260 PHYS second sem Flashcards
Gastro-intestinal Tract
mouth, pharynx, esophagus, stomach, small intestine (duodenum, jujenum, ileum) large intestine
4 Major Tissue layers of digestive tract
Mucosa, Submucosa, muscularis externa, serosa
GI tract sensory receptors
Mechanoreceptors respond to (stretch)
Chemoreceptors respond to (osmolarity and pH change)
GI tract regulatory mechanisms
Short reflex = intrinsic, respond to stimuli in tract
Long reflex = extrinsic stimuli response
Four digestive processes
Motility, secretion, absorption and digestion
Motility
Segmentation, mixing movement, facilitates absorption`
Increase in absorbtion
Villi and microvilli, increase SA
Mechanical Digestion
Chewing
Carbohydrates
Starch - 2/3s of all carbohydrates
Dissaccarides (sucrose, lactose)
Monosaccarides (glucose)
Complex carbohydrates (fibre)
Enzymes for Carbohydrates
Amylase -
From salivary glands (acts in mouth)
From Pancreas (acts in SI)
SI enzymes -
Lactase and Maltase
Starch Digestion
Starch -> amylase -> maltase -> glucose -> absorbed directly into bloodstream
Complex Carbohydrate
Humans lack enzyme to digest complex carbohydrate
Fibre moves to LI for E.Coli digestion, which causes fermentation and gas production
Protein Enzymes
Enzymes:
-pepsin (stomach)
-Trypsin, chymotrypsinm carboxypepsidase, aminopeptidase (from pancreas, acts in SI)
-Dipeptidase (SI)
Protein digestion
Protein -> Pepsin (stomach), Trypsin/Chymotrysin (SI) -> Polypeptides -> Carboxypepsidase Aminopepsidase -> Dipeptides -> Dipeptidase, Brush border enzymes (SI) -> Amino Acids -> Absorbed directly into blood
Fat Enzymes and Bile
Bile -> Made in liver, stored in gall bladder, increase SA for lipase (NOT AN ENZYME)
Enzymes -> Lipase (from pancreas, acts in SI)
Fat Digestion
Fat -> Bile -> Smaller fat globules -> Lipase -> glycerol +fatty acids
Mouth
Secretion of Mucous and salivary amylase (starch digestion)
Esophagus
Long tube, separated from stomach by gastroesophageal sphincter
Heartburn
Acid reflux, faulty valve
Stomach
3 Sections - Fundus, Body and Antrum
Spincters - Gastroesophageal + Pyloric
Rugae - Allows for expansion
Absorbs asprin and alcohol
Stomach
4 Functions -
Storage, Mixing, Secretion and Absorbtion
Storage - Can expand 20x
Stomach Secretion
Acid, which activates pepsin. (parietal cells, HCL)
Pepsin - chief cells, digest protiens
Pepsinogen
Secreted by chief cells, inactive form of pepsin
Formation of stomach acid
From parietal cells, activates pepsin, breaks down connective tissue and kills pathogens
Stomach lining is protected with mucous
Stomach Hormone
Gastrin, increase HCL secretion, increase pepsinogen and increase motility
Stimulated by proteins distension and smell
Peptic Ulcers
Hole caused by inflammation and necrosis, caused by pepsin, in stomach and duodenum
symptoms are pain and bleeding
Small intestines
3 parts, duodenum, jejunum and ileum
Site of digestion, secretion and absorption
Digestion in the duodenum
Gall bladder secretes bile
Pancreas secreates Amylase, Trypsin, Chymotrypsin, pepsidases, lipase, nucleases and bicarbonate
Cholecystokinin (CCK)
CCK acts on pancreas to release bile and enzymes, triggered by food entering SI
Release is increased if distended or if fat content is increased
Secretin
Causes pancreas to release bicarbonate, to neutralize acid
increase bile formation in liver
SI absorption
Amino acids and sugars into villi capillaries
Fatty acids in lacteals via carriers
Carbohydrate Absorption
Quickly absorbed, first 1/2 of jejunum
Fats/Protein Absorption
Slow to digest, 8-10 hours to empty
Large Intestine
Haustral contractions, NA+ reabsorption and water reabsorption
Hemorrhoids
Varicose vein in rectum
Pancreas
Endocrine and Exocrine function
Duct cells - Bicarbonate
Acinar - Secretes enzymes
Endocrine - insulin/glucagon
Liver
Functions not related to digestion
Metabolic processing of nutrients
Detox of wastes
Stores glycogen, fats iron
clotting factord
Bile
Made from bile salts in liver, recycled in gut
Kidney Function
Excretion of waste
H2O balance
Blood pressure control
Acid base balance
Nephron
Functional unit of the kidney
Types:
Cortical (short)
Juxtamedullary (long, for osmotic gradient)
Vascular nephron
blood supply to nephron, afferent towards bowmans capsule and efferent away from nephron
Tubular nephron
Bowmans capsule, proximal tubule, loop of henle, distal tube, collecting duct
Basic renal process
Glomerular filtration - fluid into tubule
Tubular reabsorption - tubule into blood
Tubular secretion - blood to tubule
Sites of renal action
Filtration - Bowmans capsule
Loop of henle - Creates osmotic gradient (reabsorption)
Reabsorption and secretion (prox dist tubule and collecting ducts)
Glomerular filtration
Filters everything but RBCs and proteins into tubules
inside bowmans capsule
substances reabsorbed in kidneys
Na+, Cl-, Ca2+, PO4, water, glucose
secretion of kindey
K+, H+, large organics
Filtration numbers
160-180L / DAY
~123mL/min
Podocytes
slits on kidneys that can change shape to control filtration
renal failure is due to large slits that allow proteins and RBC
Forces involved in glomerular filtration (3)
Glomerular capillary blood pressure (favours filtration)
Plasma colloid osmotic pressure (opposes)
Bowmans capsule hydrostatic pressure (opposes)
Glomerular filtration rate
Depends on net filtration pressure, surface area available and how permeable the glomerular membrane is (podocytes)
filtration increases as hydrostatic pressure increases
Ion movement in kidneys
Trans-cellular movement (active/passive, like sodium and glucose)
Paracellular (passive, water and ions)
Following Na+ reabsorption
water reabsorption (osmotic gradient)
cl- reabsorption (via electrical gradient)
glucose (via carrier)
glucose reabsorption
in the proximal tubule, tubular maximum is when all the glucose carriers are full
Diabetes mellitus
too much glucose and carriers are full
Urea reabsorption
passive process to equilibrium
Aldosterone
Controls Na/K pumps
released if blood volume is low
High aldosterone = high pump speed, high sodium reabsorption, high water reabsorption
ANP
over hydration, disabled Na/K pump to prevent reabsorption.
Secretion
transfer of molecules from extracellular fluid into tubules
active process
K+, H+ and large organics
Collecting ducts
Site of water reabsorption, controlled ADH
Ascending and Descending loops of henle
Descending loop is only permeable to water, becomes more concentrated
Ascending loop is only permeable to salt, filtrate becomes less concentrated
Vasa recta
blood vessel following loop of henle
Loop of Henle
Creates a large, vertical osmotic gradient in medulla
ADH
controls permeability of collecting ducts
high ADH due to high osmolarity, concentrates urine
Proximal Tubule
67% na, cl and water reabsorption
100% glucose and amino acid
Urea reabsorption
Distal Tubule
Variable Na and water reabsorption (controlled by aldosterone and ANP)
Variable K secretion/reabsorption
Variable H secretion
Collecting Duct
Variable water reabsorption controlled by ADH
Variable H secretion
Variable urea reabsorption
Excretion formula
excretion = filtration - reabsorption + secretion
Renal clearance
RC = UV/P
U = concentration of substance
V = Flow rate
P = concentration of sub in plasma
Micturition
Urination reflex - autonomic control, CNS can override
During filling
Bladder is relaxed, sphincter is contracted
During Micturition
Stretch receptors increase their firing, sphincters relax, muscles contract
Renal failure
loss of protiens, loss of rbcs, low blood pressure
Kidney stones
crystallization of minerals in either the kidney, ureters or bladder
Acid base balance
Hydrogen ion and pH balance in body
Acidosis
neurons become less excitable and CNS depression
low PH
Resp acidosis is high production of CO2
Alkalosis
neurons become hyper-excitable
high PH
resp alkalosis due to low CO2 (hyperventillation)
Body’s correction for acidosis
Buffers bind to H+
Breathing increases
Kindeys excrete H+ and keep bicarb
Type A intercalated cells
Bodys correction for alkalosis
Buffers release H+
Breathing slows down
Kidneys retain h+ and secrete bicarb
type B intercalated cells
Functions of the ovaries
Follicle development
Estrogen/progesterone production
Follicle development
Oocyte + granulosa cells = primary follicle
Follicle matures in ovary, pushed out of wall at ovulation
Ovarian tubes
Site of fertilization, fimbrae draws ovum into fallopian tubes
Uterus
Muscular wall, endometrium has basal layer and functional layer
Vagina
Birth canal, site of sperm deposition
Menstrual Cycles
Ovarian -> prepares ova
Uterine -> prepares endometrium
Ovarian cycle
28 days - two phases
Follicular phases -> Day 1-14
-maturing follicles, which secrete estrogen
Ovulation on day 14 - due to spike in FSH and LH
Luteal phase -> day 14-28
corpus luteum -> secretes estrogen and progesterone
Menstrual cycle
Menstrual phase -> day 1-7
shedding of functional layer
triggered by drop in est/prog
Proliferative phase -> day 7-14
higher estrogen, repairs wall
Secretory phase
high est/prog, endometrium thickens
Corpus luteum
If egg isn’t fertilized, corpus luteum degenerates, estrogen and progesterone drop
If egg is fertilized, secretes HCG, which maintains corpus luteum
Scrotum
Maintaining sperm temperature, 3* cooler then body temp
Testes
Produce testosterone, triggered by LH
Sperm production
Spermatogenesis
200-400 million, 64-74 days to maturation
Spermatozoan
Tail for motility, DNA head, acrosome breaks down egg wall
Seminiferous tubules
Sertoli cells -> for support
Epididymis
Site of sperm maturation
Ductus Deferens
Stores and transports sperm, stored for up to 2 months
Seminal vesicles
Fructose to nourish sperm
Alkali to neutralize vaginal acid
Prostaglandins (draw towards cervix)
Clotting factors
60%
Prostate gland
Alkali
Prostaglandins to enhance sperm motility
25-30%
Bulbourethal gland
mucous to neutralize urine and lubricate urethra
Ejaculation
Vasodilation to penis
Erection = parasympathetic
Ejaculation = sympathetic
Male fertility problems
-Blocked tubules
-Decreased sperm count
-Decreased motility
-Decreased accessory gland secretion
Cell cleavage
cell replicates into many small cells called blastomeres
5 Weeks
Heart beating, digestive system is working, placenta operational
Stages of labour
Cervical dilation (high oxytocin)
Delivery of baby
Delivery of placenta (15-30 min after)
Function of hormones
Control of enzymatic reactions
Transport of ions or molecules across cell membranes
Gene expression and protein synthesis
Tropic Hormones
Act on other endocrine glands, from hypothalamus and anterior pituitary
Hormone classifications
Peptide hormones (protein)
Steroid hormones (cholesterol)
Amine hormones (amino acids)
hormones travel freely in blood but cannot cross the cell membrane
Features of peptide hormones
-Hydrophilic
-Travel freely in blood
-Cannot enter the cell
-Quick acting
EX. Insulin, glucagon, calcitonin, parathyroid hormone
Features of steroid hormones
-Lipophilic and can enter target cell
-must travel in blood on protein
-slow acting
EX. Cortisol, estrogen and testosteron
Features of amine hormones
Ring structure, from amino acids
EX. Tryptophan (melatonin), Tyrosine (thyroid hormones, epinephrine norepinephrine and dopamine)
Hormone interactions
Synergism - additive
Permissiveness - second hormone needed to get full expression
Antagonism - pairs of hormones with opposing effects
Endocrine control
3 levels
Hypothalamic (CNS), Pituitary stim (hypothalamic trophic hormones) and Endocrine gland stim (pituitary trophic hormones)
Hypothalamus
Homeostasis, controls anterior pituitary, which then controls other endocrine glands
Posterior pituitary
hormones made in the hypothalamus are stored in here
Oxytocin and ADH
Oxytocin
Stimulates uterine contractions in childbirth
promotes milk ejection during lactation
ADH
released if blood volume is low or osmolarity is high
increase water reabsorption in kidney
Diabetes insipidus
low ADH, urinate too much
Anterior Pituitary
Secretes 6 peptide hormones
FSH, LH, Growth hormone, TSH, prolactin and ACTH (all tropic except prolactin)
Gonadotropin
FSH - promotes egg and sperm production
LH - Estrogen and testosterone secretion from gonads, ovulation
Secreting hormones
TSH - acts on thyroid to secrete TH
ACTH - acts on adrenal cortex to promote cortisol secretion
Prolactin
Non-tropic
acts on mammary glands
Growth Hormone
Causes liver to release insulin-like growth factors
stims protein synthesis and cell divison
increase fatty acids in blood and blood glucose
GH hyper secretion
too much GH, gigantism before 20 years old, bone lengthens
after 20, acromegaly, thickening of bone instead
Thyroid Gland
Produces TH and calcitonin
Thyroid hormone
acts on cells to increase metabolism
Graves disease
hyperthyroidism, an autoimmune condition
Calcitonin
comes from thyroid gland, released to lower blood calcium by bringing it into the bones, decreasing absorption and increasing excretion
PTH
parathyroid hormone, antagonist to calcitonin, released if blood calcium is low
Vitamin D
activated by PTH, deficiency is weakness in the bones
Adrenal hormones
Medulla -> epinephrine, long sympathetic response
Cortex -> Mineralocorticoids = aldosterone
Glucocorticoids = cortisol
Aldosterone
Released in Na+ is low, speeds up pump to increase Na reabsorption
Cortisol
Increases glucose balance, inhibits cell uptake and stimulates protien breakdown
adaptation of stress
Cushings syndrom
increase cortisol, which results in hyperglycaemia, weight gain, poor immune function
Pancreas excretions
Alpha cells secrete glucagon
Beta cells secrete insulin
Insulin
Released when blood glucose is high, promotes glycogen formation and cellular uptake
Glucagon
Breaks down glycogen, increases blood glucose levels
Feeding states
Absorptive state (3-4 hours after, insulin controls)
Post-Absorptive state (4+ after eating, glucagon is controller)
Diabetes Mellitus
Increase in blood glucose, high in urine
Type 1 is low insulin, Type 2 is low insulin response
