Midterm 2 Flashcards
(231 cards)
1
Q
what hormones are associated with the hypothalamus
A
antidiuretic
hormone (ADH)
oxytocin
2
Q
what hormones are associated with the anterior pituitary
A
- growth hormone (GH)
- prolactin
- thyroid-stimulating hormone (TSH)
- adrenocorticotropic hormone (ACTH)
- follicle-stimulating hormone (FSH)
- luteinizing hormone
- melanocyte-stimulating hormone (MSH)
3
Q
what hormones are stored in the posterior pituitary
A
antidiuretic
hormone (ADH)
oxytocin
4
Q
what hormones are made in the thyroid gland?
A
thyroid hormone
calcitonin
5
Q
what hormone is produced by the parathyroids glands
A
Parathyroid Hormone (PTH)
6
Q
what hormones are made in the adrenal cortex
A
- glucocorticoids (cortisone, cortisol, corticosterone)
- mineralcorticoids (e.g. aldosterone)
- sex hormones (androgens, estrogens)
7
Q
what hormones are made in the adrenal medulla
A
epinephrine and norepinephrine
8
Q
what hormones are made in the pancreas
A
glucagon
insulin
somatostatin
digestive enzymes
9
Q
what hormones do the ovaries make
A
- estrogens (estradiol and estrone)
- progestins
- relaxin
10
Q
what hormone does the kidney make
A
erythropoietin
11
Q
what hormone does the stomach make
A
gastrin
12
Q
what hormones dees the small intestine make
A
secretin
cholecystokinin
13
Q
what hormones does the placenta make
A
- estrogen
- progesterone
- chorionic gonadotropin (some species)
- relaxin (some species)
14
Q
what hormones does the thymus make
A
thymosin and thymopoietin
also primitive cells in thymus transformed into T-lymphocytes
(T-cells)
15
Q
what does the pineal body make
A
melatonin
16
Q
what is the difference between endo and exocrine glands
A
endo are ductless, excrete directly into blood stream, exo are ducted (ie liver)
17
Q
what are the animal hormone groups?
A
peptide
steroid
monoamine
18
Q
what are peptide hormones
A
- hydrophilic chains of amino acids
- receptors located on cell membranes of target cells
19
Q
what are steroid hormones
A
- synthesized from cholesterol
- hydrophobic so attach to transport protein = bound hormone
- receptors located within the cell
20
Q
what are monoamine
hormones
A
- derived from amino acids and retain an amino group
- receptors for catecholamines located on cell membranes
- receptors for thyroid hormones located in the nucleus
21
Q
describe negative vs positive feedback for hormones
A
- negative feedback
activity decreased by rising levels of hormone - positive feedback
activity increased by increased levels of hormone
22
Q
how are hormones controlled?
A
level of hormone in blood directly or indirectly
“feeds back” to the gland that produced it
23
Q
where is the hypothalamus
A
part of the diencephalon
of the brain
24
Q
what does the hypothalamus do?
A
controls activities of the
pituitary gland
25
where does the hypothalamus store it's hormones?
posterior pituitary
26
what is another name for pituitary
Hypophysis
master gland
27
what is the anterior pituitary called
adenohypophysis
28
what is the posterior pituitary called
neurohypophysis
29
what is another name for growth hormone
somatotropin/
somatotropic hormone
30
what does growth hormone do?
1. promotes body growth in young animals
2. helps regulate metabolism of proteins, lipids, and
carbohydrates in all body cells
31
what does prolactin do
1. helps trigger and maintain lactation
2. production and release continues as long as teat
continues to be stimulated by nursing or milking
32
What is Thyroid-Stimulating Hormone (TSH) also called?
thyrotropic hormone
33
what does Thyroid-Stimulating Hormone (TSH) do?
1. stimulates growth and development of thyroid gland
2. causes thyroid gland to produce its hormones
34
how is TSH regulated
1. by feedback from thyroid
2. by interaction among hypothalamus, anterior pituitary, and
thyroid glands
35
what does ACTH do?
stimulates growth and development of adrenal
cortex, and release of some of its hormones
36
How is ACTH regulated
production regulated by feedback from hormones of
the adrenal cortex
37
What does FSH do?
effects in the female:
- stimulates oogenesis
- stimulates production and secretion of estrogen
effects in the male
- stimulates spermatogenesis
38
What does luteinizing hormone do?
completes process of follicle development in ovary
LH in males stimulates interstitial cells to produce
testosterone
39
what does Melanocyte-Stimulating Hormone do
associated with control of color changes in pigment
cells of reptiles, fish, and amphibians
40
what does Antidiuretic Hormone (ADH) do?
1. helps prevent diuresis
2. released when hypothalamus detects dehydration
41
what is diabetes insipidus
ADH deficiency (PU/PD)
42
what does Oxytocin do
1. induces uterine contractions at breeding and parturition
2. causes movement of milk down to lower parts of the mammary gland (milk letdown)
43
what are the thyroid hormones?
T4 = tetraiodothyronine = thyroxine
- a prohormone, a circulating reservoir
T3 = triiodothyronine
- the active hormone
44
when are thyroid hormones made?
when TSH from anterior
pituitary stimulates the thyroid gland
45
what is the effect of thyroid hormones?
1. regulates metabolic rate of all body’s cells
2. affects metabolism of proteins, carbohydrates,
and lipids
46
what does calcitonin do
1. helps maintain blood calcium levels
2. prevents hypercalcemia by encouraging excess
calcium to be deposited in bones
47
what does parathyroid hormone do?
1. helps maintain blood calcium homeostasis
a. causes kidneys to retain calcium
b. causes intestines to absorb calcium from food
c. withdraws calcium from bones
2. exerts the opposite effect of calcitonin
48
what do glucocorticoids do?
1. cause general hyperglycemic effect
2. help maintain blood pressure
3. help body resist effects of stress
49
what does aldosterone do
regulate levels of electrolytes
50
what do alpha cells in the pancreas produce
glucagon
51
what do alpha cells in the pancreas produce
insulin
52
what doe delta cells in the pancreas produce
produce somatostatin
53
what does insulin do
lowers blood glucose levels by causing glucose, amino acids, and fatty acids in blood to be
absorbed into body cells
54
what does glucagon do
raises blood glucose levels
- stimulates liver cells to convert glycogen to glucose
- stimulates glycogenesis
55
what does FSH do
stimulates ovarian follicles to develop
56
where are progestins produced
corpus luteum
57
what is progestin used for
maintaining pregnancy
58
what is relaxin used for
- relaxation of ligaments surrounding birth canal
- mammary development
59
what is erythropoietin used for
increase production of red blood cells
60
what is gastrin used for
- causes gastric stomach glands to secrete hydrochloric acid
and digestive enzymes
- encourages muscular contractions of stomach wall
61
when is gastrin secreted
secretion stimulated by presence of food
62
when is secretin, cholecystokinin secreted
secretion in response to presence of chyme
in duodenum
63
what does secretin do
- stimulates pancreas to secrete fluid to neutralize acidic chyme
- slows movement of chyme
- stimulates gall bladder to send bile to small intestine
64
what does cholecystokinin do
- stimulates pancreas to release digestive enzymes
- slows movement of chyme
- stimulates gall bladder to send bile to small intestine
65
what does melatonin do
- affects moods and wake-sleep cycles
- may also have role in timing of seasonal estrus cycles
66
what are prostaglandins
hormone-like substances derived from unsaturated
fatty acids
67
what do prostaglandins do
- influence blood pressure, blood clotting, and inflammation
- influence functions of GI tract, kidneys, and reproductive
system
68
examples of Metabolic Waste Products
carbon dioxide and water
nitrogenous wastes (urea)
bile salts and pigments
various salts
69
what is the single most important route for removal of
waste products
urinary system
70
how do kidneys maintain homeostasis
1. blood filtration, reabsorption, secretion
2. fluid balance regulation through antidiuretic hormone (ADH), aldosterone
3. acid-base balance regulation
4. production of hormones
erythropoietin, prostaglandins
5. blood pressure regulation
71
what is a hylus
indented area on medial side of kidney. Where ureters, nerves, blood and lymph vessels enter and leave
72
funnel-shaped area inside hilus
renal pelvis
73
what does the renal corpuscle do?
filters blood in
first stage of urine
production
74
Proximal Convoluted Tubule (PCT) function
reabsorption and
secretion functions
75
Distal Convoluted Tubule (DCT) function
- primary site of ADH action,
- regulation of potassium
and acid-base balance
- DCTs from all nephrons
in the kidney empty into
collecting ducts
76
afferent
glomerular
arterioles function
carry
blood to renal
corpuscle
77
glomerular
capillaries function
filter
some plasma out
of the blood
78
peritubular
capillaries function
oxygen transfer to
cells of nephron
tubular
reabsorption and
tubular secretion
79
Mechanisms of Renal Action
1. filtration of the blood
2. reabsorption of useful substances back into the bloodstream
3. secretion of waste products from the blood
80
what does glomerular filtration rate (GFR) depend on
rate of blood flow to kidney
81
where are sodium ions reabsorbed in the nephron
ascending loop of henle
82
where is potassium and calcium reabsorbed in the nephron
in the PCT,
ascending loop of Henle, and DCT
83
where is magnesium reabsorbed in the nephron
from PCT, ascending loop of Henle, and the collecting duct
84
what is secreted by the nephron
waste products
eliminated by secretion:
hydrogen, potassium,
ammonia
also some medications
85
urine volume is determined by what
amount of water
contained in tubular filtrate when it reaches the renal pelvis
It is controlled by actions of 2 hormones:
(ADH- if absent, polyuria results) & aldosterone
86
how do kidneys regulate blood pressure
1. renin-angiotensin-aldosterone system responds when
blood pressure falls
2. renin is released, and splits enzyme angiotensin
3. increased amounts of sodium and water reabsorbed back into
bloodstream, causing an increase in blood volume
4. as blood volume increases, so does blood pressure
87
what is trigone
arrangement of
openings of ureters
into bladder and
opening from
bladder into urethra
88
what type of cells line the ureters, bladder, urethra
transitional epethilial
89
what are the 4 layers of the digestive system
mucosa
submucosa
muscular layers
serosa
90
what 2 systems regulate the gastrointestinal system?
combination of central nervous system
and endocrine system
91
what are the 2 parts of the mouth
1. vestibule: space between lips and cheeks, and outer surface of teeth
2. oral cavity: bordered by inner surface of teeth, and hard and soft palates
92
why type of teeth do omnivores, carnivores have
brachyodont teeth
93
what type of teeth do herbivores have
hypsodont teeth
94
what are the characteristics of hypsodont teeth
1. large reserve of crown
beneath gingiva
2. grow continually
95
what are the different types of teeth
1. incisor
2. canine
3. premolar
4. molar
96
how many teeth do dogs have
42
97
how many teeth do cats have
30
98
how many teeth do horses have
40/42
99
how many teeth do cows have
32
100
what do the papillae on the tongue do?
1. mechanical functions:
grooming and moving food into pharynx
2. specialized functions:
taste sensations, pain, temperature, touch,
and thermoregulation through panting (dogs)
101
what is the purpose of saliva
⚪ lubrication
⚪ antibacterial action
⚪ pH regulation
⚪ thermoregulation
⚪ enzymatic digestion
102
name the salivary glands
parotid, mandibular, and sublingual
103
movements of the temporal mandibular joint
⚪ extension
⚪ flexion
⚪ translation
104
how many layers of muscle are in the esophagus
2: circumferential, longitudinal
105
what does the Omentum do?
connects the
peritoneum that
links the stomach to
abdominal wall or
to other organs
106
functions of the stomach
1. storage of ingested food
2. mechanical and chemical breakdown of food
3. production of intrinsic factor for Vitamin B12 absorption in small intestine
107
what are the different areas of a monogastric stomach
cardia
fundus
body
duodenum
108
what is Rugae
- transient folds in
gastric mucosa
- allow stomach to
expand when
filled with food
- increase surface
area for
absorption
109
what are the different gastric pit cells and what do they secrete?
Chief- pepsinogen
Mucous neck
Parietal- H+ and Cl- ions
G-cells- gastrin
110
how is pepsinogen converted to pepsin
through presence of HCl
111
what are the 2 phases of secretion in the stomach
cephallic, gastric
112
what 3 substances stimulate secretions by glandular cells n stomach
1. acetylcholine from cholinergic neurons
2. gastrin released by G cells
3. histamine secreted by enterochromaffin-like cells (ECL-cells) in gastric mucosa
113
describe cephalic phase of gastric secretion
begins in anticipation of eating
1. enteric nervous system is stimulated
2. acetylcholine is released and binds to receptors
a. parietal cells secrete H+ and Cl- ions
b. chief cells secrete pepsinogen into stomach
c. G cells secrete gastrin into bloodstream
3. gastrin travels to parietal cells and ECL-cells,
ECL-cells release histamine
4. acetylcholine also triggers histamine release by ECL-cells. Histamine stimulates parietal cell to produce more H+ and
Cl- ions
114
describe Gastric Phase of Secretion
begins when food enters stomach
1. glandular cells stimulated by stretching of stomach wall
2. peptides formed by protein breakdown
3. released acetylcholine stimulates secretions
115
function of fundus
expands to
accommodate large
volumes of food
116
function of pyloric antrum
acts like
a pump
117
what hormones are released by small intestine that can also delay gastric emptying
⚪ secretin
⚪ cholecystokinin (CCK)
⚪ gastric inhibitory peptide (GIP)
118
what are the 2 phases of chemical digestion in the stomach
1. luminal digestion
process of hydrolysis
2. membranous chemical digestion
- hydrolysis repeated
- molecules broken down into most basic components
119
what are starches
repeating glucose monosaccharides
120
what are sugars
⚪ simple monosaccharides (glucose)
⚪multiple monosaccharides linked together (disaccharides, sucrose and lactose)
121
what is cellulose
complex carbohydrate
122
what are protiens
made of repeating amino acid units
123
describe carbohydrate digestion
- begins with amylase in saliva
- continues in stomach and small intestine
124
describe protein digestion
- begins in the stomach; continues in small intestine
-pepsinogen activated by HCl to pepsin
125
what are the 4 chambers of the ruminent stomach
reticulum
rumen
omasum
abomasum
126
are forestomachs are non-glandular
yes
127
does abomasum functions same as monogastric stomach
yes
128
rumen known as
the paunch
129
rumen characteristics
⚫occupies most of left side of abdominal cavity
⚫microorganisms ferment carbohydrates
⚫papillae in mucosa increase surface area for
absorption
⚫pillars divide rumen: dorsal sac, ventral sac, and 2 caudal sacs
130
reticulum known as
the honeycomb
131
reticulum characteristics
- located cranial to the rumen
- contents easily enter and exit to rumen
132
what is the esophageal groove
- links esophagus with omasum in young ruminant
- milk for nursing ruminant bypasses reticulorumen & goes directly to omasum and abomasum
- if groove didn’t close:
a. bacteria in reticulorumen would ferment milk
b. lactic acid produced would inhibit normal microbial action
133
omasum characteristics
- connects reticulorumen to abomasum
- folds of mucosa with papillae on surfaces
- absorption of water and salts here
134
omasum known as
“many plies” or “book stomach”
135
abomasum known as
true stomach
136
abomasum characteristics
⚫lined with glandular tissue
⚫released renin causes milk protein coagulation
⚪ prolongs time for pepsin to break down proteins
⚫functions like simple monogastric stomach
⚪ exception: abomasum is not a storage compartment
⚫continuous flow of ingesta into abomasum
137
eructation means
betching
138
what do ruminents use as a protein source
microorganisms in the forestomach
139
what do starches and sugars break down to in ruminants
volatile fatty acids
140
what happens if ruminants eat too many fats?
decreased appetite, reduced motility of
reticulorumen, decreased fermentation of cellulose
141
what are the parts of the sm intestine?
duodenum
jejunum
ileum
142
what are lacteals & what do they do
lymphatic
capillaries. They carry absorbed lipids
and fat-soluble
substances to thoracic
duct, and into vena cava
143
what is function of cholecystokinin (CCK)
⚪ inhibits gastric emptying
⚪ causes increased secretion of bicarbonate and pancreatic digestive enzymes
⚪ stimulates secretion of
enteropeptidase
144
what stimulates the production of CCK
high amino acid or fatty acid concentrations, or low pH of chyme entering duodenum
145
what is the function of secretin
⚪ decreases HCl production in the stomach
⚪ increases pancreatic and biliary bicarbonate
secretions
146
what is the endocrine function of the pancreas called
pancreatic islets
147
what is the exocrine function of the pancreas called
groups of acini
148
what do pancreatic islets secrete
- beta cells secrete insulin
- alpha cells produce glucagon
149
what do groups of ancini excrete
excretions contain bicarbonate and digestive
proenzymes (CCK starts activationof these)
Also amylase, lipase, neuclease, protease
150
what are the functions of the liver
- secretes substances essential for digestion and
absorption of nutrients
- synthesizes nutrients and regulates their release
into the bloodstream
- excretes toxic substances
(those originating within and from outside the body)
- produces plasma proteins, cholesterol, and
blood coagulation factors
151
what are the 2 surfaces of the liver
diaphragmatic surface
visceral surface
152
what is the name of the access/egress area on the liver & what goes through there
the triad- hepatic artery, hepatic portal vein and bile ducts
153
what does the gallbladder do?
- concentrates and stores bile until needed
- provides means for liver to excrete waste products
even when animal is not eating
154
what does bile do
digest high fat and peptide
concentrations
155
what is bile composed of?
⚪ bile salts
⚪ phospholipids
⚪ cholesterol
⚪ bile pigments
156
what is Enterohepatic Circulation
1. secretion of bile salts into canaliculi
2. bile salts draw water out of hepatocytes
and become a liquid bile
3. bile is released into intestine to emulsify fat
4. bile salts reabsorbed when they reach the ileum
5. bile salts enter hepatic portal vein and return to liver
6. liver reabsorbs bile salts and recycles them back to
bile
157
how is Bilirubin eliminated Through Bile
1, heme converted to biliverdin then to free or unconjugated bilirubin
2. free bilirubin is joined to glucuronic acid in liver
to form a water-soluble bilirubin glucuronide
(conjugated bilirubin)
3. released into bile and enters into small intestine
4. glucuronide removed by bacterial enzymes
most urobilinogen oxidized to urobilin and
stercobilin excreted from body in feces (urobilinogen)
5. remainder of urobilinogen reabsorbed into enterohepatic circulation taken up by liver, re-excreted into bile, re-enters enterohepatic circulation –or– bypasses liver to go to the kidneys via general circulation, is converted to urobilin, and is excreted in urine
158
nutrient processing by liver
- glucose absorbed from small intestine
⚪ enters hepatic portal vein
⚪ arrives in liver
⚪metabolized to produce energy
- fructose and galactose can be converted to
glucose by the liver
159
what is glycogenolysis
glycogen can be broken down to glucose when needed
160
what is gluconeogenesis
- synthesis of glucose from non-carbohydrate sources
- ketosis
161
what are the 2 movements by the sm intestine?
- peristalsis (propels content)
- segmentation (mixing action)
162
what are the Absorption methods Across Intestinal Mucosa
1. passive processes
- simple diffusion
2. active processes
3. multiple methods
- transport molecules
- antiports
- secondary active transport
- facilitated diffusion
163
4-step process to digest and absorb fat
⚪ emulsification
⚪ hydrolysis
⚪micelle formation
(chylomicrons)
⚪ absorption
164
what is the cecum
blind diverticulum at beginning of colon
- inconspicuous in carnivores
- large blind tube in ruminants
- huge in equines
165
what are the 3 parts of the cecum
base, main body, apex
166
what are the sacculations of the lg intestine called
haustra
167
what is the function of the haustra
1. muscles form bulging sac-like structures
- areas contract, then relax
- then different areas contract and relax
2. prolongs time contents stay in large intestine
- increase time for absorption and microbial digestion
168
motility patterns for lg intestine
⚪ segmentation
⚪ peristalsis
⚪ antiperistalsis
⚪mass movement
169
function of the large intestine
⚪ absorption of water and ions
⚪ completion of carbohydrate or protein microbial digestion
and absorption
170
what are the types of stimuli
1. mechanical (touch/ hearing/ balance)
2. thermal (hot/ cold)
3. electromagnetic (vision)
4. chemical (teste/ smell)
171
what are the 5 general senses
1. visceral sensations (hunger, thirst, hollow organ fullness)
2. touch (touch & pressure)
3. temperature
4. pain
5. proprioception (body position & movement)
172
what are visceral sensations
- miscellaneous category of interior body sensations
- vague and poorly localized
hunger
thirst
visceral stretch
- GI tract
- urinary system
173
2 types of temperature receptors
1. superficial receptors in the skin detect changes in skin temperature
2. central receptors in hypothalamus
monitor temperature of the blood
174
what are pain receptors called
nociceptors
175
classifications of pain
superficial
deep
visceral
acute
chronic
176
what is Proprioception
sense of body position and movement
- movements of limbs
- positions of joints
- state of contraction of muscles
- tension exerted on tendons and ligaments
177
what makes up the external ear?
tympanic membrane, pinna, auditory canal
178
what makes up the middle ear?
3 ossicles:
malleus = hammer incus = anvil stapes = stirrup
179
what makes up the inner ear
vestibule, oval window, round window, cochlea, semicircular canals
180
how does the middle ear change vibrations
cause vibrations to decrease in size but amplify in force
181
what is the function the Middle Ear Ossicles
act as system of levers that transmit sound wave vibrations from tympanic membrane to cochlea
malleus
182
what does the Eustachian tube connect
middle ear cavity with pharynx
183
what is the cochlea
snail shell-shaped spiral cavity in temporal bone
184
what is the fluid-filled portion that makes up receptor organ of hearing
organ of Corti
185
what is the organ of corti filled with
endolymph
186
what does the organ of corti have in it
contains hair cells (hearing receptors), supporting cells, and tectorial membrane
187
how do sound waves become electrical impulses
- sound wave vibrations cause tympanic membrane and ossicles in middle ear to vibrate
- perilymph around cochlear duct vibrates
- cochlear duct moves
- tectorial membrane and hair cells of organ of Corti rub against each other
- nerve impulses are generated
- impulses travel to brain and are interpreted as sound
188
what is equilibrium in terms of balance
helps animal maintain balance by keeping track of head’s position and movements
189
what are the balance organs?
vestibule, semi circular canals
190
what 2 parts make up the vestibule
utricle
saccule
191
what's inside the vestibule
macula
- hair cells covered by gelatinous matrix that contains otoliths
192
how does the macula transmit information to the brain
1. gravity causes otoliths and gelatinous matrix to put constant pressure on the hairs
2. movement of head bends sensory hairs
3. nerve impulse generated to give the brain information about the position of the head
193
what makes up the semicircular canals
1. ampulla
enlarged area near utricle end of each semicircular canal
2. crista ampullaris
receptor structure within the ampulla
3. cupula
cone-shaped area of supporting cells and hair cells with their processes sticking up into gelatinous structure
194
how do the semicircular canals detect motion?
1. the head moves
2. fluid movement lags in one plane of semicircular canals
3. fluid movement pulls on cupula
4. hairs are bent
5. nerve impulse is generated
6. brain receives information about motion of the head
195
do eye components detect the image?
no
196
what do photoreceptors do
1. detect the image
2. generate visual nerve impulses
197
what makes up the outer layer of the eye
cornea, sclera
198
what makes up the middle vascular layer of the eye
choroid, iris, ciliary body
199
what makes up the inner nervous layer of the eye
retina
200
what is the limbus
junction of the cornea and sclera
201
what is the choroid
- lies between sclera and retina
- consists mainly of pigment and blood vessels
- tapetum lucidum is highly reflective area in rear of eye
202
what is the iris
- pigmented muscular diaphragm
- controls amount of light that enters the posterior part of the eye
- opening in center of iris = pupil
203
what is the ciliary body
- ring-shaped structure behind the iris
- contains tiny muscles that adjust shape of the lens to allow near and far vision
204
what is the retina
- lines the back of the eye
- one component of the fundus
- contains rods and cones, the sensory receptors for vision
205
what produces the aqueous humour
cillary body
206
what are the chambers of the aqueous humour
anterior and posterior
207
what is the lens characteristics
- soft, translucent layers of fibers
- elastic and biconvex
front surface in contact with aqueous humor; back surface in contact with vitreous humor
- helps focus a clear image on the retina through accommodation process
208
what are the layers of the retina
1. pigment layer
2. photoreceptor layer
3. bipolar cell layer
4. ganglion cell layer
5. layer of nerve fibers
209
what is the optic disc
- “blind spot” of the eye
site where nerve fibers on inside of retina converge and leave the eye to form the optic nerve
210
what is the conjunctiva
- thin, moist, transparent membrane
- covers front portion of eyeball
- bulbar conjunctiva
lines interior surfaces of eyelids
- palpebral conjunctiva
211
what are the lateral and medial canthus
corners where the eyelids come together
212
what is the lacrimal apparatus
structures that produce and secrete tears and drain tears away from the surface of the eye
213
what are the tear drainage system parts
lacrimal puncta
lacrimal sacs
nasolacrimal duct
214
what are the 3 layers of tears and their characteristics
1. inner mucous layer – from cells in conjunctiva
- contains antibacterial substances
2. middle tear layer – from lacrimal glands and accessory lacrimal glands of the third eyelid
- keeps the cornea moist
3. outer oily layer – from tarsal or meibomian glands
- reduces evaporation of underlying tear layer
- prevents tears from flowing over the lid margin
215
Outline the pathway of light through the eye to the point where it is converted into
a nerve impulse
Light enters the eye through the cornea, passes through the aqueous humor, and then through the pupil, which is controlled by the iris. It then travels through the lens, which focuses the light onto the retina. In the retina, photoreceptor cells (rods and cones) detect light and convert it into electrical signals. These signals are processed by the retina's other layers and transmitted
via the optic nerve to the brain for interpretation.
216
Discuss the role of the vestibular system in maintaining balance and equilibrium.
The vestibular system, located in the inner ear, is responsible for
detecting changes in head position and motion, thereby helping to maintain balance and equilibrium. It includes the semicircular canals, which detect rotational movements, and the otolithic organs (utricle and saccule), which detect
linear acceleration and head position relative to gravity. The vestibular system sends signals to the brain to coordinate balance, posture, and eye movements
217
Explain the role of the hypothalamus in regulating the endocrine system.
The hypothalamus is the control center for the endocrine system. It
produces releasing and inhibiting hormones that regulate the secretion of
hormones from the anterior pituitary gland. It also produces hormones like oxytocin and antidiuretic hormone (ADH) that are stored and released by the posterior pituitary gland.
218
Describe the feedback loop involved in the regulation of blood glucose levels by
insulin and glucagon.
Blood glucose levels are regulated by a negative feedback loop
involving insulin and glucagon. When blood glucose levels rise, the pancreas secretes insulin, which facilitates glucose uptake by cells, lowering blood glucose levels. When blood glucose levels fall, the pancreas secretes glucagon, which stimulates the liver to release glucose into the bloodstream, raising blood glucose levels.
219
What is the function of thyroid hormones, and how do they affect metabolism?
Thyroid hormones, primarily T3 and T4, regulate metabolism by
increasing the rate of cellular respiration and energy production in cells. They also influence growth and development, protein synthesis, and the breakdown of fats and carbohydrates.
220
Discuss the role of cortisol in the body's response to stress.
Cortisol, a glucocorticoid hormone produced by the adrenal cortex, plays a crucial role in the stress response. It increases blood glucose levels by
stimulating gluconeogenesis, suppresses the immune system, and aids in the
metabolism of fats, proteins, and carbohydrates, providing the body with the
necessary energy to cope with stress.
221
How does aldosterone regulate blood pressure, and what triggers its release?
Aldosterone regulates blood pressure by increasing the reabsorption of sodium and water in the kidneys, which increases blood volume and pressure. Its release is triggered by the renin-angiotensin-aldosterone system (RAAS) in response to low blood pressure or low blood sodium levels
222
Describe the pathway of food from ingestion to elimination.
Food is ingested through the mouth, where it is chewed and mixed with
saliva. It then travels down the esophagus to the stomach, where it is mixed with gastric juices and partially digested. Next, it moves into the small intestine, where most digestion and nutrient absorption occur. The remaining indigestible material passes into the large intestine, where water is absorbed and feces are formed. Finally, feces are eliminated from the body through the rectum and anus.
223
Explain the role of the small intestine in digestion and absorption.
The small intestine is the primary site for digestion and absorption. Digestive enzymes from the pancreas and bile from the liver work to further break down food. The small intestine’s lining, which contains villi and microvilli, increases the surface area for nutrient absorption. Nutrients pass through the epithelial cells of the villi into the bloodstream.
224
What is the significance of the villi in the small intestine?
Villi are tiny, finger-like projections in the lining of the small intestine that
significantly increase the surface area for nutrient absorption. They contain
specialized cells that absorb nutrients and transport them into the bloodstream.
225
Discuss the role of gastric acid in digestion and how it is regulated.
Gastric acid (hydrochloric acid) in the stomach helps break down proteins and provides an acidic environment for the activation of pepsin. It also
kills harmful microorganisms. Gastric acid production is regulated by the hormone gastrin, which is released in response to food intake and signals the stomach to increase acid production.
226
Describe the digestive functions of the liver and pancreas.
The liver produces bile, which aids in the digestion and absorption of
fats. It also processes nutrients, detoxifies harmful substances, and stores vitamins and minerals. The pancreas produces digestive enzymes (amylase,
lipase, proteases) that are released into the small intestine to break down
carbohydrates, fats, and proteins. The pancreas also secretes insulin and
glucagon to regulate blood sugar levels
227
Describe the pathway of urine from formation to elimination
Urine is formed in the kidneys where blood is filtered through the
glomerulus, and filtrate passes through the renal tubules where reabsorption and
secretion occur. The urine then collects in the renal pelvis, flows through the
ureters to the bladder, where it is stored. During micturition, urine is expelled from the bladder through the urethra.
228
Explain the role of the glomerulus in the formation of urine.
The glomerulus is a network of capillaries in the nephron where blood
pressure forces water and small solutes from the blood into the Bowman's
capsule, forming filtrate. This filtrate then proceeds through the renal tubules
where further processing occurs.
229
What is the significance of the counter-current mechanism in the Loop of Henle?
The counter-current mechanism in the Loop of Henle creates a concentration gradient in the medulla of the kidney, which is essential for the
production of concentrated urine. It involves the flow of filtrate in opposite directions in the ascending and descending limbs of the loop, enhancing the
reabsorption of water and solutes.
230
Discuss the functions of ADH and aldosterone in maintaining fluid balance.
ADH(antidiuretic hormone) increases water reabsorption in the
collecting ducts of the kidneys, reducing urine volume and concentrating urine.
Aldosterone increases sodium reabsorption and potassium excretion in the distal convoluted tubule and collecting ducts, which helps regulate blood pressure and fluid balance by increasing water retention.
231
Describe the process of micturition and the role of the bladder in this process.
Micturition is the process of urination. The bladder stores urine until it
reaches a certain volume, causing stretch receptors to signal the brain. The
bladder then contracts to expel urine through the urethra. The internal and
external sphincters help control the release of urine
