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Flashcards in Human Physiology Deck (137):
1

Digestion

Breaks down large molecules into smaller, usable molecules & absorbing these smaller molecules

2

Mouth

Where mechanical & chemical digestion begins

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Salivary Amylase

Enzyme that begins starch digestion in saliva

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Esophagus

No digestion, transports food from throat to stomach

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Epiglottis

Keeps food away from windpipe

6

Stomach

Place for both mechanical & chemical digestion
Where protein digestion begins
It's thick, muscular walls churns food & secretes gastric juice that contains hydrochloric acid & enzymes

7

Hydrochloric Acid

Begins breakdown of muscle (meat) & activates the inactive enzyme pepsinogen to become pepsin

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Pepsin

Digests protein

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Cardiac Sphincter

At top of stomach
Keeps acidified food in stomach from back up into esophagus

10

Pyloric Sphincter

At bottom of stomach
Keeps food in stomach long enough to be digested

11

Liver

Breaks down & recycles red blood cells
Detoxifies blood - removes alcohol & drugs
Produce cholesterol
Produce urea from protein metabolism
Produce bile

12

Bile

Emulsifies fats
Neutralizes chyme (acidified food from stomach) entering small intestine

13

Small Intestine

Where all digestion is completed (in duodenum) & where nutrients are absorbed

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Intestinal Enzymes

Amylase, protease, lipase, nuclease

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Pancreatic amylase

Digests starch & is secreted into small intestine

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Peptidases

Continue to break down proteins into amino acids

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Nucleases

Hydrolyze nucleic acids into nucleotides

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Lipases

Break down fats

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Villi

Line small intestine & absorb all nutrients released from digested food

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Pancreas

Produce enzymes that break down carbohydrates, proteins, lipids, nucleic acids & secretes them into small intestine
Produce hormones to control blood sugar levels
Produce sodium bicarbonate

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Sodium bicarbonate

Produced in gallbladder
A base that neutralizes stomach acid, enabling intestinal enzymes to be effective as they require a basic environment

22

Large Intestine/Colon

Egestion - removal of undigested wastes
Vitamin Production - vit. K, B & folic acid
Reabsorption of Water

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Rectum

Egestion, removal of undigested waste

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Medulla in Gas Exchange

Sets breathing rhytm by monitoring carbon dioxide levels & by sensing changes in pH of blood

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Artery

Carries blood away from heart
Enormous pressure

26

Vein

Carries blood back to heart
Little pressure

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Capillary

Allows for diffusion of nutrients & wastes between cells & blood

28

Plasma

Liquid portion of blood, 90% water
Contains: clotting factors, hormones, antibodies, dissolved gases, nutrients, wastes

29

Red Blood Cells
(Erythrocytes)

Carry hemoglobin & oxygen, do not have oxygen
Live 120 days, formed in bone marrow & recycled in liver

30

White Blood Cells
(Leukocytes)

Fight infection, formed in bone marrow
Die fighting infection

31

Platelets
(Thrombocytes)

Clot blood
Cell fragments formed in bone marrow from megakaryocytes

32

Sinoatrial Node

Heart's pacemaker
Sets timing of contractions of heart

33

Systolic

120
Measurement of pressure when ventricles contract

34

Diastolic

80
Measurement of pressure when heart relaxes

35

Pathway of Blood

Right atrium - right AV - Right ventricle - pulmonary semilunar valve - pulmonary artery - lungs - pulmonary vein - left atrium - left AV - left ventricle - aortic semilunar valve - aorta - all cells in body - vena cava

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Endocrine System

Secretes hormones

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Hormones

Produced in endocrine glands
Move through blood to specific target cell, tissue organ - produce short-lived or long-term response

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Tropic Hormones

Stimulate other glands to release hormones - can have far reaching effect

39

Hypothalamus
(Endocrine System)

Bridge between endocrine & nervous systems in times of stress
It sends signals to adrenal gland to release adrenaline
Contains body's homeostat & centers for regulating hunger/thirst

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Growth Hormone (GH)

Anterior Pituitary
Stimulates growth of bones

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Luteinizing Hormone (LH)

Anterior Pituitary
Stimulates ovaries & testes

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Thyroid-Stimulating Hormone (TSH)

Anterior Pituitary
Stimulates thyroid gland

43

Adrenocorticotropic (ACTH) Hormone

Anterior Pituitary
Stimulates adrenal cortex to secrete glucocorticoids

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Follice-Stimulating Hormone (FSH)

Stimulates gonads to produce sperm & ova

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Oxytocin

Posterior Pituitary
Stimulates contractions of uterus + mammary glands

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Antidiuretic Hormone (ADH)

Posterior Pituitary
Promotes retention of water by kidneys

47

Thyroxin

Thyroid
Controls metabolic rate

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Calcitonin

Thyroid
Lowers blood calcium levels

49

Parathormone

Parathyroid
Raises blood calcium levels

50

Glucocorticoids

Adrenal Cortex
Raises blood sugar levels

51

Epinephrine (adrenaline)

Adrenal Medulla
Raises blood sugar level by increasing rate of glycogen breakdown by liver

52

Insulin

Pancreas
Lowers blood glucose levels

53

Glucagon

Pancreas
Raises blood sugar levels

54

Thymosin

Thymus
Stimulates T lymphocytes as part of immune response

55

Melatonin

Pineal
Involved in biorhythms

56

Estrogen

Ovaries
Stimulates uterine lining, promotes development & maintenance of primary & secondary characteristics of females

57

Progesterone

Ovaries
Promotes uterine lining growth

58

Androgens

Testes
Support sperm production & promote secondary sex characteristics

59

Feedback Mechanism

Self regulating mechanism that increase/decrease an action/level of a particular substance

60

Positive Feedback

Enhance existing response
Childbirth

61

Negative Feedback

Common in system that maintains homeostasis

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Central Nervous System

Brain & Spinal Cord

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Peripheral Nervous System

All nerves outside CNS

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Sensory (PNS)

Conveys info from sensory receptors/nerve endings

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Motor (PNS)

Stimulates voluntary & involuntary muscles & consists of 2 systems

66

Somatic System

Controls voluntary muscles

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Autonomic System

Controls involuntary muscles

68

Resting Potential

The charge change across the membrane when a neuron is not firing (-70mV)

69

Action Potential

The charge change across the membrane when a neuron is firing (30mV)

70

Depolarization

The change from a negative resting potential to a positive action potential
Opening sodium channels

71

Repolarization

The change from a positive action potential back to a negative resting potential
Opening potassium channels

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Nervous System

Secretes neurotransmitters

73

Cones

Photoreceptors in retina, distinguish different colors

74

Rods

Sensitive photoreceptors in retina
Do not distinguish different colors

75

Cornea

Tough, clear covering that protects eye & allows light to pass through

76

Humor

Fluids, maintain shape of cell

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Iris

Colored part of eye
Controls how much light enters eye

78

Lens

Focuses light onto retina

79

Pupil

Small opening, middle of iris

80

Retina

Converts light into nerve impulses that are carried to the brain

81

Auditory Canal

Ear canal, where sounds enter

82

Cochlea

Fluid-filled part of inner ear
Sends nerve impulses to brain

83

Ear Bones

Hammer, anvil, stirrup; transmit vibrations from eardrum to oval window

84

Eustachian Tube

Equalizes pressure between environment & inner ear

85

Oval Window

Sends waves of pressure to cochlea

86

Semicircular Canals

Fluid-filled, helps maintain balance

87

Tympanum

Ear drum, vibrates as sound waves hit it

88

Excretion

Removal of metabolic wastes
Includes removing carbon dioxide & water from cell respiration, & nitrogenous wastes from protein metabolism

89

Organs of Excretion

Skin, Lungs, Liver, Kidney

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Kidney

Filters about 1500L of blood per day & produce about 1.5L urine

91

Nephron

Basic functional unit of kidney
Carries out job in 4 steps; filtration, secretion, reabsorption, excretion

92

Smooth/Involuntary Muscles

Makes up walls of blood vessels & digestive tract under control of autonomic nervous system

93

Skeletal/Voluntary Muscles

Large & multinucleate, work in pairs; one muscle contracts & other relax
Bicep & tricep

94

Cardiac Muscle

Heart, generates its own action potential

95

Duodenum

First 10 inches of small intestine
Where all digestion is completed

96

Lacteal

Structures within villi that line the small intestine & that absorb fatty acids & glycerol into the lymphatic system

97

Alveoli

Microscopic air sacs in the lung where diffusion of the respiratory gases, oxygen & carbon dioxide, occurs

98

Serum

Plasma without clotting factors

99

Polarized

Condition of an axon of a nerve when it's at rest, also resting potential
Na & K are pumped to opposite sides of the membrane

100

Wave of depolarization

The condition of an axon when an impulse is passing
Also action potential

101

Myosin

Myofilaments that make up the thick filaments in skeletal muscle

102

Actin

Protein that makes up the thin myofilaments in skeletal muscle

103

Capillary
(Villus)

Absorb amino acids, vitamins & monosaccharides directly into the bloodstream

104

Microvilli

Microscopic appendages
Further enhance the rate of absorption

105

Gallbladder

Stores bile produced in liver
Body can function without it

106

Constipation

Too much water is reabsorbed from the intestine into body

107

Diarrhea

An inadequate amount of water is absorbed back into body

108

Transport of Oxygen

Carried in blood by respiratory pigment hemoglobin
Combines loosely with oxygen to form molecule oxyhemoglobin

109

Transport of Carbon Dioxide

The by-product of cell respiration, is released from every cell & dissolves in the blood

110

Carbonic acid-bicarbonate ion system

Maintains the blood at a constant pH of 7.4

111

Blood Clotting

Mechanism that begins with the release of clotting factors from platelets & damaged tissue

112

Anticlotting Factors

Constantly circulate in the plasma to prevent the formation of a clot or thrombus
Can cause serious damage in the absence of injury

113

Pulmonary Artery

Carries deoxygenated blood

114

Pulmonary Vein

Carries oxygenated blood

115

Steroid Hormones
Lipids

Diffuse directly through the plasma membrane & bind to a receptor inside the cell that triggers the cell's response

116

Nonsteroidal Hormone
(Protein/Polypeptide)

Cannot dissolve in the plasma membrane so they bind to a receptor on the surface of the cell, triggers a secondary messenger that converts extracellular chemical signal to a specific response inside the cell

117

Feedback Mechanism

Self-regulating mechanism that increases or decreases an action or the level of a particular substance

118

Positive Feedback

Enhances an already existing response
Childbirth

119

Negative Feedback

Maintains homeostasis
How body maintains proper levels of thyroxin

120

Neuron

Basic functional unit of the nervous system

121

Dendrites

Sensory
Receive incoming messages from other cells & carry the electrical signal to the cell body

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Axons

Transmit an impulse from the cell body outward another cell

123

Sympathetic System

Fight/flight response
Increase heart & breathing rate
Liver convert glycogen to glucose
Bronchi dilate & increase gas exchange
Adrenaline raises blood glucose levels

124

Parasympathetic System

Calms the body
Decreases heart/breathing rate
Enhances digestion

125

Reflex Arc

Simplest nerve response
Inborn, automatic & protective
Ex: knee jerk

126

Membrane Potential

A difference in electrical charge between the cytoplasm (negative charge) & extracellular fluid (positive charge)

127

Refractory Period

Period of repolarization
Lasts few milliseconds during which neuron cannot respond to another stimulus
Ensures that an impulse moves along an axon in 1 direction only since impulse can move only to a region where membrane is polarized

128

Synapse

A junction between 2 nerve cells
Impulses pass by diffusion of a neurotransmitter

129

Homeostasis

Any self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival

130

Neurotransmitters

Brain chemicals that communicate information through brain & body
Relays signals between neurons

131

Filtration
(Nephron)

Occurs by diffusion
It is passive & nonselective
Filtrate contains everything small enough to diffuse out of glomerulus into Bowman's capsule

Glomerulus -> Bowman's capsule -> loop of Henle -> collecting duct/tubule

132

Secretion
(Nephron)

Active, selective uptake of molecules that did not get filtered into Bowman's capsule
In tubules of nephron

133

Reabsorption
(Nephron)

Process by which most water & solutes that initially entered the tubule during filtration are transported back into the capillaries & thus back to the body

Tubulue -> loop of Henle -> collecting tubule

134

Excretion
(Nephron)

Removal of metabolic wastes
Everything that passes into collecting tubule is excreted from the body

135

Myofibrils

Fibers within cytoplasm of each skeletal muscle cells that run parallel to length of the cell

136

Sliding Filament Theory

Muscles contract as thick (myosin) & thin (actin) filaments slide over each other

137

Peristalsis

Automatic process that moves food through the digestive system