BIO211 - Connect 1

Most processes in the body are controlled by __________ feedback. If a homeostatic system is controlled by this, the resulting action will always be in the ___________ direction of the stimulus. In this way the variable is maintained with a normal level, or_________. The variable ____________ constant over time and this ________ occurs around the set point. If the stimulus increases, the homeostatic system is activated to cause a ___________ in the stimulus. In contrast, if the stimulus decreases, the homeostatic system causes a(n) _________ in the stimulus until it returns to normal.

-negative, opposite, set point, does not remain, fluctuation, decrease, increase

Homeostatic systems may be controlled by positive feedback. The stimulus here is ____________ to continue in ________ direction until a climactic event occurs. Following this event the body returns to ___________. Because their end result is to ______________ the activity, positive feedback mechanisms occur much ___________ frequently in the body than negative feedback mechanisms.

-reinforce, the same, homeostasis, increase, less

Label the components of a homeostatic control mechanism

1. Stimulus - changes in a variable that is regulated (ex: temperature, stretch in muscle) 2. Receptor - Structure that detects that stimulus (ex: sensory neurons in the skin, stretch receptors in muscle) 3.Receptor sends input information to the control center (if receptor and control center are separate structures) 4. Control center - integrates input and initiates change through the effector (usually brain or endocrine gland) 5. Control center sends output information to an effector 6. Effector - structure (ex: muscle or gland) that brings about a change to the stimulus

Select the variables that you would predict to be regulated by the body using a homeostatic mechanism.

Amount of energy you have Amount of oxygen in the body Amount of pressure to move gases Amount of pressure which moves fluids in the body Amount of heat in the body Amount of water in the body

When blood pressure is elevated, the body employs negative feedback loops to maintain homeostasis. What happens next as a response by the body?

Heart rate is decreased, which will decrease blood pressure

During childbirth, the baby pushes on the wall of the uterus. This is detected by pressure receptors that signal the brain to release oxytocin. If this is a positive feedback process, select the likely next step

Oxytocin causes the uterus to contract, further stimulating the receptors, and releasing ore oxytocin from the brain

If you study that the wall of the small intestine is composed of smooth muscle, you are practicing the study of

anatomy

Characterized by both differentiation and growth, ______________ explains increased size and functional complexity.

development

When there is a change in the internal body environment, how will the body react if it wants to maintain homeostasis by negative feedback?

oppose the change

Which of the following is TRUE of positive feedback?

the change is amplified

True or False: Some homeostatic imbalances cause a variable that is normally controlled by negative feedback to be abnormally controlled by positive feedback.

true

True or False: When a variable is regulated by negative feedback, its value fluctuates above and below the set point rather than being a constant.

true

Homeostasis is BEST described as

The maintenance of a stable internal environment despite a changing external environment

Species of life will all demonstrate _____________ over time as a result of gene mutations and rate of success with the environment.

evolution

Living things must be able to maintain a relative _______________ or set of stable internal conditions.

homeostasis

The ability to bring in nutrients, produce energy, build necessary components, and eliminate waste products is ________________.

metabolism

Which of the following are characteristics of all living things?

metabolism, reproduction, responsiveness, regulation

When blood sugar levels increase after a meal, insulin is released. This lowers sugar levels back toward normal. This is an example of

negative feedback

Which level of organization in the human body involves two or more tissue types working together to perform specific, complex functions?

organ level

All living things exhibit _____________ or complexity far greater than their inanimate surroundings.

organization

When a blood vessel is damaged, platelets attach and recruit more platelets to the area. These new platelets recruit even more, quickly increasing the number of platelets until the damage is sealed with a blood clot. This amplification is an example of

positive feedback

The body maintains homeostasis by utilizing homeostatic control systems composed of three parts. The first part, the __________, is the body structure that detects changes in a variable that is either the substance or process that is regulated. These usually consist of ______________. The change in the variable is the _______________. The second component is the ________________. It is the structure that interprets input from the receptor and initiates changes through the ____________ (the final component). This final component is the structure that brings about the change to alter the _____________.

receptor, sensory nerves, stimulus, control center, effector, stimulus

The ability to make additional copies of themselves describes the necessary life characteristic of _________________.

reproduction

All living things must also be able to interact with their respective environments and are thus said to display ______________.

responsiveness

Thermoreceptors detect body temperature and send impulses to the brain for analysis. If body temperature is low, the brain will signal skeletal muscles to perform brief, repeated contractions to help generate heat. In this example, what is the effector?

skeletal muscles

A baby suckling at the breast is one example of positive feedback in the body. When a mother breastfeeds her baby, the suckling is the initial _______________ detected by sensory _____________ in the skin of the nipple region. These transmit this input to the______________, which is the hypothalamus. The hypothalamus signals for the release of the hormone oxytocin. This homone is the "output" that is sent to the ___________, the glandular tissue of the breast. The baby feeds and this cycle ____________________.

stimulus, receptors, control center, effector, repeats as long as needed