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Stern - Homeostasis Lecture notes 2024 - gen bio 116, Lecture notes of Biology

hand typed lecture notes for sterns lectures, and it is associated with unit 2 for the exam

Typology: Lecture notes

2023/2024

Uploaded on 03/19/2024

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2/20/24 -Homeostasis
I. Intro. to Homeostasis
- CC Feedback mechanisms
II. Examples of Homeostasis
- CC, HD osmoregulation
mechanisms
III. Homeostasis in Animals
- CC SEQ homeostasis processes
- SEQ, HD glucose homeostasis
I. Intro. to Homeostasis
Remainder of semester - organ systems - focus on humans —> 3 points for each
- Anatomy (bio. form), physiology (bio function), and evolutionary history (how )
A. What is Homeostasis?
Homeo = similar, stasis standing
- The steady state of physiological conditions in the
body
B. Homeostasis is a basic characteristic of living
things
All living things regulate internal conditions in some way
C. Basic Mechanisms
Generally uses feedback regulation :
Stimulus response increase or reduce the stimulus
- which in turn can increase or decrease the response
2 types - Negative and Positive -> negative feedback much more common
Negative feedback - response to stimulus reduces stimulus
A to B B reduces intensity of A change, gets undone, stimulus and
response goes away
(1) Ex: regulate body temp, too cold body heats up etc.; balance (2)
Most biological processes (3) Returns level to a set point (4) Response reduces the stimulus
Positive feedback - response to stimulus amplifies stimulus relatively uncommon
A to B B strengthens intensity of A, increases the response in turn
(1) Ex: childbirth contractions signal uterus to release hormones (2) Stimulus brings a change in
state(3) Suckling milk production (4) Keeps building for response
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2/20/24 -Homeostasis I. Intro. to Homeostasis

  • CC Feedback mechanisms II. Examples of Homeostasis - CC, HD osmoregulation mechanisms III. Homeostasis in Animals - CC SEQ homeostasis processes - SEQ, HD glucose homeostasis I. Intro. to Homeostasis Remainder of semester - organ systems - focus on humans —> 3 points for each
  • Anatomy (bio. form), physiology (bio function), and evolutionary history (how ) A. What is Homeostasis? Homeo = similar, stasis → standing
  • The steady state of physiological conditions in the body B. Homeostasis is a basic characteristic of living things All living things regulate internal conditions in some way C. Basic Mechanisms Generally uses feedback regulation : Stimulus → response → increase or reduce the stimulus
  • which in turn can increase or decrease the response 2 types - Negative and Positive -> negative feedback much more common Negative feedback - response to stimulus reduces stimulus A to B B reduces intensity of A → change, gets undone, stimulus and response goes away (1) Ex: regulate body temp, too cold → body heats up etc.; balance (2) Most biological processes (3) Returns level to a set point (4) Response reduces the stimulus Positive feedback - response to stimulus amplifies stimulus → relatively uncommon A to B B strengthens intensity of A, → increases the response in turn (1) Ex: childbirth → contractions signal uterus to release hormones (2) Stimulus brings a change in state(3) Suckling → milk production (4) Keeps building for response

II. Examples of Homeostasis All organisms must:

  • Regulate internal environment
  • Exchange with outside environment Mechanisms depend on environment and type of organism → 3 examples of Osmoregulation A. Paramecium Unicellular protist (SAR clade) → generally aquatic (freshwater) → solute in cell (ions and stuff inside) is more inside then outside the cell (hypotonic environment)
  • Water moves inward via osmosis Has a contractile vacuole - organelle for osmoregulation
  • Pump out water to maintain water balance to prevent lysis
  • Osmotic balance- regulates solutes and water B. Jellyfish Phylum Cnidaria - Diploblastic development → 2 adult tissue layers
  • No dedicated circulatory system → all water movement is via diffusion
  • “Flat morphology” → isotonic C. Humans Terrestrial animals → first evolved from oceans - Opisthokonta → Metazoa → phylum Chordata Take our marine environment with us on the inside
  • have to keep it and maintain conditions → gasses, PH, etc. Terrestrial Adaptations
  • Amniotic sac
  • Water balance
  • scales/skin
  • Excretory system Summary - all living things have it, mechanism depend on environment and morphology, Smaller, aquatic, often have osmosis and diffusion, larger and terrestrial - dedicated transport tissues to prevent desiccation, maintain ph, and solutes

III. Homeostasis in Animals

C. Maintenance of Homeostasis 2 strategies Regulator - Uses internal mechanisms to control internal conditions, independent of external conditions Conformer - allows internal environment to vary with external changes

  • Many animals will regulate some conditions and conform to others
  • The terms are specific for each type of organ system (osmoregulation + thermoconformer) For Regulators → variables maintained at/near specific value ( set point )
  • Or normal range - variable has upper and lower limits
  • Keep at set point or within range via negative feedback Coordination and control All tissues organs, organ systems must work together- 2 major systems coordinate response to stimuli
  • Endocrine - signaling by hormones - Nervous - signaling by nerve impulse Endocrine regulation - involves hormones and feedback regulation (mostly negative)
  • Hormones - long distance chemical signals Release by specific cells, travel through body, and cause a physiological response Example - Blood glucose regulation
  • Same basic mechanism as temperature we saw earlier Two hormones
  • Insulin → store sugar
  • Glucagon → release sugar Antagonistic - opposite effects (with each other) Also involved → Pancreas → makes hormones and Liver - which stores glycogen Practice Question _________________________________________________________ Which of the following are examples of negative feedback regulation? a. Shivering to warm up b. A fever induced by an infection c. Insulin to released after a meal d. Conforming to ocean salinity