Biology Hidden Gems Eukaryotes and Human Systems Flashcards
Eukaryotes
Have a nucleus and membrane bound organelles
Nucleus
Wrapped in a double phospholipid bilayer called the nuclear envelope or membrane
Nuclear Pores
Nuclear envelope is perforated with large holes that allows RNA to exit but not DNA
Nucleolus
Area where rRNA is transcribed and subunits of the ribosome are assembled; not separated by a membrane
Endocytosis
Three types. Phagocytosis Pinocytosis Receptor mediated endocytosis
Phagocytosis
The cell membrane protrudes outward to envelope and engulf matter -Only a few cells are capable of this and the impetus is the binding of proteins on the particulate matter to protein receptors on the phagocytotic cell -Ex. Antibodies or complement proteins
Pinocytosis
-extracellular fluid is engulfed by small invaginations-Performed in random fashion by most cells; nonselective
Receptor mediated endocytosis
Refers to specific uptake of macromolecules such as hormones, nutrients; ligand binds to a receptor protein on the cell membrane and then moves to a clathrin coated pit that invaginates to form a coated vesicle -Purpose is to absorb the ligands and that’s how it differs from phagocytosis
Phospholipid bilayer of eukaryotic membrane
-Similar to prokaryotic plasma membrane except in eukaryotes the membrane invaginates and separates to form individual, membrane bound compartments and organelles.
Endoplasmic Reticulum
-A thick maze of membranous walls separating the cytosol from the ER lumen (cisternal space) -Contiguous with the cell membrane and nuclear membrane -Contiguous in places with the space between the double bilayer of the nuclear envelope
Rough/ Granular ER
ER near the nucleus has many ribosomes attached to it on the cytosolic side -Translation of the Rough ER propels proteins into the ER lumen as they are created -These proteins are tagged with a signal sequence of amino acids and sometimes glycosylated (carbohydrate chains attached) -Proteins move through the lumen towards the Golgi apparatus
Golgi Apparatus
Series of flattened, membrane bound sacs -Organizes and concentrates the proteins -Proteins without signal sequences are put in secretory vesicles and sent out of the cell -Can modify proteins by removing amino acids or glycosylating them -Some polysaccharide formation takes place in the golgi apparatus -End product is a vesicle filled with proteins that can be released from the Golgi to mature into lysosome transported to other parts of the cell such as the mitochondria or even the ER.
Secretory Vesicles
-Supply the membrane with its proteins and also act in membrane expansion -Endocytotic vesicles from the membrane are transferred to the Golgi for recycling of the cell membrane
Lysosomes
-contain acid hydrolases (hydrolytic enzymes that function best in an acid environment) such as proteases, lipases, nucleases, and glycosidases -These enzymes are capable of breaking down everything -pH 5 interior -Fuse with endocytotic vesicles and digest their contents; anything not digested is ejected from the cell -Sometimes they autolyse to kill the cell
Smooth ER
-Hydrolyzes G6P to glucose ; an important step in making glucose from glycogen -Shares in role of cholesterol formation and subsequent change into steroids with cytosol -Most of the phospholipids in the cell membrane are synthesized in the smooth ER -Oxidizes foreign substances, detoxifying drugs, pesticides, toxins, and pollutants
Adipocytes
-Contain mainly fat droplets -Important in storage and body temp regulation
Peroxisomes
-Vesicles in the cytosol -Growth by incorporating lipids and proteins from the cytosol. -Rather than budding off membranes like lysosomes, peroxisomes self replicate -Involved in production and breakdown of hydrogen peroxide -Inactivate toxic substances such as alcohol, regulate oxygen concentration, play a role in the synthesis and breakdown of lipids and in the metabolism of nitrogenous bases and carbohydrates.
Cell can be divided into
cytosol and ER lumen
Stuff can reach the ER lumen by
endocytosis without ever transporting across a membrane
Rough ER has ribosomes attached to its
cytosol
Cytoskeleton
-Structure and motility of a cell is determined by a network of filaments -Anchors some membrane proteins and other cellular components, moves components within the cell, and moves the cell itself.
Microtubules
-Larger than microfilaments and are involved in flagella and cilia construction, and the spindle apparatus -Rigid hollow tubes made from a protein called tubulin -Makes up the mitotic spindle
Tubulin
Globular protein that polymerizes into long straight filaments under certain conditions
Axoneme
Major portion of the flagellum and cilium contains 9 pairs of microtubules to its neighbor -Have a + and - end, -end attaches to microtubule-organizing center -Microtubules grow away from the MTOC at its +end -Major MTOC is the centrosome; centrioles function in production of flagella and cilia
Microfilaments
-Smaller than microtubules -Actin forms a major component of microfilaments -Produce the contracting force in muscle and are involved in cytoplasmic streaming, phagocytosis, and microvilli movement
Tight Junctions
-Form a watertight seal from cell than can block water, ions and other molecules from moving around or past cells. -Epithelial tissue of organs are held together by tight junctions to prevent waste from flowing
Desmosomes
Join two cells at a single point by attaching directly to the cytoskeleton of each cell
Gap junctions
-Small tunnels connecting cells allowing molecules and ions to move between cells -In cardiac muscle provide for the spread of the action potential
Mitochondria
-Krebs cycle happens here -DNA replicates independently; contains no histones or nucleosomes -Have their own ribosomes -Inner membrane invaginates to form cristae -Holds the electron transport chain -Area between inner and outer membrane is intermembrane space
Tissue
Cells that form groups of similar cells that work together for a common purpose
Extracellular Matrix
Some cells called fibroblasts secrete fibrous proteins such as elastin and collagen to form a molecular network that holds tissue cells in place. -Can provide structural support, help to determine shape and motility, and affect cell growth
Types of tissue
epithelial tissue, muscle tissue, connective tissue, and nervous tissue
Epithelial tissue
Separates free body surface from their surroundings
Connective tissue
Characterized by extensive matrix. Ex: Blood, lymph, bone, cartilage, etc
Neuronal communication
Tends to be rapid, direct and specific
Hormonal communication
Tends to be slower, spreads throughout the body, and affects many cells and tissues in different ways
Neurons
Rely on glucose for energy, don’t need insulin; depend on aerobic respiration efficiency -Rely on blood because they don’t have sufficient glycogen or oxygen
Electrical Synapses
Transmit in both directions unlike chemical synapses and with more speed
White Matter
Myelinated axons
Grey Matter
Neuronal cell bodies
Saltatory Conduction
Jumping nodes of ranvier
CNS
Integrates nervous signal between sensory and motor neurons
PNS
-Somatic and autonomic nervous system
Somatic nervous system
Designed to respond primarily to external environment; sensory and motor functions; uses AcH -Controls motor functions -Sensory input
ANS
-involuntary -Sympathetic and Parasympathetic -Most internal organs innervate by both
Sympathetic Nervous System
Part of ANS Dilates pupils Increases heart beat rate and stroke volume -Constricts blood vessels around digestive and excretory systems to increase blood flow to muscles -postganglionic neurons are adrenergic -“Fight or Flight”
Parasympathetic Nervous system
“Rest and Digest” conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
Lower Brain
-Medulla, hypothalamus, cerebellum -Integrates subconscious activities such as respiration, arterial pressure, salivation, emotions, reactions to pain and pleasure
Higher Brain
-Cerebral cortex, stores memories and processes thoughts
Cornea
Nonvascular
Lens
Flattened by zonule fibers; when ciliary muscles contract the zonule fibers relax and the lens becomes spherical to see close up
Cones
Distinguish colors
Rods
Work in low light, only in black and white
Three parts of the ear
Outer ear Middle ear: Malleus, Incus, stapes Inner ear: Wave in inner ear moves through cochlea. Movement is detected by hair cells and organ of Corti. Semicircular canals-detect orientation
Endocrine glands
Release hormones directly into the blood
Exocrine glands
Release enzymes to the external environment through ducts -Ex. Sweat, oil, mucous
Effects of endocrine system tend to be slower and longer lasting than
nervous system
All hormones need a
receptor–either on the membrane or in the cell
Hormone types
peptide hormones, steroid hormones, tyrosine derivatives
Peptide Hormones
Derived from peptides. -May be large or small and often attached to carbohydrates -ALL are synthesized in the rough ER as a preprohormone where it is sent to the Golgi -Are water soluble
Steroid Hormones
-Derived from cholesterol -Formed in the smooth ER and mitochondria since they are lipids -Require a protein transport molecules through the blood but diffuse across the membrane on their own -Hit receptors in the cytosol where they are transported to the nucleus and act at the transcription level -Typical effect is to increase certain membrane or cellular proteins -Important ones are the glucocorticoids and mineral corticoids of the adrenal cortex and gonadal hormones: estrogen, progesterone, and testosterone
Glucocorticoids
are part of the feedback mechanism in the immune system, which reduces certain aspects of immune function, such as inflammation. They are therefore used in medicine to treat diseases caused by an overactive immune system, such as allergies, asthma, autoimmune diseases, and sepsis.
Tyrosine Derivatives
-T3 and T4, and catecholamines (formed in the adrenal medulla) -Epinephrine and norepinephrine are water soluble -Formed by enzymes in the cytosol or on the rough ER -Thyroid hormones are lipid soluble and must be carried in blood by plasma protein carriers -Their high affinity to their binding proteins in the plasma and in the nucleus create a latent period in their response and increase the duration of the effect of the thyroid hormones. -Increase the transcription of large numbers of genes in nearly all cells of the body
Endocrine gland tend to
over secrete their hormones. -The gland lags behind the effector, respond to the condition instead of creating it -Ex. High insulin levels do NOT create low blood glucose, they are a response to blood glucose -Ex. If you have high blood pressure and decreased urine output you have low ADH levels because ADH is responding to the condition
Anterior Pituitary hormones
FLAT PEG: FSH (Follicle Stimulating Hormone), LH (Leutinizing Hormone), ACTH (Adrenocorticotropic Hormone), TSH (Thyroid Stimulating Hormone), Prolactin, Endorphins, and Growth Hormones. This mnemonic is also useful because it can help you remember which hormones belong to which class. There are two important classes of hormones: tropic (hormones that act on other endocrine glands) and direct (hormones that act directly on some other, non-endocrine, part of the body). The FLAT hormones are all tropic hormones (you can remember this by picturing a flat, tropical beach) and the PEG hormones are direct (you can remember this because you can picture a peg going directly into a piece of wood). Releases ONLY peptide hormones
hGH
-Increases growth in almost all cells of the body -Increases episodes of mitosis, cell size, rates of protein synthesis, mobilizing fat stores, use of fatty acids for energy, decreasing use of glucose -Increases AA transport across membrane, translation and transcription, and decreases breakdown of protein and AA
Endorphins
Release a happy feeling in the brain. Work on opiate receptors in the brain and decrease pain
Adrenocorticotropic hormone (ACTH)
-Stimulated by stress -Stimulates the adrenal cortex to release glucocorticoids (stress hormones)
Thyroid stimulating hormone (TSH)
-Stimulates thyroid to release T3 and T4 -Increases thyroid cell size, number -T3 and T4 concentrations have a negative feedback effect on TSH release
FSH
Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland, and regulates the development, growth, pubertal maturation, and reproductive processes of the body.
LH
In women, the hormone stimulates the ovaries to produce oestradiol. Two weeks into a woman’s cycle, a surge in luteinizing hormone causes the ovaries to release an egg during ovulation. If fertilization occurs, luteinizing hormone will stimulate the corpus luteum, which produces progesterone to sustain the pregnancy
Prolactin
-Promotes lactation -Although hypothalamus has a stimulatory effect on the release of all other anterior pituitary hormones it has an inhibitory effect on the release of prolactin -Release stimulated by suckling
Posterior Pituitary
-Oxytocin and ADH (vasopressin) are synthesized in the neural cell bodies of the hypothalamus
Oxytocin
a peptide hormone that increase uterine contractions and causes milk to be ejected from the breasts
ADH (vasopressin)
-peptide hormone that causes the collecting ducts of the kidney to become permeable to water, reducing the amount of urine and concentrating it -Since fluid is reabsorbed it also increase blood pressure
Adrenal Glands
Cortex, mineral corticoids, glucocorticoids
Cortex
Secretes ONLY steroids; mineral corticoids and glucocorticoids
Mineral Corticoids
Affect electrolyte balance in the bloodstream
Glucocorticoids
Increase blood glucose concentration and have an even greater effect on fat and protein metabolism
Adrenal Cortex
Aldosterone, Cortisol, Catecholamines the outer part of the gland—produces hormones that are vital to life, such as cortisol (which helps regulate metabolism and helps your body respond to stress) and aldosterone (which helps control blood pressure)
Aldosterone
A steroid is a mineral corticoid that acts in the distal tube and collecting duct to increase Na+ and Cl- reabsorption and K+ and H+ secretion. Causes an increase in blood pressure.
Cortisol
a steroid glucocorticoid that increase blood glucose levels by stimulating gluconeogenesis (creation of glucose and glycogen from amino acids, glycerol, lactic acid) in the liver -degrades adipose tissue to fatty acids to be used for cellular energy -Stress hormone -Diminishes capacity of immune system to fight infection -Degradation of nonhepatic proteins and amino acids and an increase in hepatic (liver) amino acids and proteins
Catecholamines
-Tyrosine and derivatives synthesized in the adrenal medulla -Epinephrine and norepinephrine-vasoconstrictors of most internal organs and skins but are vasodilators of skeletal muscles
Thyroid Hormones
T3 and T4-lipid soluble tyrosine derivatives that diffuse through the lipid bilayer and act in the nucleus of the cells of their effector -Increase resting metabolic rate -Secretion is regulated by TSH
Calcitonin
-Large peptide hormone that slightly decreases blood calcium level by decreasing osteoclast activity and number
Pancreas
Insulin-a peptide hormone released when blood levels of carbohydrates or proteins are high. -Carbohydrates are stored as glycogen in the liver and muscles, fat is stored in adipose tissue, and amino acids are taken up and turned into proteins. -Permeability of membrane to AA is increased -Intracellular metabolic enzymes are activated and even translation and transcription rates are affected -Effect is to lower blood glucose levels
Glucagon
-a peptide hormone that stimulates glycogenolysis and gluconeogenesis in the liver -Breaks down adipose tissue increasing the fatty acid level in the blood. -Net effect is to raise blood glucose
Parathyroid Hormone
-A peptide that increases blood calcium -Increases osteocyte absorption of calcium and phosphate from the bone and stimulates proliferation of osteoclasts. -Increases renal calcium reabsorption and renal phosphate excretion -regulated by calcium ion plasma concentration
Reproduction of sperm happens in the
seminiferous tubules
Spermatogonia located in the seminiferous tubules arise from epithelial tissue to become
spermatocytes, spermatids, and then spermatozoa
Sertoli cells stimulated by FSH surround and nurture the
spermatocyte and spermatids
Leydig cells release
testosterone when stimulated by LH
Sertoli cells secrete
inhibin, a peptide hormone that acts on the pituitary gland to inhibit FSH secretion
Testosterone is the primary
androgen (male sex hormone) and stimulates germ cells to become sperm
Testosterone is responsible for
secondary sex characteristics such as englargement of the larynx, growth of seminal vesicles. -Stimulates growth spurt at puberty and closure of the epiphyses of the long bones, ending growth
Spermatid
-As it becomes a spermatozoan it loses its cytoplasm and forms the head, midpiece, and tail -Head of sperm has nuclear material and acrosome that contains lysosome-like enzymes to penetrate the egg
once freed in the tubule lumen the spermatozoon is carried to the
epididymus. On ejaculation is travels through the vas deferens into the urethra.
Semen is the mixture of
spermatozoa and fluid from the seminal vesicles, prostate, and the bulbourethral (Cowper’s) glands
Spermatozoa becomes active for fertilization in a process called
capacitation in the vagina
Oogenesis begins in the
ovaries of the fetus
All the eggs are
arrested as primary oocytes at birth
At puberty, FSH stimulates growth of
granulosa cells around the primary oocyte. Granulosa cells secrete a viscous substance around the egg called the zona pellucida. This structure is called the primary follicle. -Next. theca cells differentiate from the interstitial tissues and grow around the follicle to form a secondary follicle. -Upon stimulation by LH, theca cells secrete androgen, which is converted to estradiol (a type of estrogen) by the granulosa cells in the presence of FSH and secreted into the blood -The follicle grows and bulges from the ovary -Typically, estradiol inhibits LH secretion by the anterior pituitary -Luteal Surge- However, just before ovulation (bursting of the follicle) the estradiol levels rise rapidly causing a dramatic increase in LH -Results from a positive feedback loop of rising estrogen levels which increase LH levels, which increase estrogen. -Causes the follicle to burst, releasing the egg (now a secondary oocyte)into the body cavity. -Egg is swept into fallopian tube or oviduct -remaining portion of follicle becomes the corpus luteum
Corpus Luteum
secretes estradiol and progesterone throughout pregnancy, or in the case of no pregnancy, for about two weeks until it turns into the corpus albicans
Female Menstrual Cycle phases
- Follicular phase- begins with the development of follicle and ends at ovulation 2. Luteal phase-begins with ovulation and ends with the degeneration of the corpus luteum 3. Flow-shedding of uterine lining lasting about 5 days
Fertilization
-Once in the fallopian tube, the egg is swept towards the uterus by cilia -Fertilization takes place in the fallopian tube -Entry of the sperm activates the cortical reaction which prevents other sperm from fertilizing the same egg -Now the oocyte goes through the second meiotic division to become an ovum and release a second polar body -Occurs when the nuclei of the ovum and sperm fuse to form the zygote
Cleavage
-begins while the zygote is still in the fallopian tube -Zygote goes through many cycles of mitosis–when it is 8 cells its called a morula
Morula
8 cells
Blastocyst
Fluid filled ball that forms the morula continues to divide
Implantation
When the blastocyst lodges in the uterus on the 5th to 7th day of ovulation
Human Chorionic Gonadotropin (HCG)
-A peptide hormone that is released by the egg upon implantation that prevents degradation of corpus luteum and maintains its secretion of estrogen and progesterone
Placenta
-Formed from the tissue of the egg and the mother and takes over the job of hormone secretion -At 3 months begins secreting its own estrogen and progesterone while lowering the secretion of HCG
Determination
-Process where a cell becomes committed to a specialized developmental path (a certain tissue)
Differentiation
-The specialization that occurs at the end of development forming a specialized tissue cell
Gastrula
-Formation begins in the second week and is called gastrulation -Cells begin to slowly move about the embryo for the first time -Three primary layers are formed: ectoderm, endoderm (lining of digestive tracts, liver, and pancreas), mesoderm (stuff that lies between the inner and outer covering of the body—muscle, bone, etc) -In the third week the gastrula develops into the neurula in a process called neurulation -Notochord-induces ectoderm to form neural plate
Ectoderm
the outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis and nerve tissue.
Endoderm
lining of digestive tracts, liver, and pancreas), give rise to certain organs, among them the colon, the stomach, the intestines, the lungs, the liver, and the pancreas
Mesoderm
stuff that lies between the inner and outer covering of the body—muscle, bone, etc gives rise to the skeletal muscles, smooth muscle, blood vessels, bone, cartilage, joints, connective tissue, endocrine glands, kidney cortex, heart muscle, urogenital organ, uterus, fallopian tube, testicles and blood cells from the spinal cord and lymphatic tissue
What is apoptosis regulated by
proteins
Digestive Tract
Mouth, esophagus, stomach, small intestine (duodenum, ileum, jejunum); large intestine (ascending, transverse, descending, sigmoid colon); rectum, anus
Digestion begins with
alpha amylase in the saliva. -Alpha amylase begins breaking down the long straight chains of starch into polysaccharides -Starch is the major carbohydrate in the human diet
Peristaltic action
Moves the bolus down the esophagus by swallowing; smooth muscle -wave motion -saliva lubricates food to help it move down the esophagus
Stomach
Begins protein digestion with the enzyme pepsin -Low pH of 2 in stomach assists protein digestion by denaturing proteins; kills bacteria
Chyme
Stomach mixes and stores food reducing it to a semi-fluid mass
Exocrine glands
The secretions of the exocrine gastric glands - composed of the mucous, parietal, and chief cells - make up the gastric juice
Four major cell types of the stomach
Mucous cells, Chief (peptic cells), Parietal (oxyntic cells), G cells)
Mucous cells
line stomach walls to protect cells from acidic environment; mucous is mainly sticky glycoproteins; some secrete small amount of pepsinogen
Chief (peptic) cells
secrete pepsinogen deep in the exocrine gland; pepsinogen activated by low pH (broken down into pepsin by gastric acid)
Parietal (oxyntic cells)
secrete HCl; lowers pH of stomach and raises pH of blood -bicarbonate released outside cell, hydrogen from carbonic acid released into cell
G cells
secrete gastrin, a large peptide hormone, into the blood and stimulates parietal cells to secrete HCl
Major hormones that affect secretion of stomach juices are
AcH, gastin, and histamine. AcH increases secretion of all cell types.
Small Intestine
90% of digestion and absorption occurs here -Digestion happens in duodenum; absorption in jejunum and ileum
Small intestinal wall
Nutrients absorbed through the wall of the small intestine pass into the capillary network and the lacteal
Villi
-finger-like projections in outer layer -Increase surface area of the wall allowing for greater digestion and absorption -within each villus is a capillary network and a lymph vessel called a lacteal
Microvilli
-smaller finger-like projections on each villus -appear as fuzzy covering called the brush border
Brush Border
-in small intestine -Contains membrane bound digestive enzymes that are carbohydrate digesting -Contains protein digesting enzymes called peptidases -Contains nucleotide-digesting enzymes called nucleosidases -Enterocytes-cells of the brush border that reduce di-tri-peptides to AA
Goblet Cells
-Epithelial cells that secrete mucus to lubricate the intestine and protect the bush border from mechanical and chemical damage
Lysozyme
Regulates bacteria within the intestine
Pancreas
Connected to Duodenum: Trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease, deoxyribonuclease.
Duodenum
First section of small intestine. Connected to pancreas. Has a pH of 6 due to bicarbonate ion secreted by the pancreas
Trypsin and Chymotrypsin
Degrades proteins into small polypeptides; most proteins reach the brush border as small polypeptides where they are reduced to AAs before they are absorbed by enterocytes
Pancreatic Amylase
hydrolyzes polysaccharides to disaccharides, degrades nearly all carbohydrates from the chyme into small glucose polymers
Lipase
degrades fat (triglycerides)
Bile
-produced in the liver and stored in the gall bladder -weakens bonds between fat (emulsifies) to increase surface area so lipase can break it down -reabsorbed by small intestine and sent back to the liver
Hormones in the small intestine cause
increased blood insulin levels after the meal
Large Intestine
-Major functions are water absorption and electrolyte absorption -When this fails diarrhea results -Contains E.Coli -Produces Vitamin K, B12, thiamin and riboflavin