MsState Animal Bio-1123 Exam 4

Endocrine glands

highly vascularize, ductless glands that secrete hormones which are transported by the blood to target cells

hormones

chemical signals; interacting with receptors of target cells; secreted in vary small amounts

Endocrine glands

highly vascularize, ductless glands that secrete hormones which are transported by the blood to target cells

hormones

chemical signals; interacting with receptors of target cells; secreted in vary small amounts

peptide hormones

ex: insulin; cannot cross the plasma membrane of target cells; bind with receptors located in the target cell plasma membrane; binding of the hormone receptor activates 2nd messengers in the cytoplasm of the target cell

2nd messenger

internalize the signal and bring about appropriate response in target cells

steroid hormones

ex: estrogen; cross plasma membranes of target cells and bind with receptors in the cytoplasm or nucleus; the hormone-receptor complex then binds to DNA and turns on or off genes

negative feedback systems

output of the system turns off the original stimulus; goal: prevent sudden and severe changes with the body; most common

positive feedback systems

response increases the original stimulus; activity (output) accelerated; controls infrequent events, not requiring continuous adjustment

hypothalamus

helps control heartbeat, body temperature, water balance and glandular secretions

oxytocin

target: smooth muscle
effect: stimulates contraction

antidiuretic hormone (ADH)

target: nephron
effect: increases H2O reabsorption from urine; decreases H2O loss in urine

posterior lobe of the pituitary

stores and releases oxytocin and ADH produced by the hypothalamus

Diabetes Insipidus

symptons: extreme thirst (polydipsia), large volume of urine produced (polyuria), usually caused by damage to hypothalamus or pituitary; ADH secretion/release impaired; uncommon

anterior lobe of pituitary

controlled by hypothalamus-releasing and hypothalamus-inhibiting hormones

thyroid stimulating hormone

target: thyroid gland
effect: regulates hormone secretion by the thyroid

adrenocoricotrophic hormone

target: adrenal cortex
effect: regulates secretion of hormones by cells in the adrenal cortex

prolactin

target: mammary glands
effect: milk production in pregnant females

FSH and LH

target: ovaries and testes

growth hormone

target: all body tissue
effect: growth, differentiation and development

giantism

secretion of excessive amounts of growth hormone in children before the growth plates seal; effects on skeleton: increase length of long bones, produces "giants"

pituitary dwarfism

insufficient production of growth hormone in children
dwarf: adult height of 4' 10" or less

acromegaly

secretion of excess amounts of growth hormone in adults after growth plates have sealed
effects on skeleton: bones cannot increase in length; bones can increase in width; causes overgrowth of soft tissues (=furrows on face); wide hands, feet and noses; widely spaced teeth; under bite or over bite

thyroid

H-shaped gland lying below the larynx

Triiodothyronine (T3) and Tetradiodothyronine (T4, Thyroxine)

target: all cells
effect: increase BMR (basal metabolic rate); necessary for differentiation and development

calcitonin

target: bone cells
effect: increases activity of osteoblasts; inhibits activity of osteoclasts; increases deposition of calcium in bones; decreases reabsorption of calcium from the skeleton; decrease blood calcium levels

goiter

enlarged thyroid gland

congenital hypothyroidism

insufficient secretion of T3 and T4 in infants and children; profound mental impairment; individuals are very short

myxedema

insufficient secretion of T3 and T4 in adults; (hyposecretion of T3 and T4); one form of hypothyroidism; BMR lowered; don't tolerate cold environments well because not producing as much body heat due to lowered BMR; dry skin and hair; prone to weight gain; problems concentrating; lethargic

hyperthyroidism

excessive secretion of T3 and T4; increased BMR; intolerant to heat; inablility to concentrate; weight loss

exopthalmic goiter

exophthalmos; eyes protrude from socket due to tissue swelling behind eyes

parathyroid glands

4 small glands embedded in the back of the thyroid

parathyroid hormone

target: kidney and osteoclasts
effect: increases calcium reabsorption in the kidney; increases activity of osteoclasts; both of these activities increase the blood calcium level

osteitis fibrosa cystica

severe form of hyperparathyroidism
elevated blood calcium level; bones have a moth-eaten appearance and fracture easily

adrenal glands

small pyramidal shaped glands located on top of each kidney

zona glomerulosa

region of the adrenal cortex that secretes mineralcorticoids (ex: aldosterone)
target:kidneys
effect; increase sodium and water reabsorption and increase blood volume and pressure

zona fasciculata

region of the adrenal cortex that secretes glucocorticoids (ex: cortisol)
target: all tissues
effect: regulate glucose metabolism; inhibits inflammatory response; helps body to resist stress

zona reticularis

part of the adrenal cortex that secretes estrogen and testosterone
target:gonads, skin, muscle, and bone
effect: limited secretion; stimulate reproductive organs; bring about secondary sex characteristics

hormones of the adrenal medulla

these hormones enhance the effects of the sympathetic nervous system, the fight-or-flight response
hormone: epinephrine(adrenaline) and norepinephrine
effects: increase heart rate, ventilation rate and blood flow to skeletal muscle; inhibits digestion and urine formation; dilates pupils of eyes

Cushing Syndrome

excessive secretion of the glucocorticoids; results in hyperglycemia, hypertension, edema, muscle and bone damage and minor infections becoming more severe

pancreas

primarily an exocrine gland but has distinct regions containing endocrine cells known as pancreatic islets; alpha cells and beta cells

alpha cells

secrete the hormone glucagon

beta cells

secrete the hormone insulin

glucagon

target:liver and adipose tissue
effect:increases blood glucose levels; glucose is removed from glycogen stores in the body

insulin

target:primarily liver, muscle and fat cells
effect:decreases blood glucose levels; glucose is taken up by cells

type 1 diabetes

insufficient insulin production; beta cells destroyed; require daily insulin supplements; begins at young age

type 2 diabetes

decreased sensitivity to insulin on cells; may be controled by diet in many cases; usually adult onset

fertilization

union of the egg and sperm; forms a single cell called the zygote from which we all develop

zona pellucida

an acellular material that surrounds the egg plasma membrane

corona radiata

a thin layer of follicular cells that are attached to the zona pellucida

events occurring during fertilization

1. several sperm penetrate the corona radiata
2. acrosomal enzymes digest a portion of zona pellucida
3. sperm binds to and fuses with the egg's plasma membrane
4. sperm nucleus enters the egg
5. cortical granules release enzymes. zona pellucida becomes the fertilization membrane
6. sperm and egg nuclei fuse

cleavage

early cell divisions resulting in an increase in the number of cells but not the size of the organism; 30 hours-day 3 after ovulation

growth

cells undergo division as well as increase in size

morphogenesis

the embryo begins to take shape as cells migrate

differentiation

cells take on specific structure and function (the nervous system is the first visible system)

pre embryonic development

first week following fertilization; zygote divides repeatedly as it passes from oviduct to uterus

morula

compact ball of embryonic cells; forms 3rd and 4th day after ovulation

blastocyst

hollow ball of cells; 5th day to 2nd week of development; embeds in uterus between days 6 and 7; forms the trophoblast and inner cell mass

inner cell mass

embryo develops from this region

trophoblast

becomes the chorion

amnion

secretes amnionic fluid that cushions and protects the embryo; extraembryonic membrane

yolk sac

blood cells first form here; very little yolk present in human yolk sac

chorion

forms portion of placenta

placenta

organ that provides the embryo with nourishment and gets rid of wastes

allontois

gives rise to the bladder; the blood vessels of the umbilical cord that carry blood to and from fetus

embryonic period

second week through the end of the second month; inner cell mass detaches and becomes the embryonic disk that will go through gastrulation to become 3 primary germ layers

gastrulation

formation of the 3 primary germ layers: ectoderm, mesoderm and endoderm

ectoderm derivatives

epidermis and nervous system

mesoderm derivatives

skeleton, muscles, dermis, cardiovascular system, reproductive system and urinary system

endoderm derivatives

epithelial lining of the digestive, respiratory and urinary bladder

fetal period

beginning of month 3 extending through month 9; period of rapid growth

2nd week of development

implantation occurs; amnion and yolk sac appear; embryo has tissues; placenta begins to form

3rd week of development

nervous system begins to develop; allantois and blood vessels are present; placenta is well formed

4th week of development

limb buds form; heart is noticeable and beating; nervous system is prominent; embryo has tail; other systems form

5th week of development

embryo is curved; head is large; limb buds show divisions; nose, eyes and ears are noticeable

6th week of development

fingers and toes are present; skeleton is cartilaginous

2nd month of development

all systems are developing; bone is replacing cartilage; facial features are becoming refined; embryo is less than 2 inches long

3rd month of development

gender can be distinguished by ultrasound; fingernails appear

4th month of development

skeleton is visible; hair begins to appear; fetus is 6 inches long`

5th month of development

heart beat can be heard; protective coating called vernix caseosa begins to be deposited

6th month of development

body is covered with fine hair called lanugo; skin is wrinkled and reddish

7th month of development

testes descend into scrotum; eyes are open; fetus is about 12 inches long

8th month of development

body hair begins to disappear; subcutaneous fat begins to be deposited

9th month of development

fetus is ready for birth

identical twins (monozygotic)

one egg is fertilized; genetically identical; result from separation of blastomeres or splitting of the inner cell mass; 2/3 share placenta (splitting of inner cell mass); most have individual amnions; a few share an amnion and placenta (inner cell mass split after day 9. twins risk becoming conjoined- Siamese twins)

fraternal twins (dizygotic)

two eggs are fertilized by two different sperm; each embryo has its own amnion and placenta; fequency increases with age of mother; "runs" in families

genes

units of instruction for producing or influencing a trait; you inherit 2 for each trait: 1 from father "sperm and 1 from mother "egg"

alleles

different forms of a gene for a specific trait; ex: eye color- trait, alleles:blue, brown, green, etc

genotype

the actual genes present

homozygous

if both genes (alleles) code for same form of trait; ex: blue eyes, blue eyes = bb

heterozygous

if both genes (alleles) code for different forms of same trait; ex: blue eyes, brown eyes = Bb

phenotype

the observable trait

chromatin

located in nucleus of eukaryotic cells; composed of DNA and protein; thread-like; before a cell divides, it condenses=chromosome

autosome

chromosomes not involved in sex determination; in humans: chromosome pairs 1-22 (in somatic cells)

sex chromosome

chromosomes involved in sex determination; in humans: x and y chromosomes

chromosomes

the nucleus of each somatic cell contains 46 (44 autosomes and 2 sex chromosomes); present in pairs called homologous pairs or homologs (inherit 1 from mother and 1 from father)

sex cell

nucleus of each contains 23 total chromosomes; 22 autosomes and 1 sex chromosome

karyotype

visual representation of chromosomes with in each cell; number of chromosomes, size and structure analyzed; blood cells often used; analysis is done on cells when they are dividing; chromosomes are clearly visible then

SRY gene

gene located on y chromosome; codes for testis determining factor (TDF)

testis determining factor (TDF)

early in development, the gonads are neither testes nor ovaries, they are sexually indifferent; targets the early gonads and in response testes develop

sex-linked traits

traits coded by genes on the sex chromosomes; designed as x-linked or y-linked

y-linked traits

genes on the y chromosome concerned with gender determination primarily; only expressed in males