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MCAT Biology > Physiology > Flashcards

Physiology Flashcards

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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
Q

Blood Pathway

A

Right atria –> Right ventricle –> pulmonary artery –> lungs –> pulmonary veins –> Left atria –> left ventricle –> aorta –> body –> right atria
aorta –> arteries –> arterioles –> capillaries –> veins –> heart

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26
Q

Arteries

A

Carry blood away from heart
Composed of thick walls and smooth muscle
Very elestic; keeps blood pressure relatively constant

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27
Q

Veins

A

Carry blood to heart

Contain unidirectional valves for flow

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28
Q

Circulatory Regulation

A

Regulated by sympathetic or parasympathetic nerves

29
Q

Sinoatrial Node

A

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
Q

Blood Pressure Drops

A

Severe blood pressure drops cause sympathetic system to release norepinephrine to increase heart contraction and raise blood pressure

31
Q

Cardiac Output

A

Amt of blood pumped per minute by ventricles

=(Heart Rate)(Stroke Volume)

32
Q

Poiseuilles Law

A

Flow= ∆P (πR^4)/8μL

-Flow increases by power of 4 for radius increases

33
Q

Lymphatic System

A

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
Q

Blood Clotting

A

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
Q

Respiratory System

A

O2 is brought to cells of tissues and CO2 is removed as a waste product
Also aids in pH regulation

36
Q

Breathing

A

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
Q

Gas Exchange

A

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
Q

Oxygen Transport

A

Transported by hemoglobin

Saturation curve shifts to the right w/ higher Temperature, and 2,3-BPG and lower pH

39
Q

Carbon Dioxide Transport

A

1) Dissolved in plasma ~10%
2) Binding to Hemoglobin ~20%
3) As Bicarbonate ~70%
Carbonic anhydrase catalyzes reaction
CO2 + H2O –> H2CO3 –> H+ + HCO3-

40
Q

Ventilation Rate

A 
Regulated by pH
High pH (alkaline blood) reduces ventilation
Low pH (acidic blood) increase ventilation
41
Q

Digestion

A

Proteases hydrolyze proteins to aa’s
Lipases hydrolyze fats to fatty acids and glycerol
Vitamins and essential aa’s need to be absorbed

42
Q

GI Tract

A

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
Q

Kidneys

A

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
Q

Renal Physiology

A

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
Q

Proximal Convoluted Tubule

A

Most Reabsorption happens here
Glucose, aa, and vitamins completely reabsorbed
Most Na+ and Cl- and water reabsorbed
No Regulation

46
Q

Loop of Henle

A

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
Q

Distal Convoluted Tubule

A

Impermeable to urea and water; permeable to ions
Creates more dilute urine
Regulated by aldosterone and ADH

48
Q

Aldosterone

A

Regulates Na+ absorption in Distal Tubule
Increase in aldosterone increases Na+ reabsorption
If [Na+] is low, then aldosterone is released

49
Q

Antidiuretic Hormone

A

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
Q

Gonadotropin Releasing Hormone

A

Signals ant. pituitary gland to release LH and FSH

FSH and LH travel to gonads (testes or ovaries)

51
Q

Male Anatomy

A

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
Q

Sperm Production

A

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
Q

Male Hormone Control

A

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
Q

Female Anatomy

A

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
Q

Menstrual Cycle

A

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
Q

Female Hormone Control

A

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
Q

Pregnancy

A

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
Q

Development Stages

A

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
Q

Cleavage

A

Done a series of times to produce a blastula

Blasula - hollow ball of cells (blastocoel is the hole)

60
Q

Gastrulation

A

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
Q

Birth

A

Grown fetus places pressure on uterine walls

  • sends signals releasing oxytocin
  • oxytocin induces more contractions ( (+) feedback)
62
Q

Lactation

A

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
Q

Hormones

A

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
Q

Pituitary Gland

A

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
Q

Leukocytes

A

Monocytes, Neutrophils, Lymphocytes
Phagocytes: monocytes and neutrophils
-Engulf by endocytosis

66
Q

Mast Cells

A

Derived from leukocytes

Release histamine - allows neutrophils access to tissues to defend against microbes

67
Q

Lymphocytes

A

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
Q

General Immune Response

A

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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