Biology 103 - Main points/Questions Remember Plant Hormones? What are the major human endocrine glands? What hormones do you need to know? 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 plants need to balance root and shoot growth – use AUXIN & CYTOKININ amounts (high) (low) Figure: 26-3 Title: The role of auxin and cytokinin in lateral bud sprouting Caption: A simplified diagram of the interplay of auxin (blue dots) and cytokinin (red dots) in the control of sprouting of lateral buds. Auxin is produced by shoot tips and moves downward; cytokinin is produced by root tips and moves upward. Question What result would you expect if a plant's shoot tip were removed and auxin were applied to the cut surface? (high) gradient of cytokinin

positive phototropism – controlled by …? AUXIN! Light!

In fall plants need to respond to changing environmental cues to trigger leaf senescence (death).

Figure 24.14 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) chemical molecules can spread to all tissues via the blood chemical signals can persist much longer than electrical ones 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.

Negative feedback loops fight dehydration.. Page. 626

Your body also releases a hormone ADH that signals to the kidneys. 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? Page. 626

The 5 steps of urine formation Pressure Filtration Reabsorption of water Selective reabsorption Secretion 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 issuing the command – release of the hormone from a gland

Issuing the command

Hormone signaling is a series of simple steps issuing the command transporting the signal most are transported through body by the blood

Transport

Hormone signaling is a series of simple steps issuing the command transporting the signal hitting the target hormone binds to a receptor on the target cell

“hit the target”

Hormone signaling is a series of simple steps issuing the command transporting the signal hitting the target 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!

Peptide based Steroid Bind to receptor on membrane Transported attached to a protein Bind to receptor inside the cell Water- soluble hormone Fat-soluble hormone Transport protein Signal receptor TARGET CELL Signal receptor Figure 45.5 Receptor location varies with hormone type (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 Water- soluble hormone Fat-soluble hormone Transport protein Signal receptor TARGET CELL OR Signal receptor Figure 45.5 Receptor location varies with hormone type Cytoplasmic response Gene regulation Cytoplasmic response Gene regulation (a) NUCLEUS (b)

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

Pituitary hormones

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

Degenerating corpus luteum Control by hypothalamus Inhibited by combination of estrogen and progesterone Hypothalamus – Stimulated by high levels of estrogen Estrogen production feeds back on the signal that drives estrogen release GnRH + Anterior pituitary Inhibited by low levels of estrogen – FSH LH (b) Pituitary hormones in blood LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation Figure 46.14 The reproductive cycle of the human female (c) Ovarian cycle Growing follicle Corpus luteum Degenerating corpus luteum Maturing follicle Follicular phase Ovulation Luteal phase Days | | | | | | | | 5 10 14 15 20 25 28

growth hormone (GH) Thyroid stimulating hormone (TSH) 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

What if you don’t have enough iodine? Thyroxine Modifies metabolic rate Requires iodine What if you don’t have enough iodine?

Fig. 35.11.b

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

Body cells take up more glucose. Insulin Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. STIMULUS: Blood glucose level rises. Blood glucose level declines. Homeostasis: Blood glucose level (about 90 mg/100 mL) STIMULUS: Blood glucose level falls. Blood glucose level rises. Figure 45.12 Maintenance of glucose homeostasis by insulin and glucagon Alpha cells of pancreas release glucagon. Liver breaks down glycogen and releases glucose. Glucagon

Control of Blood Calcium Two antagonistic hormones regulate calcium (Ca2+) 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 Ca2+ It releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food Calcitonin decreases level of blood Ca2+ It stimulates Ca2+ deposition in bones and secretion by kidneys

Draw the two negative feedback loops that involve these two hormones Increasing Blood Calcium level Blood Calcium level (about 10mg/100ml) Decreasing Blood Calcium level

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++

Falling blood Ca2+ level Blood Ca2+ level (about 10 mg/100 mL) PTH Parathyroid gland (behind thyroid) Figure 45.20 The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals STIMULUS: Falling blood Ca2+ level Homeostasis: Blood Ca2+ level (about 10 mg/100 mL)

Falling blood Ca2+ level Blood Ca2+ level (about 10 mg/100 mL) Fig. 45-20-2 Active vitamin D Stimulates Ca2+ uptake in kidneys Increases Ca2+ uptake in intestines PTH Parathyroid gland (behind thyroid) Stimulates Ca2+ release from bones Figure 45.20 The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals STIMULUS: Falling blood Ca2+ level Blood Ca2+ level rises. Homeostasis: Blood Ca2+ level (about 10 mg/100 mL)

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.

For the Discovery Video Endocrine System, go to Animation and Video Files.

Figure 45.1 What role do hormones play in transforming a caterpillar into a butterfly? For the Discovery Video Endocrine System, go to Animation and Video Files.

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

Brain Neurosecretory cells Corpus cardiacum PTTH Corpus allatum Prothoracic gland Ecdysone Juvenile hormone (JH) Figure 45.13 Hormonal regulation of insect development EARLY LARVA

Brain Neurosecretory cells Corpus cardiacum PTTH Corpus allatum Prothoracic gland Ecdysone Juvenile hormone (JH) Figure 45.13 Hormonal regulation of insect development EARLY LARVA LATER LARVA

Brain Neurosecretory cells Corpus cardiacum PTTH Corpus allatum Low JH Prothoracic gland Ecdysone Juvenile hormone (JH) Figure 45.13 Hormonal regulation of insect development EARLY LARVA LATER LARVA PUPA ADULT

The hormonal control of metamorphosis