Bio Midterm 2 Study Guide PDF

Everything I need to know: ​ Lecture 9: Animal Structure and Function: ○​ Biological Organization: Animals' levels of organization. ○​ Types of Tissue: Muscle (movement), Nervous (signaling), Epithelial (protection), Connective (support). ○​ Homeostasis and...

Everything I need to know: ​ Lecture 9: Animal Structure and Function: ○​ Biological Organization: Animals' levels of organization. ○​ Types of Tissue: Muscle (movement), Nervous (signaling), Epithelial (protection), Connective (support). ○​ Homeostasis and Feedback Mechanisms: Positive vs. negative feedback loops. ​ Lecture 10: Excretory System: ○​ Nitrogenous Waste: Types and their pros/cons. ○​ Kidney Functions: Filtration, reabsorption, secretion, excretion. ○​ Nephron Structure: Parts involved in urine formation. ○​ Ion Movement: Based on concentration gradients. ​ Lecture 11: Excretory System (Continued): ○​ ADH Function: Role in urine composition. ​ Lecture 12: Muscular System: ○​ Types of Muscle Tissue: Three types and locations. ○​ Muscle Structure: From overall muscle to sarcomere. ○​ Contraction Mechanism: Sliding filament mechanism. ○​ Regulation: Role of tropomyosin, troponin, myosin, and actin. ​ Lecture 13: Neuromuscular Junction: ○​ Components: Structural features of the neuromuscular junction. ○​ Acetylcholine and Calcium: Roles in contraction. ○​ Sarcoplasmic Reticulum and T-Tubules: Functions in muscle contraction. ​ Lecture 14: Sensory System I: ○​ Sensory Receptors: Types and functions. ○​ Hearing and Balance: Mechanisms involved. ​ Lecture 15: Sensory System II: ○​ Anatomy of Sensory Organs: Eye and olfactory structures. ○​ Signal Transduction: Eye focusing and olfactory processing. ​ Lecture 16: Reproductive I: ○​ Sex Determination: Genetic/hormonal aspects. ○​ Reproductive Cycles: Hormonal roles. ○​ Variability in Sexual Development: DSDs, AIS, CAH discussions. Animal Structure & Function -​ Epithelial cells → densely packed cells that are specialized or protect structures, and secrete and absorbs ions and organic molecules -​ Connective tissues → connect, surround, anchor, support, attach or allow for communication between cells & tissues -​ Muscle tissues → made up of cells specialized to contract or generate force for body movement -​ Nervous tissues → initiate/conduct electrical signals from one part of the body to another Homeostasis & Negative feedback -​ Negative feedback loop is a system that uses it’s output to regulate activity such as body temperature -​ Form example if you were to get too hot your sweating a blood vessels dilating as a response would be your body’s stimulus to regulate itself and cool down -​ Positive feedback loops do not play a huge role in homeostasis → this is when a response amplifies the stimulus and drives the process to completion -​ An example of the would be blood clotting where one clot leads to it getting worse rather than being solved by the body Forms of Nitrogenous Waste Ammonia Urea Uric Acid Toxicity Level Very toxic So toxic that it has Relatively to be diluted with non-toxic other fluids in order to safely pass through the body Type of animals Aquatic animals → Mammals, most Birds and many that have it live in water can amphibians, other reptiles,  passively diffuse sharks, & some insects, & land the ammonia at bony fishes snails any given time (including most bony fishes) Tolerated at Very low Low and diluted by Doesn’t matter concentrations other fluids other Amphibians who Least water loss are in water as often paste babies and may have ammonia eventually have urea once they are mature and on land → less water loss once mature energy Requires energy Most energetically expensive Kidney -​ Kidney has a renal cortex which is the outer layer that contains the nephrons (cortical nephron & juxtamedullary nephrons) -​ Cortical nephron (85%) - regulate water, electrolytes, excretion → loop of Henle in cortex (outer) where they create H+ gradient -​ Juxtamedullary nephron (15%) - reabsorption of water & solutes from the urine → loop of Henle in medulla (inner) where they create H+ gradient + extend deep into medulla -​ On the nephron there is the glomerulus which is the thing shaped like a lego hand and it is responsible for filtering the blood, specifically to collect fluids from it so they can be used to create urine -​ As you move down the nephron (like the arm of this lego hand) you enter the area where materials are reabsorbed back into the blood -​ As you go further you find the area where extra toxins, and waste go into the urine -​ The glomerulus is also surrounded by the bowman’s capsule and when both two are together it is considered the renal corpuscle and is the SOURCE of filtrate in the kidneys -​ Blood pressure forces blood through the slits on the glomerulus to make the filtrate -​ Small molecules can go through the bowman’s capsule such as water, ions, sugars, but larger molecules cannot -​ 1. Proximal tubule → critical reabsorption (ions, water, etc.), H+ gradient, ammonia secretion -​ NaCl in that filtrate uses transport epithelium diffuse (facilitated) allowing the Na+ ions to go into the interstitial fluid by active transport → simultaneously drives passive transport of Cl- -​ Water follows this movement of salt by osmosis + glucose, amino acids, K+ are actively transported from filtrate to interstitial fluid → then peritubular capillaries -​ These things balance the body fluids pH and secrete H+ into the lumen of the tubule -​ Synthesize and secrete ammonia NH4+ which acts as a buffer for H+ -​ Reabsorb HCO3- → more pH balance -​ 2. Descending limb of the loop of Henle → reduce filtrate volume + increase solute conc. Subsequently, major site for water reabsorption -​ Aquaporin forms water channels making epithelial cells permeable to water but not salt + small solutes so only water can exit by osmosis -​ Interstitial fluid must be hyperosmotic (high solute conc.) to the filtrate  -​ 3. Ascending limb of the loop of Henle → major site for NaCl reabsorption -​ Epithelium that lacks water channels, impermeable to water -​ Has a thick near segment adjacent to distal tubule → actively transports NaCl into interstitial fluid -​ Thin near the loop tip → -​ NaCl that has collecting in descending limb diffuses out of the permeable membrane tubule → goes into interstitial fluid, which helps maintain osmolarity -​ 4. Distal Tubule → regulates K+ and NaCl as well as pH -​ Secretes K+ and reabsorbs NaCl -​ Regulates H+ secretion + HCO3- reabsorption -​ 5. Collecting duct → either conserving water (dilute is becoming concentrated → producing urine) or producing dilute rather than urine which means duct is absorbing salts and NaCl is entering filtrate -​ When kidneys conserving water, aquaporin channels allow water to cross epithelium -​ As collecting duct traverses gradient of osmolarity the filtrate becomes concentrated losing water to the hyperosmotic interstitial fluid -​ When producing dilute rather than urine, duct absorbs salts without water, epithelium lacks aquaporin channels so NaCl goes to filtrate -​ Presence of water channels controlled by hormones ADH Role in Urine Composition -​ ADH is Antidiuretic hormone and controls how much water is reabsorbed or secreted by the kidneys (determines urine concentration) -​ When the body is dehydrated the hypothalamus stimulates the pituitary gland to release more ADH → which allows the kidneys to hold on to more water -​ When ADH is present in the blood (after being released by brain) it allows more aquaporin channels in the collecting ducts & distal convoluted tubule, allowing for more water to be reabsorbed -​ More ADH conc. urine -​ Less ADH nonconc. urine -​ Diabetes Insipidus → production of lots of dilute urine -​ Mostly due to insufficient ADH, or can be a result of a mutation in an aquaporin family member -​ Senses + Sensory Organs -​ Sensory reception involves sensory receptors and their detection of stimuli within or outside the body -​ This reception leads to a change in the flow of ions across the membrane which alters receptor potential -​ This conversion of a stimulus is known as sensory transduction & the strength of the stimuli -​ Transmission occurs in two ways -​ 1. If the sensory receptor is a neuron it generates an action potential which travels along the axon to the CNS -​ 2. If the sensory receptor is a non-neuron is conveys information to a neuron via chemical synapse (this also means they are slower at conveying information due to having to pass through more before entering the CNS) -​ Things such as the intensity of the stimulus can affect action potentials -​ Most neurons do not turn on or off and instead change the rate in which they generate action potentials (they also often are constantly generating them at a super low rate) -​ Perception → how does the brain know what the stimuli is and therefore how to generate the perception of it? -​ Connections that are premade and dedicated to a particular stimulus show the brain what is meant to be perceived Types of Sensory Receptors -​ Mechanoreceptors affect hearing, balance, touch, and things like stretching, motion, and pressure -​ They are powered by membrane potentials which are altered due to a mutation (bending, stretching, pressure) in the internal (cytoskeleton) and external (hair, etc.) things that are affected by these senses -​ These membrane potentials being altered allows for a receptor potential or a hyperpolarization/depolarization of typically an ion gradient -​ The signal of usually depolarization is sent into the ion gradient which causes it to go from resting to depolarized and the signal is followed by a repolarization signal so the gradient may return to its resting state -​ Touch receptors are often embedded in tissue -​ Both structure and location heavily affect how the brain perceives the stimuli -​ Chemoreceptor → two types 1. Detecting changes is solute concentration (called osmoreceptors) which tell the brain when to be thirsty if dehydrated  and 2. Others that response to glucose, oxygen, carbon dioxide, and amino acids -​ Electromagnetic receptor → light, electricity, and magnetism -​ Used by lots of mammals to find prey and locate where they are during migration using the Earth’s magnetic field lines -​ Thermoreceptors → detect heat and cold, in humans are in the skin and the anterior hypothalamus -​ Some flavors activate the same receptors as these temperatures such as hot foods and menthol -​ Pain receptors → detect intense pressure, temperature, or harmful chemicals, nociceptors detect noxious (harmful) conditions -​ Damaged tissues can produce prostaglandins which worsen pain in the future by increasing nociceptor sensitivity Hearing & Balance -​ Sound waves enter the pinna (ear) and go through the auditory canal till they hit the tympanic membrane, they then enter the middle ear and go from malleus to incus to stapes till they hit the oval window, here in the middle there is also the eustachian tube that balances pressure between the middle ear and atmosphere, once it hits oval window it enters the inner ear where they were fluid filled tubes called the semicircular canals (balance) as well as the cochlea (hearing) -​ The round window acts as a pressure release valve that allows fluid in the cochlea to move which is necessary for sound waves to turn into neural signals -​ The cochlea has two large canals (vestibular on top and tympanic on bottom) that are separated by a cochlear duct  -​ Inside there is the Organ of Corti which connects to the auditory nerve which are connected to the hairs inside the Corti (the bending of these hairs in what causes the change in membrane potential) Pinna + Auditory Canal Collect sound waves and send them to tympanic membrane (it vibrates) Tympanic Membrane Vibrates and sends vibrations to malleus Malleus Carry vibrations Incus Carry vibrations Stapes Vibrates against oval window so that pressure waves are created inside the cochlea Oval Window Send vibrations to cochlea through semicircular canals Semicircular Canals Pressure waves push down on cochlear duct and basilar membrane + attached hair cells (causes depolarization) Cochlea Fluid moves and moves hair cells causing the vibrations to be be better received Eustachian Tube Balances pressure, drains fluid, connection from back of ear to throat Round Window Lets out vibrations after they’ve already stimulated the hair cells reducing pressure and allowing for proper hearing Auditory Nerve Connected to the organ of Corti in the cochlea (with hair cells) that transport Equilibrium -​ Two chambers called utricle and saccule that are behind the oval window and are filled with a gelatinous material which hair cells project into is responsible for balance -​ In this gel are ‘ear stones’ which are also called otoliths and are just small calcium carbonate particles that the hair cells touch when movement occurs which allows the hair cell receptors to send proper signals to the brain -​ Three fluid filled canals connected to the utricle detect head movement and other rotational accelerations → in these canals hair cells form in clusters and a gelatinous cap forms on top of them which is what the fluid in the canals move simultaneously moving the hair cells too -​ Some other vertebrates conduct sound in a similar way but it’s not as complex as the human ear and often has no cochlea, eardrum, or opening to the outside (pinna)  -​ Most aquatic animals have a lateral line system which goes down the sides of their body and contains the same culpa and hair cell system we have in our semicircular canals which helps to detect movement -​ In animals like frogs there is an external tympanic membrane that conducts these sounds Vision & Smell -​ Compound eyes have several thousand eyes containing ommatidia which are light detectors → and have their own light-focusing lens that capture light -​ The cornea & crystalline cone of each ommatidium focus light on the rhabdom -​ Rhabdom traps light & is the photosensitive part of the ommatidium -​ Neurons located in the retina are struck by light and then this light reaches -​ the rods and cones -​ These neurons relay information to the optic nerve -​ Four cell types: ganglion cells, amacrine cells, bipolar cells, and horizontal cells -​ Ganglion which are attached to the optic nerve gather info from multiple bipolar cells -​ Bipolar cells gather information from multiple rods and cones -​ Horizontal and amacrine cells integrate information across the retina -​ The optic disk (where the optic nerve exits the retina) lack photoreceptors created blindspot -​ Rods more sensitive to light (but no color), cones less sensitive but color (don’t provide as much night vision) -​ Visual pigments contain retinal (DERIVATIVE OF VITAMIN A)which is bound to opsin (which are inside the discs of the cones → retinal has two isomers cis & trans and light shifts them between these two -​ Rhodopsin in retinal and opsin combined -​ In cones the pigment molecules are photopsins Overall Steps:  1.​ Light enters through pupil 2.​ Strike the retina (which involves passing through layers of neurons) 3.​ Reaches rods and cones (photoreceptors) a.​ Cones COLOR rods black Feature Rods Cones Shape Long & cylindrical - Short & tapered - faster optimizes light signal processing for color absorption in low-light detection conditions Outer segment Stacked discs (separate Folded membrane - from membrane) - supports rapid adaptation increases light sensitivity to changing light Light sensitivity Very high (night vision) - Lower - best in daylight good in dim environments Speed of response Slower - signals from Faster - each one has their multiple rods coverage own ganglion cell Visual activity Low - sacrifices detail for High - sharp and detailed sensitivity (again multiple (bcs of the one ganglion) ganglion cells) Sensory Transduction -​ The shift from cis to trans in which the visual pigment activates a G protein, which activates enzyme phosphodiesterase -​ In rods and cones this enzyme is called GMP which in the dark binds to sodium ion channels and keeps them open -​ However when the enzyme hydrolyzes cGMP the sodium channels close and the cell becomes hyperpolarized Steps: 1.​ Light energy causes isomerization (cis to trans/vice versa) 2.​ Causes opsin to have conformational change that activates transducin 3.​ Transducin activates phosphodiesterase which makes cGMP into GMP 4.​ LESS cGMP = sodium channels CLOSED (hyperpolarizes cell), MORE cGMP = sodium channels OPEN Olfactory: -​ Two types of sensory receptors 1. Neurons 2. Cell that regulates a neuron -​ Depends on chemoreceptors → they are in the epithelial tissue of the nasal cavity -​ These cells have long cilia that bind to odorants Sensory Transduction in Nose: -​ Olfactants bind to receptor → triggers signal transduction by G protein which leads to production of cAMP -​ cAMP opens the Na+ and K+ channels → the flow of these ions leads to depolarization of the membrane, generating action potentials Muscular System: -​ Muscle fiber made of myofibrils → made of sarcomeres which are between two Z lines (lines that help with tension between the sarcomeres so that movement does not cause injury) -​ Sarcomeres are made of thick (MYOSIN) and thin (ACTIN) filaments -​ Actin (thin) filaments go horizontally down the myofibril while myosin (thick) filaments stay between z lines -​ Muscles turn ATP into movement by contracting (shortening) → actin and myosin slide on each other -​ Sliding filament model: thick (myosin) filaments stay while think (actin) filaments slide pulling on the Z lines (shortening the sarcomere) -​ Works because myosin (thick) heads are constantly pulling on actin (thin) filaments and pulling (causes shortening) -​ The myosin heads on the thick filaments within the sarcomere are hydrolyzed by ATP which turns into ADP and a phosphate group, this then allows the head to bind to the actin (thin) filament which causes a release of the ADP and phosphate and a cross bridge is formed between the two → this allows the myosin to perform a power stroke which allows it to pull the actin (thin) filaments causes contractions -​ This cross bridge cannot be broken until the myosin head gains a new ATP which serves as the cross bridge breaker -​ Actin (thin) filaments have tropomyosin which blocks the myosin from binding to its binding sites (and troponin which does the same thing) → this allows for regulation so the myosin heads aren’t always working -​ When a neuron stimulates a muscle calcium will be released and bind to troponin → removed them and allowing myosin head binding -​ Neuromuscular Junction -​ Chemical synapse between a motor neuron and a skeletal muscle fiber 1.​ An action potential in the neuron opens the Ca2+ channels 2.​ This causes the release of ACH or acetylcholine 3.​ This ACH binds to the receptor proteins on the muscle fiber producing a new action potential -​ Sarcoplasmic reticulum → special form of endoplasmic reticulum that acts as a Ca2+ reservoir and surrounds the microfibrils in the muscle fiber -​ Transverse tubules → infoldings in the plasma membrane of the muscle fibers that conduct action potentials  1.​ An action potential reaches the synaptic terminal and causes the release of ACH 2.​ This action potential spreads and enters the transverse tubules which affect the sarcoplasmic reticulum and causes the SR calcium channels to open 3.​ Calcium is pumped out of the sarcoplasmic reticulum and into the cytosol 4.​ This calcium binds to the troponin complexes on the thin (Actin) filaments 5.​ This initiates muscle fiber contraction by allowing the myosin heads to bind to the actin (thin) filaments 6.​ Calcium is pumped back into the sarcoplasmic reticulum 7.​ once the calcium concentration is low enough the troponin complexes return to the actin (thin) filaments causing everything to go back to its resting state Reproduction -​ Androgen insensitivity syndrome (AIS) - XY but are unresponsive to androgens like testosterone → no functional ovaries, gonads do not produce typical male characteristics, normal/high testosterone (still not responsive) -​ Congenital adrenal hyperplasia (CAH) - XX but higher than usual androgen production before birth → ovaries but external genitalia might be weird, due to extra androgen before birth extra masculinization occurs -​ Sex determination: determined at fertilization where an XX or XY chromosome is picked → SRY GENE SUPER IMPORTANT because is the sex-determining or Y region on the Y chromosome that is responsible for triggering male development (without it we get ovaries)  -​ RSPO1 is secreted by XX individuals via somatic cells in early developing gonads -​ RSPO1 expression increases in the gonads which activates B-catenin and ovarian differentiation -​ WNT4 expressed before sex determination by XX gonads as ovarian development happens -​ This is expressed in both XY and XX gonads but eventually is deregulated in XY gonads due to SRY (Y-region) activity -​ RSPO1 enhances the WNT/B-catenin pathway stabilizing B-catenin which promotes ovarian differentiation and inhibits SOX-9 (key factor for testis) -​ WNT4 and RSPO1 activate B-catenin reinforcing ovarian commitment & suppressing testi structures like Sertoli cells and Leydig cells Female Pathway XX Steps: 1.​ RSPO1 and WNT4 activate the frizzles receptor on the cell surface 2.​ These signals promote ovarian development by downstream activation factors such as B-catenin 3.​ B-catenin and FOXL2 inhibit SOX9 4.​ Ovaries and granulosa cells Male Pathway XY Steps: 1.​ Unknown activates MAP3K1 triggering map kinase signaling pathway 2.​ Phosphorylation of GATA4 3.​ Expression of SRY 4.​ SOX9 induces DMRT1 and DHH signaling 5.​ Sertoli cell differentiation + testis 6.​ Leydig cells, further male structure development -​ Sexual differentiation: in males testes produce androgens which drive the development of reproductive organs and secondary sexual traits -​ In females differentiation occurs in the absence of high testosterone levels that allow for the development of ovaries & the female reproductive tract with estrogens and progesterone -​ Mullerian ducts develop in females (uterus & fallopian tubes) unless by anti-Mullerian hormone AMH -​ Mammal reproduction regulated by hormones from hypothalamus, anterior pituitary, & gonads -​ Hypothalamus releases GnRH prompting anterior pituitary to release FSH and LH, stimulating gonadal activity + sex hormones -​ Hypothalamus releases GnRH which goes to anterior pituitary which releases FSH and LH -​ In males FSH stimulates Sertoli cells (to nourish sperm) and LH Leydig cells (produce testosterone and androgens)  -​ Negative feedback: testosterone inhibits GnRH, FSH, and LH through feedback on hypothalamus and pituitary -​ Inhibin from sertoli cells reduces FSH secretion feedback on pituitary -​ Leydig cells secrete other hormones & regulators linked to reproductive growth, metabolism, and homeostasis