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MCAT Biology > Physiology > Flashcards

Physiology Flashcards

1
Q

Digestive System

A

Alimentary Canal that begins at the mouth and ends at anus

Mouth –> Esophagus –> Stomach –> Small Intestine –> Large Intestine

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2
Q

Organ

A

Structure composed of two or more tissues

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3
Q

Stomach Epithelial Cells

A 
Line inside of stomach
Secrete HCl to aid digestion
Secrete mucus to protect stomach lining
Bounded by tight junctions
Held together by desmosomes
Gap Junctions allow water soluble molecules to pass btw cytoplasms
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4
Q

Tight Junctions

A

Prevent transport of proteins from lumen to basolateral side

Hold neighboring cells together

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5
Q

Connective Tissue

A

Made of collagen, reticulin, elastin
Cartilage is secreted by fibroblast cells
Bone is collagen and CaCO3
-made by osteoblasts

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6
Q

Nerve Cells

A

Excited at dendrites which is passed down axon by action potential
AP causes neurotransmitter release at synaptic bulbs into the synaptic cleft

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7
Q

Membrane Potentials

A

[K+] is high in cell; [Na+] is high in ECM; [Cl-} is high in ECM
K+ diffuses down gradient out of cell, causing a negative cell environment. But K+ diffusion is limited by charge buildup in ECM
Regulated by Nernst eqn

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8
Q

Action Potential

A

Depolarization of membrane potential induced by a stimulus
If reaches threshold then Na+ ions burst into cell
All of none; once activated it always has the same magnitude
Stimulus –> Depolarization –> Repolarization –> Hyperpolarization –> Refractory

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9
Q

Myelinated Nerves

A

Myelin membrane made by glial cells develops a sheath

  • Acts as an electrical insulator
  • Broken by nodes of Ranvier
  • Greatly increase rate of AP conduction
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10
Q

Neuromuscular Junction

A

Synapse btw axon and muscle fiber
-Synaptic knob contains vesicles filled w/ acetylcholine
AP induces Ca2+ channels to open, causing influx of Ca2+; causes an ACh release
Ca2+ then pumped back into ECM
ACh binds to post synaptic membrane induces Na+ influx and AP
ACh induces AP as long as its in cleft; ACh is removed by hydrolysis to acetate and choline

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11
Q

EPSP and IPSP

A

Acetylcholine elicits an excitatory response on AP (EPSP)

IPSP causes a influx of K+ or Cl- to hyperpolarize membrane

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12
Q

Sarcomere

A

Contractile unit of skeletal muscle

Made of thin actin and thick myosin

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13
Q

Muscle Contraction

A

Relaxed: ATP bound to myosin, reducing affinity for actin
ATP hydrolyzed to ADP, myosin head conforms and binds actin
w/ Ca2+, Pi and ADP dissociate and cause conformation change (power stroke)
New ATP binds and myosin releases from actin
Regulated by tropomysosin, troponin and Ca2+ (from AP)

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14
Q

Tropomyosin

A

Binds in actin groove and cover myosin binding site

Actin based regulation of muscle contraction

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15
Q

Troponin

A

Interacts w/ tropomyosin, actin, and Ca2+
When Ca2+ is bound it causes tropomyosin to shift and expose myosin binding site
-allows contraction
w/o Ca2+ in a relaxed state

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16
Q

Strength of Muscle Contraction

A

Varied by size of motor unit, # of motor units, and amt of actin and myosin in cell
Motor unit - motor neuron and muscle fibers
Small motor units - used for precise control but small contraction
Large motor unit - used for large contraction

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17
Q

Central Nervous System

A

Brain and Spinal cord
Afferent nerves - bring info into brain (sensory)
Efferent nerves - bring info away from brain (motor)

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18
Q

Brain

A

Forebrain - Cerebrum, thalamus, and hypothalamus
Midbrain
Hindbrain

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19
Q

Cerebrum

A

Left and right hemispheres joined by corpus callosum
Frontal lobes - movement/personality
Parietal lobes - touch and stretch
Occipital lobes - vision
Temporal lobes - hearing
Cerebral cortex - outer layer, all gray matter

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20
Q

Thalamus

A

Relay station for visual and auditory info recieved from env.

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21
Q

Hypothalamus

A

Concerned w/ visceral activities of body

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22
Q

Pituitary Gland

A

Master Endocrine Gland

Receives info from hypothalamus and send info to regulate different areas of body

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23
Q

Parasympathetic Nervous System

A

(part of autonomic system)
Increases digestion and lowers heart rate
Lowers blood pressure
Works to conserve energy and restore bodily functions
Releases ACh

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24
Q

Sympathetic Nervous System

A

(part of autonomic system)
Increases heart rate, blood pressure, and decreases digestion
Releases norepinephrine

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25
Blood Pathway
Right atria --> Right ventricle --> pulmonary artery --> lungs --> pulmonary veins --> Left atria --> left ventricle --> aorta --> body --> right atria aorta --> arteries --> arterioles --> capillaries --> veins --> heart
26
Arteries
Carry blood away from heart Composed of thick walls and smooth muscle Very elestic; keeps blood pressure relatively constant
27
Veins
Carry blood to heart | Contain unidirectional valves for flow
28
Circulatory Regulation
Regulated by sympathetic or parasympathetic nerves
29
Sinoatrial Node
Pacemaker of heart Point of origin of electrical impulses that coordinate pumping Electrical impulse spreads out over atria, causing contraction and ventricles to fill AP ends at AV node and then travels through bundle of His AP then spreads throughout ventricles causing them to contract and pump
30
Blood Pressure Drops
Severe blood pressure drops cause sympathetic system to release norepinephrine to increase heart contraction and raise blood pressure
31
Cardiac Output
Amt of blood pumped per minute by ventricles | =(Heart Rate)(Stroke Volume)
32
Poiseuilles Law
Flow= ∆P (πR^4)/8μL | -Flow increases by power of 4 for radius increases
33
Lymphatic System
Lies parallel to systemic and pulmonary capillaries Collects excess fluid and returns it to vena cava Blocking lymph flow leads to edema Person w/ heart complication have buildup of fluid i veins which will lead to lymph buildup and edema
34
Blood Clotting
Happens via cascade Allows amplification of an initial weak signal Prothrombin --> thrombin Thrombin catalyzes fibrinogen --> fibrin Fibrin cross links to form a clot Vitamin K is essential for blood clotting
35
Respiratory System
O2 is brought to cells of tissues and CO2 is removed as a waste product Also aids in pH regulation
36
Breathing
Diaphragm and rib muscles contract which enlarges the thoracic cage (inspiration): causes a lower than atm pressure in lungs Diaphragm and rib muscles relax forcing air out (expiration) If lungs are separated from visceral pleura they collapse -Lungs are rigid only by pressure
37
Gas Exchange
Deoxygenated blood enters capillaries around alveoli -Alveoli have high P(O2) and low P(CO2), so O2 flows into blood and CO2 flows into alveoli Oxygenated blood enters systemic tissues -Cells have high P(CO2) and low P(O2), so O2 flows out of blood and CO2 into blood
38
Oxygen Transport
Transported by hemoglobin | Saturation curve shifts to the right w/ higher Temperature, and 2,3-BPG and lower pH
39
Carbon Dioxide Transport
1) Dissolved in plasma ~10% 2) Binding to Hemoglobin ~20% 3) As Bicarbonate ~70% Carbonic anhydrase catalyzes reaction CO2 + H2O --> H2CO3 --> H+ + HCO3-
40
Ventilation Rate
``` Regulated by pH High pH (alkaline blood) reduces ventilation Low pH (acidic blood) increase ventilation ```
41
Digestion
Proteases hydrolyze proteins to aa's Lipases hydrolyze fats to fatty acids and glycerol Vitamins and essential aa's need to be absorbed
42
GI Tract
1) Food masticated in mouth; salivary amylase begins starch/glycogen digestion 2) Food passes through esophagus 3) Stomach breaks down and detoxifies food; Gastrin secreted in lower stomach to break down proteins - stimulates HCl and pepsinogen secreation to cleave proteins 4) Most digestion happens in small intestine; Pancreas and liver add secretions; neutralizes acid from stomach; Secretin (hormone) causes release of bicarbonate from pancrease by ducts; liver synthesizes bile which is released by gall bladder in a duct; bile used for fat absorption 5) Large intestine reabsorbs water and ions
43
Kidneys
Three Functions: 1) Filtration ( in glomerulus and Bowman's capsule) 2) Reabsorption (takes back important organics and inorganics from filtrate) 3) Excretion (waste, salts, excess water)
44
Renal Physiology
Blood from aorta is pumped to kidney glomeruli Waste leaves kidneys by ureter and enter bladder Afferent arteriole enters glomerulus; Efferent arteriole Exits glomerulus
45
Proximal Convoluted Tubule
Most Reabsorption happens here Glucose, aa, and vitamins completely reabsorbed Most Na+ and Cl- and water reabsorbed No Regulation
46
Loop of Henle
Thin and Thick section Descending thin - permeable to H2O, impermeable to ions and urea Ascending thin - permeable to urea, impermeable to water Ascending thick - active transport of ions out of tubule, impermeable to H2O and urea
47
Distal Convoluted Tubule
Impermeable to urea and water; permeable to ions Creates more dilute urine Regulated by aldosterone and ADH
48
Aldosterone
Regulates Na+ absorption in Distal Tubule Increase in aldosterone increases Na+ reabsorption If [Na+] is low, then aldosterone is released
49
Antidiuretic Hormone
Regulates water absorption Increase in ADH increases water reabsorption Increase in water reabsorption leads to more concentrated urine If low plasma volume (low water) then release of ADH
50
Gonadotropin Releasing Hormone
Signals ant. pituitary gland to release LH and FSH | FSH and LH travel to gonads (testes or ovaries)
51
Male Anatomy
Testes carry out reproductive function Spermatogenesis - production of sperm Seminiferous Tubules - hold spermatogenic cells Testosterone is synthesized in Leydig cells Sertoli Cells promote spermatogenesis and produce inhibin Secondary male characteristics are due to testosterone
52
Sperm Production
Spermatogenic cells always in contact w/ Sertoli cells Spermatogonia divide by mitosis (Primary spermatocytes) Later spermatocytes divide by meiosis Division of gametes produces four viable sperm
53
Male Hormone Control
Leydig cells convert cholesterol to testosterone Sertoli cells make dihydrotestosterone from testosterone LH binds to Leydig cells; increases testosterone production FSH binds to Sertoli cells; converts testosterone to DHT Males constantly make LH and FSH Testosterone has (-) feedback on GnRH and LH Sertoli cells secrete inhibin which has (-) feedback on ant. pituitary Increase in Test. leads to lower LH Increase in DHT leads to increase in inhibin and lower FSH
54
Female Anatomy
Oogenesis - production of female gametes Division of Oocyte produces only one viable gamete (ovum), and two polar bodies Second meiotic division happens after fertilization Primary Follicle - Primary oocyte surrounded by follicle cells
55
Menstrual Cycle
Estrogen, LH, and FSH mature primary oocyte -Follicular phase is the development time; primary follicle gradually grows surrounded by theca and granulosa cells LH surge -Causes first meiotic division After secondary oocyte is released, ovulation has occured -Follicle becomes corpus luteum (begins luteal phase) -Corpus luteum produces estrogen and progesterone LH is constant except before ovulation (LH surge) LH surge occurs b/c follicles rapidly divide and produce lots of estrogen ( (+) feedback on LH) FSH similarly has a small surge w/ LH Estrogen surge prior to ovulation (causes LH surge) Progesterone surges after ovulation
56
Female Hormone Control
Theca cells produce testosterone which is converted to estrogen LH acts on Theca cells; FSH acts on follicle cells At low concentration of estrogen there is (-) feedback on FSH (High estrogen = high LH)
57
Pregnancy
Beginning of pregnancy has high levels of estrogen and progesterone to prevent primary follicle growth -produces by corpus luteum -inhibits FSH and LH Mammary glands grow by prolactina and CS After three months, placenta makes enough estrogen and progesterone
58
Development Stages
1) Fertilization 2) Cleavage (becomes multicellular) 3) Gastrulation (develops germ layers) 4) Neurulation (develops nervous system) 5) Neural Crest Formation (nervous system, skull, sensory organs) 6) Organogenesis (organs)
59
Cleavage
Done a series of times to produce a blastula | Blasula - hollow ball of cells (blastocoel is the hole)
60
Gastrulation
Formation of blastopore Outer layer - ectoderm (skin, eye lens, brain, nervous system) Inner layer - endoderm (inner digestive tract, respiratory tract, major glands) Mesoderm forms btw two layers (notochord, heart, skeleton, muscle, outer internal organs, reproductive organs)
61
Birth
Grown fetus places pressure on uterine walls - sends signals releasing oxytocin - oxytocin induces more contractions ( (+) feedback)
62
Lactation
Production of milk is stimulated by suckling -Releases PRH; causes prolactin release Prolactin stimulates breast to produce milk Milk ejection is (+) feedback using oxytocin
63
Hormones
Long Distance Cell communication Peptide - ex: insulin Amine - ex: epinephrine Steroids - ex: sex hormones Released by endocrine organs and travel through blood Slow response Bind to receptor and form intracellular messenger -2nd messenger passes info to some specific rxn
64
Pituitary Gland
Post. Pituitary releases oxytocin and ADH Ant. Pituitary secretes six hormones -Thyroid stimulating hormone, Adrenocorticotropic hormone, Follicle stimulating hormone, Luteinizing hormone, Growth hormone, Prolactin
65
Leukocytes
Monocytes, Neutrophils, Lymphocytes Phagocytes: monocytes and neutrophils -Engulf by endocytosis
66
Mast Cells
Derived from leukocytes | Release histamine - allows neutrophils access to tissues to defend against microbes
67
Lymphocytes
T cells and B cells T cells: Cytotoxic T cells, Helper T cells, Suppressor T cells B cells: circulate blood and lymph, humoral immunity, can differentiate into plasma cells (create antibodies)
68
General Immune Response
Macrophage engulfs foreign particle Antigenic fragments are presented on MHC I Cytotoxic T cells recognize -release factors to stimulate more cytotoxic T cells -bind and kill invading cells

MCAT Biology (2 decks)

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