Presentation on theme: "Biology 103 - Main points/Questions 1.Remember Plant Hormones? 2.What are the major human endocrine glands? 3.What hormones do you need to know? 4.How."— Presentation transcript:
Biology Main points/Questions 1.Remember Plant Hormones? 2.What are the major human endocrine glands? 3.What hormones do you need to know? 4.How are hormones controlled?
In Summer plants need to balance root and shoot growth - too much of either is a waste of resources. Do you remember how they do this?
shoot tip gradient of auxin (high) (low) (high) gradient of cytokinin plants need to balance root and shoot growth – use AUXIN & CYTOKININ amounts
positive phototropism – controlled by …? Light! AUXIN!
In fall plants need to respond to changing environmental cues to trigger leaf senescence (death).
Figure The effects of ethylene
Hormone Signals in Animals Used for longer term signals than neurons Different cells respond to different hormones Hormones often key for homeostasis
33.02 The Timescale over Which Chemical Messengers Work CD33020.GIF
There are three big advantages to using chemical hormones as messengers rather than speedy electrical signals (nervous) 1.chemical molecules can spread to all tissues via the blood 2.chemical signals can persist much longer than electrical ones 3.many different kinds of chemicals can act as hormones
Balancing water concentration The concentration of the urine is regulated to maintain homeostasis Hormones are key signaling molecules in this process.
Page. 626 As you dehydrate you get thirsty (this is controlled by the nervous system) Your body also releases a hormone ADH that signals to the kidneys. Where does water get reabsorbed in the kidney?
The 5 steps of urine formation 1.Pressure Filtration 2.Reabsorption of water 3.Selective reabsorption 4.Secretion 5.More water reabsorption
Further reabsorption of water Final step that balances water amounts Water can be variably reabsorbed into blood from collecting duct waters ability to be reabsorbed is controlled by a hormone called ADH – how?
Hormone signaling is a series of simple steps 1.issuing the command – release of the hormone from a gland
Issuing the command
Hormone signaling is a series of simple steps 1.issuing the command 2.transporting the signal –most are transported through body by the blood
Hormone signaling is a series of simple steps 1.issuing the command 2.transporting the signal 3.hitting the target –hormone binds to a receptor on the target cell
“hit the target”
Hormone signaling is a series of simple steps 1.issuing the command 2.transporting the signal 3.hitting the target 4.having an effect –After binding the receptor protein changes shape and triggers a change in cell activity
Two basic categories of hormones ADH is a peptide hormone (remember a peptide bond? –Built of amino acids The other class of hormones are steroid based –Steroids are lipids so can pass through membranes!
NUCLEUS Signal receptor (a)(b) TARGET CELL Signal receptor Transport protein Water- soluble hormone Fat-soluble hormone Peptide based –Bind to receptor on membrane Steroid –Transported attached to a protein –Bind to receptor inside the cell
Signal receptor TARGET CELL Signal receptor Transport protein Water- soluble hormone Fat-soluble hormone Gene regulation Cytoplasmic response Gene regulation Cytoplasmic response OR (a) NUCLEUS (b) Peptide based –Signals are often more transient (just in the cytoplasm) –May alter gene expression Steroid –Mostly alter gene expression –Tend to be long lasting effects
Hormones are produced in glands throughout your body
Coordination of Endocrine and Nervous Systems in Vertebrates The hypothalamus receives information from the nervous system and initiates responses through the endocrine system Attached to the hypothalamus is the pituitary gland composed of the posterior pituitary and anterior pituitary
The posterior pituitary stores and secretes hormones that are made in the hypothalamus The anterior pituitary makes and releases hormones under regulation of the hypothalamus
The posterior pituitary contains cells that originate in the hypothalamus
The hypothalamus and the posterior pituitary are connected by a tract of neurons hormones are made by cell bodies in the hypothalamus & moved to posterior pituitary –antidiuretic hormone (ADH) regulates the kidney’s retention of water –oxytocin initiates uterine contractions during childbirth and milk release in mothers
The anterior pituitary is a complete gland that produces the hormones that it secretes
The Hypothalamus and the Pituitary The hypothalamus controls production and secretion of the anterior pituitary hormones by means of a family of special hormones neurons in the hypothalamus secrete releasing hormones they travel to the anterior pituitary through a special capillary system,
Portal system of the anterior pituitary gland and hypothalamus
The Anterior Pituitary Secretes seven different hormones some you already know about… LH & FSH Some that are new to you… TSH & GH
Follicle-stimulating hormone (FSH) –in females, it triggers the maturation of egg cells and stimulates the release of estrogen –in males, it regulates sperm development Luteinizing hormone (LH) –in females, it triggers ovulation of a mature egg –in males, it stimulates the gonads to produce testosterone
Control by hypothalamus Inhibited by combination of estrogen and progesterone Stimulated by high levels of estrogen Inhibited by low levels of estrogen Hypothalamus GnRH Anterior pituitary FSH LH Pituitary hormones in blood LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation Ovarian cycle Growing follicle Maturing follicle Corpus luteum Degenerating corpus luteum Follicular phase Ovulation Luteal phase (a) (b) (c) Days | | ||| | || – – + Estrogen production feeds back on the signal that drives estrogen release
growth hormone (GH) –simulates the growth of muscle and bone throughout the body Thyroid stimulating hormone (TSH) –Stimulates thyroid to produce thyroxin – a key control of metabolism
Negative feedback (feedback inhibition) controls how target gland hormones in the anterior pituitary are produced when enough of the target hormone has been produced, the hormone then feeds back to the hypothalamus and inhibits the release of stimulating hormones from the hypothalamus and the anterior pituitary
Thyroxine –Modifies metabolic rate –Requires iodine What if you don’t have enough iodine?
Hormones are key players in maintaining homeostasis Commonly used as signals in negative feedback loops Remember Insulin & Glucagon?
Insulin and Glucagon: Control of Blood Glucose Insulin and glucagon are antagonistic hormones that help maintain glucose homeostasis The pancreas has clusters of cells that produce glucagon and insulin
Homeostasis: Blood glucose level (about 90 mg/100 mL) Glucagon STIMULUS: Blood glucose level falls. Alpha cells of pancreas release glucagon. Liver breaks down glycogen and releases glucose. Blood glucose level rises. STIMULUS: Blood glucose level rises. Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. Blood glucose level declines. Body cells take up more glucose. Insulin
Control of Blood Calcium Two antagonistic hormones regulate calcium (Ca 2+ ) in the blood of mammals –Parathyroid hormone (PTH) causes blood calcium levels to increase –Calcitonin causes blood calcium levels to decrease.
PTH increases the level of blood Ca 2+ –It releases Ca 2+ from bone and stimulates reabsorption of Ca 2+ in the kidneys –It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca 2+ from food Calcitonin decreases level of blood Ca 2+ –It stimulates Ca 2+ deposition in bones and secretion by kidneys
Blood Calcium level (about 10mg/100ml) Increasing Blood Calcium level Decreasing Blood Calcium level Draw the two negative feedback loops that involve these two hormones
Calcium Regulation What happens when calcium levels drop? Parathyroid hormone (PTH) is secreted & causes bone cells to release calcium from the bones PTH also stimulates calcium reabsorption by the kidneys and absorption by the gut So dropping Ca ++ leads to raising Ca ++
Fig PTH Parathyroid gland (behind thyroid) STIMULUS: Falling blood Ca 2+ level Homeostasis: Blood Ca 2+ level (about 10 mg/100 mL) Blood Ca 2+ level rises. Stimulates Ca 2+ uptake in kidneys Stimulates Ca 2+ release from bones Increases Ca 2+ uptake in intestines Active vitamin D
Calcium Regulation What happens when calcium levels rise? Calcitonin is secreted & causes bone cells to sequester calcium in the bones Calcitonin also slows calcium reabsorption by the kidneys So raising Ca ++ leads to falling Ca ++
Hormonal control of calcium homeostasis in mammals
What do you need to know? Control Systems - Hormones: List major plant hormones and their roles. Explain how the two basic classes of animal hormones have their effects on a cell. Describe antagonistic hormones and explain how they work together to maintain homeostasis. List some major human hormones (certainly you should know ADH, insulin, glucagon, calcitonin & PTH and you should be familiar with FSH, LH, estrogen, and progesterone), where they are produced and their roles.
Non-mammal Hormones In insects, hormonal secretion influence both metamorphosis and molting prior to molting, neurosecretory cells on the surface of the brain secrete brain hormone brain hormone then stimulates a gland in the thorax to produce molting hormone (ecdysone) juvenile hormone is produced in the brain and determines the result of a particular molt –when juvenile hormone levels are high, the molt produces another larva
Juvenile hormone promotes retention of larval characteristics Ecdysone promotes molting (in the presence of juvenile hormone) and development (in the absence of juvenile hormone) of adult characteristics
Ecdysone Prothoracic gland Brain PTTH EARLY LARVA Neurosecretory cells Corpus cardiacum Corpus allatum Juvenile hormone (JH)
Ecdysone Brain PTTH Juvenile hormone (JH) EARLY LARVA Neurosecretory cells Corpus cardiacum Corpus allatum LATER LARVA Prothoracic gland
Ecdysone Brain PTTH EARLY LARVA Neurosecretory cells Corpus cardiacum Corpus allatum LATER LARVA PUPAADULT Low JH Juvenile hormone (JH) Prothoracic gland