05. Animal Form and Function [DEFINITIONS] Flashcards
Ventricles
Ventricles are the four irregular shaped cavities formed by the central canal in the brain.
Autonomic Nervous System
The nervous system that controls the involuntary activities of the body consisting of neurons which carry impulses to control activities of smooth muscles, cardiac muscles, and glands is the autonomic nervous system.
Motor System
The nervous system that consists of neurons that carry nervous impulses to skeletal muscles controlling voluntary activities is the motor system.
Resting Potential
When a neuron is at rest (when not sending a signal/non conducting), the membrane potential is called the resting potential.
Action Potential
An action potential occurs due to a change in membrane potential above a threshold value due to a stimulus.
Depolarization
Depolarization is a change in the cell’s membrane potential such that the inside of the membrane is made less negative relative to the outside which is resulted from Na+ inflow in response to a stimulus.
Repolarization
Repolarization is when sodium channels close, blocking Na+ inflow. Here, most potassium channels open permitting K+ outflow, making the inside of the cell negative.
Hyperpolarization
Hyperpolarization is when sodium channels are closed but potassium channels are opened, resulting in the inside of the membrane being more negative.
Refractory Period
A refractory period is the short time immediately after an action potential where the neuron cannot respond to another stimulus, because of the inactivation of sodium channels. This prevents the reverse conduction of an impulse in an axon.
Synapse
A synapse is the junction where a neuron (presynaptic cell) communicates with another cell (postsynaptic cell) across a narrow gap (synaptic cleft)
Postsynaptic Cell
A postsynaptic cell is a cell that may be another neuron, muscle cell or secretory cell.
Chemical Synapse
The junction where one neuron communicates with the next cell using a chemical (neurotransmitter) is called a chemical synapse.
Electrical Synapse
Some neurons can also communicate through direct electrical connections. This is called an electrical synapse.
Neurotransmitters
Neurotransmitters are the molecules that are released from the synaptic terminals of presynaptic neuron and diffuse across the synaptic cleft, bind with the receptors at the postsynaptic membrane triggering a response.
Reflex Arc
Reflex arc is the functional unit of the vertebrate nervous system.
Sensory Neuron
A sensory neuron transmits impulses from a sensory receptor to the central nervous system.
Interneuron
The central nervous system synapses with an associated neuron called interneuron.
Motor Neuron
When an impulse is transmitted to a motor neuron by the interneuron, the motor neuron conveys the signal to effector tissues/organs.
Sensory Receptor
A sensory receptor is a specialized structure such as a specialized cell, organ or a subcellular structure which can detect a specific stimulus and convert the stimulus energy to a changing membrane potential to be transmitted to the central nervous system as action potentials for sensory perception and interpretation.
Chemoreceptors
Chemoreceptors are sensory receptors that respond to chemical stimuli
Taste receptors
Receptors that detect the five basic sensations (sweet, sour, bitter, salt, and umami- savory taste) are taste receptors
Olfactory Receptors
Olfactory receptors are cells located within the epithelium of the upper portion of the nasal cavity detecting odors
Thermoreceptors
Specialized temperature sensitive receptors which detect heat and cold on the body surface and in the internal environment of the body are thermoreceptors.
Photoreceptors
Photoreceptors are sensory receptors that are sensitive to light
Mechanoreceptors
Mechanoreceptors are receptors that respond to stimuli arising from mechanical energy deformation such as pressure, touch, stretch, motion and motion.
Pain Receptors
Pain receptors detect stimuli that reflect harmful conditions that could arise from extreme pressure, temperature, and certain
chemicals that could damage the tissues.
Lens
The lens is an elastic, biconvex, transparent disc made up of protein enclosed within a transparent capsule which lies immediately behind the pupil
Retina
the retina is the innermost lining of the eye consisting of three layers (outer pigmented epithelium, middle photoreceptive layer and inner layer with neurons)
Monocular Vision
Seeing the visual field using only one eye is called monocular vision.
Binocular Vision
Seeing the visual field using two eyes with greater overlapping fields of view is called binocular vision.
Epidermis
Epidermis is the outermost layer of skin which consists of stratified keratinized squamous epithelium. It’s not supplied with blood vessels.
Dermis
Dermis is composed of areolar connective tissue with a matrix that contains collagen fibers interlaced with elastic fibers.
Endocrine Glands
Endocrine Glands are ductless glands consisting of groups of specialized cells which secrete hormones (chemical messengers) that diffuse directly into the bloodstream and reach the specific target organs/tissues that may be located quite distantly.
Hormone
Hormones are specific types of signaling molecules secreted by an endocrine gland/endocrine cells and travels in the blood on specific target cells elsewhere in the body, changing the target cell functioning.
Homeostasis
Homeostasis is a steady state condition where body’s internal environment remains relatively constant within narrow physiological limits despite significant changes in the external environment.
Osmoregulation
Osmoregulation is the process of maintaining water and salt balance (osmotic balance) across membranes within the body’s fluids relative to the surrounding.
Reproduction
Reproduction is a biological process through which a new generation of individuals is produced from the existing organisms.
Asexual Reproduction
Asexual reproduction is a mechanism through which new individuals are generated from a single parent without the fusion of egg and sperm. It allows the rapid multiplication of individuals from single parents and relies entirely on mitotic cell division.
Budding
Budding is a form of asexual reproduction in which new individuals arise from outgrowths of an animal
Fragmentation and Regeneration
This is a form of asexual reproduction which involves breaking of the body or part of the body into several pieces, followed by the growth of a separate individual from each piece. Here, each fragment develops into a complete animal by the regrowth of lost body parts (regeneration)
Parthenogenesis
Parthenogenesis is an unusual form of asexual reproduction in which an egg develops into a complete individual without being fertilized.
Sexual Reproduction
Sexual reproduction is a mechanism through which a new individual is developed from a diploid zygote as a result of the fusion of two haploid gametes (the sperm and the egg) which are produced by two individuals (the male and the female parents respectively)
Fertilization
The union of an egg and a sperm (gametes) culminating in fusion of their nuclei is called fertilization. This could be internal or external
Internal Fertilization
In internal fertilization, sperms are deposited in or near the female reproductive tract and fertilization occurs within the female reproductive tract.
Spermatogenesis
Spermatogenesis is the process of male gamete formation which includes formation of spermatocytes from a spermatogonium, meiotic division of the spermatocytes, and transformation of the four resulting spermatids (from each spermatocyte) into spermatozoa (sperm)
Semen
Semen is the fluid that contains a mixture of sperms and the secretions of three sets of accessory glands discharged from the urethra during ejaculation.
Seminal Vesicles
The seminal vesicles are a pair of two small pouches that produce a thick, yellowish fluid that is expelled during ejaculation.
Prostate Gland
Prostate gland is found below the urinary bladder and secretes a thin, milky fluid directly into the urethra through small ducts.
Bulbourethral Glands
Bulbourethral glands are a pair of small glands found along the urethra below the prostate and secrete a clear alkaline mucus that is able to neutralize any acidic urine remaining in the urethra and lubricates the lining of the urethra.
Ovaries
Ovaries are organs found on either side of the uterus and held in place in the abdominal cavity by ligaments.
Oviducts
The oviduct or the fallopian tube is a structure that extends from the uterus toward a funnel like opening at each ovary.
Uterus
The uterus or the womb is a thick, pear shaped chamber with a highly vascularized inner lining (endometrium) and muscular walls which allows it to expand during pregnancy to accommodate the fetus
Vagina
The vagina is a muscular but elastic chamber with a stratified epithelium connected to external and internal organs of reproduction. This is the site where sperm is deposited and also serves as the birth canal.
Uterine cycle
The uterine cycle consists of changes that occur about once a month in the uterus.
Ovarian Cycle
The cycle that controls the cyclic changes in the uterus is the ovarian cycle.
Menopause
Menopause is the cessation of ovulation and menstruation in a woman where the ovarian supply of oocytes runs out and estrogen production by the ovary decreases.
Blastocyst
About five days after fertilization, a large fluid filled cavity is formed surrounding the ball of cells. With the formation of the cavity, this developing stage is referred to as the blastocyst. This includes the structures of inner cell mass and the trophoblast formed by the further rearrangements of the cells in the blastocyst.
Chorion
Chorion becomes the main embryonic portion of the placenta which is the structure for exchange of materials between the fetus and mother, and protects the embryo/fetus from immune responses of the mother.
Amnion
Amnion is a protective membrane surrounding the embryo/fetus creating a fluid filled cavity which serves as a shock absorber and helps prevent desiccation.
Yolk Sac
The yolk sac contributes to the cells that will become blood cells until the fetal liver takes over and is also the source of primordial germ cells that migrate to the developing gonads
Allantois
Allantois is a small outer-pouching of the yolk sac that serves as an early site for blood formation and is also associated with the development of the urinary bladder.
Placenta
The placenta is a disc shaped organ formed by two parts: embryonic/fetal portion formed by chorionic villi of the chorion and maternal portion formed by the endometrium.
Umbilical Cord
The umbilical cord is a flexible cord-like structure containing blood vessels and attaches embryo/fetus to the placenta during gestation.
Pregnancy
Pregnancy or gestation is the condition of carrying one or more developing offspring inside the uterus of a female
Labor
Labor is a series of strong, rhythmic uterine contractions that push the fetus and placenta out of the body
Lactation
Lactation is the secretion and ejection of mother’s milk from the mammary glands
Infertility
Infertility is the inability to conceive offspring.
Hydrostatic Skeleton
The hydrostatic skeleton is a fluid filled body cavity which is enclosed by the body wall.
Exoskeleton
The exoskeleton is a rigid outer covering of the body of the animal which acts as a skeleton.
Endoskeleton
The endoskeleton is a hard skeleton which is buried in the soft tissues of the animal. These can include plates of calcium carbonate (in echinodermates) or bones and cartilage (in chordates)
Sternum
The sternum is a long flat bone that forms the anterior part of the thoracic cage (which is made up of sternum, ribs and thoracic vertebrae)
Simple Squamous Epithelium
It is a single layer with plate-like cells which is thin and leaky. Found in places where materials exchange by diffusion.
Simple Cuboidal Epithelium
It is a single cell layer with dice shaped cells specialized for secretion found in kidney tubules, and glands like thyroid and salivary glands.
Simple Columnar Epithelium
It is a single layer with large brick-shaped cells often found in places where secretion or active absorption is important (ex: intestinal lining)
Stratified Squamous Epithelium
Connective Tissue
Connective tissues are the most abundant tissues in the body that help connect organs and tissues together structurally and functionally.
Loose Connective Tissue / Areolar Tissue
A generalized type of connective tissue containing fibroblasts, macrophages, mast cells, leukocytes and fat cells, loosely arranged and wavy in nature.
Fibrous Connective Tissue / Dense connective Tissue
Densely packed connective tissue containing collagen fibers where the matrix is relatively reduced with fewer cells. (fibrocytes)
Adipose Tissue
Specialized type of connective tissue packed with adipose cells.
Blood Tissue
It is a specialized type of connective tissue in which the matrix is not secreted by the cells and fibers.
Cartilage
This tissue consists of a matrix composed of chondroitin sulphate which is a rubbery protein-carbohydrate complex.
Bone
It is a mineralized connective tissue with a matrix that consists of collagen fibers and inorganic salts.
Muscle Tissue
Muscle tissues is responsible for movement and are made of cells composed of actin and myosin proteins
Nervous Tissue
A tissue containing neurons and glial cells
Neuron
Basic structural unit of the nervous system containing a cell body, dendrites and an axon.
Neuroglia / Glial Cells
Neuroglial cells are supportive cells of neurons
Animal Nutrition
Animal nutrition is the process by which food is taken in to make use for different body functions
Heterotrophic Nutrition
Heterotrophic nutrition is the process by which the organisms obtain organic food molecules by ingesting other organisms or by substances derived from other organisms.
Holozoic Nutrition
Most animals are holozoic where they ingest food into their alimentary canal.
Ingestion
This is the first stage of holozoic nutrition where the act of eating or feeding happens.
Digestion
Here, food is broken down into molecules small enough to pass through the membranes and enter the cells of organisms.
Digestion
Food is broken down in to smaller fragments thus increase the surface area for efficient chemical digestion.
Absorption
In this stage, the animal’s cells take up small molecules (ex: simples sugars, amino acids)
Assimilation
Assimilation is the process of utilization of absorbed nutrients for various functions of the body.
Elimination
In this process undigested materials are passed out from the alimentary canal.
Filter Feeders
They strain suspended food particles from the surrounding watery medium
Fluid Feeders
They suck nutrient rich fluid from a living host using well adapted mouth parts.
Substrate Feeders
These animals live inside their food source or on the food source eating its way through the food.
Bulk Feeders
Animals which eat comparatively large pieces of food.
Symbiosis
This is an ecological relationship between organisms of two different species that live closely together.
Mutualism
It is a close association between two living organisms of different species which benefits both partners.
Parasitism
It is a close association between two living organisms of different species which is beneficial to one (parasite) and harmful to the other (host)
Commensalism
It is a close association between two living organisms of different species which is beneficial to one and does not affect the other (neither harmful or beneficial)
Human Alimentary Canal
Human alimentary canal is a long tube/tract which connects with external environment and can fulfill steps of holozoic mode of nutrition.
Mouth / Oral Cavity
Oral cavity consists of the tongue, teeth and salivary glands where ingestion and initial steps of digestion are carried out in the oral cavity.
Tongue
Its composed of skeletal muscles and helps mix the food with saliva and make bolus of food that makes it easier for swallowing, then helps push the bolus into the posterior part of the oral cavity and into the pharynx.
Pharynx
A common passage of the respiratory tract and the digestive tract which leads to the esophagus.
Esophagus
It is a long tube which connects the pharynx and the stomach and found in the thoracic cavity.
Stomach
The stomach is a J-shaped dilated sac in the abdominal cavity
Small Intestine
It is the longest organ in the alimentary canal divided into three regions: duodenum, jejunum and ileum
Pancreas
The pancreas is pale grey gland which consists of a broad head, a body and a narrow tail.
Liver
Liver is the largest gland in the body. Its upper and anterior surfaces are smooth and convex.
Balanced Diet
The balanced diet contains the all essential nutrients required for health in the appropriate proportions.
Carbohydrates
Carbohydrates are sugars and polysaccharides
Proteins
Proteins are made of amino acids during the digestion, proteins are broken down into amino acids and absorbed into the blood stream.
Lipids
Lipids in the diet are mainly composed of fats and oils
Vitamins
Vitamins are organic compounds required in small amounts for the maintenance of normal health and metabolism
Minerals
Minerals are inorganic substances and they are also important for normal health and many body functions
Water
Water accounts for around 60% of the body mass in humans and normally is lost through urine, sweating and feces
Fibers / Dietary Fibers
Dietary fires (non starch polysaccharides) are made up of indigestible polysaccharides in the diet.
Essential Nutrients
Essential nutrients are the substances that cannot be synthesized in the body from simple precursors and must therefore be taken through the diet.
Essential Amino Acids
Essential amino acids are the amino acids that must be obtained from the food since they cannot be synthesized within the body from organic precursor molecules.
Essential Fatty Acids
Essential fatty acids are the fatty acids that should be obtained from the diet since they cannot be synthesized in the body from organic precursors.
Basal Metabolic Rate (BMR)
Basal metabolic rate is defined as the minimum metabolic rate at rest, when in a post absorptive stage (at least 12 hour fasting) and is not experiencing stress.
Energy Budget
An energy budget is a balance sheet of energy intake against energy expenditure in a particular animal.
Malnutrition
Malnutrition can arise due to the failure of obtaining an adequate nutrition when the diet lacks one or more essential nutrients or consistently supplies less chemical energy than the energy required by the body.
Obesity
Obesity arises when energy expenditure of a person is much less than the energy intake.
Gastritis
Gastritis is a condition resulting inflammation of the stomach which can be due to several reasons.
Constipation
Constipation occurs due to the slow movement of feces that promotes the water reabsorption and as a result feces become more solid.
The Open Circulatory System
It is a circulatory system in which a fluid called hemolymph that bathes the tissues and organs directly. There is no distinction between the circulatory fluid nd the interstitial fluid surrounding cells.
The Closed Circulatory System
It is a circulatory system in which is restricted to vessels and kept apart from the interstitial fluid.
Single Circulation
During single circulation, in a complete circulation through the entire body, blood passes through the heart only once.
Double Circulation
During double circulation, in a complete circulation through the entire body, blood passes through the heart twice.
Pericardium
Pericardium is the outer most layer of the human heart made up of two sacs
Myocardium
Myocardium is the middle layer of the heart composed of specialized cardiac muscle found only in the heart.
Endocardium
Endocardium is the inner layer of the heart wall which lines the chambers and valves of the heart.
Sinoatrial Node / SA Node
SA node is a small mass of specialized cells and lies in the myocardium of the right atrium near the opening of the superior vena cava. The stimulus for contraction of the heart originates in the ‘SA node’
AV Node
AV node is also a small of specialized cells situated between the wall of the left and right atria. It transmits the electrical signals from the atria into the ventricles.
Atrioventricular Bundle (Bundle of His)
AV bundle is a mass of fibers which originates from the AV node.
The Cardiac Cycle
The cardiac cycle refers to the sequences of events that take place in a complete heart beat.
Complete Cardiac Diastole
Relaxation of the atria and ventricles
Atrial Systole
Contraction of the atria
Ventricular Systole
Contraction of ventricles
Electrocardiogram (ECG)
A recording that records the electrical activity in the heart that can be detected on the surface of the skin by placing electrodes on the chest or limbs as the body tissues and fluids conduct electricity well.
Blood Pressure
The force that the blood exerts on the walls of blood vessels as it travels is referred to as blood pressure.
Systolic Pressure
Systolic pressure is the pressure produced within the arterial system when the left ventricle contracts and pushes blood into the aorta
Diastolic Pressure
Diastolic blood pressure is the blood pressure within the arteries following ejection of blood at complete cardiac diastole (when the heart is at rest)
Hypotension
Sustained reduction of blood pressure below normal limits is called hypotension
Coronary Circulation
The heart is supplied with arterial blood by the right and left coronary arteries which branch from the aorta immediately distal to the aortic valve.
Atherosclerosis
The inner lining of the arteries can be thickened and harden leading to the condition called atherosclerosis and it occurs as a result of fatty deposits especially cholesterol particles.
Stroke
Blockage due to atherosclerosis or rupture of arteries supplying blood to the brain may cause the death of nervous tissue due to the lack of oxygen and nutrients. This is referred to as a stroke.
Respiratory Pigments
Respiratory pigments are organic compounds which can combine with oxygen where the partial pressure of oxygen is high and release oxygen where partial pressure of oxygen is low.
Red Blood Cells / Erythrocytes
They are small biconcave disk-like cells which lack nuclei
Platelets
Platelets are derived from bone marrow cells. they do not have nuclei and play a major role in blood clotting.
Blood Plasma
Blood plasma consists of inorganic ions in dissolved forms, plasma proteins (ex: albumin) antibodies and fibrinogen, nutrients, metabolic wastes, respiratory gases and hormones.
Blood Clotting
When a tissue is damaged, blood flows from it and coagulates to form a blood clot. this process is known as blood clotting.
Silicosis
Silicosis is caused by long-term exposure to dust containing silica compounds
Asbestosis
This condition occurs when asbestos fibers are inhaled with dust.
Tuberculosis (TB)
Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis.
Lung Cancer
When one smokes, the nasal hairs, mucus, and cilia in the respiratory tract that otherwise is sufficient to protect the lung from chemical and biological irritants, are overwhelmed and eventually stop functioning. As a result, irritants, free radicals, carcinogens and pathogens accumulate in the lungs which eventually cause lung cancer.
Asthma
Asthma is characterized by wheezing and chest tightness causing breathing difficulty caused by the sudden contractions of smooth muscles in the walls of the bronchioles which causes the bronchioles to narrow or even close.
Tidal Volume (TV)
This is the volume of air inhaled and exhaled with each breath during normal breathing.
Inspiratory Reserve Volume (IRV)
This is the extra volume of air that can be forcibly inhaled beyond the tidal volume.
Expiratory Reserve Volume (ERV)
The extra volume of air which can be expelled from the lungs after a tidal expiration.
Residual Volume (RV)
This is the volume of air that remains in the lungs even after forceful expiration
Inspiratory Capacity (IC)
The total volume of air that can be inspired after a tidal expiration
Functional residual capacity (FRC)
The volume of air remaining in the lungs at the end of a tidal expiration
Vital Capacity (VC)
The maximum volume of air which can be inhaled and exhaled.
Total Lung Capacity (TLC)
The maximum volume of air the lungs can hold or the sum of all lung volumes.
Anatomical Dead Space
Some of the inspired air fills the system of branching conducting tubes (trachea, bronchi and bronchioles) and never contributes to the gas exchange in the alveoli. This volume is anatomical dead space.
Immunity
The state of being resistance to injury, invading pathogens and foreign substances through defensive mechanisms in the body.
Innate Immunity
Innate immunity is the ability to resist damage or diseases in the body through inherent body defenses which offer rapid responses against a broad range of pathogens and foreign substances.
External Defenses
External barriers discourage pathogens and foreign substances from penetrating the body. So they are considered the first line of defense.
Phagocytic cells
They are specialized cells that can ingest microbes, foreign particles and cell debris for intra cellular digestion and destruction.
Natural Killer Cells
These are a type of lymphocytes present in the blood and some tissues/organs such as spleen and lymph nodes which function in nonspecific defense
Antimicrobial Proteins
They are proteins present in the blood and interstitial fluids which function in innate defense by attacking microbes directly or impeding their reproduction.
Inflammatory response
This is an innate immune defense response in the body to tissue damage triggered by microbial infections or injury of the tissues.
Acquired Immunity (Adaptive Immunity)
Acquired immunity is the ability of the body to defend itself against invading foreign agents (ex: pathogens) through specific defense responses mediated by diverse T lymphocytes and B lymphocytes
Antigen
An antigen is a substance that has the ability to stimulate an immune response through T lymphocytes and B lymphocytes and to react with the specific cells or antibodies that resulted from the stimulated immune response.
Cell Mediated Immune Response
Cell mediated immune response is a type of acquired immunity in which specifically sensitized T lymphocytes attach to the antigen proliferation and eventually differentiate into “Cytotoxic T cells” that can directly kill the cells with the invading antigen.
Humoral Immune Response
Humoral immune response is a type of acquired immunity in which specifically sensitized B lymphocytes attach to a particular antigen undergo proliferation and eventually differentiate into “Plasma cells” that secrete circulating antibodies that can neutralize and inactivate the specific toxins and pathogens in the blood and lymph.
Antibodies
Antibodies are proteins secreted by plasma cells (differentiated B lymphocytes) in response to specific antigens; the antibody binds with that antigen to neutralize, inhibit or destroy it.
Active Immunity
Active immunity is a long lasting immunity mediated by the action of B lymphocytes and T lymphocytes in the body nd the resulting B and T memory cells specific for a pathogen
Naturally Acquired Active Immunity
Long lasting immunity developed in the body against various infectious diseases in response to natural infections of pathogens is called naturally acquired active immunity.
Artificially Acquired Active Immunity
Long lasting immunity induced artificially in the body against various infectious diseases through vaccination (immunization) of attenuated (virulence-reduced) pathogens is called artificially acquired active immunity.
Passive Immunity
Passive immunity is the short term immunity developed with the body due to the transfer of antibodies produced by another individual
Naturally Acquired Passive Immunity
Short term antibody mediated immunity for some infectious diseases can be developed within the body of the fetus or nursing infant due to the natural transfer of antibodies produced by the mother.
Artificially Acquired Passive Immunity
Artificially acquired passive immunity is a temporarily induced defensive protection achieved by the transfer of antibodies artificially to the blood of the recipient from another source.
Allergies
Exaggerated responses of the body to certain antigens (allergens) are called allergies
Allergens
Antigens that induce hypersensitive reactions in some persons are called allergens
Autoimmune Diseases
In some persons, the immune system becomes active against particular self-molecules of the body and begins to attack the person’s own tissues leading to an autoimmune disease.
Immunodeficiency Diseases
Immunodeficiency disease is a disorder in which responses of the immune system to antigens are defective or absent
Osmoregulation
Osmoregulation is processes by which organisms control solute concentrations and water balance within the body
Flame Cells
These are specialized excretory cells connected to a network of tubule which opens to the outside of the animal (ex: flatworms)
Nephridia
They are multicellular, tubular structures where one end of the tubule is open to the coelom while the other end opens to the outside (ex: annelids)
Malpighian Tubules
These are extensive blind end tubules immersed in hemolymph and opens in to the digestive tract (ex: insects and other terrestrial arthropods)
Green Glands / Antennal Glands
Two large glands found ventrally in the head and anterior to the esophagus (ex: crustaceans)
Sweat Glands
They are coiled tubular glands situated in the dermis and connected to a sweat duct which open as a pore on the surface of the skin (ex: human skin)
Salt Glands
They are paired glands found near the eyes to secrete excess salts (ex: marine birds and marine reptiles)
Kidney
These are the major excretory and osmoregulatory organs of all vertebrates
Human Urinary System
The human urinary system consists of two kidneys, two ureters, a urinary bladder and a urethra.
Kidneys
Kidney is a bean shaped organ which is held in position by a mass of fat and both are surrounded by a fibrous connective tissue.
Two kidneys are located on the posterior abdominal wall one on either side of the vertebral column, behind the peritoneum and below the diaphragm. Right kidney is slightly lower than the left.
Nephron
Nephron is the structural and functional unit of the kidney.
Bowman’s Capsule / Glomerular Capsule
It is a cup shaped and doubled walled structure. This is expanded and closed end of the tubular structure of the nephron
Glomerulus
The glomerulus is a ball of capillaries which is surrounded by Bowman’s capsule.
Proximal Convoluted Tubule
It is a comparatively longer and wider than the distal convoluted tubule lined by simple epithelium which has been specialized for selective reabsorption of substances (nutrients, ions and water) from the glomerular filtrate
Loop of Henle
It is a ‘U’ shaped part of the nephron with descending limb and ascending lib which are lined by simple epithelium
Distal Convoluted Tubule
It is lined by simple epithelium which has been specialized for selective reabsorption of specific ions and water. It leads into the collecting duct.
Ultrafiltration
Filtration of the blood under high pressure into the cavity of the Bowman’s capsule is called ultrafiltration
Selective Reabsorption
The process which useful molecules, ions and water from the glomerular filtrate are recovered and returned to the interstitial fluid and then into capillary network of the tubules is called selective reabsorption
Secretion
The process by which foreign materials and substances not required to the body including waste are cleared from the peritubular capillaries and interstitial fluid into the filtrate is called secretion
Bladder & Kidney Stones
These are formed due to precipitation of urinary constituents (usually oxalates and phosphates) normally in urine and are also called renal calculi
Kidney Failure
Due to the inability of the kidneys to function properly and therefore waste products and excess fluid will be accumulated in the blood. This is kidney failure.
Chronic Kidney Disease (CKD)
It is a condition of gradual loss of kidney function over time
Dialysis
Dialysis is done for the patients with kidney failure and is a process of removing excretory products, excess solutes and toxins from the blood by an artificial method
