Untitled Quiz

Disclaimer

• This study guide is not comprehensive
• The instructor provides this as a guide only
• It does not guarantee that there will be no questions outside of the study slides.
• Students should study the course material.

Study Guide

• Lecture prepared by Elda Dervishi, PhD, Assistant Professor, Cal Poly-Pomona

CNS Integrated Functions: Sensory Physiology

• Lecture prepared by Elda Dervishi, PhD, Assistant Professor, Cal Poly-Pomona

Peripheral Nervous System

• Peripheral Nervous System (peripheral nerves and receptors)
• Afferent Division (Sensory information IN)
• Efferent Division (Motor responses)

The Vertebrate Nervous System

• Diagram showing the input and output from the Central Nervous System (CNS) to the periphery.
• The diagram shows the different divisions of the Peripheral Nervous System (PNS), including the somatic nervous system, the autonomic nervous system, and the enteric nervous system.
• The diagram also shows the different components of the CNS, including the brain and spinal cord.
• Diagram labeled with key components.

Afferent Branch of Peripheral Nervous System

• Sensory pathways relay sensory information to the appropriate area of the cortex in the CNS
• Information from periphery to CNS
  • External environment - sensory
    • Special Senses (vision, hearing, taste, and smell)
  • Internal environment - visceral afferent

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

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)
• 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

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

Receptor Physiology

• Sensory receptors
• Transduction
• Adaptation

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

Receptor Potential in Specialized Afferent Ending

• Diagram showing stimulus, ion channels, action potential, and current flow between depolarized receptor ending and adjacent region.
• In specialized afferent neurons, stimulus-sensitive channels permit Na⁺ entry to produce receptor potential.
• Local current flow between the depolarized receptor ending and adjacent regions triggers the opening of voltage-gated Na⁺ channels.
• Na⁺ entry initiates an action potential in the afferent fiber that self-propagates to the CNS.

Receptor Potential in Separate Receptor Cell

• Receptors as separate cells in response to stimuli
• Diagram of separate receptor cells with channels and action potential initiation in response to stimulus-leading to opening of chemically gated ion channels.
• Net Na⁺ entry produces receptor potential, followed by depolarization and opening of voltage-gated Ca²⁺ channels.
• Ca²⁺ entry triggers neurotransmitter release, then neurotransmitter binding opens chemically gated receptor channels at afferent ending and permits Na⁺ influx.
• The resultant depolarization opens voltage-gated Na⁺ channels in the adjacent region, initiating an action potential in the afferent fiber.

Receptor Potentials

• Stimulus influences sensory receptors by opening or closing ion channels, creating a receptor potential.

Receptor Function

• Detects the Stimulus.
• Responds to stimuli by producing depolarizing graded potentials (receptor potentials)
• Converts energy from the stimulus into electrical signals- Sensory Transduction

Transduction

• Conversion of stimulus energy into electrical energy
• Examples of modality: light waves, sound waves, pressure, temperature

Law of Specific Nerve Energies

• A given Sensory Receptor displays specificity to a modality. Special cells in the eyes detect light waves, but not sound waves.
• Adequate stimulus: modality to which a sensory receptor responds best

Characteristics of Sensory Receptors Types

• Table showing classes of receptors, their corresponding sensations/visceral information and modalities
• Includes examples like photoreceptors (Vision/ photons of light), Chemoreceptors (Taste/ chemicals), Thermoreceptors (Warmth/cold) and Mechanoreceptors (Blood pressure / osmolarity of extracellular fluid and so on)

Sensory Pathways: Orders of Sensory Processing

• Diagram to show the three orders of neurons in a sensory pathway and their locations/functions within the CNS.
• First-order sensory neuron, the peripheral sensory neuron detecting the stimulus.
• Second-order sensory neuron, processing in the CNS (spinal cord or medulla oblongata, brainstem).
• Third-order sensory neuron, processing in the CNS (thalamus) continuing to the cortex.

Somatosensory Pathways

• Two main pathways for somatosensory information transmission in the CNS:
  • 1. Dorsal column-medial lemniscal pathway: transmitting fine touch, vibration, proprioceptors
  • 2. Spinothalamic tract: transmitting temperature and pain (lateral tract) and crude touch and pressure (anterior tract)
  • This diagram shows how both tracts enter the spinal cord on one side but then cross to the other side before reaching the thalamus.

Somatosensory Pathways

• These pathways transmit different types of sensory information to the thalamus, and then to the primary somatosensory cortex.
• Somatosensory information from the right side of the body is perceived in the left somatosensory cortex, and vice versa

The Dorsal Column-Medial Lemniscal Pathway

• Transmits information about mechanoreceptors and proprioceptors to the thalamus
• First-order neurons enter the spinal cord and their collaterals may terminate in the spinal cord.
• The main axons ascend in the dorsal columns to the medullary nuclei, forming synapses with second-order neurons.
• Second-order neurons then cross over, ascend as the medial lemniscus to the thalamus, and synapse with third-order neurons in the thalamus.
• Third-order neurons transmit information to the somatosensory cortex.

The Spinothalamic Tract

• Transmits information from thermoreceptors and nociceptors to the thalamus.
• First-order neurons originate in the periphery, enter the dorsal horn, and synapse with second-order neurons.
• Second-order neurons cross over to the contralateral side of the spinal cord and ascend in the anterolateral quadrant to the thalamus.
• They then synapse with third-order neurons, which terminate in the somatosensory cortex.

Autonomic Nervous System

• The lecture prepared by Elda Dervishi, PhD, Assistant Professor, Cal Poly-Pomona. This is slide 11 of the autonomic nervous system lecture notes.

The Vertebrate Nervous System

• Schematic of the CNS and PNS, emphasizing the autonomic nervous system. Include peripheral nervous system, afferent and efferent divisions, somatic nervous system, autonomic nervous system, and the enteric nervous system; and the components of CNS, including brain and spinal cord.

The Somatic Nervous System

• Control skeletal muscles -Coordinate body involuntary functions- organs systems
• 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: 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). 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

• Diagram illustrating the neuromuscular junction components and the mechanism of neurotransmission.
• includes diagram illustrating the steps in the neuromuscular junction.

The Autonomic Nervous System

• Oversees involuntary body functions
  • Regulates organ systems (cardiovascular, respiratory, digestive, urinary, reproductive)
  • Maintains water, electrolyte, nutrient and gas concentration
  • Two branches
    • Sympathetic
    • Parasympathetic
  • Receives sensory information from specialized receptors (enteroreceptors), monitoring body's internal 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

Autonomic Nervous System Anatomy

• Parasympathetic
  • "Rest and digest" or craniosacral division
  • Axons from the brainstem and sacral segments of spinal cord, innervating ganglia close to target organs.
• Sympathetic
  • "Fight or flight" or thoracolumbar division
  • Axons from the thoracic and superior lumbar spinal cord segments, innervating ganglia close to spinal cord.
• Enteric --Unique system
  • Sensory, motor, interneurons in GI tract
  • Coordinates GI tract activity without CNS input
  • Sympathetic and parasympathetic influence enteric function, but do not control it.

Anatomy of the Autonomic Nervous System

• Autonomic nervous system consists of efferent pathways with two neuron types.
• Neurons communicate with each other via synapses in peripheral structures called autonomic ganglia
• Preganglionic neuron travels from CNS to ganglia.
• Postganglionic neuron travels from ganglia to effector organs
• Autonomic ganglia are collections of nerve cell bodies outside the CNS. Each ganglion contains the axon terminals of preganglionic neurons and the cell bodies and dendrites of postganglionic neurons.

Anatomy of Autonomic Pathways

• In autonomic pathways, a preganglionic neuron travels from the CNS to a ganglion in the periphery.
• It synapses with a postganglionic neuron that innervates an effector organ (e.g., cardiac muscle, smooth muscle, glands, adipose tissue).

Anatomy of the Sympathetic Nervous System

• Preganglionic neurons originate in the 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.

Anatomy of Sympathetic Preganglionic and Postganglionic Neurons

• Preganglionic sympathetic neurons originate in the lateral horn of the spinal cord and exit through the ventral root.
• Afferent nerves travel to target organs via sympathetic chain and collateral ganglia

Parasympathetic Nervous System Anatomy

• Preganglionic neurons originate in the brainstem or sacral spinal cord (craniosacral division).
• Parasympathetic preganglionic neurons are relatively long, synapsing in ganglia near or within effector organs
• Their short postganglionic neurons travel to the effector organs

Parasympathetic Nervous System Pathways

• Diagram shows preganglionic and postganglionic pathways, with axons originating in brainstem (cranial nerves) and sacral spinal cord and terminating in ganglia near effector organs (e.g., cranial nerves, pelvic nerves).

Quick Check

• Which organ is not directly innervated by the autonomic nervous system?; Skeletal Muscle

Question

• Preganglionic fibers from the thoracic and lumbar segments of the spinal cord are part of the Sympathetic division of the ANS.

Neurotransmitters of the Autonomic Nervous System

• Preganglionic neurons of both sympathetic and parasympathetic branches release acetylcholine.
• Parasympathetic postganglionic neurons release acetylcholine.
• Sympathetic postganglionic neurons release norepinephrine and epinephrine

Autonomic Neurotransmitters

• Cholinergic neurons release acetylcholine
• Adrenergic neurons release norepinephrine

Sympathetic Nervous System. Neurotransmitters and Receptors

• Preganglionic neurons release acetylcholine.
• Postganglionic neurons release norepinephrine or epinephrine.
• Preganglionic receptors are cholinergic (nicotinic) type.
• Postganglionic receptors are adrenergic.
• Adrenal medulla (part of the sympathetic system) also releases hormones such as epinephrine directly into the bloodstream.

Parasympathetic Nervous System-Neurotransmitters and Receptors

• Acetylcholine is released from both preganglionic and postganglionic neurons. In the parasympathetic system, acetylcholine from preganglionic neurons binds to nicotinic receptors on postganglionic neurons, and then from postganglionic neurons binds to muscarinic receptors on effector organs.

Autonomic Neuroeffector Junctions

• The synapse between an efferent neuron and its effector organ is called a neuroeffector junction.

Events at the Neuroeffector Junction

• Action potential arrives at varicosity
• Voltage-gated Ca2+ channels open
• Ca2+ triggers exocytosis of neurotransmitter
• Neurotransmitter binds with receptors on effector organ
• Response in effector organ
• Neurotransmitter degraded, diffuses away, or is reuptaken.

Anatomy of Neuroeffector Junctions in the Autonomic Nervous System

• Diagram illustrating the varicosities on postganglionic axons and neurotransmitter release into the synaptic cleft. Includes the location of voltage-gated Ca2+ channels and the binding sites for neurotransmitters (such as acetylcholine or norepinephrine).

Central Control of the Autonomic Nervous System

• Hypothalamus
• Pons and medulla oblongata
  • Contains cardiovascular and respiratory centers -controlling heart, blood vessels, smooth muscle in respiratory airways.
  • Regulates automatic breathing patterns.
  • Receives input from the hypothalamus, cerebral cortex, and limbic system.
• Afferent information needed for reflex control of visceral function.

Brain Areas Exerting Control of Autonomic Functions

• Pons and medulla oblongata of brainstem
• Hypothalamus

Comparison - Summary Slide

• Sympathetic
  • Short preganglionic fiber
  • Releases neurotransmitter directly into the bloodstream
  • Long postganglionic fiber releases norepinephrine or epinephrine
• Parasympathetic
  • Long preganglionic fiber
  • Ganglia located near or in the effector organ
  • Releases acetylcholine
  • Short postganglionic fiber with nicotinic and muscarinic receptors

Comparison - Summary Slide (additional details from slide 53)

• Diagram comparing the location of CNS neurons, ganglia, preganglionic and postganglionic fibers and their neurotransmitters/receptors between the sympathetic and parasympathetic divisions of the ANS.

Muscle Physiology I

• Prepared by Elda Dervishi, PhD, Assistant Professor at Cal Poly-Pomona

Structure of a Skeletal Muscle

• Diagram illustrating the different layers within a skeletal muscle including epimysium, perimysium, endomysium and the nerves and blood vessels embedded in each layer.
• Skeletal muscle is described as a fascicle of muscle fibers organized in a particular way supported by different layers of protective connective tissue.

Structure of a Skeletal Muscle (continued)

• Diagram illustrating the inside of a muscle fiber with myofibrils and their components including Capillary, Myofibril, Endomysium, Sarcoplasm, Mitochondrion, Myosatellite cell, and Sarcolemma, and Nucleus
• The muscle fiber is described as a bundle of myofibrils organized in a cylindrical shape.

Structure of a Skeletal Muscle (continued)

• Skeletal muscles contract only when stimulated by the CNS, and are referred to as voluntary muscles.
• Skeletal muscles have an extensive vascular network to deliver oxygen and nutrients, and remove metabolic waste products.

Components of a Muscle Fiber- Terminology

• Muscle fibers surrounded by connective tissue (endomysium)
• Sarcolemma (plasma membrane)
• Sarcoplasm (cytoplasm of 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, comprised of bundles of protein filaments (myofilaments).
• Two types of myofilaments;
  • Thin filaments: Composed primarily of actin
  • Thick Filaments: Composed primarily of myosin (both fibrous and globular protein).

Components and Structure of a Muscle Fiber

• Diagram showing the location of mitochondria, sarcolemma, myofibrils, thin filaments, thick filaments, sarcoplasmic reticulum and terminal cisternae, and t-tubules within a muscle fiber.

Sarcomere - The contractile Unit

• Myofibrils are composed of smaller units called sarcomeres, arranged end-to-end.
• Interactions between filaments produce contraction.
• Sarcomere is the functional unit of contraction in a myofibril.
• The arrangement of filaments causes the striated appearance of myofibrils

Sarcomere Structure (A bands)

• M-line located in the center of the A band. Proteins stabilize position of thick filaments.
• H-band is on either side of the M line and has thick filaments but no thin filaments.
• Zone of overlap: Dark region where thin and thick filaments overlap  

Sarcomere Structure (I bands)

• Thin filaments, but not thick filaments
• Z lines bisect I bands
• Titin is an elastic, supportive protein that extends from the tips of the thick filaments to the Z line

Sarcomere Structure (additional details)

• Diagram showing the relationships of A bands, I bands and Z lines.

Structure of a Thin Filament

• Thin filament (actin) comprises F-actin, nebulin, tropomyosin, and troponin proteins arranged in a helical structure; G-actin molecules form a twisted strand. Active sites on G-actin bind to myosin. Nebulin holds the F-actin strand together.

Structure of a Thin Filament (continued)

• Thin filaments made up of actin subunits with three proteins: actin (contractile), tropomyosin (regulatory), and troponin (regulatory)
• Each G actin molecule has a myosin-binding site.

Troponin

• Regulatory protein complex of three proteins
• Attaches to actin and tropomyosin.
• Calcium binding to troponin regulates skeletal muscle contraction
• Troponin-tropomyosin complex changes shape when calcium binds for the muscle contraction.

Structure of a Thick Filament

• Myosin exhibits tails and heads, where the tails point toward the M line and the heads extend towards the thin filaments.

Crossbridge Cycle (Step 1)

• Myosin head in its energized form with ADP and Pi bound to the ATPase site.
• Myosin head binds to an actin monomer in the adjacent thin filament.

Crossbridge Cycle (Step 2- Power Stroke)

• ADP and Pi are released, The myosin head pivots toward the center of the sarcomere, pulling the thin filament along with it

Crossbridge Cycle (Step 3 - Rigor)

• Myosin and Actin tightly bound together, a condition called rigor.
• Crossbridge cycle is halted due to the lack of ATP, causing rigor mortis (post-mortem muscle stiffening)

Crossbridge Cycle (Step 4 - Crossbridge detachment.)

• A new ATP molecule binds to the myosin head.
• Triggering a change in myosin head conformation (reducing its affinity for actin).
• Myosin detaches from Actin

Crossbridge Cycle (Step 5 - Re-Cocking of myosin head.)

• ATP is split by hydrolysis into ADP and Pi, releasing energy.
• The energy is stored in the myosin head, causing it to change back to its energized conformation, preparing it to bind to actin again

Crossbridge Cycle ( continued)

• Diagram of the cycle showing energy capture, ADP/Pi bound to myosin, conformational changes and ATP binding, allowing for new cross-bridge formation

Sliding-Filament Mechanism

• During muscle contraction, H-zone and I bands shorten
• The zones of overlap widen
• The Z lines moves closer together

Sliding-Filament Mechanism (continued)

• A bands remain the same length/width during contractions.
• Thin filaments slide toward the center of the sarcomere, causing the sarcomere to shorten.

Sliding-Filament Mechanism (continued)

• Diagram of a relaxed and a contracted sarcomere, demonstrating the sliding of thin filaments toward the center of the sarcomere, shortening the sarcomere's length.

Exposing the binding site on actin

• Calcium ions bind to troponin.
• Troponin-tropomyosin complex shifts.
• Exposing active sites on actin, allowing for myosin-actin interaction.

Endocrine System: Glands and Hormone Actions

• Lecture prepared by Elda Dervishi, PhD, Assistant Professor, Cal Poly-Ponoma.

Intercellular communication - Endocrine system

• All endocrine tissues produce hormones or paracrines.
• Endocrine cells release secretions into the circulatory system, becoming hormones, or into the interstitial fluid, becoming paracrines.
• Endocrine organs are scattered throughout the body as discrete endocrine organs or as subsets of other organs that also have nonendocrine functions.

Hormones

• Messengers of the endocrine system
• Released from endocrine glands
• Into the interstitial fluid and then diffuse into the blood.
• Transported in blood to target cells with specific receptors for the hormone.

Endocrine System

• Mechanisms of intercellular communication:
  • Direct communication: through gap junctions (direct exchange between cells)
  • Paracrine communication: chemical signals transfer information from cell to cell for activity coordination within a single tissue.

Chemical Classification of Hormones

• Hormones are classified based on their chemical makeup:
  • Amino acid derivatives; derived from amino acids (e.g., melatonin, thyroid hormones, catecholamines).
  • Peptides; short chains of amino acids (e.g., ADH, oxytocin, insulin, growth hormone, prolactin).
  • Lipid derivatives; derived from lipids (e.g., eicosanoids, steroids).

Chemical Classification of Hormones (continued)

• Amino acid derivatives (biogenic amines); examples include thyroid hormones, epinephrine, norepinephrine, dopamine, serotonin, melatonin.
• Peptide hormones; examples include releasing and inhibiting hormones, thyroid-stimulation hormone (TSH), luteinizing hormone(LH), follicle-stimulating hormone (FSH).
• Lipid derivatives (eicosanoids/ steroids); examples include eicosanoids (prostaglandins), steroids (estrogen, testosterone, cortisol).

Classification of Hormones

• Hydrophilic hormones (soluble in water):
  • Peptides and catecholamines.
• Hydrophobic hormones (insoluble in water):
  • Steroid hormones.

Transport of Hormones

• Hydrophilic hormones are dissolved in plasma (water)
• Hydrophobic hormones are bound to carrier proteins. Only free hormone can bind to receptor and be metabolized.

Transport of Hormones (continued)

• Diagram of how hydrophilic (dissolved in plasma) and hydrophobic (bound to carrier proteins) hormones travel in the blood.

Endocrine Glands

• Primary endocrine organs- secretion of hormones
  • Hypothalamus, pituitary gland, thyroid, thymus, adrenal glands, pancreas
• Secondary endocrine organs- secondary secretion of hormones
  • Heart, liver, kidney, stomach, small intestine, and skin.

Hypothalamus- The Master

• Part of the brain with various functions and serves as an endocrine gland.
• Synthesizes and secretes ADH (antidiuretic hormone) and OXT (oxytocin), releasing them into the posterior pituitary.
• Secretes regulatory hormones that control anterior pituitary gland activity.
• Autonomic centers exert direct control over adrenal medulla.
• Considered a primary endocrine gland due to its secretion of hormones affecting the pituitary gland.

Pituitary Gland (continued)

• Located inferior to the hypothalamus; a small pea-sized structure connected to hypothalamus via thin stalk of tissue called infundibulum
• Releases 9 important peptide hormones binding to extracellular receptors of the target organs. Uses cAMP as a second messenger

Pituitary Gland

• Divided into anterior and posterior lobes.
• Anterior pituitary - The functional connection between the hypothalamus and the pituitary is crucial for the function of these endocrine glands.
• Posterior pituitary - It is a neural tissue.

Hormones - Anterior Pituitary

• Secrete primarily tropic hormones (trophic hormones): Regulate the secretion of other hormones.
• Stimulating/releasing hormones: Increase secretion of another hormone.
• Inhibiting hormones: Decrease secretion of another hormone

Hypothalamus Hormone

• Hypothalamus releases hormones into capillary bed.
• Hypothalamic tropic hormones enter the anterior pituitary through capillary beds.
• Tropic hormones affect hormone release from anterior pituitary (except PRL) as well as distant target endocrine glands

Tropic Hormones of Hypothalamus and Anterior Pituitary

• Diagram depicting the regulatory system from the hypothalamus to the anterior pituitary.
• The hypothalamus secretes hormones that target the hypothalamus and anterior pituitary gland, affecting hormone release, directing hormone secretion of other endocrine organs.

Prolactin releasing hormone (PRH) & Prolactin inhibiting hormone (PIH)

• PRH stimulates prolactin (PRL) secretion, important for mammary gland development and milk secretion in females.
• PIH (or dopamine) inhibits PRL release

Tropic Hormones of Hypothalamus and Anterior Pituitary (Thyrotropin-releasing hormone)

• TRH stimulates the anterior pituitary to release TSH (Thyroid Stimulating Hormone).
• TSH stimulates the thyroid gland to secrete thyroid hormones, which control metabolism.

Tropic Hormones of Hypothalamus and Anterior Pituitary (Corticotropin-releasing hormone)

• CRH stimulates the anterior pituitary to release ACTH (Adrenocorticotropic Hormone)
• ACTH stimulates the adrenal cortex to secrete glucocorticoids such as cortisol, regulating metabolism, especially under stress.

Tropic Hormones of Hypothalamus and Anterior Pituitary (Growth hormone-releasing hormone)

• GHRH stimulates the release of growth hormone (GH) from the anterior pituitary.
• GH regulates growth and metabolism and stimulates insulin-like growth factors (IGFs) by the liver.

Tropic Hormones of Hypothalamus and Anterior Pituitary (Growth hormone-inhibiting hormone)

• GHIH (somatostatin) inhibits GH secretion from the anterior pituitary, decreasing IGF release from the liver.

Tropic Hormones of Hypothalamus and Anterior Pituitary (Gonadotropin-releasing hormone)

• GnRH stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.
• FSH and LH stimulate the development of sperm and egg cells, and the secretion of sex hormones (estrogens and progesterone in females; androgens in males) by the gonads.

Tropic Hormones Anterior Pituitary: Summary

• List of hormones released by the anterior pituitary gland and their functions.
• TSH, ACTH, PRL, GH , FSH and LH

Questions?

• Name the two hormones released by the posterior pituitary gland; ADH and oxytocin.
• Name three hypothalamic tropic hormones and how they affect anterior pituitary hormone release.

Hormone Interaction

• Several hormones may influence a given body function, with effects categorized as additive (summation), synergistic (combined effect greater than the sum), or permissive (necessity of one hormone for another to function).

Hormone Interaction (continued)

• Examples of antagonistic hormone interactions:
  • Parathyroid hormone increases blood calcium levels, whereas calcitonin lowers it.
  • Glucagon increases blood glucose levels, while insulin decreases them.

Hormone Interaction (continued)

• Examples of additive or synergistic interactions:
  • Multiple hormones acting together to increase a particular physiological response.
• Permissiveness- presence of one hormone needed for other hormone to exert its full effects

The Cardiovascular System

• The cardiovascular system consists of the heart, blood vessels, and blood.

The Cardiovascular System (cont.)

• The heart is a muscular pump that generates pressure to propel blood through blood vessels to various organs.
• Blood vessels are conduits for blood, carrying oxygen, nutrients, and removing wastes from tissues.

The Cardiovascular System (cont.)

• Blood is a fluid that circulates throughout the body, transporting materials to and from cells.

The Function of Cardiovascular System

• The heart generates force to pump blood through blood vessels, carrying oxygen, nutrients to tissues, and removing carbon dioxide/other wastes.
• Sensory and endocrine factors regulate cardiovascular variables such as blood volume and pressure.

The Function of Cardiovascular System (Blood Vessels)

• Blood vessels are both sensory and effector organs, regulating blood pressure and directing blood flow to different body parts.

The Function of Cardiovascular System (Blood)

• Blood transports waste, nutrients, and hormones from one part of the body to another.
• It serves as a communication link, connecting the various organ systems.

Anatomy of The Heart

• Large muscular pump, size of a fist
• Forms a double-sided pump
  • One side pumps blood to lungs.
  • Other side pumps blood to body.
• Made of cardiac muscle, cardiac nervous tissue, connective tissues, and protective epithelial tissues.

Anatomy of The Heart (continued)

• The heart has four chambers - 2 atria: Receiving chambers - 2 ventricles: Pumping chambers
• Has a septum (wall) dividing the right and left sides. (interatrial and interventricular)
• Has a base and an apex; base is where major vessels attach (larger portion), the apex is inferior pointed portion at heart’s bottom.

The Cardiovascular System (Heart Wall)

• The heart wall has three layers
  • Endocardium (inner layer)
  • Myocardium (middle muscular layer)
  • Epicardium (outer layer)

Heart Valves

• Atrioventricular (AV) valves:
  • Left AV valve (mitral/bicuspid)
  • Right AV valve (tricuspid). Enables the AV valves to properly seal
• Semilunar valves: Aortic valve and Pulmonary valve

Action of the AV Valves

• AV valves open when atrial pressure exceeds ventricular pressure, allowing blood to flow from atria to ventricles.
• AV valves close when ventricular pressure exceeds atrial pressure, preventing backflow from ventricles to atria.
• Papillary muscles and chordae tendineae prevent backflow by tightening during ventricular contraction.

Action of the Semilunar Valves

• Semilunar valves open when ventricular pressure exceeds pressure in the arteries, allowing blood to flow out of the ventricles into the arteries.
• Semilunar valves close when ventricular pressure falls below arterial pressure, preventing backflow into the ventricles.

Path of Blood Flow Through the Cardiovascular System

• Right ventricle pumps deoxygenated blood into the pulmonary arteries to the lungs.
• Left ventricle pumps oxygenated blood into the aorta to the body.

Conduction System

• Pacemaker cells generate action potentials to coordinate/ establish heart rhythm.
• Conduction fibers rapidly conduct action potentials of pacemaker cells to myocardium.
• Ordinary muscle fibers transmit electrical potentials with conduction velocity of 0.4 m/sec
• Contractile cells generate the contractile force

Pacemaker Cells of the Myocardium

• SA node acts as the heart's pacemaker. Spontaneously generates action potentials to establish heart's rhythm
• Located in the wall of the upper right atrium; faster than other conduction cells

Pacemaker Cells of the Myocardium (continued)

• AV node: located near the tricuspid valve in the interatrial septum; slower than the SA node; receives signals from SA node via the conduction fibers and transmits them to transmit to the ventricles through the conducting tissue

Conduction Fibers of the Myocardium

• Specialized interconnecting pathways (intermodal pathways) rapidly conduct action potentials from pacemaker cells to ensure coordinated heart contractions.
• Bundle of His( conducting tissues)
• Purkinje fibers conduct action potentials throughout the ventricles

Spread of Excitation Between Cells

• Action potentials initiate at pacemaker cells and spread through conduction fibers quickly to cause atrial and ventricular depolarization.
• Intercalated disks with gap junctions enable rapid action potential transmission.
• Desmosomes in intercalated disks provide structural support, to resist mechanical stress during cardiac contractions

Spread of Action Potentials Through the Heart

• Action potentials initiated in the SA node. Travel through internodal pathways, then the AV node. Conduction through the AV bundle, right and left bundle branches, and then the Purkinje fibers. This coordinated spread causes coordinated heart contractions.

Electrical Activity in Pacemaker Cells

• Pacemaker cells do not display a true resting membrane potential, spontaneously depolarizing.
• Funny channels, slow sodium channels and voltage-gated calcium channels play key roles during the formation of pacemaker potential.

Electrical Activity in Pacemaker cells (continued)

• K+ channels close as the pacemaker potential moves upward from resting membrane potential of ~-60 mV to the threshold of ~-40 mV.
• During depolarization, voltage-gated Ca2+ channels open, letting calcium in, thus causing further depolarization and triggering an action potential.

Electrical Activity in Pacemaker cells (continued.)

• At the peak of depolarization, Ca2+ channels close, K+ channels open allowing for the outward movement of K+ and voltage returns to ~-60mV. This is the repolarization phase.

Electrical Activity in Pacemaker Cells (Depolarization to threshold)

• Funny channels open, allowing slow influx of Na+. The resulting gradual depolarization is the pacemaker potential.
• At threshold (-40 mV), Ca2+ channels open, leading to further depolarization.

Electrical Activity in Pacemaker Cells (further details.)

• T-type calcium channels, transient calcium channels are primarily responsible for the pacemaker potential. They are open for a longer duration during the depolarization phase, contributing to the gradual depolarization and pacemaker potential.

Excitation-Contraction Coupling in Cardiac Muscle

• Depolarizing current spreads to contractile cells via gap junctions.
• The action potential travels along plasma membrane and T-tubules.
• Ca channels open in the plasma membrane and the SR causing Ca2+ release from SR.
• Ca2+ binds to troponin, exposing myosin-binding sites
• This results in the Crossbridge cycle (muscle fiber contraction)
• Finally Ca2+ transport back into the SR and ECF allowing for tropomyosin to block myosin.

Mechanical Events of the Cardiac Cycle

• Two main periods of the cardiac cycle are systole (ventricular contraction; includes isovolumetric contraction and ventricular ejection) and diastole (ventricular relaxation; includes isovolumetric relaxation and ventricular filling).

Opening of Valves During the Cardiac Cycle

• Atria pumps blood into ventricles (AV valves open) when ventricular pressure is low.
• Ventricles contract (AV valves close); blood pressure in ventricles is higher than in atria.
• Blood is pushed into the aorta and the pressure in ventricles are equal or higher than in arterial pressure( Semilunar valves open).

Four Phases of Cardiac Cycle (Ventricular Filling)

• Blood returns to the heart via the veins; filling the relaxed atria.
• Pressure in the veins is higher than the pressure in the atria, forcing blood into the ventricles.
• All valves are closed except the AV valves, which are open..
• Pressure in the atria is higher than in the ventricles. Blood flows freely into the relaxed ventricles. Atria contracts to finish filling the ventricles.

Four Phases of Cardiac Cycle (Isovolumetric Ventricular Contraction)

• Systole begins the ventricles contract; Pressure within ventricles increase.
• AV valves close
• Semilunar valves are still closed. No blood enters or leaves the ventricle

Four Phases of Cardiac Cycle (Ventricular Ejection)

• Ventricular pressure rises and exceeds pressure in the arteries; thus, the semilunar valves open
• Blood is forced out into the aorta/pulmonary arteries
• Volume in ventricles decrease

Four Phases of Cardiac Cycle (Isovolumetric Ventricular Relaxation)

• Ventricles relax; ventricular pressure drops below arterial pressure
• The semilunar valves close.
• AV valves open once ventricular pressure decreases below atrial pressure.
• Blood flows into the relaxed ventricles

Cardiac Cycle (additional details)

• Illustrates the coordinated sequence of events in the cardiac cycle, including atrial contraction, ventricular filling, isovolumetric contraction, ventricular ejection, and isovolumetric relaxation.

Four Phases of Cardiac Cycle

• The first heart sound occurs when the AV valves close, marking the beginning of systole/ beginning of isovolumetric contraction

Hormonal Control of Heart Rate

• Epinephrine increases heart rate by increasing action potential frequency at the SA node and increasing conduction velocity.
• Excess thyroid hormones lead to tachycardia. Insufficient thyroid hormones slow heart rate.
• Insulin and glucagon primarily affect myocardial contractile force (but glucagon has an additional influence on heart rate).

Respiratory System: Pulmonary Ventilation

• Focuses on the processes of breathing by Elda Dervishi, PhD, Assistant Professor, Cal Poly-Pomona

Functions of Respiratory System

• Respiration: gas exchange
• Moves air in and out of