Hormones and the Endocrine System - PowerPoint PPT Presentation

1 / 39
About This Presentation
Title:

Hormones and the Endocrine System

Description:

Hormones and the Endocrine System Chapter 45 Hormones The Body s Long-Distance Regulators Chemical signals secreted into the circulatory system that communicate ... – PowerPoint PPT presentation

Number of Views:577
Avg rating:3.0/5.0
Slides: 40
Provided by: Ahma87
Category:

less

Transcript and Presenter's Notes

Title: Hormones and the Endocrine System


1
Hormones and the Endocrine System
  • Chapter 45

2
Hormones
  • The Bodys Long-Distance Regulators
  • Chemical signals secreted into the circulatory
    system that communicate regulatory messages
    within the body
  • Hormones may reach all parts of the body
  • But only certain types of cells, target cells,
    are equipped to respond

3
Endocrine system and the Nervous system
  • The two systems animals have of internal
    communication and regulation
  • The nervous system
  • Conveys high-speed electrical signals along
    specialized cells called neurons
  • The endocrine system
  • made up of endocrine glands
  • Secretes hormones that coordinate slower but
    longer-acting responses to stimuli
  • The two systems often function together in
    maintaining homeostasis, development, and
    reproduction

4
Control Pathways and Feedback Loops
  • There are three types of hormonal control
    pathways
  • Simple endocrine pathway
  • Simple neurohormone pathway
  • Simple neuroendocrine pathway

5
(No Transcript)
6
Hormones and Cell Responses
  • Hormones convey information via the blood stream
    to target cells throughout the body
  • Three major classes of molecules function as
    hormones in vertebrates
  • Proteins and peptides
  • Amines derived from amino acids
  • Steroids
  • Signaling by any of these molecules involves
    three key events
  • Reception
  • Signal transduction
  • Response

7
Cell-Surface Receptors
  • The receptors for most water-soluble hormones
  • Are embedded in the plasma membrane, projecting
    outward from the cell surface
  • Binding of a hormone to its receptor
  • Initiates a signal transduction pathway leading
    to specific responses in the cytoplasm or a
    change in gene expression

8
Different Effects of the Same Hormone
  • The same hormone may have different effects on
    target cells that have
  • Different receptors for the hormone
  • Different signal transduction pathways
  • Different proteins for carrying out the response

9
Hormone- Epinephrine
10
Intracellular Receptors
  • Lipid-Soluble Hormones
  • Steroids, thyroid hormones, and the hormonal form
    of vitamin D
  • Enter target cells and bind to specific protein
    receptors in the cytoplasm or nucleus
  • The protein-receptor complexes
  • Then act as transcription factors in the nucleus,
    regulating transcription of specific genes

(b) Receptor in cell nucleus
11
Local Regulators? Paracrine Signaling
  • Various types of chemical signals elicit
    responses in nearby target cells
  • Local regulators have various functions and
    include
  • Neurotransmitters
  • Cytokines and growth factors
  • Nitric oxide
  • Prostaglandins

12
The major human endocrine glands
  • Tropic hormonestarget other endocrine glands and
    are important tounderstanding chemical
    coordination.
  • Humans havenine endocrineglands.
  • The hypothalamus and the pituitary gland
  • Control much of the endocrine system

13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
Relation Between the Hypothalamus and Pituitary
Gland
  • The hypothalamus integrates endocrine and nervous
    function.
  • Neurosecretory cells of the hypothalamus produce
    hormones.
  • Releasing hormones stimulate the anterior
    pituitary (adenohypophysis) to secrete hormones.
  • Inhibiting hormones prevent the anterior
    pituitary from secreting hormones.

17
The posterior pituitary (neurohypo-physis)
  • Stores andsecretes hormonesproducedby
    thehypothalamus

18
Hormones manufactured by the hypothalamus and
released by the posterior pituitary
  • Oxytocin a peptide.
  • Stimulates contraction of the uterus and mammary
    glands.
  • Secretion regulated by the nervous system.
  • Antidiuretic hormone (ADH) a peptide.
  • Promotes retention of water by the kidneys.
  • Secretion regulated by water/salt balance.

19
Anterior Pituitary Hormones
20
Anterior Pituitary Hormones
  • Growth hormone (GH) a protein.
  • Stimulates growth and metabolism.
  • Secretion regulated by hypothalamic hormones.
  • Acts directly on tissues or acts via growth
    factors.
  • Gigantism excessive GH during development.
  • Acromegaly excessive GH production during
    adulthood.
  • Hypopituitary dwarfism childhood GH deficiency

21
Anterior Pituitary Hormones(Tropic)
  • Gonadotropins glyocoproteins.
  • Follicle-stimulating hormone (FSH).
  • Stimulates production of sperm and ova.
  • Secretion regulated by hypothalamic hormones.
  • Luteinizing hormone (LH).
  • Stimulates ovaries and testes.
  • Secretion regulated by hypothalamic hormones.

22
Anterior Pituitary Hormones(Tropic)
  • Thyroid-stimulating hormone (TSH) a
    glycoprotein.
  • Stimulates thyroid gland.
  • Secretion regulated by thyroxine in blood.
  • Secretion regulated by hypothalamic hormones.
  • Adrenocorticotropic hormone (ACTH) a peptide
  • Stimulates adrenal cortex secretion of
    glucocorticoids
  • Secretion regulated by glucocorticoids and
    hypothalamic hormone

23
Anterior Pituitary Hormones(Nontropic)
  • Prolactin (PRL) a protein.
  • Stimulates milk production and secretion.
  • Secretion regulated by hypothalamic hormones.
  • Melanocyte-stimulating hormone (MSH) a peptide.
  • May play a role in fat metabolism.
  • Endorphins peptides.
  • Inhibit pain perception.
  • Effects mimicked by heroin and other opiate drugs.

24
Nonpituitary hormones help regulate metabolism,
homeostasis, development, and behavior
  • Regulate various functions in the body

25
The hypothalamus and anterior pituitary
  • Control the secretion of thyroid hormones through
    two negative feedback loops

Figure 45.9
26
Thyroid Hormones
  • The thyroid gland
  • Consists of two lobes located on the ventral
    surface of the trachea
  • Produces two iodine-containing hormones,
    triiodothyronine (T3) and thyroxine (T4) The
    thyroid hormones
  • Play crucial roles in stimulating metabolism and
    influencing development and maturation

27
Hyperthyroidism, excessive secretion of thyroid
hormones
  • Can cause Graves disease in humans

28
Calcitonin?Calcium Homeostasis
29
Insulin and Glucagon
30
Diabetes Mellitus
  • Diabetes mellitus, perhaps the best-known
    endocrine disorder
  • Is caused by a deficiency of insulin or a
    decreased response to insulin in target tissues
  • Is marked by elevated blood glucose levels

31
  • Type I diabetes mellitus (insulin-dependent
    diabetes)
  • Is an autoimmune disorder in which the immune
    system destroys the beta cells of the pancreas
  • Type II diabetes mellitus (non-insulin-dependent
    diabetes)
  • Is characterized either by a deficiency of
    insulin or, more commonly, by reduced
    responsiveness of target cells due to some change
    in insulin receptors

32
Adrenal Hormones Response to Stress
  • The adrenal glands
  • Are adjacent to the kidneys
  • Are actually made up of two glands the adrenal
    medulla and the adrenal cortex

33
Catecholamines from the Adrenal Medulla
  • The adrenal medulla secretes epinephrine and
    norepinephrine
  • Hormones which are members of a class of
    compounds called catecholamine
  • These hormones
  • Are secreted in response to stress-activated
    impulses from the nervous system
  • Mediate various fight-or-flight responses

34
Stress Hormones from the Adrenal Cortex
  • Function in the bodys response to stress
  • Fall into three classes of steroid hormones
  • Glucocorticoids, such as cortisol
  • Influence glucose metabolism and the immune
    system
  • Mineralocorticoids, such as aldosterone
  • Affect salt and water balance
  • Sex hormones
  • Are produced in small amounts

35
  • Stress and the adrenal gland

Stress
Nerve signals
Hypothalamus
Spinal cord (cross section)
Releasing hormone
Nerve cell
Anterior pituitary
Blood vessel
Adrenal medulla secretes epinephrine and
norepinephrine.
Nerve cell
Adrenal cortex secretes mineralocorticoids and
glucocorticoids.
ACTH
Adrenal gland
Kidney
(a) Short-term stress response
(b) Long-term stress response
Effects of epinephrine and norepinephrine
Effects of mineralocorticoids
Effects of glucocorticoids
1. Glycogen broken down to glucose
increasedblood glucose
1. Retention of sodiumions and water bykidneys
1. Proteins and fatsbroken down andconverted to
glucose,leading to increasedblood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
2. Increased bloodvolume and bloodpressure
5. Change in blood flow patterns, leading to
increased alertness and decreased digestive
and kidney activity
2. Immune system may be suppressed
Figure 45.13a,b
36
Gonadal Sex Hormones
  • The gonadstestes and ovaries
  • produce most of the bodys sex hormones
    androgens, estrogens, and progestins
  • The testes primarily synthesize androgens, the
    main one being testosterone
  • Which stimulate the development and maintenance
    of the male reproductive system

37
Testosterone causes an increase in muscle and
bone mass
  • Is often taken as a supplement to cause muscle
    growth, which carries many health risks

38
Estrogen And Progesterone
  • Estradiol ? most important of Estrogens
  • Responsible for the maintenance of the female
    reproductive system and the development of female
    secondary sex characteristics
  • Progestins? progesterone
  • Primarily involved in preparing and maintaining
    the uterus?supports growth and development of the
    embryo

39
Melatonin and Biorhythms
  • The pineal gland is a small mass of tissue near
    the center of the mammalian brain
  • Secretes the hormone, melatonin, an amine.
  • Involved in biological rhythms associated with
    reproduction.
  • Secretion regulated by light/dark cycles
Write a Comment
User Comments (0)
About PowerShow.com