Endocrine system – made up of glands that release chemical messages into the blood (circulatory system).
Hormones – the chemical messages released that affect the activities of other cells ( target cells ) in the body.
Hormones have specific shapes that allow them to bind to receptor molecules.
Receptor Molecules – found on the outside of cell membranes.
Receptor molecules only bind with hormones of the same shape!
Gland – organ that produces and releases a chemical message (hormone).
- Ex: pancreas, testes, ovaries, etc.
Pancreas – an endocrine organ located behind the stomach.
- releases the hormone insulin to lower amount of glucose (sugar) in the blood.
Testes – male reproductive gland that releases the hormone testosterone .
- testosterone stimulates the production of secondary sex characteristics.
Ovaries – female reproductive gland that releases the hormones estrogen and progesterone.
- estrogen stimulates the production of secondary sex characteristics.
- progesterone prepares uterus for a fertilized egg.
Dynamic Equilibrium – the constant, small corrections an organism ’ s body makes in order to maintain homeostasis.
Normal Time Blood sugar level
Control of the Endocrine System
Hormones (and all body systems) are controlled by systems called Feedback Mechanisms :
1. Positive Feedback
Positive feedback – a change ( stimulus ) that creates a positive response and leads to more of that response.
2. Negative Feedback
Negative feedback – a change ( stimulus ) that leads to canceling a response.
Thermostat senses room is cold. Sends signal to turn on heat. Room temperature goes up. Negative feedback tells thermostat to stop turning on heat.
Negative Feedback (Example for Regents) Brain detects high blood sugar level (lots of glucose). Sends signal to pancreas to release the hormone insulin. Sugar (Glucose) level in blood drops. Negative feedback low glucose level in blood means stop insulin production.
Feedback in Plants
Guard cells – two crescent shaped cells that control the opening/closing of pores ( stoma ) in a leaf.
- Opens to let gases in/out (CO 2 /O 2 ).
- Closes to conserve water .
- Gas exchange occurs during the process of photosynthesis.
Feedback in Plants
Male Reproductive System a. Testes b. Vas deferens c. Prostate d. Urethra e. Penis f. Bladder g. Rectum
Male Reproductive System
Testes – male reproductive organ that produce testosterone and sperm.
Vas deferens – tube that carries sperm from testes to the prostate gland.
Prostate – produce fluid for sperm.
Urethra – connected to vas deferens and takes sperm through penis.
Penis – releases sperm from the body.
Female Reproductive System a. Ovary Side Front a. Ovary b. Oviduct b. Oviducts c. Uterus c. Uterus d. Cervix d. Cervix e. Vagina e. Vagina f. Bladder g. Rectum c. Uterus f. Bladder
Female Reproductive System
Ovary – female reproductive organ that produces hormones and eggs.
Oviduct (fallopian tube) – tube that carries egg. Where fertilization occurs.
Uterus – site where embryo implants and develops.
Cervix – Outer end of the uterus.
Vagina – birth canal that leads to outside of body.
Summary of Menstrual Cycle
Fertilization – the process of a sperm joining an egg.
- occurs in the oviduct (fallopian tube) of the female.
Facts about Fertilization:
400-600 million sperm are released, only 1% make it to the oviduct.
When sperm and egg join, the two nuclei combine: 23 + 23 = 46 (humans)
c. Zygote – fertilized egg formed.
Types of Fertilization
External Fertilization – fertilization occurs outside of the organism’s body.
- Ex: Fish, amphibians, etc.
Internal Fertilization – fertilization that occurs inside the organism’s body.
- Ex: reptiles, birds, mammals, etc.
Differentiation – cells of the developing zygote become different from each other, or “specialized”.
- 3 layers of cells form:
Endoderm – inner layer (stomach, lungs)
Mesoderm – middle layer (bone, muscle)
Ectoderm – outer layer (skin, nerves)
Embryo – the zygote develops into an embryo.
Uterus adapts to nurture embryo:
Placenta – organ responsible for diffusion of nutrients, O 2 /CO 2 , and wastes from mom to embryo.
Umbilical cord – connects placenta to embryo.
Amnion – fluid-filled sac that protects embryo.
Embryonic Development Animations
Fertilization and Development Summary 1. Meiosis – produces haploid sperm and egg 2. Fertilization – sperm and egg meet to make a diploid zygote. 3. Differentiation – zygote divides by mitosis into an organism.
Fertilization and Development Summary Meiosis n= 23 Fertilization 2n=46 Differentiation by mitosis 2n=46 New multicellular organism 2n=46
Plants have hormones too!
Animals are not the only organisms that use hormones!
Auxin – a plant hormone produced in the stem that promotes growth of plant.
Makes plant grow = Auxin power!!! YEAH BABY YEAH!!!!!