on G-actin Prevents actin-myosin interaction - Troponin A globular protein Binds tropomyosin, G-actin and Ca2+ Structure of a Thick Filament Tails face M line Heads face thin filaments Crossbridge Cycle Myosin head undergoes conformation changes swiveling back-and-forth Provides the power stroke for muscle contraction When the crossbridge changes conformation it binds ATP – This is called: Low-energy conformation As ATP it is hydrolyzed to ADP and Pi, it transfer E to the myosin crossbridge. – This is called: High-energy conformation – ADP and Pi bound to myosin Sliding-Filament Mechanism Within a sarcomere during contraction – H zone and I bands shortens – Zones of overlap widen – Z lines move closer together – A band stays same length/width – Thin filaments slide toward center of sarcomere – Sarcomere shortens Sliding is due to cyclical formation/breaking of cross bridges = crossbridge cycle Sliding-Filament Mechanism Sliding-Filament Mechanism Exposing the binding site on actin Crossbridge Cycle Step 1. Binding of myosin to actin We start with myosin in its energized form; that is, ADP and Pi are bound to the ATPase site of the myosin head In this state, the myosin head binds to an actin monomer in the adjacent thin filament Crossbridge Cycle Step 2. Power stroke When power stroke occurs the bound ADP and phosphate group are release During this process, the myosin head pivots toward the middle of the sarcomere, pulling the thin filament along with it Crossbridge Cycle Step 3. Rigor. As the power stroke ends, ADP is released from the myosin head and the myosin molecule goes into its low-energy state. In this state, myosin and actin are tightly bound together, a condition called rigor Rigor mortis—the stiffening of the body that occurs after animal death Occurs because the crossbridge cycle gets stuck at this step due to (1) an excess of calcium and (2) a lack of ATP due to the termination of energy production Rigor mortis continues until enzymes leaked by disintegrating cellular components begin to break down the myofibrils Crossbridge Cycle Step 4. Unbinding of myosin and actin- Cross bridge detachment A new ATP enters the binding site on the myosin head Triggering a conformational change in the head, – which decreases the affinity of myosin for actin, so the myosin detaches from the actin The active site is now exposed and able to form another cross-bridge Crossbridge Cycle Step 5. Cocking of the myosin head. Soon after it binds to myosin’s binding site, ATP is split by hydrolysis into ADP and Pi, which releases energy. Some of the energy is captured by the myosin molecule as it goes into its high-energy conformation. Although ATP has been hydrolyzed at this point, the end- products of the reaction (ADP and Pi) remain bound to the ATPase site. Crossbridge Cycle Ca ions are actively transported from the cytosol to the sarcoplasmic reticulum by ion pumps. If calcium is present, the cycle will continue by revisiting step 1. Myosin reactivation occurs when free myosin head splits ATP into ADP and P. The energy released is used to recock the myosin head Role of Calcium in Contraction No Calcium - troponin holds tropomyosin over myosin binding sites on actin – No crossbridges form between actin/myosin – Muscle relaxed Role of Calcium in Contraction a. action potential. b. Synaptic vesicle which stores and releases AcH c. axon terminal d. Chemically gated ion channel opened by acetylcholine e. Acetylcholine. f. Synaptic cleft. g. Motor end plate. h. acetycholinerase (AChE).  Endocrine System: Glands and Hormone Actions 15 Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 85 Intercellular communication - Endocrine system Include all endocrine and tissues that produce hormones or paracrines Endocrine cells release secretions into cellular fluid Endocrine organs are scattered throughout body as discrete endocrine organs as subsets of other organs having nonendocrine functions 86 Hormones Messenger of endocrine system = hormone – Released from endocrine gland into the interstitial fluid and then diffuse into the blood – Transported in blood to target cell Target cell - cells in body with receptors specific to the hormone 87 Endocrine System Mechanisms of intercellular communication - Direct communication Exchange of ions and molecules between adjacent cells across gap junctions Occurs between two cells of the same type Highly specialized and relatively rate - Paracrine Communication Chemical signals transfer information from cell to cell within a single tissue 88 Chemical Classification of Hormones Amino acids derivates- melatonin-from tryptophane Peptide hormones- thyroid stimulating hormone, oxytocin, prolactin Lipid derivates or steroid hormones- estrogen 89 Chemical Classification of Hormones Amino acid derivates (biogenic amines) Small molecules structurally related to amino acids Thyroid hormones Catecholamines epinephrine, norepinephrine and dopamine Serotonin and melatonin 90 Chemical Classification of Hormones Peptide hormones Bigger molecules Chains of amino acids Different categories such as: Glycoproteins Proteins more than 200 amino acids long have carbohydrate side chains Ex: TSH (thyroid-stimulating hormone), LH (luteinizing hormone), FSH (follicle stimulating hormone) 91 Chemical Classification of Hormones Peptide hormones Short-chain polypeptides Antidiuretic Hormone (ADH) and Oxytocin Small proteins Insulin Growth hormone Prolactin 92 Chemical Classification of Hormones Lipid derivatives: Eicosanoids and steroids Eicosanoids Derive from arachidonic acid, (fatty acid) Paracrines that coordinate cellular activity Affect enzymatic processes (blood clotting) Some eicosanoids (leukotrienes) have secondary roles as hormones Prostaglandins coordinate local cellular activities 93 Chemical Classification of Hormones Lipid derivatives: Steroids Derive from cholesterol Include several hormones Calcitriol (kidney) Corticosteroids from adrenal cortex Androgens (testes in males) Estrogens and progesterone (ovaries in females) 94 Classification of Hormones – Hydrophilic hormones – Hydrophobic hormones 95 Transport of Hormones – Hydrophilic hormones Peptides, catecholamines Dissolved in plasma – Hydrophobic hormones Steroids (estrogen, testosterone, and progesterone), thyroid hormones Bound to carrier proteins Only free hormone can bind to receptor and be metabolized Carrier proteins increase the half life or hormones – so they are present in the blood for longer period by decreasing the rate of their metabolism 96 Transport of Hormones 97 Endocrine Glands – The organs of the endocrine system are derived from epithelial tissue Primary endocrine organs: – primary function: secretion of hormones: hypothalamus, pituitary gland, thyroid, thymus, adrenal glands, pancreas Secondary endocrine organs – secretion of hormones is secondary: heart, liver, kidney, stomach, small intestine and skin 98 Hypothalamus- The Master It is a part of the brain with many functions in addition to its role as an endocrine gland Synthesizes: ADH (antidiuretic hormone) and OXT (oxytocin) and transport them to posterior pituitary gland for release Secretes: regulatory hormones that control secretory activity of anterior pituitary gland Contains autonomic centers that exert direct control over adrenal medulla It is considered a primary endocrine gland because it secretes several hormones most of which affect the pituitary gland 99 Pituitary Gland Hangs inferior to hypothalamus Pituitary gland- also called the hypophysis A pea-sized structure that is connected to the hypothalamus by a thin stalk of tissue called the infundibulum Stem that hangs down, that attaches the hypothalamus and pituitary Releases 9 important peptide hormones Cant get in so: Binds to extracellular receptors Uses cAMP as second messenger 100 Pituitary Gland The pituitary gland is divided into two structurally and functionally sections: - Anterior Pituitary Lobe - The connection between hypothalamus and two lobes of pituitary are critical to the function of both endocrine glands glandular tissue) - Posterior Pituitary Lobe - a neural tissue/ also called neurohypophysis 101 Hypothalamus & Pituitary Gland 102 Hormones- Anterior Pituitary The anterior lobe of the pituitary gland and the cells of the hypothalamus that control it, secrete primarily: - Tropic hormones (also called trophic hormones) - Regulate the secretion of other hormones - Stimulating/releasing hormone - increases the secretion of another hormone - Inhibiting hormone - decreases the secretion of another hormone 103 Hypothalamus Hormone Hypothalamus secretes hormone into capillary bed: - Blood with tropic hormones enters portal vein - Hypothalamic hormones access anterior pituitary secretory cells through capillary beds - These tropic hormones act on endocrine cells in the anterior pituitary to affect the release of hormones that (except for prolactin) are also tropic hormones - Anterior pituitary hormones enter bloodstream in same capillary bed - Travel to distant endocrine gland to trigger to stimulate and release of hormone 104 Tropic Hormones of Hypothalamus and Anterior Pituitary 105 Tropic Hormones of Hypothalamus and Anterior Pituitary Prolactin releasing hormone (PRH) - Stimulates the anterior pituitary to release prolactin (PRL) - Which stimulates mammary gland development and milk secretion in females Prolactin inhibiting hormone (PIH), or dopamine - A catecholamine - Inhibits the release of prolactin 106 Tropic Hormones of Hypothalamus and Anterior Pituitary Thyrotropin releasing hormone (TRH, or thyrotropin) - Stimulates the release of thyroid stimulating hormone (TSH) from the anterior pituitary - TSH then stimulates the secretion of thyroid hormones by the thyroid gland. - Thyroid hormones regulate metabolism 107 Tropic Hormones of Hypothalamus and Anterior Pituitary Corticotropin releasing hormone (CRH) - stimulates the release of adrenocorticotropic hormone (ACTH) by the anterior pituitary. - ACTH then stimulates the secretion of glucocorticoids, such as cortisol, from the adrenal cortex, the outer layer of the adrenal gland. - Cortisol is the main hormone that regulates metabolism when the body is stressed. 108 Tropic Hormones of Hypothalamus and Anterior Pituitary Growth hormone releasing hormone (GHRH) - Stimulates the secretion of growth hormone (GH) by the anterior pituitary. - GH regulates growth and energy metabolism but also functions as a tropic hormone by stimulating the secretion of insulin-like growth factors (IGFs) by the liver 109 Tropic Hormones of Hypothalamus and Anterior Pituitary Growth hormone inhibiting hormone (GHIH), or somatostatin - Inhibits the secretion of growth hormone by the anterior pituitary - thereby decreasing IGF release from the liver 110 Tropic Hormones of Hypothalamus and Anterior Pituitary Gonadotropin releasing hormone (GnRH) - Stimulates the release of the gonadotropins: - Follicle stimulating hormone (FSH) - FSH promotes the development of egg cells in females and sperm cells in males - it stimulates the secretion of estrogens in females and inhibin in both sexes. - Luteinizing hormone (LH) by the anterior pituitary - LH stimulates ovulation in females, - Stimulates the secretion of sex hormones (estrogens and progesterone in females and androgens in males) by the gonads 111 Tropic Hormones Anterior Pituitary: Summary - Thyroid Stimulating Hormone (TSH) - Adrenocorticotropic Hormone (ACTH) - Prolactin (PRL) - Growth Hormone (GH) - Gonadotropins - Follicular Stimulating Hormone - Luteinizing Hormone 112 Questions? Name the two hormones released in the posterior pituitary gland. Name three hypothalamic tropic hormone and explain how it affects the release of a hormone in the anterior pituitary gland. 113 Hormone Interaction Often more than one hormone affects a given body function Examples: Blood calcium levels are regulated by: calcitonin, parathyroid hormone, and 1,25-dihydroxy vitamin D3 Blood glucose levels are regulated by insulin, glucagon, epinephrine, cortisol, and growth hormone 114 Hormone Interaction When the effects of the hormones oppose each other, a process called antagonism Examples: Parathyroid hormone increases blood calcium levels, whereas calcitonin decreases blood calcium levels Glucagon increases blood glucose levels, whereas insulin decreases blood glucose levels. 115 Hormone Interaction When two or more hormones produce the same type of response in the body, the effect can be: – Additive in which case the net effect equals the sum of the individual effects – Synergistic in which case the net effect is greater than the sum of the individual effects In some cases, the presence of one hormone is needed for another hormone to exert its actions, – a process called permissiveness 116  The Cardiovascular System: 17 Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 117 The Cardiovascular System The heart a muscular pump that drives the flow of blood through blood vessels Blood vessels conduits through which the blood flows Blood a fluid that circulates around the body carrying materials to and from the cells 118 The Function of Cardiovascular System The heart - Generate the force that propels blood through the blood vessels - Pumps blood through vessels to various organs - and the blood carries oxygen and nutrients to tissues, - and removes carbon dioxide and other wastes - Sensory and endocrine function - that help regulate cardiovascular variables such: - as blood volume and blood pressure 119 The Function of Cardiovascular System Blood vessels - Conduits for blood - Important sensory and effector organs - that regulate blood pressure - and the distribution of blood to various parts of the body 120 The Function of Cardiovascular System Blood - Transport waste, nutrients - Transports hormones from one part of the body to another - Serves as a communication link acting in conjunction with nervous system 121 Anatomy of The Heart It is a large muscle- size of fist Forms a double- sided pump - one side pumps blood to the lungs and receives blood from the lungs - the other side pumps blood to the body and receives blood from the body Made up of: – cardiac muscle, cardiac nervous tissue, protective epithelial and connective tissues 122 Anatomy of The Heart R L Four chambers – 2 Atria – 2 Ventricles Septum (wall) – Interatrial – Interventricular Base Apex 123  The Cardiovascular System: The heart wall consists of three layers: a. Endocardium (inner) b. Myocardium (middle) c. Epicardium (outer) Heart Valves Atrioventricular valves = AV valves – Left AV valve = bicuspid valve = mitral valve – Right AV valve = tricuspid valve – Papillary muscles and chordae tendinae Enable AV valves to seal properly Semilunar valves – Aortic Valve – Pulmonary Valve 125 Action of the AV Valves 126 Action of the Semilunar Valves 127 Path of Blood Flow Through the Cardiovascular System Right ventricle contain deoxygenated blood Left ventricle contain oxygenated blood 128 Conduction System Pacemaker cells – Spontaneously generate action potentials – Coordinate and establish heart rhythm Conduction fibers – Rapidly conduct action potentials initiated by pacemaker cells to myocardium – Conduction velocity = 4 meters/second – Ordinary muscle fibers= 0.4 meter/second Conduction system= pacemaker cells + conduction fibers Contractile cells= The cells that generate the contractile force 129 Pacemaker Cells of the Myocardium Pacemaker of the heart determine the pace of the heart beat by firing action potentials Sinoatrial node (SA) – located in the wall of the upper right atrium – faster inherent rate of spontaneous depolarization 130 Pacemaker Cells of the Myocardium Cont Atrioventricular node (AV) – located near the tricuspid valve in the interatrial septum SA node and AV nodes are connected by conduction fibers – SA node drives the depolarization of the cells in the AV node and throughout the heart – establishing the heart rate 131 Conduction Fibers of the Myocardium Specialized to quickly conduct action potentials – generated by pacemaker cells from place to place through the myocardium – thereby triggering heart muscle contractions Internodal pathways Bundle of His Purkinje fibers 132 Spread of Excitation Between Cells Action potential initiate at pacemaker cells Moves rapidly through the conduction fibers The conduction system cause atria to depolarize and contract as a unit The wave of excitation moves – through the ventricles causing them to contract as a unit Rapid transmission of action potential is due to – presence of gap junctions and conduction pathways Gap junctions are concentrated in structures called Intercalated disks – Junctions between adjacent myocardial cells – Desmosomes (protein fibers) to resist mechanical stress – Gap junctions for electrical coupling 133 Spread of Action Potentials Through the Heart The spread of action potential through the heart: a) starting with depolarization of the SA node and ending with the f) return of the heart to the resting state 134 Electrical Activity in Pacemaker cells Pacemaker cells do not have a “true” resting membrane potential The voltage starts at ~ -60mV – and SPONTANEOUSLY moves upward – until it reaches the threshold of -40mV – This is due to so called funny currents present only in pacemaker cells 135 Electrical Activity in Pacemaker cells Cont When membrane potential becomes – lower than -40mV K+ channels close and Funny channels open allowing slow influx of Na+ The resulting depolarization it is called “pacemaker potential” At threshold (-40mV) – Ca2+ channels open and Ca flows inside the cell – causing further Depolarization 136 Electrical Activity in Pacemaker cells Cont At the peak of the depolarization (+10mV): – Ca channels inactivate and K+ channels open – and K+ flows outward – and the voltage returns to – 60mV – This is the falling phase of the action potential or Repolarization 137 Electrical Activity in Pacemaker Cells Membrane potential showing action potentials Pacemaker potential and pacemaker potentials Initial period of spontaneous depolarization to subthreshold - funny channels open - sodium moves in - K movement out of the cell decreases Later period of spontaneous depolarization to threshold - T-type (transient) calcium channels open, - Ca moves in 138 Electrical Activity in Pacemaker Cells Cont Rapid depolarization L-type (long lasting) calcium channels open – Ca moves in – These channels stay open longer and close slowly – As they open they allow some sodium to come in – This adds to the depolarizing effect 139 Electrical Activity in Pacemaker Cells Cont Repolarization phase of action potential K channels open K moves out Ca channels begin to close – decreasing the flow of Ca into the cell 140 Excitation-Contraction Coupling in Cardiac Muscle Cont 141 Mechanical Events of the Cardiac Cycle Two main periods of cardiac cycle – Systole Ventricle contraction – Diastole Ventricle relaxation 142 Opening of Valves During the Cardiac Cycle – Valves open passively due to pressure gradients AV valves open when – P atria > P ventricles Semilunar valves open when – P ventricles > P arteries 143 Four Phases of Cardiac Cycle Ventricular filling – Blood return to the heart via systemic and pulmonary Aorta (to the body) Pulmonary artery (to the lungs) veins – Enters the relaxed atria and passes through the AV valves and into the ventricles under its own pressure. The pressure in the veins is > than that in the atria. – During this time the pulmonary and aortic semilunar valves are closed because ventricular pressure is lower than that in the aorta and pulmonary arteries. – Pressure atria > Pressure ventricles – Late in diastole (at the end of phase 1), the atria contract, driving more blood into the ventricles. – Shortly thereafter, the atria relax and systole begins. – AV valves open 144 Four Phases of Cardiac Cycle Isovolumetric ventricular contraction Aorta (to the body) Pulmonary artery (to the lungs) – At the beginning of systole (phase 2), the ventricles contract, which raises the pressure within them. – When ventricular pressure exceeds atrial pressure, AV valves are closed produce the first heart beat – The semilunar valves remain closed because ventricular pressure is not yet high enough to force them open – At this point no blood entering or exiting ventricle – Even though the ventricles are contracting, the volume of blood within them remains constant – Phase 2 ends when the ventricular pressure is great enough to force open the semilunar valves so that blood can leave the ventricles 145 Four Phases of Cardiac Cycle Aorta (to the body) Pulmonary artery Ventricular ejection (to the lungs) – In the remainder of systole (phase 3), blood is ejected into the aorta and pulmonary arteries through the open semilunar valves, and ventricular volume falls. – Semilunar valves are open – Pressure ventricles > Pressure arteries – Ventricular pressure rises to a peak and then begins to decline. – When it falls below aortic pressure, the semilunar valves close, ending ejection (and systole) and marking the beginning of diastole. 146 Four Phases of Cardiac Cycle Aorta (to the body) Pulmonary artery (to the lungs) Isovolumetric Ventricular Relaxation – At the onset of early diastole (phase 4), Ventricle relaxes – Some blood is present in the ventricles – Ventricular pressure is too low to keep the semilunar valves open and too high to allow the AV valves to open – All valves are closed (AV and semilunar valves) – No blood entering or exiting ventricle – Once ventricular pressure decreases to less than atrial pressure, the AV valves open again, blood enters the ventricles from the atria. This marks the beginning of phase 1, and the pump cycle begins once again 147 Cardiac Cycle 148 Four Phases of Cardiac Cycle The first heart sound occurs when the atrioventricular valves close; thus, it marks: The beginning of systole and the beginning of isovolumetric contraction. Hormonal Control of Heart Rate Epinephrine- increases action potential frequency at the SA node and, therefore, increases heart rate. In addition, epinephrine increases the velocity of action potential conduction through cardiac muscle fibers. Thyroid hormones- Excess thyroid hormones -a heart rate of greater than 90 beats per minute (tachycardia) is common. Insufficient thyroid hormone slows your heart rate. Insulin and Glucagon- Secreted by pancreas. These hormones primarily increase the force of myocardial contraction, but glucagon also promotes increased heart rate. 150 Respiratory System: Pulmonary Ventilation 21-22 Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 151 Functions of Respiratory System Respiration= the process of gas exchange Provides tissues for gas exchange between the air and bloodstream Moves air in and out of the body Regulate pH of the blood Protects the body from dehydration, temperature fluctuations and the entrance of pathogens 152 Anatomy of the Respiratory System Made up of: Nasal cavity Oral cavity Pharynx Larynx Trachea Lungs – Bronchi, bronchioles and alveoli 153 Ventilation vs Respiration Ventilation- is breathing: The movement of air in and out of the lungs through breathing Conduction of the air Respiration- is not breathing Involves gas exchange oxygen and carbon dioxide Requires coordination of respiratory and circulatory systems 154 External Respiration Step 1. Ventilation or gas exchange between the atmosphere and alveoli in the lungs Step 2. Exchange of O2 and CO2, between air in the alveoli and the blood in the pulmonary capillaries Step 3. Transport of O2 and CO2 by the blood between the lungs and the tissue Step 4. Exchange of O2 and CO2 between the blood and tissues by diffusion 155 Overview of Internal Respiration 156 Respiratory Tract Includes: all air passageways leading from pharynx to lungs Functionally divided: – Conducting zone the upper part of the respiratory tract – starts with larynx – conducting air from the larynx to the lungs 157 Respiratory Tract – Respiratory zone the lowermost part of the respiratory tract contains the sites of gas exchange within the lungs Anatomical difference: Thickness of the walls 158 Structures of the Respiratory Zone It is the site of gas exchange The arrangement of structures in the respiratory zone – maximizes surface area and minimizes thickness – thereby facilitating the diffusion of oxygen and carbon dioxide between air and blood 159 Structures of the Respiratory Zone 160 Epithelium of the Respiratory Zone 161 Anatomy of the Respiratory Zone 162  Characteristics of the respiratory zone that facilitate the exchange of gases Thickness of the respiratory membrane Great surface area Diffusion of Gases Across Respiratory Membrane The exchange of O2 and CO2 between alveoli and blood occurs by simple diffusion across the respiratory membrane The rate of transport in simple diffusion depends: - Magnitude of the concentration gradient - Surface area of the membrane - Permeability of the membrane to that particular substance/gas Respiratory membrane - Single layer of type 1 of epithelial cells lining the alveolus - The alveolar and capillary basement membranes 164 Diffusion of Gases Across Respiratory Membrane 165 Oxygen Transport in the Blood Oxygen not very soluble in plasma Thus only 3.0 mL/200 ml arterial blood oxygen dissolved in plasma (1.5%) Other 197 mL arterial blood oxygen transported by hemoglobin (98.5 %) 166 Hemoglobin Hemoglobin located in red blood cells 4 globins – 2 alpha – 2 beta 4 heme groups Oxygen binds to heme group Thus each hemoglobin can bind 4 oxygens 167 Transport of Oxygen (a) Formation of oxyhemoglobin – Once oxygen diffuses from alveolar air to blood in pulmonary capillaries it diffuses into erythrocytes and binds to hemoglobin for transport in the blood 168 Transport of Oxygen b) Dissociation of oxygen from hemoglobin In systemic capillaries: hemoglobin in erythrocytes releases oxygen – which then diffuses from the blood into tissue cells 169 Factors Affecting Affinity of Hemoglobin For Oxygen Temperature Work to promote oxygen unloading from hemoglobin in pH respiring tissues and oxygen loading onto hemoglobin in CO2 the lungs. 2,3- biphosphoglycerate (2,3- BPG) Carbon monoxide 170 Effects of Temperature Temperature affects The affinity of hemoglobin for oxygen by altering the tertiary structure of the hemoglobin molecule Affects the tertiary structure of all proteins Temperature increase during metabolism: Decreasing the affinity of hemoglobin for oxygen Result: more oxygen is unloaded in tissue that is highly active The decrease in temperature of blood as it travels to the lungs: Increases hemoglobin’s affinity for oxygen Result: Promoting oxygen loading 171 Haldane Effect The Haldane effect describes the ability of hemoglobin to carry increased amounts of carbon dioxide (CO2) in the deoxygenated state as opposed to the oxygenated state First described by John Scott Haldane oxygenation of blood in the lungs displaces carbon dioxide from hemoglobin increasing the removal of carbon dioxide Consequently, oxygenated blood has a reduced affinity for carbon dioxide. 172 Effects of pH - Bohr Effect The effect of pH on hemoglobin- oxygen dissociation curve is known as the Bohr effect When oxygen binds to hemoglobin, hydrogen is released Hb + O2 → Hb.O2 + H+ – An increase in hydrogen ion concentration will decrease in pH) pushes the reaction to the left causing some oxygen to dissociate from hemoglobin – When hydrogen ions bind to hemoglobin, they decrease the affinity of hemoglobin for oxygen and oxygen is unloaded The hydrogen ion concentration increase in active tissue, which facilitates oxygen unloading. 173 Effects of CO2 – Carbamino Effect The PCO2 affects the affinity of hemoglobin for oxygen because carbon dioxide reacts reversibly with certain amino groups in hemoglobin to form carbaminohemoglobin (HbCO2):Hb + CO2 → HbCO2 When carbon dioxide is bound to hemoglobin, it changes hemoglobin’s conformation and decreases its affinity for oxygen—a phenomenon known as the carbamino effect. The binding of carbon dioxide to hemoglobin is also one of the mechanisms of carbon dioxide transport in the blood. 174 Carbon Monoxide Carbon monoxide is toxic When present, it binds to hemoglobin more readily than oxygen, which prevents oxygen from binding Result: decreases the oxygen-carrying capacity of blood 175 Carbon Dioxide Transport Mechanisms Although carbon dioxide is more soluble in plasma than oxygen, it is still not very soluble 10% dissolved in plasma – It is soluble in plasma – But when in contact with water, coverts to bicarbonate ion 60% in plasma as bicarbonate ions (HCO3-) – Bicarbonate is formed from CO2 within erythrocytes in systemic capillaries where CO2 levels are highest 30% transported bound to hemoglobin as carbaminohemoglobin – This contribute to Haldane effect 176 Carbonic Anhydrase Enzyme Present in erythrocytes. Converts carbon dioxide and water to carbonic acid CA CO2 + H2O → H2CO3 → H+ + HCO3- Implications: this reaction is important in acid-base balance because an increase in PCO2 causes an increase in the acidity of the blood (the concentration of hydrogen ions increases), and a decrease in PCO2 causes a decrease in the acidity of the blood (the concentration of hydrogen ions decreases). 177 Respiratory Control Centers of the Pons Pontine Respiratory Group (PRG/ pneumotaxic center): – Contains inspiratory, expiratory, and mixed neurons, which have activity associated with both inspiration and expiration – PRG- May regulate transitions between inspiration and expiration 178 Respiratory Control Centers of the Medulla Two respiratory control centers are located on each side of the medulla 1. Ventral respiratory group (VRG) - VRG contains two regions of primarily expiratory neurons - One region of primarily inspiratory neurons 2. Dorsal respiratory group (DRG) - Contains primarily inspiratory neurons * Some expiratory neurons Brainstem centers of respiratory control. Areas containing predominantly inspiratory neurons are indicated by blue. Areas of predominantly expiratory neurons are indicated by yellow, Areas of scattered inspiratory and expiratory neurons as well as mixed neurons are indicated by green. 179  Excretory System: Renal Function 25-26 Lecture prepared by: Elda Dervishi, PhD Assistant Professor Cal Poly-Pomona Copyright ® Cal Poly- Pomona Elda Dervishi, AVS 3350 Domestic Animal Physiology 180 Functions of the Urinary System Regulate plasma ionic composition by increasing or decreasing the excretion of ions in the urine Na+, K+, Ca2+, Mg2+, Cl-, bicarbonate and phosphates Regulate plasma volume by controlling the rate at which water is excreted in the urine direct effect on total blood volume and thus on blood pressure Regulate plasma osmolarity Because the kidneys vary the rate at which they excrete water relative to solutes, they have the ability to regulate the osmolarity (solute concentration) of the plasma 181 Functions of the Urinary System Regulate plasma pH By regulating the concentration of bicarbonate and hydrogen ions in the plasma, the kidneys partner with the lungs to regulate blood pH. Remove metabolic waste products and foreign substances from plasma By excreting wastes and other undesirable substances in the urine, they clear the plasma urea and uric acid that are generated during protein and nucleic acid catabolism clear foreign substances such as food additives, drugs, or pesticides 182 Structures of the Urinary System 2 Kidneys - form urine 2 Ureters - transport urine from kidneys to bladder Bladder - store urine Urethra - excrete urine from bladder to outside of body 183 Anatomy of the Kidneys Paired organs, bean shaped (in mammalians) Suspended from the dorsal abdominal wall by a peritoneal fold and the blood vessels that serve them They are located slightly cranial to the mid‐lumbar region one on each side of the vertebral column They are separated from the abdominal cavity by their envelope of peritoneum for this reason they are called retroperitoneal structures 184 Macroscopic Anatomy of the Kidney A cross section of a kidney reveals two major regions: 1- Cortex A reddish-brown outer layer 2- Medulla An inner region which is darker and has a striped appearance The medulla is subdivided into a number of conical sections called Renal pyramids 185 Macroscopic Anatomy of the Kidney 186 Macroscopic Anatomy of the Kidney Papillae (singular: papilla) The tips of the renal pyramids Collecting Ducts Tubules that drain into Minor Calyces (singular: calyx) The minor calyces converge to form two or three larger passageways called Major Calyces Major Calyces drain into a single funnel-shaped passage called the Renal Pelvis, the initial portion of the ureter 187 Microscopic Anatomy of the Kidney Within a kidney’s renal pyramids > a million microscopic subunits called Nephrons Nephrons = functional units of the kidneys – Function: filtering the blood and forming the urine 188 Microscopic Anatomy of the Kidney Nephron = functional unit of kidneys - Function: filters blood and form urine Composed of 1- Renal corpuscle the site where blood is filtered, origin of filtrate (or tubular fluid) 2- Renal tubules through which the filtrate travels and become modified to form urine 189 Anatomy of a Nephron Each renal corpuscle consist of: Bowman’s capsule Glomerulus- tuft of capillaries Also shown are the blood supply to the renal corpuscle and the collecting duct associated with the nephron Each renal tubule consist of numerous continuous tubular segments 190 Renal Corpuscle Blood enters via afferent arteriole Glomerular capillaries As blood flows through glomerular capillaries, protein-free plasma filter across the walls of the capillaries Bowman’s capsule by a process called glomerular filtration The remaining blood leave the glomerulus via an efferent arteriole 191 Renal Corpuscle It has as a unique arrangement of efferent and afferent arterioles Allows for greater regulation of glomerular filtration The walls of the arterioles contain: Smooth muscle can contract or relax in response to: input from paracrine and sympathetic nervous system Regulating their diameter leads to regulation of glomerular filtration 192 Renal Tubules As the glomerular filtrate is formed, it flows from Bowman’s capsule Proximal tubule (highly folded) – Proximal convoluted tubule – Proximal straight tubule Loop of Henle – Descending limb – Thin ascending limb – Thick ascending limb Distal convoluted tubule – Connecting tubule (joins the nephron with collecting duct Collecting duct (empty in to the minor calyces) 193 Cortical and Juxtamedullary Nephrons Cortical (80-85%) Located almost entirely within the renal cortex Only the tip of the loop of Henle dips into the renal medulla Juxtamedullary (15-20%) Located in both the cortex and medulla The renal corpuscle is located near the border between the cortex and the medulla Bowman’s capsule and the proximal and distal convoluted tubules are located in the renal cortex The loop of Henle dips deep into the medulla 194 Cortical and Juxtamedullary Nephrons Both – urine formation Juxtamedullary nephrons – Maintaining medullary osmotic gradient which is crucial to the kidney’s ability to produce highly concentrated urine and conserving water 195 Juxtaglomerular Apparatus The initial portion of the distal tubule comes into contact with a nephron’s afferent and efferent arterioles = juxtaglomerular apparatus Function of Juxtaglomerular apparatus: - regulate blood volume and blood pressure 196 Juxtaglomerular Apparatus Juxtaglomerular Apparatus has two components: Macula densa specialized cluster of the tubule’s epithelial cells Granular cells The wall of the afferent arterioles contain secretory granules containing Renin Function: sense changes in renal perfusion pressure, via stretch receptors in the vascular walls Renin Function: increase in blood pressure leading to restoration of perfusion pressure in the kidneys 197 Juxtaglomerular Apparatus 198 Blood Supply to Kidney The renal artery branches – will branch → segmental arteries – segmental arteries will brunch→ into smaller interlobar arteries – interlobar arteries → arcuate arteries – arcuate arteries → interlobular arteries from interlobular arteries: – blood is carried to individual nephrons by the afferent arterioles → lead into the glomerular capillary beds 199 Blood Supply to Kidney Coming off each of the glomerular capillary beds is the efferent arteriole Efferent arteriole leads into one of two different types of capillary beds: – the peritubular capillaries located around the renal tubules – and the vasa recta located around the loops of Henle The peritubular capillaries+ vasa recta will drain into interlobular veins and finally to renal vein 200 Basic Renal Processes In the kidneys water and solutes are exchanged between plasma and fluid in the renal tubules to regulate the composition of plasma Substances removed from the plasma are excreted in the urine 201 Basic Renal Processes Three exchange processes within the renal nephrons: Glomerular filtration bulk flow of protein-free plasma from the glomerular capillaries into Bowman’s capsule 202 Basic Renal Processes Reabsorption Selective transport of molecules from the lumen of the renal tubules to the interstitial fluid outside the tubules to the peritubular capillaries and returned to the general circulation 203 Basic Renal Processes Secretion This is the selective transport of molecules from the peritubular fluid to the lumen of the renal tubules These secreted molecules come from the plasma of the peritubular capillaries 204 Basic Renal Processes Excretion – No exchange is the bulk flow of the urine out of the body 205 Basic Renal Processes The three exchange processes in the renal tubules. Filtration: occurs in the renal corpuscle, is the bulk flow of protein-free plasma from the glomerulus into Bowman’s capsule. Reabsorption: which occurs along the tubules, is the movement of water or solute from the lumen of the tubules into the peritubular capillaries. Secretion: occurs along the tubules, but it is the movement of the solute from the peritubular capillaries into the lumen of the tubules. 206 Glomerular Filtration Movement of protein- free plasma from glomerulus to Bowman’s capsule The filtrate resembles plasma in composition, except that it lacks most of the proteins found in plasma Glomerular Filtration Rate GFR = 125 mL/min or 180 liters/day 207 Reabsorption Movement from tubules into peritubular capillaries (returned to blood) Most occurs in proximal and distal convoluted tubule Most solutes are transported actively, against their electrochemical gradients 208 Rates of Reabsorption of Water and Select Solutes Normal Rates of Filtration and Reabsorption for Water and Selected Solutes This table shows how extensive the absorption is. Solutes are reabsorbed actively (against their electrochemical gradient, as they move from tubular lumen to the plasma) 209 Solute Reabsorption Most occurs in proximal convoluted tubule Most reabsorption of water and solutes occur in the proximal tubule Loop of Henle and the collecting ducts are important in water reabsorption Some in distal convoluted tubule When a substance is reabsorbed it must cross 2 barriers: – The renal tubule epithelium – Capillary endothelium cells 210 Reabsorption Barrier For reabsorption to occur: A substance must cross the epithelial cells of the capillary – The primary barriers are: the apical and basolateral membranes of the tubule epithelial cells – because capillary walls are highly permeable Therefore cells lining renal tubule are the primary barrier to reabsorption 211 Reabsorption Barrier Cells lining renal tubule are the primary barrier to reabsorption 212 Secretion In tubular secretion Molecules move from the plasma of peritubular capillaries into the renal tubules to become part of the filtrate Secretion follows the same processes as reabsorption It involves the same barriers, except that movement goes in the reverse direction Some substances diffuse from plasma into the filtrate, Others substances are actively transported 213 Secretion Secretion by active transport requires: either that proteins in the basolateral membrane actively transport the solute from peritubular fluid to inside the epithelial cell, or that proteins in the apical membrane actively transport the solute from inside the epithelial cell into the filtrate Result: an increase in the quantity of solute excreted in the urine, which decreases the solute’s plasma concentration 214 Secretion Among Secreted Substances: – Potassium – Hydrogen ions – Choline – Creatinine – Penicillin 215 Anatomy of the Urinary Bladder, Urethra and Process of Micturition involuntary control involuntary control voluntary control 216