Mcat Bio Ch.5

Front 1

What is the difference between exocrine and endocrine glands?

Back 1

Exocrine glands release enzymes to the external environment through ducts while endocrine glands release hormones directly into bodily fluids.

Front 2

All hormones need a ________ to be effective.

Back 2

Receptor. The receptor is either located on the cell surface, for peptide hormones, and cell nucleus, for steroid hormones.

Front 3

What is the difference between the speed of the endocrine system and the nervous system?

Back 3

The endocrine system is slow, indirect and long lasting while the nervous system is very rapid and targets specific areas.

Front 4

What are the three types of hormones?

Back 4

1.Peptide
2.Steroid
3.Tyrosine derivatives

Front 5

Describe peptide hormones.

Back 5

All peptide hormones are made in the rough ER
-They first start off as preprohormones, then are cleaved into prohormones
-They are then transferred to the Golgi so that they can be transformed into the final hormone product
-They are then released via secretory vesicles
They are water soluble, can't pass thru membranes

Front 6

What is the effector?

Back 6

It is the target cell, the cell that the hormone has its effect on.

Front 7

Hormones can activate what?

Back 7

An intracellular second messenger, e.g. cAMP, aGMP or calmodulin.

Front 8

Which peptide hormones come from the ant. pit?

Back 8

FSH, LH, ACTH, hGH, TSH, Prolactin

Front 9

Which pep. hormones come from the post. pit?

Back 9

ADH and oxytocin.

Front 10

Which peptide hormones come from the pancreas?

Back 10

Glucagon and insulin.

Front 11

Describe steroid hormones.

Back 11

They resemble cholesterol
They are formed in the smooth ER and mitochondria.
They are often bound to a transporter in the blood because they are water immiscible.
Once they reach the effector, they bind to a receptor in the cytosol. The hormone-receptor unit then travels to the nucleus where it affects transcription.
Therefore, steroid hormones alter protein abundances, either in the cytosol or on the cell membrane.

Front 12

What are the important steroid hormones?

Back 12

1.the glucocorticoids and the mineral corticoids of the adrenal cortex:
-cortisol and aldosterone
2.the gonadal hormones:
-estrogen, progesterone and testosterone

Front 13

What hormones are the tyrosine derivatives?

Back 13

The thyroid hormones:
- T3 and T4
The catecholamines formed in the adrenal medulla:
-epinephrine and norepinephrine

Front 14

What are some properties of tyrosine derivatives?

Back 14

Lipid soluble and must be carried in the blood with carrier proteins.
Bind to receptors inside nucleus.
They are slowly released to target tissues.
Once in the cell, they have a slow but lasting effect.
They increase the transcription of large numbers of genes.

Front 15

Describe the catecholamines.

Back 15

Epine. and norepine. are water soluble and bind to cell membrane receptors.

Front 16

Human growth hormone

Back 16

Peptide
Ant Pit
Stimulates growth in almost all cells by increasing episodes of mitosis, increasing rate of protein synthesis, using fat stores for energy, decreasing use of glucose.
Effect on cells: Increase a.a. transport across cell membrane, increasing translation and transcription, decreasing breakdown of protein and a.a.

Front 17

Adrenocorticotropic hormone (ACTH)

Back 17

Peptide
Ant PIt
Stimulates adrenal cortex to release glucocorticoids (stress hormones)
Triggered by stress

Front 18

Thyroid stimulating hormone (TSH)

Back 18

Peptide
Ant Pit
Stimulates thyroid to release T3 and T4
Increases thyroid cell size and number

Front 19

Prolactin

Back 19

peptide
Ant PIt
Promotes lactation, which is the production of milk.
Prolactin is inhibited before birth by progesterone and estrogen.
Triggered by suckling.

Front 20

What is the difference between the ant. pit, post. pit, and hypothalamus?

Back 20

The hypoth. controls the release of ant. pit. hormones with the release of its own hormones.
The post pit contains neural tissue and releases hormones that are sent to it from the hypothalamus.

Front 21

Oxytocin

Back 21

peptide
post. pit
increases uterine contractions and causes milk ejections.

Front 22

Antidiuretic hormone (vasopressin)

Back 22

peptide
post pit
Concentrates urine, causes collecting ducts of the kidney to become permeable to water.
Increases blood pressure

Front 23

Where is the adrenal cortex located and what is its purpose?

Back 23

It is located on top of the kidneys.
It contains a cortex and a medulla.
The cortex produces 2 types of steroid hormones: mineral corticoids and glucocorticoids.
The medulla produces epinephrine and norepinephrine.

Front 24

Aldosterone

Back 24

steroid
adrenal cortex
mineral corticoid (affects mineral concentration in blood)
increases Na and reabsorption and K and secretion in the collecting duct
secondary effect: raises blood pressure

Front 25

Cortisol

Back 25

steroid
adrenal cortex
glucocorticoid (affects protein and fat metabolism)
stimulates gluconeogenesis in the liver
degrades adipose tissue to be used for energy
degradation of non-hepatic proteins, decrease in non-hepatic a.a.
increase in liver and plasma proteins and a.a.
anti-inflammatory, immune suppressant

Front 26

Catecholamines

Back 26

Tyrosine derivatives synthesized in adrenal medulla:
epinephrine and norepinephrine
vasoconstrictors in internal organs and skin
vasodialators of skeletal muscle
fight or flight, therefore are also considered stress hormones

Front 27

T3 and tyroxine (T4)

Back 27

Act at the nucleus of cells
tyrosine derivatives
increase basal metabolic rate
secretion is regulated by TSH

Front 28

Calcitonin

Back 28

peptide
slight decrease on blood calcium levels by decreasing osteoclast activity

Front 29

insulin

Back 29

Pancreas (islets of Langerhans)
peptide
released by beta cells
binds to cell membrane receptors, causes secondary cascade and causes cells (except neurons) to become more permeable to sugar and a.a.
Causes storage of glycogen in the liver muscles, fat to be stored in adipose tissue.
Lowers blood glucose levels
Released when blood glucose or proteins is high.

Front 30

Glucagon

Back 30

peptide
pancreas alpha cells
opposite of insulin
stimulates glucogenolysis and gluconeogenesis in liver
acts via cAMP
raises blood glucose levels

Front 31

Parathyroid glands

Back 31

Four of them attached to the back of the thyroid
release parathyroid hormone

Front 32

PTH

Back 32

peptide
increases blood calcium
stimulates osteoclasts
increases renal calcium reabsorption and renal phosphate excretion
increases calcium and phosphate uptake in gut
increases production of a postcursor of vit D
secretion is regulated by calcium concentration in blood

Front 33

What do the semniferous tubules do and where are they located?

Back 33

Site of sperm production
spermatogonia arise from the epithelium and become spermatozoa
sertoli cells surround the spermatocytes and spermatids while leydig cells are located in the interstitium b/w tubules and release testosterone

Front 34

testosterone

Back 34

released by leydig cells which is stimulated by LH
responsible for developpment of secondary male characteristics (puberty stuff)
stimulates closure of epiphyses of the long bones, ending the growth in height

Front 35

How does sperm travel from teste to the outside world?

Back 35

it goes to the epididymusm then vas defrens then urethra.

Front 36

What is the compostition of semen?

Back 36

spermatazoa and other fluids collected from the seminal vesicles, prostate and the bulbourethral glands (aka Cowper's glands)

Front 37

When does oogenesis begin?

Back 37

in the fetal stage of development
arrested as primary oocytes at birth

Front 38

What is the next change that happens in oogenesis?

Back 38

at puberty, FSH stimulates the granulosa cells to create the zona pellucida
LH stimulates theca cells to release androgen which is then converted to estradiol (a type of estrogen)

Front 39

what happens right before ovulation?

Back 39

estrogen spikes causing a spike in LH (luteal surge)
this a positive feedback loop caused by rising estrogen levels which increase LH levels, which therefore increase estrogen
this surge causes ovulation, and the egg enters the falopian/uterine tube or oviduct

Front 40

after ovulation?

Back 40

the remaning follicle becomes the corpus luteum, which secretes estradiol and progesterone throughout pregnancy
if no pregnancy, it secretes for 2 weeks then becomes the corpus albicans

Front 41

when are the greatest quantities of each hormone released?

Back 41

FSH, LH: right before ovulation (luteal surge->positive feedback loop)
estrogen: right before ovulation (positive feedback loop), also is high after ovulation due to corpus luteum
Progesterone: after ovulation (from corpus luteum)

Front 42

Fertilization usuaully occurs where?

Back 42

in the fallopian tube
it happens when the nuclei of the ovum and of the sperm fuse together to form the zygote

Front 43

Development of zygote to placenta formation

Back 43

1. cleavage happens when the zygote is in the fallopian tubes
2. many cycles of mitosis result in the zygote being compromised of eight or more cells, called a morula. theses cells are totipotent
3.Cells continue to divide for four days and create a fluid filled ball called a blastocyst. blastocyst is made up of embryonic stem cells
4. the blastocyst implants in the uterine wall on the 5th to 7th day after ovulation
5. after implantation, egg begins secreting human chorionic gonadotropin, which prevents degradation of corpus luteum which maintains secretion of estrogen and progesterone. HCG is the first detectable sign of pregnancy
6.placenta is formed and takes over the secretion of hormones. it begins secreteing estrogen and progesterone while decreasing HCG

Front 44

what is the difference between cell differentiation and determination?

Back 44

determination is when a cell is commited to a certain fate in the future and differentiation is when the cell has become specialized.

Front 45

what is the gastrula?

Back 45

It is the stage after the blastula in embryo development. It is formed in a process called gastrulation which forms three layers:
1.ectoderm
2.mesoderm
3.endoderm
It appears 2 weeks after fertilization

Front 46

What do the three layers of the gastrula become?

Back 46

ectoderm: outer coverings of body
skin, nails, tooth enamel and nervous system and sense organs
endoderm: digestive tract and liver and pancreas
mesoderm: middle stuff
muscle, bone, and the rest

Front 47

what is a neurula?

Back 47

3 weeks after fertilization occur, the neurula is formed by neurulation
the notochord induces the overlying ectoderm to thicken and form the neural plate. the notochord (made from the mesoderm) degenerates while a neural tube forms from the neural plate to become the spinal chord. this is important for creating the axis of the body