Human Physiology Flashcards
1
Q
~Hydra
A
● Cnidarians
● Digestion occurs in the gastrovascular cavity with only one opening
● Cells of the gastrodermis secrete digestive enzymes into the cavity for extracellular digestion
● Some specialized nutritive cells have flagella that move the food around the cavity
● Some have pseudopods that engulf food particles
2
Q
~Gastrodermis
A
● lining of the gastrovascular cavity in hydra
● Secrete digestivve enzymes into the cavity for extracellular digestion
3
Q
~Earthworm
A
● THe digestive tract is a long, straight tube
● The mouth ingests decaying organic matter along with soil
● From the mouth, food moves to the esophagus and then to the crop
● The gizzards grinds up the food
● THe rest of the digestive tract consists of the intestines where chemical digestion and absorption occur
● Absorption is enhanced by the presence of typhlosole
4
Q
~Crop
A
Where food is stored in earthworms
5
Q
~Gizzard
A
● Posterior to the crop
● COnsists of thick, muscular walls
● Grinds up the food with the help of sand and soil that were ingested along with the organic matter
6
Q
~Typhlosole
A
● Large fold in the upper surface of the intestine in earthworms
● Increases the surface area
7
Q
~Grasshopper
A
● Has a digestive tract that consists of a long tube consisting of a crop and gizzard
● Has a specialized mouth parts for tasting, biting and crushing food
● Has a gizzard htat contains plates
● The idgestive tract is also responsible for removing nitrogenous waste from the animal (uric acid)
8
Q
~Plates
A
● Made of chitin
● Help in grinding the food
9
Q
~Digestion
A
● Breaking down large food molecules into smaller usable molecules
10
Q
~Absorption
A
● Diffusion of these smaller molecules in the body’s cells
11
Q
~Smooth (involuntary) muscle
A
● Made up the digestive tract
● Pushes the food along the digestive tract by peristalsis
12
Q
~Human digestive system
A
● Two important functions: digestion and absorption
● About 30 feet (9m) long
13
Q
~Salivary amylase
A
● Released by salivary glands
● Begins hte chemical breakdown of starch
14
Q
~Esophagus
A
● Food is directed into the esophagus, not windpipe
● No digestion occurs here
15
Q
~Epiglottis
A
● A flap of cartilage in the back of the pharynx (throat)
16
Q
~Stomach
A
● Churns food mechanically and secrete gastric juice
● Contains rennin
17
Q
~Gastric juice
A
● Begins the digestion of proteins
18
Q
~Gastric pits
A
● Contained in the lining of the stomach
● Lined with three types of cells, chief cells, parietal cells and the cell that secretes mucus
19
Q
~Chief cells
A
● Secrete pepsinogen, the inactive form of pepsin htat becomes activated by acid
20
Q
~Parietal cells
A
● Secrete the hydrochloric acid that keeps the pH of gastric juices at 2-3 and activates pepsinogen
● HCl also kills ingested microorganisms and breaks down protein
21
Q
~Mucus
A
● Produced by the third type of gastric pits
● Protects the stomach linign from the two cell-digesting substances
22
Q
~Rennin
A
● In stomach of all mammals
● Aid in the digestion of the protein in milk
23
Q
~Lower esophageal sphincter
A
● At the top of the stomach
● Keeps food int he stomach from backing up into the esophagus and burning it
24
Q
~Pyloric sphincter
A
● At the bottom of the stomach
● Keeps hte food in the stomach long enough to be digested
25
~Ulcer
● Excessive acid can cause an ulcer to form in the esophagus, the stomach or the duodenum
● A common cause is a particular bacerium, Helicobacter pylori, which can be effectively treated with antibiotics
26
~Duodenum
● Digestion is completed here
● Intestinal enzymes and pancreatic amylases hydrolyze starch and glycogen into maltose
● Bile is released and peptidases, necleases and lipases continued to break polymers into monomers
27
~Bile
● Proudced in the liver and stored in the gallbladder
● Released into the small intestine as needed and acts as an emulsifier to break down fats, creating greater surface area for digestive enzymes
28
~Peptidases
● Such as trypsin and chymotropsin
| ● Continue to bereak down proteins
29
~Nucleases
● Nucleic acis are hydrolyzed by nucleases
30
~Lipases
● Break down fats
31
~Lower part of small intestine
● Once digestion is complete, the lower part of the small intestine is the site of absorption
● Villi are present
32
~Villi
● Millions of fingerlike projections absorb all the nutrients that were previously released from digested food
● Each villus contains capillaries, which absorb amino acis, vitamins, and monosacchraides, and a lacteal, a small vessel of the lymphtic system, which absorbs fatty acids and glycerol
● contains microvilli
33
~Microvilli
● Each epithelial cell of the villus has many microscopic cytoplasmic appendages called microvilli that greatly increase the rate of nutritnet absorption by the villi
34
~Large intestion/colon
● Serves three main functions: egestion, vitamin production, and removal of excess water
35
~Egestion
● The removal of undigested waste
36
~Vitamin production
● From bacteria symbionts living in the colon
37
~Removal of excess water
● The samll intestine and colon reabsorb 90% of the water that entered the alimentary canal
● If too much water is removed from the intestine, constipation results
● IF inadequate water is removed, diarrhea results
38
~Rectum
● The last 7-8 inches (18-20 cm) of the gastrointestinal tract
● Stores feces until their release
39
~Anus
● The opening at the end of the digestive tract
40
~Gastrin
● Site of production: stomach wall
| ● Effect: stimulates sustained secretion of gastric juice
41
~Secretin
● Site of production: duodenum wall
| ● Effect: stimulates pancreas to release bicarbonate to neutralize acid in duodenum
42
~Cholecystokinin (CCK)
● Site of production: duodenum wall
| ● Effect: stimulates pancreas to release pancreatic enzymes and gall bladder to release bile into small intestine
43
~Respiration
● Exchange of respiratory gases, oxygen, and carbon dioxide, between the external environment and the cell or body
● Occurs passively by diffusion
● Respiratory surfaces must be thin, be moist and have large surface areas
44
~Gas exchange in simple animals (sponges and hydra)
● Gas exchange occurs over the entire surface of the organism wherever cells are in direct contact with the environment
45
~Gas exchange in earthworms and flatworms
● External respiratory surface bcause diffusion of oxygen and carbon dioxide occurs at the skin
● Oxygen is carried by hemoglobin dissolved in blood
46
~Gass exchange in arthropods and crustaceans
● Internal respiratory surface
● Air enters the body through spiracles and travels through a system of tracheal tubes into the body, hwere diffusion occurs in sinuses or hemocoels
● in arthropods and in some mollusks, oxygen is carried by hemocyanin
47
~Hemocyanin
● Oxygen carrier in arthropods and some mmollusks
| ● Molecule similar to hemoglobin but with copper instead of iron as its core atom
48
~Gas exchange in aquatic animals
● Countercurrent exchange to maximize hte diffusion of respiratory gases
49
~Gas exchange in human
● Air enters the nasal cavity and is moistened, warmed, and filtered
● Air paases through the larynx and down the trachea and bronchi into the tiniest bronchioles which end in microsopic air sacs called alveoli where diffusion of respiratory gases occurs
● Internal respiratory surface
50
~Medulla
● In the brain
● Contains the breathing control center, and sets the rhythm of breathing and monitors CO2 level int he blod by sensing changes in pH of hte blood
51
~Chemoreceptors
● Located in the nodes of neural tissue in teh aorta and carotid arteries leaving the heart
● If O2 level drop dratically, these receptors become activated and send nerve impulses to the medulla
52
~Hemoglobin
● Oxygen is carried in the human blood by the respiratory pigement
● Can combine loosely with four oxygen molecules, forming the molecule oxyhemoglobin
● Allosteric molecule and exhibits cooperativity
● Sensitive to pH
53
~Cooperativity
● Once one hemoglobin subunit binds to one oxygen molecule, it undergoes a shape chagne and binds more easily to the remaining three oxgyen molecules
54
~Dissociation curve of two mammals, one has higher metabolism
● The one that has higher metablolism, its body cells have a correspondingly higher oxygen requirment
● The accomodate hte animal\s oxygen needs, the organism's hemoglobin has a dissociation curve located to the right of the other's hemoglobin
● Higher metabolism = drops off O2 at cells more easily than lower metabolism
55
~Dissociation curve of fetal and maternal
● Fetal hemoglobin has a higher affinity fro oxygen than adult hemoglobin so it can take oxyn from the maternal hemoglobin
● The curve of fetal hemoglobin does not have the S shape common to the other curves
- It bonds to each oxygen atom with the same ease; there is no cooperativity
56
~Dissociation curve of high altitudes mammals vs sea level mammals
● Since less oxygen is available at high altitudes, mammals that evolved thier must have hemoglobin with a greater affinity for oxygen
57
~Saturation-dissociation curves
● The further to the right hte curve is, the less afinity the hemoglobin has for oxygen
58
~Transport of CO2
● Very little is transported by hemoglobin
● Most CO2 is carried in the plasma as part of the reversible blood buggering carbonic-acid-bicarbonate ion system, which maintians the blood at a constant pH 7.4
59
~Bicarbonate ion
● Produced in a two-stage reaction
● First, CO2 combines with H2O to form carbonic acid (H2CO3)
- This reaction is catalyzed by carbonic acid anhydrase found in red blood cells
● Then carbonic acid dissociates into a bicarbonate ion and proton
- THe protons can be given up into the plasma, which lowers the blood pH, or taken up by the bicarbonate ion, which raises the blood pH
60
~Ciruculation in primitive animals (sponge and hydra)
● no circulatory systems
| ● All their cells are in direct ocntact with the environment, and such as sytem is unnecessary
61
~Circulation in earthworm
● Closed circulatory system where blood is pumped by the heart through arteries, veins and capillaries
● Oxygen is carried by hemoglobin that is dissolved in the blood
62
~Circulation in arthropods
● Opencirculatory system
● After blood is pumped by the heart into an artery, it leaves the vessels and seeps through saces called sinuses or hemocoels as it feeds body cells
● The blood then moves back into a vein and circulates back to the heart
● This sytem lacks capillaries
● Arthropod blood is colorless and does not carry oxygen
63
~Human circulation
● Closed circulatory system with arteries, veins and capitallaries
64
~Plama
● Liquid portion of the blood
● Contains clotting factors, hormones, antibodies, dissolved gases, nutrients, and wastes
● Maintain proper osmotic potential of blood, 300 mosm/L
65
~Red Blood Cell
● Erythrocytes
● Carry hemoglobin and oxygen
● Do not have a nucleus and live only about 120 days
● Formed in the bone marrow and recycled in the liver
66
~White Blood Cell
● Leukocytes
● Fight infection and are formed in the bone marrow
● Die fighting infection and are one component of pus
● One type of leukocyte--the B lynphcyte--produces antibodies
67
~Platelets
● Thrombocytes
● These are not cellsbut cell fragments that are formed in the bone marrow from megakaryocytes
● Clot blood
68
~Stem cells
● Multipotent cells that are fomed by bone marrow
| ● These keep dividing and constatnly replenish the pouplation of blood cells throughout a person's life
69
~Mechanism of blood clotting
● Begins with the release of clotting factors from platelets and damaged tissue
● Activation of inactive plasma proteins
● Anticlotting factors normally circulate in the plasma to prevent the formation of a clot or thrombus, which can cause serious damage in the absence of injurty
70
~Artery and arteriole
● Function: carry blood away from the heart under enormous pressues
● Structure: walls made of thick, elastic, smooth muscle
71
~Vein and venule
● Function: carry blood back to the heart under very little pressue
● Structure: thin walls have valves to help prevent back flow
- Located within skeletal muscle, which propels blood upward and back to heart as the body moves
72
~Capillary
● Function: allows for diffusion of nutrients and wastes between cells and blood
● Structure: walls are one-cell thick and so small that blood cells travel in single file
73
~Heart
● located beneath the sternum and is about the size of a clenched fist
● Beats about 70 beats per minute and pumps baout 5 quarts (5L) of blood per minute or the total volume of blood in the body each minute
74
~Atria
● Two atria in the heart receive blood from the body cells
75
~Ventricles
● Two ventricles pump blood out of the heart
76
~Cardiac muscle cells
● Individual cells have the ability to contract even when removed from the heart
77
~Sinoatrial (SA) node
● Pacemaker of the heart
● Sets hte timing of the contractions of th heart
● Located in the wall of the rihgt atrium
● Generates and sends eletrcal signals to the atrioventricular (AV) node
● Action potention is generated by voltage-gated Ca channels
78
~His and Purkinje fibers
● From the pacemaker, impulses are sent to the bundle of His and Purkinje fibers, which trigger the ventricles to contract
79
~Electrocardiogram (EKG)
● Electrical impulses travel through the cardiac and body tissues to the skin, hwere they can be detected by an EKG
80
~Blood pressure
● lowest in the veins
● Highest in the arteries whent eh ventricles contract
● All normal, resting adults is 120/80
81
~Systolic number (120)
● Measurement of hte pressure when teh ventricles contract
82
~Diastolic number
● Measurement of the pressure when the heart relaxes
83
~Renal circulation
● Circulation in kidneys
84
~Croronary circulation
● Circulation in the heart
85
~Hepatic circulation
● Circulation in liver
86
~Pulmonary circulation
● Incluses pulmonary artery, lungs, and pulmonary vein
87
~Chemical signals
● Endocrine system secrets hormones
● Nervous system secretes neurotransmitters
● Even though the two systems are seaprate, there is overlap between them, and together they work to regulate the body
88
~Epinephrine/adrenaline
● Functions as the fight-or-flight hormone secreted by the adrenal gland as well as a neurotransmitter that sneds a messgae from one neuron to another
● Speeds up the heart rate
● Increases blood glucose levels by increasing rate of glycogen breakdown by liver
● Gland: Adrenal medulla
89
~Hormones
● Produced in ductless (endocrine) glands and move through the blood to a specific target cell, tissue, or organ that can be far from the original endocrine gland
● Can roduce an immediate short-lived response (adrenaline/epinephrine)
● Can dramatically alter the development of an entire organism (ecdysone)
90
~Ecdysone
● Controls metamorphossi in insects
91
~Tropic hormones
● Far-reaching effect because they stimulate other glands to release hormones
● TSH (thyroid-stimulating hormone)
92
~Thyroid-stimulating hormone (TSH)
● Stimulates the thyroid to release thyroxin
93
~Pheromones
● Carry a message between different individuals of the same species
94
~Nitric oxide (NO)
● In vertebrates, this gas is produced by one cell and diffuses to and affectes only neighboring cells before it is broken down
95
~Growthn hormone (GH)
● Gland: Anterior pituitary
| ● Effect: Stimulates growth of bones
96
~Luteinizing hormone (LH)
● Gland: Anterior pituitary
| ● Effect: Stimulates ovaries and testes to release follicle/sperm production
97
~Adrenocorticotropic hormone (ACTH)
● Gland: Anterior pituitary
| ● Effect: Stimulates adrenal cortex to secrete glucocorticois (to regulate blood sugar)
98
~Follicle-stimulating hormone (FSH)
● Gland: Anterior pituitary
| ● Effect: Stimulates gonads to produce sperm and ova (grow and mature follicles)
99
~Prolactin
● Gland: Anterior pituitary
| ● Effect: Stimulates mammary glands to produce milk
100
~Oxytocin
● Gland: Posterior pituitary
● Effect: Stimulates contractions of uterus and milk production by mammary glands
● Targets thebrain, influencing behaviors related to trust, maternal care, pair bonding, and sexual activity
101
~Antidiuretic hormone (ADH)
● Gland: Posterior pituitary
● Effect: Promotes retention of water by kidneys
● Also known as vasopressin
● Targets the nephron and decreasing urine volume
● Regulates blood osmolarity
102
~Thyroxin (T3 and T4)
● Gland: Thyroid (at the neck)
● Effect: Controls metabolic rate
● Require iodine to be produced
103
~Calcitonin
● Gland: Thyroid
| ● Effect: Lowers blood calcium levels
104
~Parathormone
● Gland: Parathyroid
| ● Effect: Raises blood calcium levels
105
~Glucocorticoids
● Gland: Adrenal cortex
| ● Effect: Raises blood sugar levels
106
~Norepinephrine/noradrenaline
● Gland: Adrenal medulla
| ● Effect: opposite of epinephrine/adrenaline
107
~Insulin
● Gland: Pancreas (islets of Langerhans)
● Secreted by Beta cells
● Effect: Lowers blood glucose levels
108
~Glucagon
● Gland: Pancreas (islets of Langerhans)
● secreted by Alpha cells
● Effect: Raises blood glucose levels by causing breakdown of glycogen into glucose
109
~Thymosin
● Gland: Thymus
| ● Effect: stimulates T lymphocytes
110
~Melatonin
● Gland: Pineal
| ● Effect: involved in biorhythms
111
~Estrogen
● Gland: Ovaries
● Effect: Stimulates uterine lining, promotes development and maintenance of primary and secondary characteristics of female
112
~Progesterone
● Gland: Ovaries
| ● Effect: promotes uterine lining growth
113
~Androgens
● Gland: Testes
| ● Effect: Support sperm production and promote secondary sex characteristics
114
~Hypothalamus
● Bridge between the endocrine and nervous systems
● Cotnains the body's termostat and centers for regulating hunger and thirst
● Signals from hypothalamus travel tot he posterior pituitary and anterior pituitary
115
~Posterior Pituitary
● Two hormones are released upon recieving nerve immpulses from the ypothalamus
- Oxytocin
- Antidiuretic hormone (ADH)
116
~Anterior Pituitary
● All hormones released by anterior pituitary are controlled by at least one hormone from the hypothalamus, either a releasing or an inhibiting hormone
● Hypothalamus releases prolactin-releasing hormone into tiny capitallries so it can immediately reach the anterior pituitary that simualtes the release of prolactin
117
~Feedback mechanism
● Self-regulating mechanism that increases or decreases the level of a particular substance
118
~Positive feedback
● Enhaces an already existing response
● For example, during labor, the pressue of hte baby's head against sensors near the opening of the uterus stimulates more uterine contractions, which causes increased pressure against hte uterine opening, which causes yet more contractions
119
~Negative feedback
● Common in the endocrine system that maintains homeostasis
| ● For example, when the level of thyroxin in adequate, the hypothalamus stops stimulating the pituitary
120
~Lipid/steriod hormones
● Diffuse directly through the plasma membrane an dbind to a receptor inside hte nucleus that triggers the cell's response
121
~Protein/peptide hormones
● Cannot dissolve in the plasma membrane, so they bind to the receptor on the surface of the cell
● Once the hormone (the first messenger) binds to the receptor ont he surface of hte cell, it triggers a secondary messenger, such as c-AMP inside the cell, which converts the extracellular chemical signal to a specific response
122
~Tetosterone
● Example of steroid hormone
● Secreted by cells int eh testes and travels throught he blood, entering cells all over the body
● Readily passes through the cell membrane and binds to a receptor in the cytoplasm, activating it
- Only cells with testosterone receptors can respond to testosterone
● The activated receptor enters hte nucleus and acts as a transcription factor, turning on specific genes that control male characteristics
123
~Androgen insensitivity syndrome (AIS)
People with this condition are born with the XY genotype but lack testosterone receptors in all their cells
● Individuals with AIS do not develop male reproductive ducts, male genitals, or male secondary sexual characterisitcs
124
~Bisphenol A (BPA)
● Industrial compound used in the manufacture of plastics
● The danger of this coumpound is htat it mimics the feminizing hormone estrogen and can set up an estrogen signal transduction pathway even though no estrogen is present
125
~Ectotherms
● Animals that gain most of their body heat from their environment
● Have such a low metabolic rate that the amount of heat they can generate is too small to have any effect on body temperature
● Temperature equilibrates to the environemnt
● Must maintain adequate body temperatuer through behavioral mean
● Include fish, amphibians, reptiles
126
~Endotherms
● Animals that use metabolic processes (oxidizing sugar) to produce body heat
● Body temperature remains constant (average is 37 celcius)
● Include all mammals and birds
● Endothermy consumes many energy
127
~Poikilotherm
● hHaving a body temperature htat varies with the environment
128
~Hemeotherm
● Having a constant body temperature despite fluctuations in environmental temperaure
129
~North-south cline
● Anatomical difference across a geographic range
130
~Countercurrent heat exchange
● Mechanism that has evolved in a variety of organisms
● Helps to warm or cool extremities
● Two vessels (artery and vein) running in parallel direction
131
~Osmoregulation
● Management of the body's water and solute concentration
| ● Organisms in different environments face different problems maintinaing the proper concentration of body fluids
132
~Osmoregulation in marine vertebrates
● Ocean is a strongly dehydrating environment because it is very hypertonic to the organisms living in it
● Fish constantly lose water through their gills and skin to the surrounding environment
● To counteract the problem, they produce very little uring and drink large amounts of seawater
● Extra salt that is taken in with the seawater is actively transported out through the gills
133
~Osmoregulation in freshwater organisms
● Environemtn is hypotonic to the organisms, and they are constantly gaining water and losing salt
● Freshwater fish excrete copious amounts of dilute urine
134
~Osmoregulation in terrestial organisms
● Face entirely different problems
● Have had to evolve machanisms and structures that enable them to rid themselves of metabolic wastes while retaining as much water as possible
135
~Protista excretory structures
● Contractile vacuole
136
~Platyhelminthes/planaria excretory structures
● Flame cells
137
~Earthworm excretory structures
● Nephridia (metanephridia)
138
~Insects excretory structures
● Malpighian tubules
139
~Human excretory structures
● Nephrons
140
~Excretion
● Removal of metabolic wastes, which include carbon dioxide and water from cell respiration and nitrogenous wastes from protein metabolism
● Organs of excretion in humans are the skin, lungs, kidney and the liver (where urea is produced)
● From the collecting tubule or duct, urine passes through the ureter to the urnary bladder where it's temporarily stored until it passes out of the body via the urethra
141
~Ammonia
● Very soluable in water and highly toxic
| ● Excreted generally by organisms that live in water, including the hydra and fish
142
~Urea
● Not as toxic as ammonia
● Excreted by earthworms and humans
● In mammals, it is formed in the liver from ammonia
143
~Uric Acid
● Pastelike substance that is not soluble in water and therefore not very toxic
● Excreted by insects, many reptiles, and birds, with a minimum of water loss
144
~Kidney
● Functions as both an osmoregulator (regulates blood volume and concentration) and an organ of excretion
● Adjust both the volume and hte concentration of urine depending ont he animal's intake of water and salt and the production of urea
145
~Dilute/hyposmotic urine
● If fluid intake is high and salt intake is low, the kidney will produce large volumes of this
146
~Concentrated/hyperosmotic urine
● In periods of high salt intake where water is unavailable, the kidney can produce this
147
~Nephron
● Functional unit of the kidney
● Consists of the glomerulus, which sits inside a cuplie structure called Bowman's capsule and connects to a long narrow tube, the renal tubule
● Carries out its job in four steps: filtration, secretion, reabsorption and excretion
148
~Filtration
● Occurs as blood pressure forces fluid from the blood in the glomerulus into Bowman's capsule
● Specialized cells of Bowman's capsule are modified into podocytes
● Occurs by diffusion and is passive and nonselective
● Filtrate contains everything small enough to diffuse out of the glomerulus, including glucose, salts, vitamins, waste such as urea, and other small molecules
● The filtrate travesl intot he proximal tubule from the Bowman's capsule
149
~Glomerulus
● Cluster of capillaries connected to the nephron
| ● Sits inside of Bowman's capsule
150
~Podocytes
● Along with slit pores, increase the rate of filtration
151
~Secretion
● Occurs in the proximal and distal tubules
● Active, selective uptake of certain drugs and toxic molecules that did not get filtered into Bowman's capsule
● Also secretes ammonia to neutralize the acidic filtrate
152
~Reabsorption
● Process by which most of the water and solutes (glucose, amino acids and vitamins) that initially entered the tubule during filtration are transported back into the peritubular capillaries and, ths back to the body
● Begins in the proximal convoluted tubule and continues in the loop of Henle and collecting tubule
153
~Loop of Henle
● Move salts from the filtrate and accumulate them in the medulla surrounding the loop of Henle and the collecting tubule
● Acts as a countercurrent exchange mechanism, maintaining a steep salt gradient surrounding the loop
● This gradient ensures that water molecules will continue to flow out of the collecting tubule of hte nephron, thus creating hypertonic urine and conserving water
● The longer the loop of Henle, the greater is the reabsorption of water
154
~Aldosteron
● Hormone released by the adrenal glands in response to a decrease in blood pressure or volume
● Acts on the distal tubules of hte nephron to reabsorb more sodium ions and water, thus increasing blood volume and pressure
155
~Antidiuretic hormone (ADH) on kidney
● AKA vasopressin
● Is produced by the hypothalamus and both sotred in and released from the posterior pituitary
● Released in response to dehydration due to excessive sweating or inadequate water intake, which causes the blod to become too concnetrated (osmolarity to increase)
● Increases the permeability of the collecting tubules to water by opening renal aquaporins (transmembrane proteins that function as water channels)
● This opening allows more water to be reabsorbed and urin volume to be reduced
156
~Renin
● Hormone released from the kidneys
| ● Converts an inactive protein into active angiotensin, which stimualtes the adreanl cortex to release aldosterone
157
~Diuretic
● Presciption drug for high blood pressure
● Commonly called a water pill
● Reduces blood volume by increasing the amount of water released in urine
158
~Angiotensin-converting enzyme (ACE) inhibitor
● Prevents the formation of angiotension II
| ● ACE inhibitors inhibit the formation of aldosterone and thereby decrease volume
159
~Central nervous sytem (CNS)
● Consists of the brain and spinal cord
160
~Peripheral nervous sytem (PNS)
● Consists of all nerves outside the CNS
161
~Sensory system
● Conveys information from sensory receptros or nerve endings
162
~Motor system
● Somatic system and autonomic system
163
~Somatic system
● controls the voluntary muscles
164
~Autonomic system
● Ctonrols involuntary muscles
| ● Sympathetic and parasympathetic
165
~Sympathetic system
```
● Fight or flight response
● Increase heart and breathing rate
● Liver converts glycogen to glucose
● Bronchi of lungs dilate and increase gas exchange
● Adrenalin raises blood glucose levels
```
166
~Parasympathetic System
● Opposes the sympathetic system
● Calms the body
● Decreases heart/breathing rate
● Enhances digestion
167
~Dendrites
● Sensory part of neuron
● Receive incoming messages from other cells and carry the electrical signal to the cell body
● Can have hundreds of dendrites
168
~Axon
● Transmit an impulse from the cell body outward to another cell
● Many are wrapped in a fatty myelin sheath that is formed by Schwann cells
● There is only one axon per neuron
169
~Sensory neurons
● Receive an initial stimulus from a sense organ, such as the eyes and ears, or from another neuron
170
~Motor neuron
● Stimulates effectors (muscles or glands)
| ● Can stimulate a digestive gland to release a digestive enzyme or to stimulate a muscle to contract
171
~Interneuron/association neuron
● Resides within the spinal cord and brain, receives sensory stimuli and transfers the information directly to a motor neuron or to the brain for processing
172
~Reflex arc
● Simplest nerve response
● Inborn, automatic, and protective
● Example is the knee-jerk reflex
173
~Knee-jerk reflex
● Consists of only two types of neurons :sensory and motor
● A stimulus, a tap from a hammer, is felt in the sensory neuron of the kneecap, which sends an impulse to the motor neuron, which directs the thigh muscle to contract
174
~Complex reflex arc
● Consists of three neurons, sensory, motor and interneuron
● A sensory neuron transmits an impulse to the interneuron in the spinal cord, which sends one impulse to the brain for processing and also one to the motor neuron to effect change immediately (at the muslce)
● This is the type of response that quickly jerks your hand away from a hot iron before your brain has figured out what occured
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~Membrane potential
● All living things exhibit it
● A difference in electrical charge between the cytoplasm (negatively charged) and extracellular fluid (positively charged)
● Physiologists measure this difference in membrane potential using microelectrodes connected to a voltmeter (between -50mV and -100 mV)
● The larger the membrane potential, the stronger the stimulus must be to cause the nerve to fire
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~Polarized state/resting potential
● About -70 mV
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~Sodium-potassium pump
● Maintains the polarization by actively pumping ions that leak across the membrane
● Patassium ions leak passively down the gradient across the cell membrane through "leak channels" in resting neurons
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~Resting threshold
● In order for the nerve to fire, a stimulus must be strong enough to overcome the resting threshold
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~Gated-ion channels
● Neurons have channels that open or close in response to a stimulus and play an essential role in transmission of electrical impulses
● Allow only one kind of ion, such as sodium or potassium, to flow through them
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~Sodium ion-gated channels
● If a stimulus triggers the channel to open, sodium flows into the cytoplasm, resulting in a decrease in polarization to about -60 mV
● The membrane becomes somewhat depolarized, soit is easier for the nerve to fire
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~Potassium ion-gated channel
● if this channel opens, the membrane potential increases and the membrane becomes hyperpolarized, to about -75 mV, so that it is harder for the neuron to fire
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~Action potential/impulse
● Can be generated only in the axon of a neuron
● When an axon is stimulated sufficiently to overcome the threshold, the permeability of a region of hte membrane suddenly changes and hte impulse can pass
● Soium channels open, potassium channels open, the rapid movement of ions or wave of depolarization reverses hte polarity of the membrane and is called an action poential
● Lasts a very short time
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~Refractory period
● The period of repolarization of sodium-potassium pump
● Lasts a few milliseconds
● During this period, the neuron cannot respond to another stimulus
● Ensures that an impulse moves along an axon in one direction only since the impulse can move only to a region where hte membrane is polarized
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~Vesicles
● Each containing thousands of molecules of neurotransmitter
● Found in the cytoplasm at the terminal branch of the presynaptic neuron
● The sudden rise in Ca levels stimulates the vesicles to fuse with the presynaptic membrane and release the neurotransmitter by exocytosis into the synaptic cleft
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~Calcium-gated channels
● Depolarization of the presynaptic membrane causes Ca ions to rush intot he terminal branch through channels
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~Neurotransmitters
● Contained in vesicles
● Once released by exocytosis into the synaptic cleft, it bonds with receptors on the postsynaptic side, altering the membrane potential of the postsynaptic cell and resulting in a response
● The cell will either be inhibited or excited
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~Neurons in vertebrates
● In vertebrates, synapses between motor neurons and muscle cells are always excitatory
● However, synapses between neurons can also be inhibitory by causing hyperpolarization ofthe postsynaptic cell
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~Esterase
● Shortly after hte neurotransmitter is released into the synapse, it is destroyed by the enzyme and recycled by the presynaptic neuron
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~Acetylcholine
● THe neurotransmitter at all neuromuscular junctions
| ● Stimulates some cells to release the gas nitric oxice (NO), which in turn stimulates other cells
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~Examples of neurotransmitter
● Serotonin, epinephrine, norepinephrine, dopamine, acetylcholine
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~Cerebrum
● Learning, emotion, memory, perception
● Divided into right an dleft hemispheres
● The left side of the brain receives information from and controls hte right side of hte body and vice versa
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~Cerebellum
● Coordinates movement and balance; helps in learning and remembring motor skills
● Receives sensory information about the position of joints and muscles
● Monitors motor commands from the cerebrum and integrates hte information as it carries out coordination
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~Brainstem
● Includes medulla oblongata
● Controls several automatic homeostatic functions, including breathing, heart and blood vessel activity, swallowing and digestion
● Receives the integrates several types of sensory information and sends it to specific regions of the forebrain
● Transfers information between the PNS and other parts of the brain
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~Cones
● Modified neurons
● Photoreceptors in the retina that distinguish different colors
● Embedded with visual pigments
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~Cornea
● Tough, clear covering that protects the eye and allos light to pass through
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~Humor
● Fluid that maintain the shape of the eyeball
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~Iris
● Colored part of the eye that controls the size of the pupil and how much light enters the eye
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~Lens
● Focuses light on the retina
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~Opsin
● A membrane protein bound to a light-absorbing pigment molecule
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~Pupil
● Small opening int he middle of the iris where light enters the eye
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~Retina
● On the back of the eyeball
● Converts light to nerve impulses that are carried to the brain
● Consists of 5 layers of neurons
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~Retinal
● Light-absorbing pigment in rods and cones
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~Rhodopsin
● A visual pigment consisting of retinal and opsin
| ● Upon absorbing light, retinal changes shape and separates from opsin
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~Rods
● Modified neurons
● Photoreceptors in the retina that are extremely sensitive but distinguish only black and white
● Embedded with the visual pigemnet retinal
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~Signal transduction pathway and amplification cascade
● THe stimulation of retinal activates a G prtoein-signaling mechanism that ultimately alters the membrane potential and closes Na channels
● Each single molecule of photoexcited rhodopsin activates several hundred enzyme molecules, each of which activates several hundred molecules of cGMP, closing Na channels, and causing an impulse to be sent to the optic nerve
● From optic nerve, impulses travel to the cortex of the brain where hte messages are interpreted and seeing actually occur
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~Smooth/involuntary muscle
● Makes up the walls of the blood vessels and the digestive tract
● Because of the arrangement of its actin and myosin filaments, it does not have a striated appearance
● Udner control of the autonomic nervous system
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~Cardiac muscle cells
● Makes up the heart
● Generates its own action potential
● Individual heart cells will beat on their own in a saline solution
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~Skeletal/voluntary muscle
● Very large and multinucleate
● Work in pairs, one muslce contracts while the other relaxes
● Ex) Biceps and triceps
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~Muscle fibers
● Each muscle consists of bundleso f thousndas of muscle fibers
● Individual cylindrical muscle cells
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~Sarcolemma
● Modified plasma membrane that surrounds each muscle fiber and can propagate an action potential
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~Sarcoplasmic reticulum (SR)
● Modified endoplasmic reticulum that contains sacs of Ca ions necessary for normal muscle contraction
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~T system
● A system of tubules that runs perpendicular tot he SR and that connects the SR to the extracellular fluid
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~Sarcomere
● Functional unit of the muscle fiber (cell)
| ● Boundaries are the Z lines, which give skeletal muscle its characteristic striated appearance
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~Sliding Filament THeory
● The contraction of hte sarcomere depends on two molecules: troponin and tropomyosin, in addition to Ca ions to form and break cross-bridges
● Muslce contracts as thick and thin filaments slide over each other
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~Myofibrils
● Within the cytoplasm of each muscle cell are thousands of fibers called myofibrils that run parallel to the length of the cell
● Consists of thick and thin filaments
● Each thin filament consists of two strands of actin proteins wound around one another
● Each thick filament is composed of two long chains of myosin molecules each with a globular head at one end
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~Neuromuscular junction
● The axon of a motor neuron synapses on a skeletal muscle here
● Acetylcholine binds to receptors on the sarcolemma, depolarizes the muscle cell membrane and sets up an action potential
● The impulse moves along the sarcolemma into the T system and stimulates sarcoplasmic reticulum to release Ca
● The Ca ions then alter the troponin-tropomyosin relationship and the muscle contracts
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~Twitch
● Single action potential in a muscle will cause the muscle to contract locally and minutely for a few milliseconds and then relax
● The brief contraction is called a twitch
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~Summation effect
● If a second action potential arrives before the first response is over, there will be this effect and the contraction will be larger
● if a muscle receives a series of overlapping action potentials, even further summantion will occur
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~Tetanus
● If the rate of stimulation is fast enough, the twitches will blur into one smooth, sustained contraction called tetanus
● It is what occurs when a large muscle such as the biceps muscle contracts
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~Fatigue
● If the muscle continues to be stmulated without respite, it will eventually fatige and relax
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~What do fats, starch, nucleic acis and proteins break down into respectively?
● Fats get broken down into glycerol and fatty acids
● Starch into monosaccharides
● Nucleic acis into nucleotides
● Proteins into amino acids
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~What breaks down foods in the mouth?
● THe tongue and differently shaped teeth work together to break down food mechanically
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~What are the different types of teeth in human and what are their functions?
● Incisors for cutting
● Canine for tearing
● Molars for grinding
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~What are the conditions of respiratory surfaces?
● Thin
● moist
● Large surface areas
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~How do humans breathe?
● As the rib cage expands and the diaphragm contracts and lowers, the chest cavity expands, making the internal pressure lower than atmospheric pressue
- Air is drawn into the lungs by negative pressure
● RIb cage contracts and diaphragm relaxes, the chest cavity contracts, increasing the pressure, air moves out
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~Why does CO2 change the blood pH?
● CO2 dissolves in blood to form carbonic acid
| ● The higher the CO2 concentration in the blood, the lower the pH
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~Why is hemoglobin sensitive to pH?
● A drop in pH lowers the affinity of hemoglobin for oxygen (Bohr shift)
● Because CO2 dissovles in water to form carbonic acid, actively respiring tissue which releases large quantities of CO2, will lower the pH of its surroundings and induce hemoglobin to release its oxygen at the cells where needed
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~What is the pathway of normal clot formation?
● Damaged tissue and platelets -> THromboplastin + Ca -> Prothrombina (inactive) to Thrombin (active) -> Fibrinogen (inactive) to Fribrin (active -> clot
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~What influenced the heart's pacemaker?
● Two sets of nerves that cause it to speed up or slow down
● Hormones such as adrenalin
● Body temperature
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~What is the pathway of blood?
● Bood enters the heart through the veno cava
● Vena cava -> right atrium -> right atrioventricular (AV) valve (tricuspid valve) -> right ventricle -> pulmonary semilunar valve -> pulmonary artery -> lungs -> pulmonary vein -> left atrium -> biscupid (left AV valve) -> left ventricle -> aortic semilunar valve -> aorta -> to all the cells in the body
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~What are the two major regulatory systems that release chemicals in animals?
● The endocrine system
| ● The nervous system
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~How does hypothalamus act as a part of the nervous system?
● Acts as part of the nervous system when in time so stress, it sends electrical signals to the adrenal galnd to release adrenaline
● Acts like a nerve when it secretes gonadotropic-releasing hormone (GnRH) from neurosecretory cells that stimulate the anterior pituitary to secrete FSK and LH
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~How does hypothalamus act as a part of the endocrine system?
● Acts as an endocrine gland when it produces oxytocin and antidiuretic hormone that it stores in the posterior pituitary
● Initiates endocrine signaling appropritate to the environmental conditions in response to information recieved from nerves
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~How does ADH play a role in the behavior in prairie voles?
● Prairie voles's rbinas have large numbers of vasopressin receptors
● The male prairie voles hover over their young pups, care for them and act aggressively toward intruders
● If the males are injected with a drug that blocks the vasopressin receptor, the males fail to form pair-bonds after mating
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~What are the two types of hormones?
● Lipid/steroid homones
| ● Protein/peptide hormones
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~How does epinephrine function?
● THe hormone acts as the first messenger when it binds to and activates G protein membrane receptors on the surface of liver cells
● The activated G protein then activates adenylyl cyclase in the membrane to produce cAMP (second messenger)
● This begins kinase cascade that does two things
- activates glycogen phosphorylase to convert glycogen into glucose
- inhibits the conversion of glucose into glycogen
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~What are some examples of behavioral chagnes that alter body temperature?
● A snake can wamr itself in the sun or cool off by hiding under a rock
● Animals on a cold winter prairie huddle together to decrease heat loss
● Bees swarming in a hive raise the temperature inside the hive
● Dogs pant and sweat through their tongues to cool themselves off
● Elephants lack sweat glands but they cool themselves off by squirting water onto their skins and flapping thier ears like fans
● Humans shiver, jump around, and develop goose bumps to keep warm
● Birds migrate to a warmer climate and a better source of food to feed themselves and their youngs
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~What is impoortant when discussing thermoregulation?
● The source of heat used to maintain its body temperature
239
~When do mammals save energy and how?
● During torpor, estivation, summer torpor, or hibernation
| ● Decreasing their metabolic rate and body temperature
240
~What is am example of north-south cline
● The size of the ears in a jackrabbit
● Jackrabbits living in cold northern regions have small ears to minimize heat loss
● Rabbits in warm, osuthern regions have long ears to dissipate heat from the man capillaries that make their eaars appear pink
241
~How do ion channels generate actioan potential?
● Sodium channels open first, when an axon is stimulated to overcome the threshold and sodium ions flood into the cell, down the concentration gradient
● In response, potassium channels open and potassium ions flood out of the cell
● This wave of depolarization reverses the polarity of the membrane and is called an actiaon potention
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~Why does the impulse traveel faster if the axon is large or myelinated?
● THe myelin reduces ion leakage
● Voltage-gated channels are located ont he nodes, the impulse leaps from node to node (Ranvier) in saltatory (jumping) fashion
● THe impulse moves along the axon propagating itself without losing any strength
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~Why is the action potential an all-or-none event?
● Either the stimulus is strong enough to cause an action potential or it isnot
● The body distinguishes between the a strong stimulus and a weak one by the frequency of action potentials
● A strong stimulus sets up more action potentials than a weak one does
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~How does a postsynatic neuron determine the action potential?
● It may receive 100 impulses from presynaptic neurons, releasing a variety of different neurotransmitters
● All of these impulses are integrated and summed up into either hyperpolarization (inhibited) or hypopolorization (stimulated)
245
~What is the sensory phase in vision?
● The sensory phase of vision begins when photons of light pass through the lends, which focuses hte light onto the retina
● THe light is absorbed by photoreceptors in some of those neurons (rods and cones)
- While in a photoreceptor, each photon causes a change in shape of retinal from cis to trans, which results in the excitement of the visual pigmenet rhodopsin
● Triggers a signal transduction npathway and amplification cascade
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~Why do mammals have poorer color vision than other vertebrates?
● May result from our long evolutionary history of nocturnal living in which we have lost much of hte color vision found in toher vertebrates
● In human, another opsin molecule has evolved by means of gene deplication
● If the gene is nonfunctional, it results in red-green color blindness in whose men
247
~What are the three types of muscles?
● Smooth
● Cardiac
● Skeletal
248
~What are the modified structures that enable the skeletal muscle cell to contract?
● Sarcolemma
● Sarcoplasmic reticulum (SR)
● T system
● Sarcomere
