Chapter 26: Regulation Part I - The Endocrine System

Chapter 26: Regulation Part I - The Endocrine SystemNEW AIM: How do chemical signals coordinate body functions?

I. Exocrine vs. Endocrine glandsA. Exocrine

- have ducts (tubes made of cells) that carry secretion products to an outside surfaceEx. Sweat (eccrine), sebaceous, mammary, digestive (pancreas, liver, gall bladder), etc…

Remember that the lining of your digestive tract, nephron tubules, etc… are external surfaces – you do not need to cross any cell layers to get there.

Chapter 26: Regulation Part I - The Endocrine SystemAIM: How do chemical signals coordinate body functions?

I. Exocrine vs. Endocrine glandsB. Endocrine

- ductless, hormones secreted into blood- IMPORTANT: hormones circulate and influence ONLY cells with receptors for them (target cells) - >50 known hormones in vertebrates

Fig. 26.1

There are two main types of hormone secreting cells

1. Endocrine cells, which typically secrete their hormone in response to a chemical stimulus like a ligand or an environmental change like high glucose levels that triggers signal transduction.

2. Neurosecretory cells, which are neurons (wire-like cells that transmit electrical signals) that secrete hormones. These cells are typically activated by an electrical signal and use electrical signals to secrete their hormones. Most are found in the hypothalamus – the master endocrine organ


II. The Endocrine SystemA. Endocrine glandsB. Chemical regulatory system of body

Nervous system = other regulatory system of body

Fig. 26.3

Ex. Regulates metabolic rate, growth, maturation, reproduction, blood glucose, blood calcium, etc…

Why do we need two regulatory systems?

Endocrine = slower and more prolonged (long-lasting) effect

Both systems work closely together (interdependent)


II. The Endocrine SystemD. Amino acid based vs. steroid hormones

i. Amino acid based (3 types)1. amine (modified amino acid) - ex. epinephrine

epinephrine

gastrin insulin

2. Peptide - ex. gastrin3. protein hormones - ex. insulin



i. Amino acid based (3 types)

How do amino acid based hormones “talk” to cells?

Fig. 26.2

4. Bind and activate surface receptors

1. amine (modified amino acid)2. Peptide

3. protein hormones

5. Result: Turn genes On/Off or activate/deactivate enzymes, etc…

(can’t cross PM)



ii. Steroid hormone1. Lipids made from cholesterolEx. Testosterone and estrogen

testosterone estrogencholesterol



ii. Steroid hormone1. Lipids made from cholesterolEx. Testosterone and estrogen

How do steroid hormones “talk” to cells?

Fig. 26.2

4. Turn genes ON/OFF ONLY

3. Receptor protein usually a transcription factor

2. Cytoplasmic receptor protein



Fig. 26.2



iii. Exception to the rulea. Thyroxine (T4) and triiodothyronine (T3)

triiodothyronine (T3)

- amine hormones- produced by thyroid- relatively non-polar, behave like steroids


II. The Endocrine SystemE. Endocrine glands of vertebrates

i. Some have ONLY endocrine function

Ex. Thyroid and pituitary

ii. Some also have a non-endocrine function

Fig. 26.3

Ex. pancreasExocrine = digestive enzymesEndocrine = insulin release


II. The Endocrine SystemE. Major vertebrate endocrine glands and their hormones

Pg. 521


II. The Endocrine SystemE. Major vertebrate endocrine glands and their hormones

i. Steroid hormones made only by sex organs (testes and ovaries) and adrenal glands (specifically the adrenal cortex)


II. The Endocrine SystemF. The hypothalamus

i. Part of brain

iii. Connects nervous system to endocrine system- receives info from nerves about internal and external environment

iv. Closely tied to pituitary gland – in fact, the posterior pituitary is made of cells that extend from the hypothalamus

ii. Master control center of endocrine system

Fig. 26.4


II. The Endocrine SystemF. The Pituitary

i. Two parts

- composed of nervous tissue (extension of hypothalamus)1. Posterior lobe (posterior pituitary)

Fig. 26.4

- stores and secretes hormones made in hypothalamus

- Made of neurosecretory cells



i. Two parts2. Anterior lobe (anterior pituitary)

Fig. 26.4

a. composed of NON-nervous glandular tissue (endocrine cells)b. synthesizes own hormones, most control other endocrine glandsc. hormone release controlled by…Hypothalamus hormones



i. Two parts

a. composed of NON-nervous glandular tissue2. Anterior lobe (anterior pituitary)

b. synthesizes own hormones, most control other endocrine glandsc. hormone release controlled by…Hypothalamus hormones

- Hypothalamus hormones that control AP1. Releasing hormones

2. Inhibiting hormones

- Bunch of different hormones that signal AP to release a certain hormone

- Bunch of different hormones that signal AP to stop releasing a certain hormone


II. The Endocrine SystemG. Example you need to know: Hypothalamus and AP interaction (Example)

2. Hypothalmus secretes TRH into blood1. cold external temperature

TRH = TSH releasing hormone

3. TRH stimulates AP to secrete TSH (thyroid stimulating hormone) into blood Hypothalamus hormones

4. TSH stimulates thyroid to secrete the hormone thyroxine (T4) into the blood

5. Thyroxine (T4) binds to thyroxine receptors, which are found on most cells instructing them to increases metabolic rate of body cells – heat generated

NEGATIVE FEEDBACK

Fig. 26.4

(hypothalamus regulates body temp through thyroid)

6. Thyroxine (T4) and TSH inhibit hypothalamus from secreting TRH


II. The Endocrine System

Hmm..what kind of receptor TRH binds to?

Hypothalamus hormones

Fig. 26.4


II. The Endocrine SystemG. Example you need to know: Hypothalamus and AP interaction (Example)

1. cold external temperature

TRH = TSH releasing hormone

3. TRH stimulates AP to secrete TSH (thyroid stimulating hormone) into blood

4. TSH stimulates thyroid to secrete the hormone thyroxine (T4) into the blood

5. Thyroxine (T4) binds to thyroxine receptors, which are found on most cells instructing them to increases metabolic rate of body cells – heat generated

NEGATIVE FEEDBACK(hypothalamus regulates body temp through thyroid)

6. Thyroxine (T4) and TSH inhibit hypothalamus from secreting TRH

2. Hypothalmus secretes TRH into blood


II. The Endocrine SystemH. The Hypothalamus and Posterior pituitary (PP)i. REMINDER: hormones made in hypothalamus and stored/released in PP

1. oxytocin- causes uterine muscles to contract during child birth – polypeptide hormone

- mammary glands to pump milk2. ADH (antidiuretic hormone or vasopressin)

- Target organs are kidneys - reabsorb water from collecting duct of nephrons

Fig. 26.5

- Polypeptide hormone, see excretory system

ii. Neurosecretory cells extend into PP where they secrete hormone into blood

It is typically administered intravenously immediately after child birth as well to keep the contractions going to make sure the placenta comes out / is delivered.

Target organs (the organs targeted by the hormone)


II. The Endocrine SystemI. The Hypothalamus and Anterior pituitary (AP)

- neurosecretory cells of hypothalamus secrete RH or IH (releasing hormone / inhibitory hormone)

1. Hormones from AP that control other endocrine glands:

TSH - thyroid stimulating hormone

Fig. 26.5

- blood carries RH/IH to AP to control hormone secretion – each hormone released by AP is contolled by a different RH/IH

ACTH - adrenocorticotropic hormoneFSH - follicle stimulating hormoneLH - luteinizing hormone

2. Other hormonesGH - growth hormonePRL - prolactinEndorphins (endogenous morphine)

FLAGTEP




Fig. 26.5

2. Other hormonesGH - growth hormonePRL - prolactinEndorphins

FLAGTEP

Human Growth Hormone (hGH) is a protein. It targets many cells and stimulates growth of these cells as well as mitotic division. As you might have hypothesized, levels of GH in the blood fall off with age.




Fig. 26.5


FLAGTEP

Prolactin is a protein as well. It promotes lactation (production of milk) in females.




Fig. 26.5


FLAGTEP

Beta-endorphin: A 31 amino acid polypeptide. Endorphins are neurotransmitters, which means they talk to neurons and tell them to fire or not to fire. We will discuss this in detail with the nervous system. In general, endorphins are released during exercise, excitement, and pain and bring about feelings of well being and pain reduction similar to morphine (endo – form within, orphin – morphine = endorphine)


II. The Endocrine SystemJ. Thyroid

1. located just below larynx

Fig. 26.3

- Thyroxine T4 2. Hormones produced (amine)

- Triidodthyronine T3


Both contain iodine




Fig. 26.6A




Both contain iodineRemember the Goiter - lack of iodine in diet – causes thyroid to swell like a balloon as it tries to make T3 and T4 under excessive TSH stimulation.




Fig. 26.6



Goiter - lack of iodine in dietWhy a goiter forms




Fig. 26.6



Goiter - lack of iodine in dietWhy a goiter forms

Iodized salt


II. The Endocrine System2. Blood calcium homeostasis (10mg/100ml)

A. Some uses of calcium

i. Help neurons to transmit signals

ii. Muscle contraction

iii. Blood clotting (coagulation)iv. Cotransport across PM

Cotransport occurs when a cell uses energy to actively pump a substance like Ca++ or H+ across a membrane resulting in an electrochemical gradient similar to the pumping of H+ into the intermembrane space of the mitochondria or into the thylakoid disk. When the substance diffuses back passively, the energy is used to transport another molecule with it from low to high concentration (active) – therefore your link facilitated diffusion with active transport.

v. IP3 regulated cell signalling



A. Some uses of calcium

i. Help neurons to transmit signals

ii. Muscle contraction

iii. Blood clotting (coagulation)iv. Cotransport across PM

v. IP3 regulated cell signalling



C. Hormones involved

B. NOT UNDER HYPOTHALAMUS/PITUITARY CONTROL

2. Blood calcium homeostasis (10mg/100ml in blood normally)

Fig. 26.3

- secreted by thyroid

- lower blood Ca++

It is a polypeptide:

i. Calcitonin (calcium in)




i. Calcitonin (calcium in)


2. Blood calcium homeostasis (10mg/100ml)

Fig. 26.3


- lowers blood Ca++

ii. Parathyroid hormone (PTH)

- secreted by parathyroid glands

- raises blood Ca++

PTH (protein)




i. Calcitonin



Fig. 26.3


- lower blood Ca++


- secreted by parathyroid

- raises blood Ca++

**These are antagonistic hormones(opposite effects)




i. Calcitonin




- lower blood Ca++


- secreted by parathyroid

- raises blood Ca++


four embedded in thyroid



D. Mechanism of action


Fig. 26.7

four embedded in thyroid

i. Calcitonin targets:

- bone, kidneys

ii. PTH targets:

- intestines, bone, kidneys

IMPORTANT: What you need to realize is that the levels are ALWAYS fluctuating up and down like a sinusoidal wave. This is a hallmark of feedback. It never stays at 10mg/100ml and this goes for the concentration of anything in your body like protein levels in a cell or blood glucose…. Nothing is static, everything is dynamic.



Fig. 26.7



B. Pancreas

i. Endocrine and exocrine gland

A. NOT UNDER HYPOTHALAMUS/PITUITARY CONTROL

3. Blood glucose regulation (90mg/100ml)

Fig. 26.3



B. Pancreas

i. Endocrine and exocrine gland

ii Islets of Langerhan

- endocrine portion

A. NOT UNDER HYPOTHALAMUS/PITUITARY CONTROL


- made of alpha (α) and beta (β) cells



i. insulin- produced by beta cells

ii. glucagon- produced by alpha cells



- raises blood glucose

- lowers blood glucose


insulin

glucagon- Glucose is gone (glucagon…get it?)



i. Insulin targets:- liver, body cells (fat cells, muscle cells)

ii. Glucagon targets:

- liver



Fig. 26.8

Hyperglycemia vs. Hypoglycemia



STORY:You eat a candy bar or anything with carbs and your blood sugar raises above 90mg/100ml. Proteins on the surface of pancreatic beta cells located in the Islets of Langerhan signal the beta cells to secrete insulin (take glucose in) into the blood. Insulin circulates and binds to insulin receptors on hepatic (liver) cell, adipocytes (fat cells), and myocytes (muscle cells). Signal transduction occurs and the cells send glucose transporter proteins to their membranes. Glucose enters by facilitated diffusion and is converted to glycogen in liver and muscle, and to triglycerides in adipocytes. The blood sugar levels drop causing the beta cells to stop secreting insulin.



Fig. 26.8



STORY:When they fall too low, the proteins on the surface of pancreatic alpha cells also located within the Islets of Langerhan send a signal into the alpha cells causing them to secrete glucagon (glucose is gone) into the blood. Glucagon will circulate and bind to glucagon receptors located on hepatocytes and adipocytes causing them to breakdown glycogen and release glucose. Why would you not signal the myocytes to release glucose? Because the muscles always need the glucose to make ATP so they can contract. Muscles do not store it for the body, they store it for themselves. The blood sugar levels rise causing the alpha cells to stop secreting glucagon.



Fig. 26.8



i. Diabetes mellitusa. body cells do not absorb glucose (blood glucose high)

d. Two types

E. disorders


1. Type I insulin dependent (early onset)

b. affects 5 out of 100 in USc. 350,000 die from disease/year

- autoimmune disease against beta cells

- develops before age 15 typically

- don’t produce enough insulin

- insulin injection required- genetically engineered (human insulin gene put into a plasmid and inserted into bacteria)

Insulin pump attached to user




d. Two types

E. disorders


1. Type II NON-insulin dependent (late or adult onset)


- faulty/missing insulin receptors on cells

- 90% of US cases are Type II

- Insulin is being made just not being “seen”

- typically develops after 40

- control sugar intake (diet)- drugs that reduce glucose levels

- Treatment




d. Two types

E. disorders


1. Type II NON-insulin dependent (late or adult onset)


i. Cause- Genetic predisposition combined with environmental triggers like obesity, hypertension, elevated cholesterol, high fat diets and inactive lifestyle.

- Managed by exercise and diet management

ii. Treatment



i. Diabetes mellitusa. body cells do not absorb glucose (hyperglycemia = blood glucose high)

d. Type I and Type II

E. disorders


Fig. 26.8

e. Result


- Cells don’t take up glucose resulting in high blood glucose levels, burn fat/proteins instead- Glucose seen in urine because kidneys can’t take it out of the proximal tubule quick enough

- High glucose levels cause

Chapter 25: Control of the Internal EnvironmentAIM: How do organisms deal with metabolic waste?

III. Human Excretory System

Fig. 25.9

iii. Each extracts tiny amount of filtrate

C. How does the kidney extract filtrate?

i. Functional unit of the kidney (tiny filtering unit)ii. ~1,000,000 per kidney

1. The Nephron


III. Human Excretory System

Fig. 25.9

- Flow chart through nephron

C. How does the kidney extract filtrate?

1. The Nephron

http://www.biologymad.com/resources/kidney.swf


III. Human Excretory SystemC. nephron

Fig. 25.10

Urine is produced in 4 major processes

IMPORTANT: Water, urea, salts, monomers, toxins, etc… are forced out of the glomerulus capillaries by high blood pressure into Bowman’s capsule and enter the nephron tubule non-selectively. The only selective filter is the size of the molecule. Glucose and smaller enters automatically. The kidney can only control what is taken back (reabsorbed) into the blood, NOT what goes into Bowman’s and the nephron tubule!!


III. Human Excretory SystemC. nephron

Fig. 25.11

The proximal tubule of the kidney cannot take in the excess glucose fast enough. High glucose in tubule means low water potential…water enters the tubule and leaves body!! Excessive urination and thirst with diabetes.



i. Diabetes mellitus

E. disorders


Fig. 26.9



i. On top of each kidney – kidney hat

ii. Secrete hormones involved in the organisms response to physical and/or emotional stress

A. Adrenal glands (two)

4. Mobilizing response to stress

iii. Two glands in one

Fig. 26.3

Fig. 26.10



A. Adrenal glands (two)

4. Mobilizing response to stress

Fig. 26.10



A. gonads

5. Sex hormones

Fig. 27.2

i. sex glands- ovaries and testes- secrete hormones in addition to gamete production

Fig. 27.3



A. gonads

4. Sex hormones


ii. Sex hormones (3 categories) - all present in males AND females at different levels.

1. Estrogensa. High in females compared to androgensb. Maintain female reproductive systemc. Promote development of female secondary sex characteristics:

- smaller body size, higher pitch voice, breasts, wider hips



A. gonads

4. Sex hormones


ii. Sex hormones (3 categories) - all present in males AND females at different levels.

2. progestinsa. ex) progesteroneb. Prepare uterus to support the embryo



A. gonads

4. Sex hormones


ii. Sex hormones (3 categories) - all present in males AND females at different levels.3. androgens

- testosterone is the main onea. High in males compared to estrogens

b. Development and maintenance of male reproductive systemc. Promote development of male secondary sex characteristics:

- low-pitched voice, facial hair, large skeletal muscles



A. gonads

4. Sex hormones


ii. Sex hormones (3 categories) - all present in males AND females at different levels.- estrogens, progestins, androgens

- FSH and LHiii. Regulated by hypothalamus and AP

Fig. 26.5

FLAGTEP


II. The Endocrine System4. Sex hormones

B.Steroid Biosynthesis (just for fun)

Chapter 27: Reproduction and Embryonic DevelopmentAIM: How have humans evolved to reproduce?

VI. Human ReproductionA. Female Anatomy

Fig. 27.2

Chapter 27: Reproduction and Embryonic DevelopmentNEW AIM: How have humans evolved to reproduce?


Fig. 27.2

Chapter 27: Reproduction and Embryonic DevelopmentNEW AIM: How have humans evolved to reproduce?


Follicle cells

Oocyte (immature ovum)

A follicle containing ovum (oocyte)

Corpus luteum (yellow body)

LM or a follicle


Ovarian cycle (top) and menstrual cycle (bottom) must be synchronized…explain why.


VI. Human ReproductionD. Hormones synchronize cyclical changes in the ovary and uterus

iii. Ovarian and menstrual cycles are synchronizedd. Five hormones involved

Fig. 27.5

- RH, FSH, LH, estrogen, progesterone (page 542)

FSH stimulate follicle to grow and mature

LH causes ovulation and maintains corpus luteum

Estrogen (secreted by follicle) - Low levels inhibit hypothalamus - High levels stimulate hypothalamus

Estrogen and Progesterone (secreted by corpus luteum)

- Promote growth of endometrium lining

- Promote growth of endometrium lining- Inhibit hypothalamus



iii. Ovarian and menstrual cycles are synchronized

Fig. 27.5

RH stimulates release of FSH and LH from AP

FSH stims growth of follicle

Follicle secretes estrogen(as follicle gets bigger, more estrogen is secreted)

Low estrogen at first inhibits hypothalamus, keeps FSH and LH low (neg. feedback)

Follicle keeps getting bigger, more estrogen secreted

High estrogen now stimulates hypothalamus (pos. feedback)

FSH and LH spike

e. Ovarian cycle regulation: Preovulation




Fig. 27.5

f. Ovarian cycle regulation: Ovulation and Postovulation

LH peak stimulates completion of meiosis I (formation of secondary oocyte), ovulation, development of corpus luteum (CL) – LH also keeps CL from degenerating (breaking down)

CL secretes high levels of estrogen and progesterone which 1. promote growth of endometrium 2. shut down (neg. feedback) hypothalamus

FSH and LH levels drop

LH drop results in degeneration of CL. CL basically destroys itself by secreting progesterone and estrogen

CL stops secreting progesterone and estrogens causing endometrium to break down and negative feedback to be remove from the hypothalamus…FSH and LH secreted once again to start another cycle.




Fig. 27.5

g. Menstrual cycle regulation

- controlled by estrogen and progesterone alone

- low levels trigger release

- high levels trigger thickening




Fig. 27.5

h. What if fertilization occurs?- embryo (specifically the chorion, which is the embryonic half of the placenta) will secrete the hormone HCG (human chorionic gonadotropin)

- HCG acts like LH - maintains CL regardless of low LH

- CL keeps making progesterone and estrogen so endometrium stays intact




Fig. 27.5

I . How do birth control pills work?

They can be a combination of progesterone and estrogen or progesterone-only.


“Plan B”Emergency Contraceptive

Fig. 27.5

Levonorgestral (second generation progesten)

How do you hypothesize this drug works?

It acts like natural progesterone, inhibits hypothalamus and prevents LH spike…no ovulation!!


VI. Human ReproductionE. Fertilization

i. Sperm cell

Fig. 27.9

a. acrosome- membrane enclosed vesicle

b. Haploid nucleus- contains enzymes to help sperm penetrate egg

c. Absorbs fructose and burns it for ATP in single spiral mitochondrion - it’s a long swim

(flagellum)- flagellum needs ATP to move



ii. ovum

b. Much larger than sperm – an unfertilized chicken egg (the one you eat) is a single cell!!c. Sole provider of mitochondria (your mitochondrial DNA is from your mom ONLY)

a. Egg cell

Largest cell on Earth…the Ostrich egg.



iii. The process

(flagellum)

Fig. 27.9

- egg has 3 barriers that sperm must to breach

1. Jelly coat2. Vitelline layer3. Plasma membrane

Recall gametic isolationIf enzymes are not able to break down jelly coat or proteins on sperm do not bind to proteins on vitelline membrane.



iii. The process

(flagellum)

Fig. 27.9

- After sperm nucleus enters (before fusion):

1. PM becomes impenetrable to other sperm (<1sec)2. Vitelline layer hardens and separates from PM

3. Space b/w PM and vitelline layer fills w/ fluid

- Vitelline layer now called fertilization envelope (FE)

How are other sperm prevented from entering?

- FE blocks any other sperm


VII. Embryonic DevelopmentA. Embryonic Development (4 phases)

i. Cleavage (3 hours)

b. embryo doesn’t grow larger, just more cells

d. Then forms blastula - hollow (fluid filled) ball of cells

a. rapid mitosis

Fig. 27.10

- Blastocoel = fluid filled centermorula

c. First results in morula - solid ball of cells

http://www.exploratorium.edu/imaging_station/gallery.php?Asset=Sea%20urchin%20fertilization&Group=&Category=Sea%20Urchins&Section=Introduction




Watch the videos



A. Embryonic Development (4 phases)ii. Gastrulation (15 to 20 hours)

a. more mitosis

Fig. 27.11

VII. Embryonic Development

- Cells sort into three GERM layers if triploblastic (two if diploblastic) that differentiate to all cells of adult

b. blastula becomes gastrula (a lot of cell movement = gastrulation)

http://academic.reed.edu/biology/courses/BIO351/movie.html

http://academic.reed.edu/biology/courses/BIO351/movie.html


A. Embryonic Development (4 phases)ii. Gastrulation

- Cells sorted into three GERM layers that differentiate to all cells of adult

b. blastula becomes gastrula (a lot of cell movement)

a. more mitosis

Fig. 27.11

1. ectoderm

2. endoderm

3. mesoderm

- becomes nervous sys. and outer skin

- becomes inner lining of digestive tract, resp. system reproductive system, bladder and urethra (epithelial linings)- becomes liver, pancreas, thyroid, PT, thymus (endocrine)

-becomes skeletal, muscular, circulatory, excretory, reproductive systems, adrenal cortex, notochord (becomes vertebrae in vertebrates).


Chapter 18: The Evolution of Animal DiversityAIM: What major types of animals have evolved?

Animals can be characterized by body plans4. Protostome vs Deuterostome Development


A. Embryonic Development (4 phases)iii. Neuralation – development of the neural tube from the ectoderm

Fig. 27.12


Neural tube will develop into brain and spinal cord, while notochord will become vertebrae


A. Embryonic Development (4 phases)iv. Organ formation (organogenesis) begins after gastrulation

Fig. 27.12




Fig. 27.15

A. Embryonic Development (4 phases)iv. Organ formation (organogenesis) begins after gastrulation


B. Embryonic Development in humans (internal development)i. Conception (fertilization) to birth - 38 week (~9 month) gestation period

Fig. 27.12


- 1 month in mice- 22 months in elephants

ii. Gestation = pregnancy


i. Conception (fertilization) to birth - 38 weeks

Fig. 27.12

- 1 month in mice- 22 months in elephants

ii. Gestation = pregnancy

B. Embryonic Development in humans (internal)VII. Embryonic Development


iii. The placenta

Fig. 27.12

a. contains tissue of both mother and fetus

e. There is NO contact b/w maternal and fetal blood

B. Embryonic Development in humans (internal development)VII. Embryonic Development

b. Nourishes and feeds fetusc. Gas exchange

d. Waste disposal


iv. The four extraembryonic (outside the embryo) membranes

Fig. 27.12

a. chorion

- secretes HCG- the embryo’s half of the placenta

- Chorionic villi

- contain embryonic blood vessels

- outgrowth of chorion

- site of nutrient, O2, waste, water, antibody exchange

- bath in maternal blood of endometrium


- alcohol, drugs, chemical from tobacco smoke, etc… can cross to fetus


b. amnion

- amniotic cavity filled with protective amniotic fluid

- membrane that encloses embryo

c. Yolk sac- early site for the formation of blood (nourishment in reptiles and birds = egg yolk)

d. allantois- small, part of umbilical cord/urinary bladder


Fig. 27.12

iv. The extraembryonic membranes (four)


iv. Umbilical cord- attaches fetus to placenta- artery and vein


Fig. 27.12

Be able to label…


i. Development outside females bodyb. Terrestrial animals

- Reptiles, birds, arthropods- A few mammals:

D. External developmentVII. Embryonic Development

Duck-billed platypus and echidnas (monotremes)

Echidnas

1. Egg laying

- fewer eggs produced than aquatic (more likely to survive - parental care)




- Egg laying

What are the requirements of the growing embryo within the egg?

1. Nutrients for biosynthesis and cell respiration (ATP).

2. Gas exchange (cell respiration)3. Waste storage

- Extraembryonic membranes provide a favorable environment for embryo

Be able to label…




- Extraembryonic membranes provide a favorable environment for embryo- Egg laying (amniotic egg)

1. Amnion (similar to placental mammals)

2. Yolk sac- surrounds yolk (food supply), blood vessels transport food to embryo from yolk

3. allantois- respiratory membrane- site of nitrogenous waste (uric acid) storage

4. chorion- outer membrane separating inner ones from environment, gas exchange




- Shell- Egg laying

eggshell

1. Provides protection2. Hard shells in birds

- 95% Calcium carbonate3. Many reptiles and all mammals generally lay soft shell eggs

Soft shell eggs (grass snake)

Chapter 26: Regulation Part I - The Endocrine System

Documents

Transcript of Chapter 26: Regulation Part I - The Endocrine System